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Polymers
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Mechanical and Structure–Property Relationships of Polymer Composites
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Mechanical and Structure–Property Relationships of Polymer Composites

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Processing and Engineering".

Deadline for manuscript submissions: closed (10 October 2023) | Viewed by 27172

Special Issue Editor

Dr. Zilu Wang

E-Mail Website
Guest Editor
Department of Chemistry, University of North Carolina Chapel Hill, Chapel Hill, NC 27599, USA
Interests: polymer physics; polymer reactions; polymer composite; graphene; computation; molecular simulation; 2D material; soft material
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Polymer composites comprise a combination of regular polymer materials with other components, such as inorganic fillers (glass, carbon, metal particles/fibres/sheets), other polymeric components (Kevlar, cellulose etc.) or even liquid/gases. These combinations, implemented through chemical/physical connection between different components, leads to rather complex phase structure at the micro/nanoscale and exhibit unique mechanical responses to external stimuli.

This Special Issue will present the latest findings from the widespread research community in this field to promote a greater understanding and improved design of microscopic phase structures required for the obtainment of mechanical properties for many advanced applications.

Dr. Zilu Wang
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • polymer composites
  • mechanical property
  • phase structure
  • filler
  • nanomaterial
  • smart material

Published Papers (15 papers)

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Research

20 pages, 11654 KiB  
Article
Metal–Metal Bonding Process Research Based on Xgboost Machine Learning Algorithm
by Jingpeng Feng, Lihua Zhan, Bolin Ma, Hao Zhou, Bang Xiong, Jinzhan Guo, Yunni Xia and Shengmeng Hui
Polymers 2023, 15(20), 4085; https://doi.org/10.3390/polym15204085 - 14 Oct 2023
Viewed by 871
Abstract
Conventionally, the optimization of bonding process parameters requires multi-parameter repetitive experiments, the processing of data, and the characterization of complex relationships between process parameters, and performance must be achieved with the help of new technologies. This work focused on improving metal–metal bonding performance [...] Read more.
Conventionally, the optimization of bonding process parameters requires multi-parameter repetitive experiments, the processing of data, and the characterization of complex relationships between process parameters, and performance must be achieved with the help of new technologies. This work focused on improving metal–metal bonding performance by applying SLJ experiments, finite element models (FEMs), and the Xgboost machine learning (ML) algorithm. The importance ranking of process parameters on tensile–shear strength (TSS) was evaluated with the interpretation toolkit SHAP (Shapley additive explanations) and it optimized reasonable bonding process parameters. The validity of the FEM was verified using SLJ experiments. The Xgboost models with 70 runs can achieve better prediction results. According to the degree of influence, the process parameters affecting the TSS ranked from high to low are roughness, adhesive layer thickness, and lap length, and the corresponding optimized values were 0.89 μm, 0.1 mm, and 27 mm, respectively. The experimentally measured TSS values increased by 14% from the optimized process parameters via the Xgboost model. ML methods provide a more accurate and intuitive understanding of process parameters on TSS. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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19 pages, 10704 KiB  
Article
Regulation Mechanism of Special Functional Groups Contained in Polymer Molecular Chains on the Tribological Properties of Modified Ti6Al4V
by Mengmeng Liu, Jing Ni, Caixia Zhang, Lihui Wang, Yue Guo and Zhifeng Liu
Polymers 2023, 15(20), 4060; https://doi.org/10.3390/polym15204060 - 12 Oct 2023
Cited by 1 | Viewed by 896
Abstract
Polymer coatings can effectively improve the surface tribological properties of human implant materials, thereby increasing their service life. In this study, poly(vinylsulfonic acid, sodium salt) (PVS), poly(acrylic acid) (PAA) and poly(vinylphosphonic acid) (PVPA) were used to modify Ti6Al4V surfaces. Experimental analyses were combined [...] Read more.
