Polymers

Editorial

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6 pages, 217 KiB

Open AccessEditorial

Special Issue: Synthesis, Processing, Structure and Properties of Polymer Materials

by Andrzej Puszka and Beata Podkościelna

Polymers 2022, 14(21), 4550; https://doi.org/10.3390/polym14214550 - 27 Oct 2022

Cited by 2 | Viewed by 2082

Abstract

Polymeric materials are widely used in many different technical fields [...] Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

Research

Jump to: Editorial, Review

15 pages, 2047 KiB

Open AccessArticle

Effects of Different Concentrations of Arsine on the Synthesis and Final Properties of Polypropylene

by Joaquín Hernández-Fernández, Yoleima Guerra, Esneyder Puello-Polo and Edgar Marquez

Polymers 2022, 14(15), 3123; https://doi.org/10.3390/polym14153123 - 31 Jul 2022

Cited by 23 | Viewed by 2535

Abstract

This article studies the effects of arsine on the synthesis and thermal degradation of 4 samples of virgin polypropylene (PP-virgin) and proposes reaction mechanisms that allow understanding of its behaviour. Different points are monitored during the polypropylene synthesis to perform TGA, DSC, FT-IR, [...] Read more.

This article studies the effects of arsine on the synthesis and thermal degradation of 4 samples of virgin polypropylene (PP-virgin) and proposes reaction mechanisms that allow understanding of its behaviour. Different points are monitored during the polypropylene synthesis to perform TGA, DSC, FT-IR, RDX, and MFI analyses later. The content of AsH₃ in polypropylene varies between 0.05 and 4.73 ppm, and of arsenic in virgin PP residues between 0.001 and 4.32 ppm for PP0 and PP10, increasing in fluidity index from 3.0 to 24.51. The origin of thermo-oxidative degradation is explained by the reaction mechanisms of the Molecule AsH₃ with the active titanium center of the ZN catalyst and the subsequent oxidation to form radical complexes. OO-AsH-TiCl₄-MgCl₂ and (OO-as-OO)₂ -TiCl₄-MgCl₂, which, by radical reactions, give rise to the formation of functional groups aldehyde, ketone, alcohol, carboxylic acid, CO, CO₂, PP-Polyol, PP-Polyether, and PP-Isopropylethers. These species caused the TG and DTG curves to increase degradation peaks in pp samples. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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20 pages, 2979 KiB

Open AccessArticle

Synthesis and Characterization of New Polycarbonate-Based Poly(thiourethane-urethane)s

by Andrzej Puszka and Janusz W. Sikora

Polymers 2022, 14(14), 2933; https://doi.org/10.3390/polym14142933 - 20 Jul 2022

Cited by 11 | Viewed by 3068

Abstract

The new segmented poly(thiourethane-urethane)s (PTURs) based on 1,1′-methanediylbis(4-isocyanatocyclohexane) (HMDI, Desmodur W^®), polycarbonate diol (PCD, Desmophen C2200) and (methanediyldibenzene-4,1-diyl)dimethanethiol were synthesized by one-step melt polyaddition method. The obtained PTURs, with a content of 30–60 wt% of the hard segments (HS), were [...] Read more.

The new segmented poly(thiourethane-urethane)s (PTURs) based on 1,1′-methanediylbis(4-isocyanatocyclohexane) (HMDI, Desmodur W^®), polycarbonate diol (PCD, Desmophen C2200) and (methanediyldibenzene-4,1-diyl)dimethanethiol were synthesized by one-step melt polyaddition method. The obtained PTURs, with a content of 30–60 wt% of the hard segments (HS), were tested in which the influence of changes in the HS content on their properties was determined. The polymers were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), thermal analysis (DSC, TGA) and thermomechanical analysis (DMTA). Additionally, tensile strength, optical (refractive index, UV-VIS and color) and surface properties of the obtained polymers (contact angle and surface free energy) and adhesion to copper were examined. FTIR analysis verified the supposed structure of the polymers obtained and showed a complete conversion of the isocyanate groups. TGA analysis confirmed the relatively good thermal stability of the polymers. On the other hand, after performing the DSC analysis, it was possible to state that the obtained materials were partially or completely amorphous, and the microphase separation decreased with increasing HS content in the polymer. Similar observations were made from the DMTA data. In addition, the hardness, tensile strength, modulus of elasticity, storage modulus, adhesion to copper, refractive index and total free surface energy increased with increasing HS content in the polymer. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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13 pages, 2939 KiB

Open AccessArticle

A Supramolecular Hydrogel Based on Copolymers of Acrylic Acid and Maleic Anhydride Derivatives with Terpyridine Motifs

by Zheng Chi, Chenchen Ma, Ziyuan He, Zihan Ma, Xuegang Chen and Zhaoge Huang

Polymers 2022, 14(14), 2857; https://doi.org/10.3390/polym14142857 - 13 Jul 2022

Cited by 3 | Viewed by 2188

Abstract

A kind of terpyridine derivative (NH₂-Tpy) in which the amino was incorporated by a short alkyl chain was synthesized. Through grafting of terpyridine units into the hydrophilic copolymers of maleic anhydride and acrylic acid PAAMa via the reaction of [...] Read more.

A kind of terpyridine derivative (NH₂-Tpy) in which the amino was incorporated by a short alkyl chain was synthesized. Through grafting of terpyridine units into the hydrophilic copolymers of maleic anhydride and acrylic acid PAAMa via the reaction of the amino groups in NH₂-Tpy and the maleic anhydride units, a series of gelator polymers—P1, P2, and P3—containing different contents of terpyridine units was synthesized. Under coordination of Ni²⁺ and terpyridine ligands in linear polymers, the supramolecular hydrogels H1, H2, and H3 with different cross-linking degrees were prepared. The linear polymers P1–P3 had a strong absorption peak at about 290 nm in the UV-vis spectra which was attributed to π–π* transition, and there was a new peak at about 335 nm led by the metal-to-ligands charge transfer (MLCT) when coordinated with Ni²⁺ ions. According to the rheological behaviors, the storage modulus (G′) was larger than the loss modulus (G′′). These hydrogels showed typical gel-like characteristics when the terpyridine content of the hydrogels exceeded 10%, and the hydrogels showed liquid-like characteristics when the terpyridine content of the hydrogels was less than 7%. The results of the micromorphological investigation of the xerogels from SEM illustrated the metal–terpyridine coordination cross-linking could have an important influence on the microstructures of the resulting hydrogels. Furthermore, these hydrogels based on supramolecular cross-links exhibited reversible solution–gel transition at different environmental temperatures. At the same time, the equilibrium swelling of the supramolecular hydrogels was 8.0–12.3 g/g, which increased with the decrease in the content of the terpyridine units in the resulting hydrogels. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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14 pages, 20809 KiB

Open AccessArticle

Preparation and Characterization of Strongly Sulfonated Acid Block and Random Copolymer Membranes for Acetic Acid Esterification with 2-Propanol

by Verónica Rosiles-González, Ronan Le Lagadec, Paulina Varguez-Catzim, María I. Loria-Bastarrachea, Abigail González-Díaz, Emanuel Hernández-Núñez, Manuel Aguilar-Vega and María Ortencia González-Díaz

Polymers 2022, 14(13), 2595; https://doi.org/10.3390/polym14132595 - 27 Jun 2022

Cited by 3 | Viewed by 2105

Abstract

In this paper, we report the synthesis of block and random copolymers of 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and methyl methacrylate (MMA), with different AMPS feed ratios. These solution-processable copolymers with strongly sulfonated acid groups resulted in membranes with tunable ion exchange (IEC) and [...] Read more.

