Polymers

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6 pages, 174 KiB

Open AccessEditorial

Progress in Polyurethane and Composites

by Chang-An Xu and Zhuohong Yang

Polymers 2024, 16(14), 2031; https://doi.org/10.3390/polym16142031 - 17 Jul 2024

Viewed by 2070

Abstract

Polyurethane materials have received increasing attention as daily materials due to their unique structures and properties [...] Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

Research

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15 pages, 5668 KiB

Open AccessArticle

Development and Application of a Lignin-Based Polyol for Sustainable Reactive Polyurethane Adhesives Synthesis

by Víctor M. Serrano-Martínez, Carlota Hernández-Fernández, Henoc Pérez-Aguilar, María Pilar Carbonell-Blasco, Avelina García-García and Elena Orgilés-Calpena

Polymers 2024, 16(13), 1928; https://doi.org/10.3390/polym16131928 - 6 Jul 2024

Cited by 2 | Viewed by 1706

Abstract

In response to the environmental impacts of conventional polyurethane adhesives derived from fossil fuels, this study introduces a sustainable alternative utilizing lignin-based polyols extracted from rice straw through a process developed at INESCOP. This research explores the partial substitution of traditional polyols with [...] Read more.

In response to the environmental impacts of conventional polyurethane adhesives derived from fossil fuels, this study introduces a sustainable alternative utilizing lignin-based polyols extracted from rice straw through a process developed at INESCOP. This research explores the partial substitution of traditional polyols with lignin-based equivalents in the synthesis of reactive hot melt polyurethane adhesives (HMPUR) for the footwear industry. The performance of these eco-friendly adhesives was rigorously assessed through Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), rheological analysis, and T-peel tests to ensure their compliance with relevant industry standards. Preliminary results demonstrate that lignin-based polyols can effectively replace a significant portion of fossil-derived polyols, maintaining essential adhesive properties and marking a significant step towards more sustainable adhesive solutions. This study not only highlights the potential of lignin in the realm of sustainable adhesive production but also emphasises the valorisation of agricultural by-products, thus aligning with the principles of green chemistry and sustainability objectives in the polymer industry. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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13 pages, 1770 KiB

Open AccessArticle

Synthesis of Room Temperature Curable Polymer Binder Mixed with Polymethyl Methacrylate and Urethane Acrylate for High-Strength and Improved Transparency

by Ju-Hong Lee, Won-Bin Lim, Jin-Gyu Min, Jae-Ryong Lee, Ju-Won Kim, Ji-Hong Bae and Pil-Ho Huh

Polymers 2024, 16(10), 1418; https://doi.org/10.3390/polym16101418 - 16 May 2024

Cited by 1 | Viewed by 1197

Abstract

Urethane acrylate (UA) was synthesized from various di-polyols, such as poly(tetrahydrofuran) (PTMG, Mn = 1000), poly(ethylene glycol) (PEG, Mn = 1000), and poly(propylene glycol) (PPG, Mn = 1000), for use as a polymer binder for paint. Polymethyl methacrylate (PMMA) and UA were blended [...] Read more.

Urethane acrylate (UA) was synthesized from various di-polyols, such as poly(tetrahydrofuran) (PTMG, Mn = 1000), poly(ethylene glycol) (PEG, Mn = 1000), and poly(propylene glycol) (PPG, Mn = 1000), for use as a polymer binder for paint. Polymethyl methacrylate (PMMA) and UA were blended to form an acrylic resin with high transmittance and stress-strain curve. When PMMA was blended with UA, a network structure was formed due to physical entanglement between the two polymers, increasing the mechanical properties. UA was synthesized by forming a prepolymer using di-polyol and hexamethylene diisocyanate, which were chain structure monomers, and capping them with 2-hydroxyethyl methacrylate to provide an acryl group. Fourier transform infrared spectroscopy was used to observe the changes in functional groups, and gel permeation chromatography was used to confirm that the three series showed similar molecular weight and PDI values. The yellowing phenomenon that appears mainly in the curing reaction of the polymer binder was solved, and the mechanical properties according to the effects of the polyol used in the main chain were compared. The content of the blended UA was quantified using ultravioletvisible spectroscopy at a wavelength of 370 nm based on 5, 10, 15, and 20 wt%, and the shear strength and tensile strength were evaluated using specimens in a suitable mode. The ratio for producing the polymer binder was optimized. The mechanical properties of the polymer binder with 5–10 wt% UA were improved in all series. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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14 pages, 3392 KiB