Polymer coatings can effectively improve the surface tribological properties of human implant materials, thereby increasing their service life. In this study, poly(vinylsulfonic acid, sodium salt) (PVS), poly(acrylic acid) (PAA) and poly(vinylphosphonic acid) (PVPA) were used to modify Ti6Al4V surfaces. Experimental analyses were combined with molecular simulation to explore the regulation mechanism of special functional groups contained in polymer molecular chains on the tribological properties of modified surfaces. In addition, the bearing capacities and velocity dependence of different polymer modified surfaces during friction were also explored. The PVS coating, due to physical adsorption, can have an anti-friction effect under NaCl solution lubrication, but is not durable under long-term or repeated usage. Both PAA and PVPA molecular chains can form chemical bonds with Ti6Al4V. Phosphate acid groups can firmly bind to the substrate, and the adsorption of salt ions and water molecules can form a hydrated layer on the PVPA coating surface, achieving ultra-low friction and wear. The adsorption of salt ions would aggravate the surface wear of the PAA-modified Ti6Al4V due to the unfirm binding of carboxyl groups to the substrate, resulting in a high friction coefficient. This study can provide effective guidance for the design of modified polymer coatings on metals. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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13 pages, 2137 KiB  
Article
Incorporation of Chitosan in Polyurethanes Based on Modified Castor Oil for Cardiovascular Applications
by Maria Morales-González, Kelly Navas-Gómez, Luis E. Diaz, José A. Gómez-Tejedor and Manuel F. Valero
Polymers 2023, 15(18), 3733; https://doi.org/10.3390/polym15183733 - 11 Sep 2023
Cited by 1 | Viewed by 988
Abstract
The increased demand for vascular grafts for the treatment of cardiovascular diseases has led to the search for novel biomaterials that can achieve the properties of the tissue. According to this, the investigation of polyurethanes has been a promising approach to overcome the [...] Read more.
The increased demand for vascular grafts for the treatment of cardiovascular diseases has led to the search for novel biomaterials that can achieve the properties of the tissue. According to this, the investigation of polyurethanes has been a promising approach to overcome the present limitations. However, some biological properties remain to be overcome, such as thrombogenicity and hemocompatibility, among others. This paper aims to synthesize polyurethanes based on castor oil and castor oil transesterified with triethanolamine (TEA) and pentaerythritol (PE) and with the incorporation of 1% chitosan. Analysis of the wettability, enzymatic degradation, mechanical properties (tensile strength and elongation at break), and thermal stability was performed. Along with the evaluation of the cytotoxicity against mouse fibroblast (L929) and human dermal fibroblast (HDFa) cells, the hemolysis rate and platelet adhesion were determined. The castor-oil-based polyurethanes with and without 1% chitosan posed hydrophobic surfaces and water absorptions of less than 2% and enzymatic degradation below 0.5%. Also, they were thermally stable until 300 °C, with tensile strength like cardiovascular tissues. The synthesized castor oil/chitosan polyurethanes are non-cytotoxic (cell viabilities above 80%) to L929 and HDFa cells and non-thrombogenic and non-hemolytic (less than 2%); therefore, they are suitable for cardiovascular applications. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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14 pages, 5918 KiB  
Article
Inorganic Fillers and Their Effects on the Properties of Flax/PLA Composites after UV Degradation
by Moumita Sit, Saeid Dashatan, Zhongyi Zhang, Hom Nath Dhakal, Moussa Khalfallah, Nicolas Gamer and Jarren Ling
Polymers 2023, 15(15), 3221; https://doi.org/10.3390/polym15153221 - 28 Jul 2023
Cited by 1 | Viewed by 1066
Abstract
The present investigation seeks to assess the impact of fillers on the mechanical characteristics of entirely biodegradable composites, introducing an advanced solution to fulfil long-term durability demands within point-of-purchase (POP) industries. The inclusion of calcium carbonate (CaCO3) fillers on the various [...] Read more.