In this paper, we report the synthesis of block and random copolymers of 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and methyl methacrylate (MMA), with different AMPS feed ratios. These solution-processable copolymers with strongly sulfonated acid groups resulted in membranes with tunable ion exchange (IEC) and water absorption capacities. AFM images confirmed the microphase separation of PAMPS-b-PMMA-1:1 block copolymer membrane, annealed under the appropriate conditions. The resulting copolymers from the random combination of a 1:1 molar ratio of AMPS and MMA monomers are effective at enhancing the esterification conversion of acetic acid, when compared with a reaction catalyzed by PAMPS-b-PMMA block copolymers and the previously studied catalytic membranes. With the PAMPS-co-PMMA-1:1 membrane, the esterification reaction using acetic acid achieved 85% isopropyl acetate. These results are closely correlated with the increase in IEC (2.63 mmol H⁺g⁻¹) and the relationship between weight loss (20.3%) and swelling degree (68%) in 2-propanol. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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16 pages, 4893 KiB

Open AccessArticle

Alkali-Grafting Proton Exchange Membranes Based on Co-Grafting of α-Methylstyrene and Acrylonitrile into PVDF

by Shufeng Li, Xuelin Li, Pengfei Fu and Yao Zhang

Polymers 2022, 14(12), 2424; https://doi.org/10.3390/polym14122424 - 15 Jun 2022

Cited by 3 | Viewed by 1849

Abstract

A novel alkali-induced grafting polymerization was designed to synthesize a PFGPA proton exchange membrane based on the co-grafting of α-methyl styrene (AMS) and acrylonitrile (AN) into the poly(vinylidenedifluoride) (PVDF) membrane. Three kinds of alkali treatments were used: by immersing the PVDF membranes into [...] Read more.

A novel alkali-induced grafting polymerization was designed to synthesize a PFGPA proton exchange membrane based on the co-grafting of α-methyl styrene (AMS) and acrylonitrile (AN) into the poly(vinylidenedifluoride) (PVDF) membrane. Three kinds of alkali treatments were used: by immersing the PVDF membranes into a 1 M NaOH solution and mixing the PVDF powders with 16% or 20% Na₄SiO₄. Then, AMS with AN could be co-grafted into the PVDF backbones in two grafting solvents, THF or IPA/water. Finally, the grafted membranes were sulfonated to provide the PFGPA membranes. In the experiments, the Na₄SiO₄ treatments showed a greater grafting degree than the NaOH treatment. The grafting degree increased with the increasing amount of Na₄SiO₄. The grafting solvent also influenced the grafting degree. A 40–50 percent grafting degree was obtained in either the THF or IPA/water solvent after the Na₄SiO₄ treatment and the THF resulted in a greater grafting degree. FTIR and XPS testified that the PFGPA membranes had been prepared and a partial hydrolysis of the cyano group from AN occurred. The PFGPA membranes with the grafting degree of about 40–50 percent showed a better dimensional stability in methanol, greater water uptake capabilities, and lower ion exchange capacities and conductivities than the Nafion 117 membranes. The PFGPA membrane with the 16% Na₄SiO₄ treatment and THF as the grafting solvent exhibited a better chemical stability. The obtained experimental results will provide a guide for the synthesis of alkali-grafted PFGPA membranes in practical use. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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11 pages, 7096 KiB

Open AccessArticle

Preparation and Properties of Novel Crosslinked Polyphosphazene-Aromatic Ethers Organic–Inorganic Hybrid Microspheres

by Yan Wang, Yunwu Yu, Long Li, Hongbo Zhang, Zheng Chen, Yanchao Yang, Zhenhua Jiang and Jianxin Mu

Polymers 2022, 14(12), 2411; https://doi.org/10.3390/polym14122411 - 14 Jun 2022

Cited by 3 | Viewed by 1855

Abstract

A series of novel crosslinked polyphosphazene-aromatic ether organic–inorganic hybrid microspheres with different structures were prepared via precipitation polycondensation between hexachlorocyclotriphosphazene (HCCP) and bisphenol monomers. The bisphenol monomers have different numbers of –CF₃ in the side group, which correspond to distinct oligomeric species-absorbing [...] Read more.

A series of novel crosslinked polyphosphazene-aromatic ether organic–inorganic hybrid microspheres with different structures were prepared via precipitation polycondensation between hexachlorocyclotriphosphazene (HCCP) and bisphenol monomers. The bisphenol monomers have different numbers of –CF₃ in the side group, which correspond to distinct oligomeric species-absorbing mechanisms. The wetting behavior of the microsphere surface was evaluated using a water contact angle (CA) measurement, which increased with the increase in the content of –CF₃ in polyphosphazene. We also investigated the effects of HCCP concentration and ultrasonic power on the morphology of the microspheres. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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11 pages, 3918 KiB

Open AccessArticle

Surface Modification of γ-Al₂O₃ Nanoparticles Using Conductive Polyaniline Doped by Dodecylbenzene Sulfonic Acid

by Cheng-Ho Chen, Ying-Chen Lin and Hung-Mao Lin

Polymers 2022, 14(11), 2232; https://doi.org/10.3390/polym14112232 - 31 May 2022

Cited by 2 | Viewed by 1622

Abstract

In this study, electrically conductive PANDB/γ-Al₂O₃ core–shell nanocomposites were synthesized by surface modification of γ-Al₂O₃ nanoparticles using polyaniline doped with dodecylbenzene sulfonic acid. The PANDB/γ-Al₂O₃ core–shell nanocomposites were synthesized by in situ polymerization. Pure [...] Read more.

In this study, electrically conductive PANDB/γ-Al₂O₃ core–shell nanocomposites were synthesized by surface modification of γ-Al₂O₃ nanoparticles using polyaniline doped with dodecylbenzene sulfonic acid. The PANDB/γ-Al₂O₃ core–shell nanocomposites were synthesized by in situ polymerization. Pure PANDB and the PANDB/γ-Al₂O₃ core–shell nanocomposites were characterized using Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, and measurement of a four-point probe. The conductivity of the PANDB/γ-Al₂O₃ core–shell nanocomposite was about 0.72 S/cm when the weight ratio of aniline/γ-Al₂O₃ was 3/1. The results showed that the conductivity of the PANDB/γ-Al₂O₃ core–shell nanocomposite decreased with increasing amounts of γ-Al₂O₃ nanoparticles. The transmission electron microscopy results indicated that the γ-Al₂O₃ nanoparticles were thoroughly coated with PANDB to form a core–shell structure. Transmission electron microscopy and field emission scanning electron microscopy images of the conductive PANDB/γ-Al₂O₃ core–shell nanocomposites also showed that the thickness of the PANDB layer decreased as the amount of γ-Al₂O₃ was increased. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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18 pages, 10612 KiB

Open AccessArticle

Functionalization of Polymer Surface with Antimicrobial Microcapsules

by Iva Rezić, Maja Somogyi Škoc, Mislav Majdak, Slaven Jurić, Katarina Sopko Stracenski and Marko Vinceković

Polymers 2022, 14(10), 1961; https://doi.org/10.3390/polym14101961 - 11 May 2022

Cited by 10 | Viewed by 2685

Abstract

The development of antimicrobial polymers is a priority for engineers fighting microbial resistant strains. Silver ions and silver nanoparticles can assist in enhancing the antimicrobial properties of microcapsules that release such substances in time which prolongs the efficiency of antimicrobial effects. Therefore, this [...] Read more.

