Polymers

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18 pages, 6807 KiB

Open AccessArticle

Lab-Scale Twin-Screw Micro-Compounders as a New Rubber-Mixing Tool: ‘A Comparison on EPDM/Carbon Black and EPDM/Silica Composites’

by Nazlı Yazıcı, Mehmet Kodal and Güralp Özkoç

Polymers 2021, 13(24), 4391; https://doi.org/10.3390/polym13244391 - 15 Dec 2021

Cited by 7 | Viewed by 3993

Abstract

The research and development (R&D) in rubber formulation development require reproducible, repeatable, fast, accurate, and efficient sample preparation. The lab-scale formulation development is conventionally carried out using small-scale internal mixers and two-roll mills. However, high torque laboratory twin-screw micro-compounder, which have been serving [...] Read more.

The research and development (R&D) in rubber formulation development require reproducible, repeatable, fast, accurate, and efficient sample preparation. The lab-scale formulation development is conventionally carried out using small-scale internal mixers and two-roll mills. However, high torque laboratory twin-screw micro-compounder, which have been serving the plastic industry for more than 30 years, can be used to formulate new rubber compounds for fast and accurate sample preparation that on top can contribute to the economics of R&D. In this study, we investigated the possibility of using lab-scale 15 mL high torque twin-screw micro-compounder as a tool for new rubber compound development. For this purpose, we formulated EPDM/carbon black and EPDM/silica recipes through conventional way using a Banbury mixer followed by a two-roll mill, and through the possible way using a lab-scale 15 mL twin-screw micro-compounder. We crosslinked both systems via hot press at a predefined temperature and time. The rheological and mechanical properties of the compounds were investigated. Moreover, the dispersion of carbon black and silica in the EPDM matrix was judged by DisperGrader and scanning electron microscope (SEM). The conventional way of sample preparation was compared with a possible sample preparation method based on materials’ parameters and ease of operation. Full article

(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)

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23 pages, 7833 KiB

Open AccessArticle

Functional Properties of Kenaf Bast Fibre Anhydride Modification Enhancement with Bionanocarbon in Polymer Nanobiocomposites

by Samsul Rizal, Abdul Khalil H.P.S., E. M. Mistar, Niyi Gideon Olaiya, Umar Muksin, Marwan Marwan, Ikramullah, A. B. Suriani, C. K. Abdullah and Tata Alfatah

Polymers 2021, 13(23), 4211; https://doi.org/10.3390/polym13234211 - 1 Dec 2021

Cited by 9 | Viewed by 2614

Abstract

The miscibility between hydrophilic biofibre and hydrophobic matrix has been a challenge in developing polymer biocomposite. This study investigated the anhydride modification effect of propionic and succinic anhydrides on Kenaf fibre’s functional properties in vinyl ester bionanocomposites. Bionanocarbon from oil palm shell agricultural [...] Read more.

The miscibility between hydrophilic biofibre and hydrophobic matrix has been a challenge in developing polymer biocomposite. This study investigated the anhydride modification effect of propionic and succinic anhydrides on Kenaf fibre’s functional properties in vinyl ester bionanocomposites. Bionanocarbon from oil palm shell agricultural wastes enhanced nanofiller properties in the fibre-matrix interface via the resin transfer moulding technique. The succinylated fibre with the addition of the nanofiller in vinyl ester provided great improvement of the tensile, flexural, and impact strengths of 92.47 ± 1.19 MPa, 108.34 ± 1.40 MPa, and 8.94 ± 0.12 kJ m⁻², respectively than the propionylated fibre. The physical, morphological, chemical structural, and thermal properties of bionanocomposites containing 3% bionanocarbon loading showed better enhancement properties. This enhancement was associated with the effect of the anhydride modification and the nanofiller’s homogeneity in bionanocarbon-Kenaf fibre-vinyl ester bonding. It appears that Kenaf fibre modified with propionic and succinic anhydrides incorporated with bionanocarbon can be successfully utilised as reinforcing materials in vinyl ester matrix. Full article

(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)

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15 pages, 10829 KiB

Open AccessArticle

Functionalized-CNT Polymer Composite for Microwave and Electromagnetic Shielding

by Muhammed Kallumottakkal, Mousa I. Hussein, Yousef Haik and Tarik Bin Abdul Latef

Polymers 2021, 13(22), 3907; https://doi.org/10.3390/polym13223907 - 12 Nov 2021

Cited by 7 | Viewed by 2589

Abstract

In this research work, we studied the microwave properties of multi-wall carbon nanotube (MWCNT) surface functionalized with metallic oxides composites. Three different concentrations (5%, 10%, and 20%) of metallic oxides were used, namely cobalt, iron, and cobalt ferrite. The surface-decorated CNTS were impregnated [...] Read more.