The present investigation seeks to assess the impact of fillers on the mechanical characteristics of entirely biodegradable composites, introducing an advanced solution to fulfil long-term durability demands within point-of-purchase (POP) industries. The inclusion of calcium carbonate (CaCO3) fillers on the various properties of the flax fibre-reinforced composites, after accelerated irradiation in an ultraviolet (UV) radiation exposure has been investigated in the present study. Different types of flax fibre-reinforced poly lactic acid (PLA) biocomposites (with and without filler) were fabricated. The mechanical (tensile and flexural), and physical properties of the specimens were assessed after 500 h of exposure to accelerated UV irradiation of 0.48 W/m2 at 50 °C and were compared with those of the unexposed specimens. The results indicate that the presence of the inorganic filler significantly improved the performance of the biocomposites compared to the unfilled biocomposites after UV exposure. After adding 20% of fillers, the tensile strength was increased by 2% after UV degradation, whereas the biocomposite without filler lost 18% of its strength after UV exposure. This can be attributed to the change in the photo-degradation of the PLA due to the presence of the CaCO3 filler, which acts as a safeguard against UV light penetration by creating a protective barrier. The scanning electron microscopy (SEM) images of the degraded specimen surface show substantial difference in the surface topography of the composites with and without fillers. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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19 pages, 2966 KiB  
Article
Synthesis and Investigation of the Properties of Biphasic Hybrid Composites Based on Bentonite, Copper Hexacyanoferrate, Acrylamide and Acrylic Acid Hydrogel
by Galymzhan Kulamkadyrovich Mamytbekov, Dmitry Anatol’evich Zheltov and Yernat Rashidovich Nurtazin
Polymers 2023, 15(12), 2586; https://doi.org/10.3390/polym15122586 - 6 Jun 2023
Cited by 1 | Viewed by 1061
Abstract
This article presents a study of the synthesis and characterization of new biphasic hybrid composite materials consisting of intercalated complexes (ICC) of natural mineral bentonite with copper hexaferrocyanide (phase I), which are incorporated into the bulk of the polymer matrix (phase II). It [...] Read more.
This article presents a study of the synthesis and characterization of new biphasic hybrid composite materials consisting of intercalated complexes (ICC) of natural mineral bentonite with copper hexaferrocyanide (phase I), which are incorporated into the bulk of the polymer matrix (phase II). It has been established that the sequential modification of bentonite with copper hexaferrocyanide and introduction of acrylamide and acrylic acid cross-linked copolymers into its volume by means of in situ polymerization promote the formation of a heterogeneous porous structure in the resulting hybrid material. The sorption abilities of prepared hybrid composite toward radionuclides of liquid radioactive waste (LRW) have been studied, and the mechanism for binding radionuclide metal ions with the components of the hybrid composition have been described. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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19 pages, 5850 KiB  
Article
A Novel P/N/Si-Containing Vanillin-Based Compound for a Flame-Retardant, Tough Yet Strong Epoxy Thermoset
by Siyuan He, Cheng Chi, Chaohua Peng, Birong Zeng, Yongming Chen, Zhongxi Miao, Hui Xu, Weiang Luo, Guorong Chen, Zhenping Fu and Lizong Dai
Polymers 2023, 15(10), 2384; https://doi.org/10.3390/polym15102384 - 19 May 2023
Viewed by 1568
Abstract
It is still extremely challenging to endow epoxy resins (EPs) with excellent flame retardancy and high toughness. In this work, we propose a facile strategy of combining rigid–flexible groups, promoting groups and polar phosphorus groups with the vanillin compound, which implements a dual [...] Read more.
It is still extremely challenging to endow epoxy resins (EPs) with excellent flame retardancy and high toughness. In this work, we propose a facile strategy of combining rigid–flexible groups, promoting groups and polar phosphorus groups with the vanillin compound, which implements a dual functional modification for EPs. With only 0.22% phosphorus loading, the modified EPs obtain a limiting oxygen index (LOI) value of 31.5% and reach V-0 grade in UL-94 vertical burning tests. Particularly, the introduction of P/N/Si-containing vanillin-based flame retardant (DPBSi) improves the mechanical properties of EPs, including toughness and strength. Compared with EPs, the storage modulus and impact strength of EP composites can increase by 61.1% and 240%, respectively. Therefore, this work introduces a novel molecular design strategy for constructing an epoxy system with high-efficiency fire safety and excellent mechanical properties, giving it immense potential for broadening the application fields of EPs. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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13 pages, 2436 KiB  
Article
Effect of Recycling PET Fabric and Bottle Grade on r-PET Fiber Structure
by Nanjaporn Roungpaisan, Natee Srisawat, Nattadon Rungruangkitkrai, Nawarat Chartvivatpornchai, Jirachaya Boonyarit, Thorsak Kittikorn and Rungsima Chollakup
Polymers 2023, 15(10), 2330; https://doi.org/10.3390/polym15102330 - 17 May 2023
Cited by 4 | Viewed by 3611
Abstract
PET knitted fabric was melted and cooled by hot pressing at 250 °C to obtain a compacted sheet. Only white PET fabric (WF_PET) was used to study the recycling process by compression and grinding to powder and then melt spinning at different take-up [...] Read more.