The development of antimicrobial polymers is a priority for engineers fighting microbial resistant strains. Silver ions and silver nanoparticles can assist in enhancing the antimicrobial properties of microcapsules that release such substances in time which prolongs the efficiency of antimicrobial effects. Therefore, this study aimed to functionalize different polymer surfaces with antimicrobial core/shell microcapsules. Microcapsules were made of sodium alginate in shell and filled with antimicrobial silver in their core prior to application on the surface of polymer materials by dip-coating methodology. Characterization of polymers after functionalization was performed by several spectroscopic and microscopic techniques. After the characterization of polymers before and after the functionalization, the release of the active substances was monitored in time. The obtained test results can help with the calculation on the minimal concentration of antimicrobial silver that is encapsulated to achieve the desired amounts of release over time. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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19 pages, 4740 KiB

Open AccessArticle

Thermoplastic Starch with Poly(butylene adipate-co-terephthalate) Blends Foamed by Supercritical Carbon Dioxide

by Chih-Jen Chang, Manikandan Venkatesan, Chia-Jung Cho, Ping-Yu Chung, Jayashree Chandrasekar, Chen-Hung Lee, Hsin-Ta Wang, Chang-Ming Wong and Chi-Ching Kuo

Polymers 2022, 14(10), 1952; https://doi.org/10.3390/polym14101952 - 11 May 2022

Cited by 13 | Viewed by 3468

Abstract

Starch-based biodegradable foams with a high starch content are developed using industrial starch as the base material and supercritical CO₂ as blowing or foaming agents. The superior cushioning properties of these foams can lead to competitiveness in the market. Despite this, a [...] Read more.

Starch-based biodegradable foams with a high starch content are developed using industrial starch as the base material and supercritical CO₂ as blowing or foaming agents. The superior cushioning properties of these foams can lead to competitiveness in the market. Despite this, a weak melting strength property of starch is not sufficient to hold the foaming agents within it. Due to the rapid diffusion of foaming gas into the environment, it is difficult for starch to maintain pore structure in starch foams. Therefore, producing starch foam by using supercritical CO₂ foaming gas faces severe challenges. To overcome this, we have synthesized thermoplastic starch (TPS) by dispersing starch into water or glycerin. Consecutively, the TPS surface was modified by compatibilizer silane A (SA) to improve the dispersion with poly(butylene adipate-co-terephthalate) (PBAT) to become (TPS with SA)/PBAT composite foam. Furthermore, the foam-forming process was optimized by varying the ratios of TPS and PBAT under different forming temperatures of 85 °C to 105 °C, and two different pressures, 17 Mpa and 23 Mpa were studied in detail. The obtained results indicate that the SA surface modification on TPS can influence the great compatibility with PBAT blended foams (foam density: 0.16 g/cm³); whereas unmodified TPS and PBAT (foam density: 0.349 g/cm³) exhibit high foam density, rigid foam structure, and poor tensile properties. In addition, we have found that the 80% TPS/20% PBAT foam can be achieved with good flexible properties. Because of this flexibility, lightweight and environment-friendly nature, we have the opportunity to resolve the strong demands from the packing market. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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15 pages, 2449 KiB

Open AccessArticle

Estimating the Shear Resistance of Flocculated Kaolin Aggregates: Effect of Flocculation Time, Flocculant Dose, and Water Quality

by Kevin Pérez, Norman Toro, Matías Jeldres, Edelmira Gálvez, Pedro Robles, Omar Alvarado, Pedro G. Toledo and Ricardo I. Jeldres

Polymers 2022, 14(7), 1381; https://doi.org/10.3390/polym14071381 - 29 Mar 2022

Cited by 4 | Viewed by 2394

Abstract

The resistance of kaolin aggregates to shearing in water clarification and recovery operations is a critical input in designing thickener feed wells. A recently formulated but already available criterion is used to determine the shear strength of flocculated kaolin aggregates. The flocculant is [...] Read more.

The resistance of kaolin aggregates to shearing in water clarification and recovery operations is a critical input in designing thickener feed wells. A recently formulated but already available criterion is used to determine the shear strength of flocculated kaolin aggregates. The flocculant is a high molecular weight anionic polyelectrolyte. The resistance of the aggregates is evaluated as a function of flocculation time, flocculant dosage, and water quality. The determination is based on a standardized experimental method. First, the time evolution of the average size of kaolin flocs is measured when aggregates are exposed to incremental shear rates from a predetermined base value. Then, the results are fitted to a pseudo-first-order model that allows deriving a characteristic value of the shear rate of rupture associated with the upper limit of the strength of the aggregates. In seawater, at a given dose of flocculant, the strength of the aggregates increases with time up to a maximum; however, at longer times, the resistance decreases until it settles at a stable value corresponding to stable aggregates in size and structure. A higher flocculant dosage leads to stronger aggregates due to more bridges between particles and polymers, leading to a more intricate and resistant particle network. In industrial water with very low salt content, the resistance of the kaolin aggregates is higher than in seawater for the same dose of flocculant. The salt weakens the resistance of the aggregates and works against the efficiency of the flocculant. The study should be of practical interest to concentration plants that use seawater in their operations. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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19 pages, 14560 KiB

Open AccessArticle

Preparation, Properties and Water Dissolution Behavior of Polyethylene Oxide Mats Prepared by Solution Blow Spinning

by Miguel Ángel Lorente, Gustavo González-Gaitano and Javier González-Benito

Polymers 2022, 14(7), 1299; https://doi.org/10.3390/polym14071299 - 23 Mar 2022

Cited by 19 | Viewed by 3108

Abstract

The relationship between processing conditions, structure and morphology are key issues to understanding the final properties of materials. For instance, in the case of polymers to be used as scaffolds in tissue engineering, wound dressings and membranes, morphology tuning is essential to control [...] Read more.

The relationship between processing conditions, structure and morphology are key issues to understanding the final properties of materials. For instance, in the case of polymers to be used as scaffolds in tissue engineering, wound dressings and membranes, morphology tuning is essential to control mechanical and wettability behaviors. In this work, the relationship between the processing conditions of the solution blow spinning process (SBS) used to prepare nonwoven mats of polyethylene oxide (PEO), and the structure and morphology of the resulting materials are studied systematically, to account for the thermal and mechanical behaviors and dissolution in water. After finding the optimal SBS processing conditions (air pressure, feed rate, working distance and polymer concentration), the effect of the solvent composition has been considered. The structure and morphology of the blow spun fibers are studied as well as their thermal, mechanical behaviors and dissolution in water. We demonstrate that the morphology of the fibers (size and porosity) changes with the solvent composition, which is reflected in different thermal and mechanical responses and in the dissolution rates of the materials in water. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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18 pages, 3634 KiB

Open AccessArticle

Estimation of Tensile Modulus of a Thermoplastic Material from Dynamic Mechanical Analysis: Application to Polyamide 66

by Albert Serra-Aguila, Josep Maria Puigoriol-Forcada, Guillermo Reyes and Joaquin Menacho

Polymers 2022, 14(6), 1210; https://doi.org/10.3390/polym14061210 - 17 Mar 2022

Cited by 8 | Viewed by 3569

Abstract

The mechanical properties of thermoplastic materials depend on temperature and strain rate. This study examined the development of a procedure to predict tensile moduli at different strain rates and temperatures, using experimental data from three-point-bending dynamic mechanical analysis (DMA). The method integrated different [...] Read more.

The mechanical properties of thermoplastic materials depend on temperature and strain rate. This study examined the development of a procedure to predict tensile moduli at different strain rates and temperatures, using experimental data from three-point-bending dynamic mechanical analysis (DMA). The method integrated different classical concepts of rheology to establish a closed formulation that will allow researchers save an important amount of time. Furthermore, it implied a significant decrease in the number of tests when compared to the commonly used procedure with a universal testing machine (UTM). The method was validated by means of a prediction of tensile moduli of polyamide PA66 in the linear elastic range, over a temperature range that included the glass-transition temperature. The method was applicable to thermo-rheologically simple materials under the hypotheses of isotropy, homogeneity, small deformations, and linear viscoelasticity. This method could be applicable to other thermoplastic materials, although it must be tested using these other materials to determine to what extent it can be applied reliably. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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11 pages, 4233 KiB

Open AccessArticle

Study on Fire Behavior, Thermal Stability and Degradation Kinetics of Thiol-Ene with Poly(aminopropyl/phenyl)silsesquioxane

by Jiangbo Wang

Polymers 2022, 14(6), 1142; https://doi.org/10.3390/polym14061142 - 12 Mar 2022

Cited by 3 | Viewed by 2221

Abstract

In this article, the flame retardant poly(aminopropyl/phenyl)silsesquioxane (PA) was incorporated into thiol-ene (TE), to obtain a flame-retardant thiol-ene (FRTE) composite. The cone calorimeter (CONE) measurement results showed that, compared with neat TE, the peak of heat release rate (PHRR) and total heat release [...] Read more.