Open AccessArticle

A Novel Polyfunctional Polyurethane Acrylate Derived from Castor Oil-Based Polyols for Waterborne UV-Curable Coating Application

by Youmin Tuo, Xubiao Luo, Yahong Xiong, Chang-An Xu and Teng Yuan

Polymers 2024, 16(7), 949; https://doi.org/10.3390/polym16070949 - 30 Mar 2024

Cited by 5 | Viewed by 1213

Abstract

Because of its unique molecular structure and renewable properties, vegetable oil has gradually become the focus of researchers. In this work, castor oil was first transformed into a castor oil-based triacrylate structure (MACOG) using two steps of chemical modification, then it was prepared [...] Read more.

Because of its unique molecular structure and renewable properties, vegetable oil has gradually become the focus of researchers. In this work, castor oil was first transformed into a castor oil-based triacrylate structure (MACOG) using two steps of chemical modification, then it was prepared into castor oil-based waterborne polyurethane acrylate emulsion, and finally, a series of coating materials were prepared under UV curing. The results showed that with the increase in MACOG content, the glass transition temperature of the sample was increased from 20.3 °C to 46.6 °C, and the water contact angle of its surface was increased from 73.85 °C to 90.57 °C. In addition, the thermal decomposition temperature, mechanical strength, and water resistance of the samples were also greatly improved. This study not only provides a new idea for the preparation of waterborne polyurethane coatings with excellent comprehensive properties but also expands the application of biomass material castor oil in the field of coating. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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20 pages, 7625 KiB

Open AccessArticle

Incorporation of Graphene Nanoplatelets into Fiber-Reinforced Polymer Composites in the Presence of Highly Branched Waterborne Polyurethanes

by Ayşe Durmuş-Sayar, Murat Tansan, Tuğçe Çinko-Çoban, Dilay Serttan, Bekir Dizman, Mehmet Yildiz and Serkan Ünal

Polymers 2024, 16(6), 828; https://doi.org/10.3390/polym16060828 - 16 Mar 2024

Cited by 1 | Viewed by 1964

Abstract

Enhancing interfacial interactions in fiber-reinforced polymer composites (FRPCs) is crucial for improving their mechanical properties. This can be achieved through the incorporation of nanomaterials or chemically functional agents into FRPCs. This study reports the tailoring of the fiber–matrix interface in FRPCs using non-functionalized [...] Read more.

Enhancing interfacial interactions in fiber-reinforced polymer composites (FRPCs) is crucial for improving their mechanical properties. This can be achieved through the incorporation of nanomaterials or chemically functional agents into FRPCs. This study reports the tailoring of the fiber–matrix interface in FRPCs using non-functionalized graphene nanoplatelets (GNPs) in combination with a waterborne, highly branched, multi-functional polyurethane dispersion (HBPUD). A unique ultrasonic spray deposition technique was utilized to deposit aqueous mixtures of GNP/HBPUDs onto the surfaces of carbon fiber fabrics, which were used to prepare epoxy-prepreg sheets and corresponding FRPC laminates. The influence of the polyurethane (PU) and GNP content and their ratio at the fiber–matrix interface on the tensile properties of resulting high-performance composites was systematically investigated using stress–strain analysis of the produced FRPC plates and SEM analysis of their fractured surfaces. A synergistic stiffening and toughening effect was observed when as low as 20 to 30 mg of GNPs was deposited per square meter of each side of the carbon fiber fabrics in the presence of the multi-functional PU layer. This resulted in a significant improvement in the tensile strength from 908 to 1022 MPa, while maintaining or slightly improving the initial Young’s modulus from approximately 63 to 66 MPa. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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16 pages, 6621 KiB