PET knitted fabric was melted and cooled by hot pressing at 250 °C to obtain a compacted sheet. Only white PET fabric (WF_PET) was used to study the recycling process by compression and grinding to powder and then melt spinning at different take-up speeds compared to PET bottle grade (BO_PET). PET knitted fabric had good fiber formability and was better suited for melt spinning of recycled PET (r-PET) fibers than the bottle grade. Thermal and mechanical properties of r-PET fibers improved in terms of crystallinity and tensile strength with increasing take-up speed (500 to 1500 m/min). Fading and color changes from the original fabric were relatively small compared with PET bottle grade. Results indicated that fiber structure and properties can be used as a guideline for improving and developing r-PET fibers from textile waste. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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12 pages, 3501 KiB  
Article
Dual-Wavelength Lasing with Orthogonal Circular Polarizations Generated in a Single Layer of a Polymer–Cholesteric Liquid Crystal Superstructure
by Donghao Yang, Marouen Chemingui, Yu Wang, Xinzheng Zhang, Irena Drevensek-Olenik, Faheem Hassan, Qiang Wu, Yigang Li, Lotfi Saadaoui and Jingjun Xu
Polymers 2023, 15(5), 1226; https://doi.org/10.3390/polym15051226 - 28 Feb 2023
Cited by 2 | Viewed by 2479
Abstract
We investigate the laser emission from a polymer–cholesteric liquid crystal superstructure with coexisting opposite chiralities fabricated by refilling a right-handed polymeric scaffold with a left-handed cholesteric liquid crystalline material. The superstructure exhibits two photonic band gaps corresponding to the right- and left-circularly polarized [...] Read more.
We investigate the laser emission from a polymer–cholesteric liquid crystal superstructure with coexisting opposite chiralities fabricated by refilling a right-handed polymeric scaffold with a left-handed cholesteric liquid crystalline material. The superstructure exhibits two photonic band gaps corresponding to the right- and left-circularly polarized light. By adding a suitable dye, dual-wavelength lasing with orthogonal circular polarizations is realized in this single-layer structure. The wavelength of the left-circularly polarized laser emission is thermally tunable, while the wavelength of the right-circularly polarized emission is relatively stable. Due to its relative simplicity and tunability characteristics, our design might have broad application prospects in various fields of photonics and display technology. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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15 pages, 5029 KiB  
Article
Response-Surface-Methodology-Based Increasing of the Isotropic Thermal Conductivity of Polyethylene Composites Containing Multiple Fillers
by Hannelore Ohnmacht, Rudinei Fiorio, Tom Wieme, Dagmar R. D’hooge, Ludwig Cardon and Mariya Edeleva
Polymers 2023, 15(1), 39; https://doi.org/10.3390/polym15010039 - 22 Dec 2022
Cited by 2 | Viewed by 1500
Abstract
To optimize the thermal conductivity of high-density polyethylene, 15 hybrid filler composites containing either aluminum oxide, graphite, expanded graphite, carbon nanotubes or a combination of the former, have been studied using an extrusion-compression processing tandem. The experimental density of the cube-shaped specimens is [...] Read more.
To optimize the thermal conductivity of high-density polyethylene, 15 hybrid filler composites containing either aluminum oxide, graphite, expanded graphite, carbon nanotubes or a combination of the former, have been studied using an extrusion-compression processing tandem. The experimental density of the cube-shaped specimens is substantially lower than the theoretical density calculated by the linear mixing rule, mainly for the composites with high filler contents. The morphology of the composites, as studied by scanning electron microscopy (SEM), highlighted a good dispersion quality and random orientation of the fillers in the test specimens but also revealed air inclusions in the composites, explaining the density results. It is shown that the addition of filler(s) increases both the melt viscosity (up to ca. 270%) and the thermal conductivity (up to ca. 1000%). Hence, a very strong increase of TC can be practically hampered by a too high viscosity to enable processing. Supported by ANOVA analysis, the application of response surface methodology (RSM), assuming a perfect compression, indicates that all fillers have a significant effect on the thermal conductivity and synergistic effects can be achieved. The regression model obtained can adequately predict the thermal conductivity of composites of various compositions, as already confirmed based on three validation experiments in the present work. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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22 pages, 6567 KiB  
Article
The Mechanical, Thermal, and Chemical Properties of PLA-Mg Filaments Produced via a Colloidal Route for Fused-Filament Fabrication
by Jaime Orellana-Barrasa, Ana Ferrández-Montero, Aldo. R. Boccaccini, Begoña Ferrari and José Ygnacio Pastor
Polymers 2022, 14(24), 5414; https://doi.org/10.3390/polym14245414 - 10 Dec 2022
Cited by 3 | Viewed by 1501
Abstract
The effect of Mg particles on the thermal, chemical, physical, and primarily mechanical properties of 3D-printed PLA/Mg composites is studied in this paper. Recently, new colloidal processing has been proposed to introduce Mg particles into the PLA matrix, which ensures good dispersion of [...] Read more.