In this article, the flame retardant poly(aminopropyl/phenyl)silsesquioxane (PA) was incorporated into thiol-ene (TE), to obtain a flame-retardant thiol-ene (FRTE) composite. The cone calorimeter (CONE) measurement results showed that, compared with neat TE, the peak of heat release rate (PHRR) and total heat release (THR) of FRTE have decreased by almost 23.7% and 14.5%, respectively. Thermogravimetric analysis (TGA) results further confirmed that the flame retardant PA could induce the initial thermal degradation of TE, and increased the amounts of residual char. Moreover, the activation energies of FRTE were calculated through the Kissinger and Flynn–Wall–Ozawa methods. Compared with the neat TE, the activation energies of FRTE were raised by the addition of PA. It indicated that the flame retardant PA promoted cross-linking reactions of TE, to form a compact char layer and retarded further the thermal degradation of the polymer matrix. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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16 pages, 4884 KiB

Open AccessArticle

Enhancement of the Properties of Hybridizing Epoxy and Nanoclay for Mechanical, Industrial, and Biomedical Applications

by Zainab Fakhri Merzah, Sokina Fakhry, Tyser Gaaz Allami, Nor Yuliana Yuhana and Ahmed Alamiery

Polymers 2022, 14(3), 526; https://doi.org/10.3390/polym14030526 - 28 Jan 2022

Cited by 21 | Viewed by 3107

Abstract

The strong demand for plastic and polymeric materials continues to grow year after year, making these industries critical to address sustainability. By functioning as a filler in either a synthetic or natural starch matrix, nanoclay enables significant reductions in the impact of nonbiodegradable [...] Read more.

The strong demand for plastic and polymeric materials continues to grow year after year, making these industries critical to address sustainability. By functioning as a filler in either a synthetic or natural starch matrix, nanoclay enables significant reductions in the impact of nonbiodegradable materials. The effect of treated nanoclay (NC) loading on the mechanical and morphological properties (EP) of epoxy is investigated in this research. The NC-EP nanocomposites were prepared via casting. The investigation begins with adding NC at concentrations of 1, 2, and 3 weight percent, followed by the effect of acid treatment on the same nanocomposites. The evaluation is focused on four mechanical tensile strength parameters: Young’s modulus, maximum load, and % elongation. The addition of NC improved the mechanical properties of the four components by 27.2%, 33.38%, 46.98%, and 43.58%, respectively. The acid treatment improved 35.9%, 42.8%, 51.1%, and 83.5%, respectively. These improvements were attributed to NC’s ability to alter the structural morphology as assessed by field emission scanning electron microscopy (FESEM), a tool for analysing the microstructure. FESEM images were used to visualise the interaction between the NC and EP nanocomposites. The dynamic mechanical properties of the hybrid nanocomposites were investigated using storage modulus, loss modulus, and tan(delta). The results have shown that the viscoelastic properties improved as the fraction of NC increased. The overall findings suggest that these nanocomposites could be used in various industrial and biomedical applications. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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20 pages, 6261 KiB

Open AccessArticle

Nanocomposites of PCL and SBA-15 Particles Prepared by Extrusion: Structural Characteristics, Confinement of PCL Chains within SBA-15 Nanometric Channels and Mechanical Behavior

by Tamara M. Díez-Rodríguez, Enrique Blázquez-Blázquez, Nadine L. C. Antunes, M. Rosário Ribeiro, Ernesto Pérez and María L. Cerrada

Polymers 2022, 14(1), 129; https://doi.org/10.3390/polym14010129 - 30 Dec 2021

Cited by 6 | Viewed by 1917

Abstract

A study of different nanocomposites based on poly(ε-caprolactone) (PCL) and mesoporous SBA-15 silica that were prepared by melt extrusion was carried out by analyzing the possible effect of this filler on the crystalline details of PCL, on its mechanical behavior, and on the [...] Read more.

A study of different nanocomposites based on poly(ε-caprolactone) (PCL) and mesoporous SBA-15 silica that were prepared by melt extrusion was carried out by analyzing the possible effect of this filler on the crystalline details of PCL, on its mechanical behavior, and on the eventual observation of the confinement of the polymeric chains within the hollow nanometric silica channels. Thus, simultaneous Small-Angle and Wide-Angle X-ray Scattering (SAXS/WAXS) synchrotron experiments at variable temperature were performed on these PCL nanocomposites with different mesoporous silica contents. The importance of the morphological and structural features was assessed by the changes that were observed during the mechanical response of the final materials, which determined that the presence of mesoporous particles leads to a noticeable reinforcing effect. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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9 pages, 6273 KiB

Open AccessArticle

Polymer-Templated Durable and Hydrophobic Nanostructures for Hydrogen Gas Sensing Applications

by Mohammad Kamal Hossain and Qasem Ahmed Drmosh

Polymers 2021, 13(24), 4470; https://doi.org/10.3390/polym13244470 - 20 Dec 2021

Cited by 2 | Viewed by 2716

Abstract

A simple and hands-on one-step process has been implemented to fabricate polymer-templated hydrophobic nanostructures as hydrogen gas sensing platforms. Topographic measurements have confirmed irregular hills and dips of various dimensions that are responsible for creating air bubble pockets that satisfy the Cassie–Baxter state [...] Read more.

A simple and hands-on one-step process has been implemented to fabricate polymer-templated hydrophobic nanostructures as hydrogen gas sensing platforms. Topographic measurements have confirmed irregular hills and dips of various dimensions that are responsible for creating air bubble pockets that satisfy the Cassie–Baxter state of hydrophobicity. High-resolution field-emission scanning electron microscopy (FESEM) has revealed double-layer structures consisting of fine microscopic flower-like structures of nanoscale petals on the top of base nanostructures. Wetting contact angle (WCA) measurements further revealed the contact angle to be ~142.0° ± 10.0°. Such hydrophobic nanostructures were expected to provide a platform for gas-sensing materials of a higher surface area. From this direction, a very thin layer of palladium, ca. 100 nm of thickness, was sputtered. Thereafter, further topographic and WCA measurements were carried out. FESEM micrographs revealed that microscopic flower-like structures of nanoscale petals remained intact. A sessile drop test reconfirmed a WCA of as high as ~130.0° ± 10.0°. Due to the inherent features of hydrophobic nanostructures, a wider surface area was expected that can be useful for higher target gas adsorption sites. In this context, a customized sensing facility was set up, and H₂ gas sensing performance was carried out. The surface nanostructures were found to be very stable and durable over the course of a year and beyond. A polymer-based hydrophobic gas-sensing platform as investigated in this study will play a dual role in hydrophobicity as well as superior gas-sensing characteristics. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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18 pages, 20539 KiB

Open AccessArticle

Synthesis and Spectroscopic Analyses of New Polycarbonates Based on Bisphenol A-Free Components

by Krystyna Wnuczek, Andrzej Puszka and Beata Podkościelna

Polymers 2021, 13(24), 4437; https://doi.org/10.3390/polym13244437 - 17 Dec 2021

Cited by 14 | Viewed by 4208

Abstract

This paper discusses a new synthesis of bisphenol A-free polycarbonates based on four aliphatic-aromatic systems. In the first stage, different types of monomers (with/without sulfur) derived from diphenylmethane were synthesized. Then, new polycarbonates were prepared in the reactions with diphenyl carbonate (DPC) by [...] Read more.