Open AccessArticle

Synthesis and Properties of Cationic Core-Shell Fluorinated Polyurethane Acrylate

by Junhua Chen, Xiaoting Lu, Jinlian Chen, Shiting Li, He Zhang, Yinping Wu, Dongyu Zhu and Xiangying Hao

Polymers 2024, 16(1), 86; https://doi.org/10.3390/polym16010086 - 27 Dec 2023

Cited by 5 | Viewed by 1535

Abstract

Vinyl-capped cationic waterborne polyurethane (CWPU) was prepared using isophorone diisocyanate (IPDI), polycarbonate diol (PCDL), N-methyldiethanolamine (MDEA), and trimethylolpropane (TMP) as raw materials and hydroxyethyl methacrylate (HEMA) as a capping agent. Then, a crosslinked FPUA composite emulsion with polyurethane (PU) as the shell [...] Read more.

Vinyl-capped cationic waterborne polyurethane (CWPU) was prepared using isophorone diisocyanate (IPDI), polycarbonate diol (PCDL), N-methyldiethanolamine (MDEA), and trimethylolpropane (TMP) as raw materials and hydroxyethyl methacrylate (HEMA) as a capping agent. Then, a crosslinked FPUA composite emulsion with polyurethane (PU) as the shell and fluorinated acrylate (PA) as the core was prepared by core-shell emulsion polymerization with CWPU as the seed emulsion, together with dodecafluoroheptyl methacrylate (DFMA), diacetone acrylamide (DAAM), and methyl methacrylate (MMA). The effects of the core-shell ratio of PA/PU on the surface properties, mechanical properties, and heat resistance of FPUA emulsions and films were investigated. The results showed that when w(PA) = 30~50%, the stability of FPUA emulsion was the highest, and the particles showed a core-shell structure with bright and dark intersections under TEM. When w(PA) = 30%, the tensile strength reached 23.35 ± 0.08 MPa. When w(PA) = 50%, the fluorine content on the surface of the coating film was 14.75% and the contact angle was as high as 98.5°, which showed good hydrophobicity; the surface flatness of the film was observed under AFM. It is found that the tensile strength of the film increases and then decreases with the increase in the core-shell ratio and the heat resistance of the FPUA film is gradually increased. The FPUA film has excellent properties such as good impact resistance, high flexibility, high adhesion, and corrosion resistance. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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14 pages, 4045 KiB

Open AccessArticle

Investigation of Novel Solid Dielectric Material for Transformer Windings

by Aysel Ersoy, Fatih Atalar and Alper Aydoğan

Polymers 2023, 15(24), 4671; https://doi.org/10.3390/polym15244671 - 11 Dec 2023

Cited by 2 | Viewed by 1252

Abstract

Improvement techniques aimed at enhancing the dielectric strength and minimizing the dielectric loss of insulation materials have piqued the interest of many researchers. It is worth noting that the electrical breakdown traits of insulation material are determined by their electrochemical and mechanical performance. [...] Read more.