The effect of Mg particles on the thermal, chemical, physical, and primarily mechanical properties of 3D-printed PLA/Mg composites is studied in this paper. Recently, new colloidal processing has been proposed to introduce Mg particles into the PLA matrix, which ensures good dispersion of the particles and better thermal properties, allowing for thermal processing routes such as extrusion or 3D printing via fused-filament fabrication. The thermal and physical properties are here studied in 1D single-filament-printed PLA/Mg composites with 0 to 10 wt.% of Mg particles by Differential Scanning Calorimetry (DSC); we analyse the PLA chain modifications produced, the crystallinity fraction, and the different crystalline forms of the PLA after thermal processing. Fourier Transform Infrared Spectroscopy (FTIR) is used to confirm the influence of the PLA/Mg colloidal processing after printing. The mechanical properties are measured with a universal tensile test machine on the 1D single-printed filaments via fused-filament fabrication (FFF); the filaments were naturally aged to stable conditions. Filaments with and without a notch are studied to obtain the materials’ tensile strength, elastic modulus, and fracture toughness. Different analytical models to explain the results of the PLA-Mg were studied, in which the minimum values for the interface strength of the PLA-Mg composites were calculated. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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11 pages, 3931 KiB  
Article
Mechanical Properties of 3D-Printed PEEK/HA Composite Filaments
by Jianfeng Kang, Jibao Zheng, Yijun Hui and Dichen Li
Polymers 2022, 14(20), 4293; https://doi.org/10.3390/polym14204293 - 12 Oct 2022
Cited by 15 | Viewed by 2508
Abstract
The incorporation of bioactive ceramic into polyether ether ketone (PEEK) was expected to improve the bioinertia and hydrophobicity of pure PEEK, further facilitating osseointegration and bone ingrowth. However, the addition of bioceramic also changes the anisotropy of mechanical properties and failure mechanism of [...] Read more.
The incorporation of bioactive ceramic into polyether ether ketone (PEEK) was expected to improve the bioinertia and hydrophobicity of pure PEEK, further facilitating osseointegration and bone ingrowth. However, the addition of bioceramic also changes the anisotropy of mechanical properties and failure mechanism of composite. Therefore, three-dimensional printed (3D-printed) PEEK/hydroxyapatite (HA) composite filaments with differing proportions (HA content: 10–30 wt%) were prepared using physical mixture and melting extrusion processes. The tensile elastic modulus and tensile strength of composite filaments were tested experimentally. These microscopic models, with multiple diameter variations and differing dispersity of HA particles, were built to estimate mechanical properties using finite element analysis. Based on a generalized version of Hooke’s Law, the influence of diameter variation and particle clustering on the elastic modulus was evaluated. The mathematical relationship between the elastic modulus and volume fraction of the bioceramic was established using the Halpin–Tsai model. The results showed that with an increase in HA content from 10 wt% to 30 wt%, the elastic modulus of the composite increased from 2.36 GPa to 2.79 GPa, tensile strength decreased from 95 MPa to 74 MPa, and fracture elongation decreased from 63% to 23%, presenting brittle fracture failure. When the dispersion of particles was uniform, the elastic modulus was less affected by diameter variation, but the modulus anisotropic coefficient was greatly affected by the composition ratio, particle diameter, and dispersity. Hence, 3D-printed PEEK/HA composite filaments can meet the strength requirements of human bone, and understanding the influence of mechanical anisotropy plays a very important role in the design, manufacture, and clinical application of medical implants. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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22 pages, 5749 KiB  
Article
Effect of Different Comonomers Added to Graft Copolymers on the Properties of PLA/PPC/PLA-g-GMA Blends
by Lixin Song, Qian Zhang, Yongsheng Hao, Yongchao Li, Weihan Chi, Fei Cong, Ying Shi and Li-Zhi Liu
Polymers 2022, 14(19), 4088; https://doi.org/10.3390/polym14194088 - 29 Sep 2022
Cited by 7 | Viewed by 2119
Abstract
The melt-free radical grafting of glycidyl methacrylate (GMA) onto poly (lactic acid) (PLA) with styrene (St), α-methylstyrene (AMS), and epoxy resin (EP) as comonomers in a twin-screw extruder was used to prepare PLA-g-GMA graft copolymers. The prepared graft copolymers were then used as [...] Read more.