This paper discusses a new synthesis of bisphenol A-free polycarbonates based on four aliphatic-aromatic systems. In the first stage, different types of monomers (with/without sulfur) derived from diphenylmethane were synthesized. Then, new polycarbonates were prepared in the reactions with diphenyl carbonate (DPC) by transesterification and polycondensation reactions. Three different catalysts (zinc acetate, 4-(dimethylamino)pyridine and benzyltriethylammonium chloride) were tested. The structures of the compounds were confirmed by Nuclear Molecular Resonance spectroscopy (NMR) in each stage. The chemical structures of the obtained polycarbonates were verified by means of Attenuated Total Reflectance Fourier Transform infrared spectroscopy (ATR-FTIR). The presence of a carbonyl group in the infrared spectrum confirmed polycarbonate formation. Thermal studies by differential scanning calorimetry (DSC) were carried out to determine the melting temperatures of the monomers. A gel permeation chromatography analysis (GPC) of the polycarbonates was performed in order to investigate their molar masses. Thermal analysis proved the purity of the obtained monomers; the curves showed a characteristic signal of melting. The obtained polycarbonates were characterized as having high resistance to organic solvents, including tetrahydrofuran. The GPC analysis proved their relatively large molar masses and their low dispersity. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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15 pages, 5717 KiB

Open AccessArticle

Evaluation of Mechanical and Tribological Properties of Corn Cob-Reinforced Epoxy-Based Composites—Theoretical and Experimental Study

by Ahmed Fouly, Hany S. Abdo, Asiful H. Seikh, Khalid Alluhydan, Hend I. Alkhammash, Ibrahim A. Alnaser and Mohamed S. Abdo

Polymers 2021, 13(24), 4407; https://doi.org/10.3390/polym13244407 - 15 Dec 2021

Cited by 21 | Viewed by 3524

Abstract

Epoxy is considered to be the most popular polymer and is widely used in various engineering applications. However, environmental considerations require natural materials-based epoxy. This necessity results in further utilization of natural materials as a natural reinforcement for different types of composites. Corn [...] Read more.

Epoxy is considered to be the most popular polymer and is widely used in various engineering applications. However, environmental considerations require natural materials-based epoxy. This necessity results in further utilization of natural materials as a natural reinforcement for different types of composites. Corn cob is an example of a natural material that can be considered as an agricultural waste. The objective of the present work is to improve the economic feasibility of corn cob by converting the original corn cob material into powder to be utilized in reinforcing epoxy-based composites. In the experiment, the corn cob was crushed and ground using a grain miller before it was characterized by scanning electron microscopy (SEM). The corn cob powder was added to the epoxy with different weight fractions (2, 4, 6, 8, 10 wt%). In order to prevent corn cob powder agglomeration and ensure homogeneous distribution of the reinforcement inside the epoxy, the ultrasonic technique and a mechanical stirrer were used. Then, the composite’s chemical compositions were evaluated using X-ray diffraction (XRD). The mechanical experiments showed an improvement in the Young’s modulus and compressive yield strength of the epoxy composites, increasing corn cob up to 8 wt% by 21.26% and 22.22%, respectively. Furthermore, tribological tests revealed that reinforcing epoxy with 8 wt% corn cob can decrease the coefficient of friction by 35% and increase wear resistance by 4.8%. A finite element model for the frictional process was constructed to identify different contact stresses and evaluate the load-carrying capacity of the epoxy composites. The finite element model showed agreement with the experimental results. An epoxy containing 8 wt% corn cob demonstrated the optimal mechanical and tribological properties. The rubbed surfaces were investigated by SEM to identify the wear mechanism of different composites. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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18 pages, 2768 KiB

Open AccessArticle

Synthesis and Characterization of Polyurethanes from Residual Palm Oil with High Poly-Unsaturated Fatty Acid Oils as Additive

by Javier Chavarro Gomez, Rabitah Zakaria, Min Min Aung, Mohd Noriznan Mokhtar and Robiah Yunus

Polymers 2021, 13(23), 4214; https://doi.org/10.3390/polym13234214 - 1 Dec 2021

Cited by 18 | Viewed by 3074

Abstract

In the effort to produce renewable and biodegradable polymers, more studies are being undertaken to explore environmentally friendly sources to replace petroleum-based sources. The oil palm industry is not only the biggest vegetable-oil producer from crops but also one the biggest producers of [...] Read more.

In the effort to produce renewable and biodegradable polymers, more studies are being undertaken to explore environmentally friendly sources to replace petroleum-based sources. The oil palm industry is not only the biggest vegetable-oil producer from crops but also one the biggest producers of residual oil that cannot be used for edible purposes due to its low quality. In this paper the development of biopolymers from residual palm oil, residual palm oil with 10% jatropha oil, and residual palm oil with 10% algae oil as additives were explored. Polyols from the different oils were prepared by epoxydation with peroxyacetic acid and alcoholysis under the same conditions and further reacted with poly isocyanate to form polyurethanes. Epoxidized oils, polyols and polyurethanes were analyzed by different techniques such as TGA, DSC, DMA, FTIR and H-NMR. Overall, although the IV of algae oil is slightly higher than that of jatropha oil, the usage of algae oil as additive into the residual palm oil was shown to significantly increase the hard segments and thermal stability of the bio polyurethane compared to the polymer with jatropha oil. Furthermore, when algae oil was mixed with the residual palm oil, it was possible to identify phosphate groups in the polyol which might enhance the fire-retardant properties of the final biopolymer. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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16 pages, 80956 KiB

Open AccessArticle

A Study of the Strength Performance of Peat Soil: A Modified Cement-Based Stabilization Agent Using Fly Ash and Polypropylene Fiber

by Mohammed K. H. Radwan, Foo Wei Lee, Yoke Bee Woon, Ming Kun Yew, Kim Hung Mo and Soon Han Wai

Polymers 2021, 13(23), 4059; https://doi.org/10.3390/polym13234059 - 23 Nov 2021

Cited by 10 | Viewed by 4092

Abstract

The use of cement as a soil stabilization agent is one of the common solutions to enhancing the engineering properties of soil. However, the impact and cost of using cement have raised environmental concerns, generating much interest in the search for alternative materials [...] Read more.

The use of cement as a soil stabilization agent is one of the common solutions to enhancing the engineering properties of soil. However, the impact and cost of using cement have raised environmental concerns, generating much interest in the search for alternative materials to reduce the use of cement as a stabilizing agent in soil treatment. This study looked into limiting cement content in peat soil stabilization by using fly ash waste and polypropylene fiber (PPF). It focused on soil mechanical mediation for stabilization of peat with fly ash cement and PPF cement by comparing the mechanical properties, using unconfined compressive strength (UCS) and California bearing ratio (CBR) tests. The control (untreated) peat specimen and specimens with either fly ash (10%, 20% and 30%) and PPF (0.1%, 0.15% and 0.2%) were studied. Test results showed that 30% of fly ash and cement content displays the highest UCS and CBR values and gives the most reliable compressibility properties. On the other hand, UCS and CBR test results indicate optimum values of PPF–cement stabilizing agent content in the specimen of 0.15% PPF and 30% cement. Selected specimens were analyzed using scanning electron microscopy (SEM), and PPF threads were found to be well surrounded by cement-stabilized peat matrices. It was also observed that the specimen with 30% fly ash generated more hydration products when compared to the specimen with 100% cement content. It is concluded that the use of fly ash cement and PPF cement as stabilizing agents to limit the cement usage in peat soil treatment is potentially viable. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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13 pages, 37934 KiB

Open AccessArticle

Preparation and Characterization of Highly Porous Polyacrylonitrile Electrospun Nanofibers Using Lignin as Soft Template via Selective Chemical Dissolution Technique

by Mohd Adib Tajuddin Ahmad and Norizah Abdul Rahman

Polymers 2021, 13(22), 3938; https://doi.org/10.3390/polym13223938 - 15 Nov 2021

Cited by 6 | Viewed by 2918

Abstract

In this study, polyacrylonitrile (PAN) was mixed with a renewable polymer, lignin, to produce electrospun nanofibers by using an electrospinning technique. Lignin was utilized as a soft template that was removed from the nanofibers by using a selective dissolution technique to create porous [...] Read more.