In this research work, we studied the microwave properties of multi-wall carbon nanotube (MWCNT) surface functionalized with metallic oxides composites. Three different concentrations (5%, 10%, and 20%) of metallic oxides were used, namely cobalt, iron, and cobalt ferrite. The surface-decorated CNTS were impregnated into polyurethane (PU) matrix. The surface-decorated MWCNTs and the MWCNTs-PU composites were characterized using electron microscopy. The dielectric properties of the samples are studied using an open-ended coaxial probe technique in a wide frequency range of (5–50 GHz). The metallic oxide-decorated surface MWCNTs-PU composites demonstrated different microwave-frequency absorption characteristics depending on the concentration of the metallic oxides. Full article

(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)

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13 pages, 6482 KiB

Open AccessArticle

Boron Nitride-Filled Linear Low-Density Polyethylene for Enhanced Thermal Transport: Continuous Extrusion of Micro-Textured Films

by Özgün Güzdemir, Sagar Kanhere, Victor Bermudez and Amod A. Ogale

Polymers 2021, 13(19), 3393; https://doi.org/10.3390/polym13193393 - 2 Oct 2021

Cited by 11 | Viewed by 2419

Abstract

With shrinking size of electronic devices, increasing performance and accompanying heat dissipation, there is a need for efficient removal of this heat through packaging materials. Polymer materials are attractive packaging materials given their low density and electrical insulating properties, but they lack sufficient [...] Read more.

With shrinking size of electronic devices, increasing performance and accompanying heat dissipation, there is a need for efficient removal of this heat through packaging materials. Polymer materials are attractive packaging materials given their low density and electrical insulating properties, but they lack sufficient thermal conductivity that inhibits heat transfer rate. Hexagonal boron nitride (BN) possesses excellent thermal conductivity and is also electrically insulating, therefore BN-filled polymer composites were investigated in this study. Results showed successful continuous extrusion of BN-filled linear low-density polyethylene through micro-textured dies that is a scalable manufacturing process. Through-thickness thermal conductivity measurements established that 30 vol% BN content led to an over 500% increase in thermal conductivity over that of pure polymer. Textured film surface provided about a 50% increase in surface area when compared with non-textured films. This combination of increased surface area and enhanced thermal conductivity of BN-filled textured films indicates their potential application for improved convective thermal transport. Full article

(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)

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6 pages, 654 KiB

Open AccessCommunication

Increasing the Gas Barrier Properties of Polyethylene Foils by Coating with Poly(methyl acrylate)-Grafted Montmorillonite Nanosheets

by Judith E. Rauschendorfer and Philipp Vana

Polymers 2021, 13(19), 3228; https://doi.org/10.3390/polym13193228 - 23 Sep 2021

Cited by 6 | Viewed by 2343

Abstract

Low-density polyethylene (LDPE) foils were coated with a thin film of polymer-grafted Montmorillonite (MMT) nanosheets, which form a barrier against gas diffusion due to their unique brick-and-mortar arrangement. The MMT nanosheets were grafted with poly(methyl acrylate) (PMA), a soft and flexible polymer. Already [...] Read more.

Low-density polyethylene (LDPE) foils were coated with a thin film of polymer-grafted Montmorillonite (MMT) nanosheets, which form a barrier against gas diffusion due to their unique brick-and-mortar arrangement. The MMT nanosheets were grafted with poly(methyl acrylate) (PMA), a soft and flexible polymer. Already very thin films of this nanocomposite could reduce gas permeability significantly. The impact of the topology of the surface-grafted polymer on gas permeability was also studied. It was found that grafting MMT nanosheets with a mixture of star-shaped and linear PMA and with PMA that is cross-linked via hydrogen bonds further decrease gas permeability. The presented strategy is quick and simple and allows for the easy formation of effective gas barrier coatings for LDPE foils, as used in food packaging. Full article