The melt-free radical grafting of glycidyl methacrylate (GMA) onto poly (lactic acid) (PLA) with styrene (St), α-methylstyrene (AMS), and epoxy resin (EP) as comonomers in a twin-screw extruder was used to prepare PLA-g-GMA graft copolymers. The prepared graft copolymers were then used as compatibilizers to prepare PLA/PPC/PLA-g-GMA blends by melt blending with PLA and polypropylene carbonate (PPC), respectively. The effects of different comonomers in the PLA-g-GMA graft copolymers on the thermal, rheological, optical, and mechanical properties and microstructure of the blends were studied. It was found that the grafting degree of PLA-g-GMA graft copolymers was increased to varying degrees after the introduction of comonomers in the PLA-g-GMA grafting reaction system. When St was used as the comonomer, the grafting degree of the PLA-g-GMA graft copolymer increased most significantly, from 0.8 to 1.6 phr. St as a comonomer also most improved the compatibility between PLA and PPC, and the haze of the blends was reduced while maintaining high transmittance. In addition, the PLA-g-GMA graft copolymer with the introduction of St as a comonomer significantly improved the impact toughness of the blends, while the thermal stability and tensile strength of the blends remained largely unchanged. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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16 pages, 5274 KiB  
Article
Mechanical, Hydrophobic, and Barrier Properties of Nanocomposites of Modified Polypropylene Reinforced with Low-Content Attapulgite
by Chi-Hui Tsou, Rui Zeng, Chih-Yuan Tsou, Jui-Chin Chen, Ya-Li Sun, Zheng-Lu Ma, Manuel Reyes De Guzman, Lian-Jie Tu, Xin-Yuan Tian and Chin-San Wu
Polymers 2022, 14(17), 3696; https://doi.org/10.3390/polym14173696 - 5 Sep 2022
Cited by 9 | Viewed by 1857
Abstract
Attapulgite (ATT) has never been used as a barrier additive in polypropylene (PP). As a filler, ATT should be added in high content to PP. However, that would result in increased costs. Moreover, the compatibility between ATT and the PP matrix is poor [...] Read more.
Attapulgite (ATT) has never been used as a barrier additive in polypropylene (PP). As a filler, ATT should be added in high content to PP. However, that would result in increased costs. Moreover, the compatibility between ATT and the PP matrix is poor due to the lack of functional groups in PP. In this study, carboxylic groups were introduced to PP to form a modified polypropylene (MPP). ATT was purified, and a low content of it was added to MPP to prepare MPP/ATT nanocomposites. The analysis from FTIR indicated that ATT could react with MPP. According to the results of oxygen and water permeability tests, the barrier performance of the nanocomposite was optimal when the ATT content was 0.4%. This great improvement in barrier performance might be ascribed to the following three reasons: (1) The existence of ATT extended the penetration path of O2 or H2O molecules; (2) O2 or H2O molecules may be adsorbed and stored in the porous structure of ATT; (3) Most importantly, –COOH of MPP reacted with –OH on the surface of ATT, thereby the inner structure of the nanocomposite was denser, and it was less permeable to molecules. Therefore, nanocomposites prepared by adding ATT to MPP have excellent properties and low cost. They can be used as food packaging materials and for other related applications. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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14 pages, 3869 KiB  
Article
Properties and Fabrication of Waterborne Polyurethane Superhydrophobic Conductive Composites with Coupling Agent-Modified Fillers
by Fangfang Wang, Jihao Ci and Jiang Fan
Polymers 2022, 14(15), 3093; https://doi.org/10.3390/polym14153093 - 29 Jul 2022
Cited by 2 | Viewed by 1490
Abstract
The addition of abundant fillers to obtain conductive and superhydrophobic waterborne polyurethane (WPU) composites generally results in increased interfaces in the composites, leading to reduced adhesion and poor corrosion resistance. Fillers such as Polytetrafluoroethylene (PTFE) and multi-walled carbon nanotubes (MWCNTs) were first treated [...] Read more.