In this study, polyacrylonitrile (PAN) was mixed with a renewable polymer, lignin, to produce electrospun nanofibers by using an electrospinning technique. Lignin was utilized as a soft template that was removed from the nanofibers by using a selective dissolution technique to create porous PAN nanofibers. These nanofibers were characterized with Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), thermogravimetry analysis (TGA), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) to study their properties and morphology. The results showed that lignin can be homogeneously mixed into the PAN solution and successfully electrospun into nanofibers. FESEM results showed a strong relationship between the PAN: lignin ratio and the diameter of the electrospun fibers. Lignin was successfully removed from electrospun nanofibers by a selective chemical dissolution technique, which resulted in roughness and porousness on the surface of the nanofibers. Based on the BET result, the specific surface area of the PAN/lignin nanofibers was more than doubled following the removal of lignin compared to PAN nanofibers. The highest specific surface area of nanofibers after selective chemical dissolution was found at an 8:2 ratio of PAN/lignin, which was 32.42 m²g⁻¹ with an average pore diameter of 5.02 nm. The diameter of electrospun nanofibers was also slightly reduced after selective chemical dissolution. Porous PAN nanofibers can be seen as the precursors to the production of highly porous carbon nanofibers. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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31 pages, 162161 KiB

Open AccessArticle

Axial Compression Behavior of Ferrocement Geopolymer HSC Columns

by Taha Awadallah El-Sayed

Polymers 2021, 13(21), 3789; https://doi.org/10.3390/polym13213789 - 1 Nov 2021

Cited by 28 | Viewed by 2093

Abstract

Geopolymer concrete (GC) is a substantial sort that is created by utilizing metakaolin, ground granulated blast furnace slag (GGBS), silica fumes, fly ash, and other cementitious materials as binding ingredients. The current study concentrated on the structural behavior of the ferrocement geopolymer HSC-columns [...] Read more.

Geopolymer concrete (GC) is a substantial sort that is created by utilizing metakaolin, ground granulated blast furnace slag (GGBS), silica fumes, fly ash, and other cementitious materials as binding ingredients. The current study concentrated on the structural behavior of the ferrocement geopolymer HSC-columns subjected to axial loading and produced using rice straw ash (RSA). The major goal of this research was to use the unique features of the ferrocement idea to manufacture members that function as columns bearing members. As they are more cost-effective and lower in weight, these designed elements can replace traditional RC members. The study also intended to reduce the cost of producing new parts by utilizing low-cost materials such as light weight expanded and welded wire meshes, polyethylene mesh (Tensar), and fiber glass mesh. For this purpose, an experimental plan was conducted and a finite element prototype with ANSYS2019-R1 was implemented. Nine geopolymer ferrocement columns of dimensions of 150 mm × 150 mm × 1600 mm with different volume-fraction and layers as well as a number of metallic and nonmetallic meshes were examined under axial compression loading until failure. The performance of the geopolymer columns was examined with consideration to the mid-span deflection, ultimate failure load, first crack load with various phases of loading, the cracking patterns, energy absorption and ductility index. Expanded or welded ferrocement geopolymer columns showed greater ultimate failure loads than the control column. Additionally, using expanded or welded columns had a considerable effect on ultimate failure loads, where the welded wire mesh exhibited almost 28.10% compared with the expanded wire mesh. Columns reinforced with one-layer of nonmetallic Tensar-mesh obtained a higher ultimate failure load than all tested columns without concrete cover spalling. The analytical and experimental results were in good agreement. The results displayed an accepted performance of the ferrocement geopolymer HSC-columns. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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17 pages, 7909 KiB

Open AccessArticle

Failure Investigation of Layered LFT SB1plus Package after Ballistic Tests for Level IIA

by Cătălin Pîrvu and Lorena Deleanu

Polymers 2021, 13(17), 2912; https://doi.org/10.3390/polym13172912 - 29 Aug 2021

Cited by 4 | Viewed by 2392

Abstract

The main objective of this study focuses on designing and testing body protection systems using advanced materials based on aramid fibers, for high impact speeds of up to 420 ± 10 m/s. Ballistic applications of aramid fiber-based composites mostly include soft body armors. [...] Read more.

The main objective of this study focuses on designing and testing body protection systems using advanced materials based on aramid fibers, for high impact speeds of up to 420 ± 10 m/s. Ballistic applications of aramid fiber-based composites mostly include soft body armors. The investigation of the failure mechanisms identifies issues of protective fabrics, major challenges and technological problems for efficient development of these systems. The authors present an investigation on the failure processes and destructive stages of a ballistic package made of successive layers of LFT SB1plus, a trade name for a multiaxial fabric by Twaron Laminated Fabric Technology (LFT), taking into account the particular test conditions from NIJ Standard-0101.06 Ballistic Resistance of Body Armor. The main parameter of interest was the backface signature (BFS), but also details of projectile arrest and SEM investigation could offer arguments for using this material for individual protection. For the reported tests, the maximum and minimum values for BFS were 12 mm and 24 mm, the mean value being 18.66 mm and the standard deviation being 3.8 mm. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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14 pages, 25001 KiB

Open AccessArticle

Radiation-Based Crosslinking Technique for Enhanced Thermal and Mechanical Properties of HDPE/EVA/PU Blends

by Jang-Gun Lee, Jin-Oh Jeong, Sung-In Jeong and Jong-Seok Park

Polymers 2021, 13(16), 2832; https://doi.org/10.3390/polym13162832 - 23 Aug 2021

Cited by 16 | Viewed by 4015

Abstract

Crosslinking of polyolefin-based polymers can improve their thermal and mechanical properties, which can then be used in various applications. Radiation-induced crosslinking can be done easily and usefully by irradiation without a crosslinking agent. In addition, polymer blending can improve thermal and mechanical properties, [...] Read more.