(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)

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12 pages, 3443 KiB

Open AccessArticle

Novel Approaches to In-Situ ATR-FTIR Spectroscopy and Spectroscopic Imaging for Real-Time Simultaneous Monitoring Curing Reaction and Diffusion of the Curing Agent at Rubber Nanocomposite Surface

by Shun Muroga, Yu Takahashi, Yuta Hikima, Seisuke Ata, Sergei G. Kazarian, Masahiro Ohshima, Toshiya Okazaki and Kenji Hata

Polymers 2021, 13(17), 2879; https://doi.org/10.3390/polym13172879 - 27 Aug 2021

Cited by 3 | Viewed by 4259

Abstract

Here, we propose a novel attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy method for simultaneously monitoring the curing reaction and the diffusion behavior of curing agents at the surface of rubber in real-time. The proposed scheme was demonstrated by fluorine rubber (FKM) [...] Read more.

Here, we propose a novel attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy method for simultaneously monitoring the curing reaction and the diffusion behavior of curing agents at the surface of rubber in real-time. The proposed scheme was demonstrated by fluorine rubber (FKM) and FKM/carbon nanotube (CNT) nanocomposites with a target curing agent of triallyl-isocyanurate (TAIC). The broadening and the evolution of the C=O stretching of TAIC were quantitatively analyzed to characterize the reaction and the diffusion. Changes in the width of the C=O stretching indicated the reaction rate at the surface was even faster than that of the bulk as measured by a curemeter. The diffusion coefficient of the curing agent in the course of heating was newly calculated by the initial increase in the absorbance and our model based on Fickian diffusion. The diffusion coefficients of TAIC during curing were evaluated, and its temperature and filler dependency were identified. Cross-sectional ATR-FTIR imaging and in situ ATR-FTIR imaging measurements supported the hypothesis of the unidirectional diffusion of the curing agent towards the heated surface. It was shown that our method of in situ ATR-FTIR can monitor the degrees of cure and the diffusion coefficients of curing agents simultaneously, which cannot be achieved by conventional methods, e.g., rheological measurements. Full article

(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)

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18 pages, 6927 KiB

Open AccessArticle

Effect of In-Mold Annealing on the Properties of Asymmetric Poly(l-lactide)/Poly(d-lactide) Blends Incorporated with Nanohydroxyapatite

by Martin Boruvka, Cenek Cermak, Lubos Behalek and Pavel Brdlik

Polymers 2021, 13(16), 2835; https://doi.org/10.3390/polym13162835 - 23 Aug 2021

Cited by 7 | Viewed by 2263

Abstract

The proper choice of a material system for bioresorbable synthetic bone graft substitutes imposes strict requirements for mechanical properties, bioactivity, biocompatibility, and osteoconductivity. This study aims to characterize the effect of in-mold annealing on the properties of nanocomposite systems based on asymmetric poly( [...] Read more.

The proper choice of a material system for bioresorbable synthetic bone graft substitutes imposes strict requirements for mechanical properties, bioactivity, biocompatibility, and osteoconductivity. This study aims to characterize the effect of in-mold annealing on the properties of nanocomposite systems based on asymmetric poly(l-lactide) (PLLA)/Poly(d-lactide) (PDLA) blends at 5 wt.% PDLA loading, which was incorporated with nano-hydroxyapatite (HA) at various concentrations (1, 5, 10, 15 wt.%). Samples were melt-blended and injection molded into “cold” mold (50 °C) and hot mold (100 °C). The results showed that the tensile modulus, crystallinity, and thermal-resistance were enhanced with increasing content of HA and blending with 5 wt.% of PDLA. In-mold annealing further improved the properties mentioned above by achieving a higher degree of crystallinity. In-mold annealed PLLA/5PDLA/15HA samples showed an increase of crystallinity by ~59%, tensile modulus by ~28%, and VST by ~44% when compared to neat hot molded PLLA. On the other hand, the % elongation values at break as well as tensile strength of the PLLA and asymmetric nanocomposites were lowered with increasing HA content and in-mold annealing. Moreover, in-mold annealing of asymmetric blends and related nanocomposites caused the embrittlement of material systems. Impact toughness, when compared to neat cold molded PLLA, was improved by ~44% with in-mold annealing of PLLA/1HA. Furthermore, fracture morphology revealed fine dispersion and distribution of HA at 1 wt.% concentration. On the other hand, HA at a high concentration of 15 wt.% show agglomerates that worked as stress concentrators during impact loading. Full article