The addition of abundant fillers to obtain conductive and superhydrophobic waterborne polyurethane (WPU) composites generally results in increased interfaces in the composites, leading to reduced adhesion and poor corrosion resistance. Fillers such as Polytetrafluoroethylene (PTFE) and multi-walled carbon nanotubes (MWCNTs) were first treated by a coupling agent to reduce the contents of the fillers. Thus, in this work, WPU superhydrophobic conductive composites were prepared using electrostatic spraying (EsS). The polar groups (-OH and -COOH, etc.) on the WPU, PTFE, and MWCNTs were reacted with the coupling agent, making the WPU, PTFE, and MWCNTs become crosslinked together. Thus, the uniformity of the coating was improved and its curing interfaces were reduced, causing enhanced corrosion resistance. The dehydration reaction that occurred between the silane coupling agent and the polar surface of Fe formed -NH2 groups, increasing the adhesion of the coating to the steel substrate and then solving the problems of low adhesion, easy delamination, and exfoliation. With the increased content of the modified fillers, the conductivity and hydrophobic property of the composite were amplified, and its corrosion resistance and adhesion were first strengthened and then declined. The composite with the WPU, PTFE, MWCNTs, and KH-550 at a mass ratio of 7:1.5:0.1:0.032 held excellent properties; its volume resistivity and WCA were 1.5 × 104 Ω·cm and 155°, respectively. Compared with the pure WPU coating, its adhesive and anticorrosive properties were both better. This provides a foundation for the fabrication and application of anticorrosive and conductive waterborne composites. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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17 pages, 5411 KiB  
Article
Synergistic Effects of DOPO-Based Derivative and Organo-Montmorillonite on Flame Retardancy, Thermal Stability and Mechanical Properties of Polypropylene
by Weijiang Huang, Kui Wang, Chunyun Tu, Xiaolu Xu, Qin Tian, Chao Ma, Qiuping Fu and Wei Yan
Polymers 2022, 14(12), 2372; https://doi.org/10.3390/polym14122372 - 11 Jun 2022
Cited by 15 | Viewed by 2130
Abstract
Polypropylene (PP), as a general thermoplastic polymer, is broadly used in different fields. However, the high flammability, melt dripping and poor mechanical properties of PP are a constraint to the expansion of its applications. In this paper, PP composites containing a combination of [...] Read more.
Polypropylene (PP), as a general thermoplastic polymer, is broadly used in different fields. However, the high flammability, melt dripping and poor mechanical properties of PP are a constraint to the expansion of its applications. In this paper, PP composites containing a combination of a phenethyl-bridged DOPO derivative (PN-DOPO) and organic montmorillonite (OMMT) were prepared via melt blending. The synergistic effects of PN-DOPO and OMMT on the flame retardancy, thermal stability and mechanical properties of PP composites were investigated systematically. The results showed that 20 wt% addition of PN-DOPO with OMMT improved the flame retardancy of PP composites. In particular, the introduction of 17 wt% PN-DOPO and 3 wt% OMMT increased the LOI values of the PP matrix from 17.2% to 23.6%, and the sample reached the V-0 level and reduced the heat release rate and total heat release. TGA indicated that OMMT could improve the thermal stability of the PP/PN-DOPO blends and promote the char residues of PP systems. Rheological behaviour showed a higher storage modulus, loss modulus and complex viscosity of PP/PN-DOPO/OMMT composites, suggesting a more effective network structure. In addition, the tensile strength, flexural properties and impact strength of the PP/PN-DOPO/OMMT composites actually increased for a good dispersion effect. Combined with the char layer analysis, the introduction of OMMT promoted more continuous and compact structural layers containing an aluminium–silicon barrier and phosphorus-containing carbonaceous char in the condensed phase. OMMT can improve the flame retardancy, thermal stability and mechanical properties of PP, and, thus, PN-DOPO/OMMT blends can serve as an efficient synergistic system for flame-retarded PP composites. Full article
(This article belongs to the Special Issue Mechanical and Structure–Property Relationships of Polymer Composites)
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