Crosslinking of polyolefin-based polymers can improve their thermal and mechanical properties, which can then be used in various applications. Radiation-induced crosslinking can be done easily and usefully by irradiation without a crosslinking agent. In addition, polymer blending can improve thermal and mechanical properties, and chemical resistance, compared to conventional single polymers. In this study, high-density polyethylene (HDPE)/ethylene vinyl acetate (EVA)/polyurethane (PU) blends were prepared by radiation crosslinking to improve the thermal and mechanical properties of HDPE. This is because HDPE, a polyolefin-based polymer, has the weaknesses of low thermal resistance and flexibility, even though it has good mechanical strength and machinability. In contrast, EVA has good flexibility and PU has excellent thermal properties and wear resistance. The morphology and mechanical properties (e.g., tensile and flexure strength) were characterized using scanning electron microscopy (SEM) and a universal testing machine (UTM). The gel fraction, thermal shrinkage, and abrasion resistance of samples were confirmed. In particular, after storing at 180 °C for 1 h, the crosslinked HDPE-PU-EVA blends exhibited ~4-times better thermal stability compared to non-crosslinked HDPE. When subjected to a radiation dose of 100 kGy, the strength of HDPE increased, but the elongation sharply decreased (80%). On the other hand, the strength of the HDPE-PU-EVA blends was very similar to that of HDPE, and the elongation was more than 3-times better (320%). Finally, the abrasion resistance of crosslinked HDPE-PU-EVA was ~9-times better than the crosslinked HDPE. Therefore, this technology can be applied to various polymer products requiring high heat resistance and flexibility, such as electric cables and industrial pipes. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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18 pages, 4324 KiB

Open AccessArticle

Biocomposites of Epoxidized Natural Rubber/Poly(Lactic Acid) Modified with Natural Substances: Influence of Biomolecules on the Aging Properties (Part II)

by Anna Masek and Stefan Cichosz

Polymers 2021, 13(11), 1677; https://doi.org/10.3390/polym13111677 - 21 May 2021

Cited by 9 | Viewed by 2878

Abstract

The aim of this study is to present the possible influence of natural substances on the aging properties of epoxidized natural rubber (ENR) and poly(lactic acid) (PLA) eco-friendly elastic blends. Therefore, the ENR/PLA blends were filled with natural pro-health substances of potentially antioxidative [...] Read more.

The aim of this study is to present the possible influence of natural substances on the aging properties of epoxidized natural rubber (ENR) and poly(lactic acid) (PLA) eco-friendly elastic blends. Therefore, the ENR/PLA blends were filled with natural pro-health substances of potentially antioxidative behavior, namely, δ-tocopherol (vitamin E), curcumin, β-carotene and quercetin. In this way, the material biodeterioration potential was maintained and the material’s lifespan was prolonged while subjected to increased temperatures or high-energy UVA irradiation (340 nm). The investigation of the samples’ properties indicated that curcumin and quercetin are the most promising natural additives that may contribute to the delay of ENR/PLA degradation under the above-mentioned conditions. The efficiency of the proposed new natural anti-aging additives was proven with static mechanical analysis, color change investigation, as well as mass loss during a certain aging. The aging coefficient, which compares the mechanical properties before and after the aging process, indicated that the ENR/PLA performance after 200 h of accelerated aging might decrease only by approximately 30% with the blend loaded with quercetin. This finding paves new opportunities for bio-based and green anti-aging systems employed in polymer technology. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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Review

Jump to: Editorial, Research

15 pages, 3314 KiB

Open AccessReview

Skillful Control of Dispersion and 3D Network Structures: Advances in Functional Organic–Inorganic Nano-Hybrid Materials Prepared Using the Sol-Gel Method

by Hiroki Ikake, Shuta Hara and Shigeru Shimizu

Polymers 2022, 14(16), 3247; https://doi.org/10.3390/polym14163247 - 9 Aug 2022

Cited by 8 | Viewed by 2578

Abstract

Organic–inorganic hybrid materials have become indispensable high-performance and highly functional materials. This is owing to the improved dispersion control in hybrid materials and emergence of functional ionic liquids. Harmonization of both these factors has enabled the utilization of functional 3D network structures and [...] Read more.

Organic–inorganic hybrid materials have become indispensable high-performance and highly functional materials. This is owing to the improved dispersion control in hybrid materials and emergence of functional ionic liquids. Harmonization of both these factors has enabled the utilization of functional 3D network structures and nanodispersions in composite materials. Polymeric materials endow materials with flexibility, toughness, and shape-memory properties, whereas inorganic materials provide materials with unique optical, electrical, and magnetic properties due to their nanosize. Organic–inorganic hybrid materials have evolved into novel materials that go beyond the composite rule. In this review, the historical development of hybrid materials prepared using the sol-gel method and the birth of ionic liquids have been summarized. In addition, the historical results leading to the development of functional 3D network structures and dispersion control have also been presented, as well as a review of the research on functional ionic liquids, which are of current interest. The authors also summarize the results of their research on functional ionic liquids. The design of new organic–inorganic hybrid materials has been discussed and the future prospects of new polymer composite materials provided. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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17 pages, 4372 KiB

Open AccessReview

Bioinspired Bottlebrush Polymers for Aqueous Boundary Lubrication

by Xiaoyan Liu and Per M. Claesson

Polymers 2022, 14(13), 2724; https://doi.org/10.3390/polym14132724 - 3 Jul 2022

Cited by 13 | Viewed by 4628

Abstract

An extremely efficient lubrication system is achieved in synovial joints by means of bio-lubricants and sophisticated nanostructured surfaces that work together. Molecular bottlebrush structures play crucial roles for this superior tribosystem. For example, lubricin is an important bio-lubricant, and aggrecan associated with hyaluronan [...] Read more.

An extremely efficient lubrication system is achieved in synovial joints by means of bio-lubricants and sophisticated nanostructured surfaces that work together. Molecular bottlebrush structures play crucial roles for this superior tribosystem. For example, lubricin is an important bio-lubricant, and aggrecan associated with hyaluronan is important for the mechanical response of cartilage. Inspired by nature, synthetic bottlebrush polymers have been developed and excellent aqueous boundary lubrication has been achieved. In this review, we summarize recent experimental investigations of the interfacial lubrication properties of surfaces coated with bottlebrush bio-lubricants and bioinspired bottlebrush polymers. We also discuss recent advances in understanding intermolecular synergy in aqueous lubrication including natural and synthetic polymers. Finally, opportunities and challenges in developing efficient aqueous boundary lubrication systems are outlined. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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24 pages, 2853 KiB

Open AccessReview

Biopackaging Potential Alternatives: Bioplastic Composites of Polyhydroxyalkanoates and Vegetal Fibers

by Natalia Gómez-Gast, Ma Del Rocío López Cuellar, Berenice Vergara-Porras and Horacio Vieyra

Polymers 2022, 14(6), 1114; https://doi.org/10.3390/polym14061114 - 10 Mar 2022

Cited by 16 | Viewed by 5514

Abstract

Initiatives to reduce plastic waste are currently under development worldwide. As a part of it, the European Union and private and public organizations in several countries are designing and implementing regulations for single-use plastics. For example, by 2030, plastic packaging and food containers [...] Read more.

Initiatives to reduce plastic waste are currently under development worldwide. As a part of it, the European Union and private and public organizations in several countries are designing and implementing regulations for single-use plastics. For example, by 2030, plastic packaging and food containers must be reusable or recyclable. In another approach, researchers are developing biopolymers using biodegradable thermoplastics, such as polyhydroxyalkanoates (PHAs), to replace fossil derivatives. However, their production capacity, high production costs, and poor mechanical properties hinder the usability of these biopolymers. To overcome these limitations, biomaterials reinforced with natural fibers are acquiring more relevance as the world of bioplastics production is increasing. This review presents an overview of PHA–vegetal fiber composites, the effects of the fiber type, and the production method’s impact on the mechanical, thermal, barrier properties, and biodegradability, all relevant for biopackaging. To acknowledge the behaviors and trends of the biomaterials reinforcement field, we searched for granted patents focusing on bio-packaging applications and gained insight into current industry developments and contributions. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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26 pages, 6193 KiB

Open AccessReview

Polymer/Carbon Nanotube Based Nanocomposites for Photovoltaic Application: Functionalization, Structural, and Optical Properties

by Boubaker Zaidi, Nejmeddine Smida, Mohammed G. Althobaiti, Atheer G. Aldajani and Saif D. Almdhaibri

Polymers 2022, 14(6), 1093; https://doi.org/10.3390/polym14061093 - 9 Mar 2022

Cited by 17 | Viewed by 3500

Abstract

We present a systematic review of nanostructured organic materials, including synthesis methods, functionalization, and applications. First, we report the chemical and physical procedures used for preparing the polymer/carbon nanotube composites described in the literature over the last decade. We compare the properties of [...] Read more.