Improvement techniques aimed at enhancing the dielectric strength and minimizing the dielectric loss of insulation materials have piqued the interest of many researchers. It is worth noting that the electrical breakdown traits of insulation material are determined by their electrochemical and mechanical performance. Possible good mechanical, electrical, and chemical properties of new materials are considered during the generation process. Thermoplastic polyurethane (TPU) is often used as a high-voltage insulator due to its favorable mechanical properties, high insulation resistance, lightweight qualities, recovery, large actuation strain, and cost-effectiveness. The elastomer structure of thermoplastic polyurethane (TPU) enables its application in a broad range of high-voltage (HV) insulation systems. This study aims to evaluate the feasibility of using TPU on transformer windings as a solid insulator instead of pressboards. The investigation conducted through experiments sheds light on the potential of TPU in expanding the range of insulating materials for HV transformers. Transformers play a crucial role in HV systems, hence the selection of suitable materials like cellulose and polyurethane is of utmost importance. This study involved the preparation of an experimental setup in the laboratory. Breakdown tests were conducted by generating a non-uniform electric field using a needle–plane electrode configuration in a test chamber filled with mineral oil. Various voltages ranging from 14.4 kV to 25.2 kV were applied to induce electric field stress with a step rise of 3.6 kV. The partial discharges and peak numbers were measured based on the predetermined threshold values. The study investigated and compared the behaviors of two solid insulating materials under differing non-electric field stress conditions. Harmonic component analysis was utilized to observe the differences between the two materials. Notably, at 21.6 kV and 25.2 kV, polyurethane demonstrated superior performance compared to pressboard with regards to the threshold value of leakage current. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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21 pages, 5211 KiB

Open AccessArticle

Advanced Anticorrosive Graphene Oxide-Doped Organic-Inorganic Hybrid Nanocomposite Coating Derived from Leucaena leucocephala Oil

by Wejdan Al-otaibi, Naser M. Alandis, Yasser M. Al-Mohammad and Manawwer Alam

Polymers 2023, 15(22), 4390; https://doi.org/10.3390/polym15224390 - 12 Nov 2023

Cited by 4 | Viewed by 1350

Abstract

Metal corrosion poses a substantial economic challenge in a technologically advanced world. In this study, novel environmentally friendly anticorrosive graphene oxide (GO)-doped organic-inorganic hybrid polyurethane (LFAOIH@GO-PU) nanocomposite coatings were developed from Leucaena leucocephala oil (LLO). The formulation was produced by the amidation reaction [...] Read more.

Metal corrosion poses a substantial economic challenge in a technologically advanced world. In this study, novel environmentally friendly anticorrosive graphene oxide (GO)-doped organic-inorganic hybrid polyurethane (LFAOIH@GO-PU) nanocomposite coatings were developed from Leucaena leucocephala oil (LLO). The formulation was produced by the amidation reaction of LLO to form diol fatty amide followed by the reaction of tetraethoxysilane (TEOS) and a dispersion of GO_x (X = 0.25, 0.50, and 0.75 wt%) along with the reaction of isophorane diisocyanate (IPDI) (25–40 wt%) to form LFAOIH@GO_x-PU₃₅ nanocomposites. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR); ¹H, ¹³C, and ²⁹Si nuclear magnetic resonance; and X-ray photoelectron spectroscopy. A detailed examination of LFAOIH@GO_0.5-PU₃₅ morphology was conducted using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. These studies revealed distinctive surface roughness features along with a contact angle of around 88 G.U preserving their structural integrity at temperatures of up to 235 °C with minimal loading of GO. Additionally, improved mechanical properties, including scratch hardness (3 kg), pencil hardness (5H), impact resistance, bending, gloss value (79), crosshatch adhesion, and thickness were evaluated with the dispersion of GO. Electrochemical corrosion studies, involving Nyquist, Bode, and Tafel plots, provided clear evidence of the outstanding anticorrosion performance of the coatings. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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17 pages, 6974 KiB

Open AccessArticle

Flexural Response of Concrete Specimen Retrofitted with PU Grout Material: Experimental and Numerical Modeling

by Sadi Ibrahim Haruna, Yasser E. Ibrahim, Zhu Han and Abdulwarith Ibrahim Bibi Farouk

Polymers 2023, 15(20), 4114; https://doi.org/10.3390/polym15204114 - 17 Oct 2023

Cited by 5 | Viewed by 1326

Abstract

Polyurethane (PU) composite is increasingly used as a repair material for civil engineering infrastructure, including runway, road pavement, and buildings. Evaluation of polyurethane grouting (PUG) material is critical to achieve a desirable maintenance effect. This study aims to evaluate the flexural behavior of [...] Read more.