(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)

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26 pages, 23727 KiB

Open AccessArticle

Changes in Electrical Conductance of Polymer Composites Melts Due to Carbon Nanofiller Particles Migration

by Oleg V. Lebedev, Galina P. Goncharuk and Alexander N. Ozerin

Polymers 2021, 13(7), 1030; https://doi.org/10.3390/polym13071030 - 26 Mar 2021

Cited by 11 | Viewed by 2326

Abstract

In this work, the results of investigation of the effect of polymer composite melts electrical conductance increase with time are presented. The conductance time dependencies were obtained for composites based on polypropylene filled with carbon nanoparticles of different types. The dependencies were analyzed [...] Read more.

In this work, the results of investigation of the effect of polymer composite melts electrical conductance increase with time are presented. The conductance time dependencies were obtained for composites based on polypropylene filled with carbon nanoparticles of different types. The dependencies were analyzed to demonstrate the possibility of correlation of the conductance kinetics with different composite parameters, such as the filler geometry. Additional studies were carried out, such as electron microscopy study, conductance measurements after consecutive surface layer removal, and composite melt conductance measurements using a three-electrode scheme. The results showed that the increased electrical conductance of the composite materials can be attributed to the formation of an enriched with the filler particles surface layer, which happens during the stay of the composite in a melt state. Analysis of the experimental data, along with the results of numerical modeling, allowed to suggest a possible filler distribution transformation scheme. The physical premises behind the investigated effect are discussed. Full article

(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)

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Review

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31 pages, 10259 KiB

Open AccessReview

Silicone Rubber Composites Reinforced by Carbon Nanofillers and Their Hybrids for Various Applications: A Review

by Vineet Kumar, Md Najib Alam, Amutheesan Manikkavel, Minseok Song, Dong-Joo Lee and Sang-Shin Park

Polymers 2021, 13(14), 2322; https://doi.org/10.3390/polym13142322 - 15 Jul 2021

Cited by 93 | Viewed by 11516

Abstract

Without fillers, rubber types such as silicone rubber exhibit poor mechanical, thermal, and electrical properties. Carbon black (CB) is traditionally used as a filler in the rubber matrix to improve its properties, but a high content (nearly 60 per hundred parts of rubber [...] Read more.

Without fillers, rubber types such as silicone rubber exhibit poor mechanical, thermal, and electrical properties. Carbon black (CB) is traditionally used as a filler in the rubber matrix to improve its properties, but a high content (nearly 60 per hundred parts of rubber (phr)) is required. However, this high content of CB often alters the viscoelastic properties of the rubber composite. Thus, nowadays, nanofillers such as graphene (GE) and carbon nanotubes (CNTs) are used, which provide significant improvements to the properties of composites at as low as 2–3 phr. Nanofillers are classified as those fillers consisting of at least one dimension below 100 nanometers (nm). In the present review paper, nanofillers based on carbon nanomaterials such as GE, CNT, and CB are explored in terms of how they improve the properties of rubber composites. These nanofillers can significantly improve the properties of silicone rubber (SR) nanocomposites and have been useful for a wide range of applications, such as strain sensing. Therefore, carbon-nanofiller-reinforced SRs are reviewed here, along with advancements in this research area. The microstructures, defect densities, and crystal structures of different carbon nanofillers for SR nanocomposites are characterized, and their processing and dispersion are described. The dispersion of the rubber composites was reported through atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The effect of these nanofillers on the mechanical (compressive modulus, tensile strength, fracture strain, Young’s modulus, glass transition), thermal (thermal conductivity), and electrical properties (electrical conductivity) of SR nanocomposites is also discussed. Finally, the application of the improved SR nanocomposites as strain sensors according to their filler structure and concentration is discussed. This detailed review clearly shows the dependency of SR nanocomposite properties on the characteristics of the carbon nanofillers. Full article

(This article belongs to the Special Issue Advances in Nanofillers Reinforced Polymer Nanocomposites)

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