We present a systematic review of nanostructured organic materials, including synthesis methods, functionalization, and applications. First, we report the chemical and physical procedures used for preparing the polymer/carbon nanotube composites described in the literature over the last decade. We compare the properties of different polymer-based prototypes of organic nanocomposites functionalized with carbon nanotubes. Theoretical and experimental vibrational investigations provide evidence of the molecular structure describing the interaction between both components, showing that the allowed amount of carbon nanotubes and their dispersion states differ across polymers. Moreover, the nature of the solvent used in the preparation has a significant impact on the dispersion process. The integration of these materials in photovoltaic applications is discussed, where the impact of nanoparticles is evidenced through the correlation between experimental analyses and theoretical approaches based on density functional theory. Alterations in optical properties, evaluated from the absorption and luminescence process, are coherent with the solar spectrum, and a good distribution of donor/acceptor interpenetration was observed. In all cases, it was demonstrated that the performance improvement is physically related to the charge transfer from the organic matrix to the nanoparticles. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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30 pages, 5417 KiB

Open AccessReview

Bioactive Graphene Quantum Dots Based Polymer Composite for Biomedical Applications

by Seyyed Mojtaba Mousavi, Seyyed Alireza Hashemi, Masoomeh Yari Kalashgrani, Navid Omidifar, Sonia Bahrani, Neralla Vijayakameswara Rao, Aziz Babapoor, Ahmad Gholami and Wei-Hung Chiang

Polymers 2022, 14(3), 617; https://doi.org/10.3390/polym14030617 - 5 Feb 2022

Cited by 82 | Viewed by 8257

Abstract

Today, nanomedicine seeks to develop new polymer composites to overcome current problems in diagnosing and treating common diseases, especially cancer. To achieve this goal, research on polymer composites has expanded so that, in recent years, interdisciplinary collaborations between scientists have been expanding day [...] Read more.

Today, nanomedicine seeks to develop new polymer composites to overcome current problems in diagnosing and treating common diseases, especially cancer. To achieve this goal, research on polymer composites has expanded so that, in recent years, interdisciplinary collaborations between scientists have been expanding day by day. The synthesis and applications of bioactive GQD-based polymer composites have been investigated in medicine and biomedicine. Bioactive GQD-based polymer composites have a special role as drug delivery carriers. Bioactive GQDs are one of the newcomers to the list of carbon-based nanomaterials. In addition, the antibacterial and anti-diabetic potentials of bioactive GQDs are already known. Due to their highly specific surface properties, π-π aggregation, and hydrophobic interactions, bioactive GQD-based polymer composites have a high drug loading capacity, and, in case of proper correction, can be used as an excellent option for the release of anticancer drugs, gene carriers, biosensors, bioimaging, antibacterial applications, cell culture, and tissue engineering. In this paper, we summarize recent advances in using bioactive GQD-based polymer composites in drug delivery, gene delivery, thermal therapy, thermodynamic therapy, bioimaging, tissue engineering, bioactive GQD synthesis, and GQD green resuscitation, in addition to examining GQD-based polymer composites. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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22 pages, 2844 KiB

Open AccessReview

A Review of Prestressed Fibre-Reinforced Polymer Matrix Composites

by Raphael Olabanji Ogunleye and Sona Rusnakova

Polymers 2022, 14(1), 60; https://doi.org/10.3390/polym14010060 - 24 Dec 2021

Cited by 7 | Viewed by 4499

Abstract

This review examines various studies on reducing tensile stresses generated in a polymer matrix composite without increasing the mass or dimension of the material. The sources of residual stresses and their impacts on the developed composite were identified, and the different techniques used [...] Read more.

This review examines various studies on reducing tensile stresses generated in a polymer matrix composite without increasing the mass or dimension of the material. The sources of residual stresses and their impacts on the developed composite were identified, and the different techniques used in limiting residual stresses were also discussed. Furthermore, the review elaborates on fibre-prestressing techniques based on elastically (EPPMC) and viscoelastically (VPPMC) prestressed polymer matrix composites, while advantages and limitations associated with EPPMC and VPPMC methods are also explained. The report shows that tensile residual stresses are induced in a polymer matrix composite during production as a result of unequal expansion, moisture absorption and chemical shrinkage; their manifestations have detrimental effects on the mechanical properties of the polymer composite. Both EPPMC and VPPMC have great influence in reducing residual stresses in the polymer matrix and thereby improving the mechanical properties of composite materials. The reports from this study provide some basis for selecting a suitable technique for prestressing as well as measuring residual stresses in composite materials. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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23 pages, 10938 KiB

Open AccessReview

Liquid Crystals Investigation Behavior on Azo-Based Compounds: A Review

by Nurul Asma Razali and Zuhair Jamain

Polymers 2021, 13(20), 3462; https://doi.org/10.3390/polym13203462 - 9 Oct 2021

Cited by 26 | Viewed by 2923

Abstract

Liquid crystal is an intermediate phase between the crystalline solid and an isotropic liquid, a very common substance in our daily lives. Two major classes of liquid crystal are lyotropic, where a liquid crystal is dissolved in a specific solvent under a particular [...] Read more.

Liquid crystal is an intermediate phase between the crystalline solid and an isotropic liquid, a very common substance in our daily lives. Two major classes of liquid crystal are lyotropic, where a liquid crystal is dissolved in a specific solvent under a particular concentration and thermotropic, which can be observed under temperature difference. This review aims to understand how a structure of a certain azo compound might influence the liquid crystal properties. A few factors influence the formation of different liquid crystals: the length of the alkyl terminal chain, inter/intra-molecular interaction, presence of spacer, spacer length, polarization effects, odd-even effects, and the presence of an electron-withdrawing group or an electron-donating group. As final observations, we show the compound’s different factors, the other liquid crystal is exhibited, and the structure–property relationship is explained. Liquid crystal technology is an ideal system to be applied to products to maximize their use, especially in the electronic and medical areas. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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31 pages, 17247 KiB

Open AccessReview

A Review on Synthesis, Structural, Flame Retardancy and Dielectric Properties of Hexasubstituted Cyclotriphosphazene

by Siti Nur Khalidah Usri, Zuhair Jamain and Mohamad Zul Hilmey Makmud

Polymers 2021, 13(17), 2916; https://doi.org/10.3390/polym13172916 - 30 Aug 2021

Cited by 25 | Viewed by 4102

Abstract

Hexachlorocyclotriphosphazene is a ring compound consisting of an alternating phosphorus and nitrogen atom with two chlorine substituents attached to the phosphorus atom. The six chlorine atoms attached to this cyclo compound can be substituted with any different nucleophile that leads to changes in [...] Read more.

Hexachlorocyclotriphosphazene is a ring compound consisting of an alternating phosphorus and nitrogen atom with two chlorine substituents attached to the phosphorus atom. The six chlorine atoms attached to this cyclo compound can be substituted with any different nucleophile that leads to changes in different chemical and physical properties. The major topics that were investigated in this research are the flame retardancy and dielectric properties of cyclotriphosphazene compounds. Cyclotriphosphazene compounds have high potential to act as a flame retardant, and this compound consists of two active elements attributed to its high flame-retardant character. This compound also demonstrated good ability as a flame retardant due to its low toxicity and less smoke produced. In addition, cyclotriphosphazene compounds were also investigated for their dielectric properties. Cyclotriphosphazene has high potential in the electrical field since it has dielectric properties that can be widely studied in the investigation of any potential application. This review presented literature studies focused on recent research development and studies in the field of cyclotriphosphazene that focused on synthesis, structural, flame retardancy, and dielectric properties of hexachlorocyclotriphosphazene compounds. Full article

(This article belongs to the Special Issue Synthesis, Processing, Structure and Properties of Polymer Materials)

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