Polyurethane (PU) composite is increasingly used as a repair material for civil engineering infrastructure, including runway, road pavement, and buildings. Evaluation of polyurethane grouting (PUG) material is critical to achieve a desirable maintenance effect. This study aims to evaluate the flexural behavior of normal concrete repaired with polyurethane grout (NC-PUG) under a three-point bending test. A finite element (FE) model was developed to simulate the flexural response of the NC-PUG specimens. The equivalent principle response of the NC-PUG was analyzed through a three-dimensional finite element model (3D FEM). The NC and PUG properties were simulated using stress–strain relations acquired from compressive and tensile tests. The overlaid PUG material was prepared by mixing PU and quartz sand and overlayed on the either top or bottom surface of the concrete beam. Two different overlaid thicknesses were adopted, including 5 mm and 10 mm. The composite NC-PUG specimens were formed by casting a PUG material using different overlaid thicknesses and configurations. The reference specimen showed the highest average ultimate flexural stress of 5.56 MPa ± 2.57% at a 95% confidence interval with a corresponding midspan deflection of 0.49 mm ± 13.60%. However, due to the strengthened effect of the PUG layer, the deflection of the composite specimen was significantly improved. The concrete specimens retrofitted at the top surface demonstrated a typical linear pattern from the initial loading stage until the complete failure of the specimen. Moreover, the concrete specimens retrofitted at the bottom surface exhibit two deformation regions before the complete failure. The FE analysis showed good agreement between the numerical model and the experimental test result. The numerical model accurately predicted the flexural strength of the NC-PUG beam, slightly underestimating Ke by 4% and overestimating the ultimate flexural stress by 3%. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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14 pages, 5716 KiB

Open AccessArticle

Effects of Grafting Degree on the Formation of Waterborne Polyurethane-Acrylate Film with Hard Core–Soft Shell Structure

by Yong Rok Kwon, Seok Kyu Moon, Hae Chan Kim, Jung Soo Kim, Miyeon Kwon and Dong Hyun Kim

Polymers 2023, 15(18), 3765; https://doi.org/10.3390/polym15183765 - 14 Sep 2023

Cited by 3 | Viewed by 1446

Abstract

Waterborne polyurethane-acrylate (WPUA) grafted with polyurethane was prepared to improve the film-forming ability of hard-type acrylic latex. To balance the film-formation ability and hardness, the WPUA latex was designed with a hard core (polyacrylate) and soft shell (polyurethane). The grafting ratio was controlled [...] Read more.

Waterborne polyurethane-acrylate (WPUA) grafted with polyurethane was prepared to improve the film-forming ability of hard-type acrylic latex. To balance the film-formation ability and hardness, the WPUA latex was designed with a hard core (polyacrylate) and soft shell (polyurethane). The grafting ratio was controlled through varying the content of 2-hydroxyethyl methacrylate (HEMA) used to cap the ends of the polyurethane prepolymer. The morphologies of the latex particles, film surface, and fracture surface of the film were characterized through transmission electron microscopy, atomic force microscopy, and scanning electron microscopy, respectively. An increase in the grafting ratio resulted in the enhanced miscibility of polyurethane and polyacrylate but reduced adhesion between particles and increased minimum film formation temperature. In addition, grafting was essential to obtain transparent WPUA films. Excessive grafting induced defects such as micropores within the film, leading to the decreased hardness and adhesive strength of the film. The optimal HEMA content for the preparation of a WPUA coating with excellent film-forming ability and high hardness in ambient conditions was noted to be 50%. The final WPUA film was prepared without coalescence agents that generate volatile organic compounds. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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15 pages, 4821 KiB

Open AccessArticle

Aqueous Cationic Fluorinated Polyurethane for Application in Novel UV-Curable Cathodic Electrodeposition Coatings

by Junhua Chen, Zhihao Zeng, Can Liu, Xuan Wang, Shiting Li, Feihua Ye, Chunsheng Li and Xiaoxiao Guan

Polymers 2023, 15(18), 3725; https://doi.org/10.3390/polym15183725 - 11 Sep 2023

Cited by 5 | Viewed by 1604

Abstract

Aqueous polyurethane is an environmentally friendly, low-cost, high-performance resin with good abrasion resistance and strong adhesion. Cationic aqueous polyurethane is limited in cathodic electrophoretic coatings due to its complicated preparation process and its poor stability and single performance after emulsification and dispersion. The [...] Read more.

Aqueous polyurethane is an environmentally friendly, low-cost, high-performance resin with good abrasion resistance and strong adhesion. Cationic aqueous polyurethane is limited in cathodic electrophoretic coatings due to its complicated preparation process and its poor stability and single performance after emulsification and dispersion. The introduction of perfluoropolyether alcohol (PFPE-OH) and light curing technology can effectively improve the stability of aqueous polyurethane emulsions, and thus enhance the functionality of coating films. In this paper, a new UV-curable fluorinated polyurethane-based cathodic electrophoretic coating was prepared using cationic polyurethane as a precursor, introducing PFPE-OH capping, and grafting hydroxyethyl methacrylate (HEMA). The results showed that the presence of perfluoropolyether alcohol in the structure affected the variation of the moisture content of the paint film after flash evaporation. Based on the emulsion particle size and morphology tests, it can be assumed that the fluorinated cationic polyurethane emulsion is a core–shell structure with hydrophobic ends encapsulated in the polymer and hydrophilic ends on the outer surface. After abrasion testing and baking, the fluorine atoms of the coating were found to increase from 8.89% to 27.34%. The static contact angle of the coating to water was 104.6 ± 3°, and the water droplets rolled off without traces, indicating that the coating is hydrophobic. The coating has excellent thermal stability and tensile properties. The coating also passed the tests of impact resistance, flexibility, adhesion, and resistance to chemical corrosion in extreme environments. This study provides a new idea for the construction of a new and efficient cathodic electrophoretic coating system, and also provides more areas for the promotion of cationic polyurethane to practical applications. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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Review

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25 pages, 4782 KiB

Open AccessReview

An Advanced Review: Polyurethane-Related Dressings for Skin Wound Repair

by Wenzi Liang, Na Ni, Yuxin Huang and Changmin Lin

Polymers 2023, 15(21), 4301; https://doi.org/10.3390/polym15214301 - 1 Nov 2023

Cited by 2 | Viewed by 4234

Abstract

The inability of wounds to heal effectively through normal repair has become a burden that seriously affects socio-economic development and human health. The therapy of acute and chronic skin wounds still poses great clinical difficulty due to the lack of suitable functional wound [...] Read more.

The inability of wounds to heal effectively through normal repair has become a burden that seriously affects socio-economic development and human health. The therapy of acute and chronic skin wounds still poses great clinical difficulty due to the lack of suitable functional wound dressings. It has been found that dressings made of polyurethane exhibit excellent and diverse biological properties, but lack the functionality of clinical needs, and most dressings are unable to dynamically adapt to microenvironmental changes during the healing process at different stages of chronic wounds. Therefore, the development of multifunctional polyurethane composite materials has become a hot topic of research. This review describes the changes in physicochemical and biological properties caused by the incorporation of different polymers and fillers into polyurethane dressings and describes their applications in wound repair and regeneration. We listed several polymers, mainly including natural-based polymers (e.g., collagen, chitosan, and hyaluronic acid), synthetic-based polymers (e.g., polyethylene glycol, polyvinyl alcohol, and polyacrylamide), and some other active ingredients (e.g., LL37 peptide, platelet lysate, and exosomes). In addition to an introduction to the design and application of polyurethane-related dressings, we discuss the conversion and use of advanced functional dressings for applications, as well as future directions for development, providing reference for the development and new applications of novel polyurethane dressings. Full article

(This article belongs to the Special Issue Progress in Polyurethane and Composites)

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