Durability and Degradation of Polymeric Materials II

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

Deadline for manuscript submissions: closed (25 July 2023) | Viewed by 53107

Special Issue Editor


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Guest Editor
Mechanical and Aerospace Engineering Department, College of Engineering, United Arab Emirates University, Al-Ain 15551, United Arab Emirates
Interests: materials science and engineering; materials characterization; polymeric and composite materials; biomaterials and tissue engineering; biomechanics; durability and degradation of polymeric and composite materials; welding of metallic and polymeric materials; corrosion; fatigue and fracture mechanics; renewable energy; finite element method
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Special Issue Information

Dear Colleagues,

Starting from the 20th century, the usage of polymers has been exponentially growing, and it has found application in almost all sectors, replacing many conventional materials, including metals. However, under the influence of environmental factors, such as light, heat, and chemicals, the degradation of polymers occurs, which then alters their material properties. Furthermore, environmental concerns surrounding the disposal of polymeric materials have turned the scientific world to think about highly durable polymers. Researchers have already produced advanced polymeric materials that can meet a wide range of high-end applications.

This upcoming Special Issue aims to provide a platform for researchers and practitioners to present new research and developments (research/reviews) focusing on the following topics:

  • The production of durable polymers;
  • Chemical degradation;
  • Recycling;
  • The bio/thermal degradation of polymers;
  • The assessment of polymer durability;
  • Various studies on degradation of polymers;
  • The environmental impact of polymers;
  • The recycling and upcycling of polymers;
  • Durable designs and polymer engineering.

Prof. Dr. Abdel-Hamid I. Mourad
Guest Editor

Manuscript Submission Information

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Keywords

  • the production of durable polymers
  • chemical degradation
  • recycling
  • the bio/thermal degradation of polymers
  • the assessment of polymer durability
  • various studies on degradation of polymers
  • the environmental impact of polymers
  • the recycling and upcycling of polymers
  • durable designs and polymer engineering

Published Papers (22 papers)

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18 pages, 5766 KiB  
Article
Thermal Degradation Studies of Poly(2-ethyl hexyl acrylate) in the Presence of Nematic Liquid Crystals
by Amina Bouriche, Lamia Alachaher-Bedjaoui, Ana Barrera, Jean-Noël Staelens and Ulrich Maschke
Polymers 2023, 15(19), 3934; https://doi.org/10.3390/polym15193934 - 29 Sep 2023
Cited by 1 | Viewed by 835
Abstract
The thermal degradation behavior of Poly(2-ethyl hexyl hcrylate) (Poly(2-EHA)), blended with a commercially available nematic liquid crystal (LC) mixture, was investigated by thermal gravimetric analysis (TGA). Different heating rates, ranging from 5 to 200 °C/min, were applied under an inert atmosphere. Based on [...] Read more.
The thermal degradation behavior of Poly(2-ethyl hexyl hcrylate) (Poly(2-EHA)), blended with a commercially available nematic liquid crystal (LC) mixture, was investigated by thermal gravimetric analysis (TGA). Different heating rates, ranging from 5 to 200 °C/min, were applied under an inert atmosphere. Based on the TGA results, activation energies (Eα) at different conversion rates (α) were determined using three integral isoconversion methods: Flynn-Wall-Ozawa (FWO), Tang, and Kissinger-Akahira-Sunose (KAS). It can be noticed that the global evolution of these activation energies was the same for the three models. The coefficient of determination R2 presented values generally higher than 0.97. Using these models, the Eα value for the LC remains constant at 64 kJ/mol for all conversions rates. For the polymer Poly(2-EHA), applying the Tang and FWO models, the activation energy presents a variation ranging from 80 kJ/mol, for conversion α = 0.1, to 170 kJ/mol, for α = 0.9. For the third model (KAS), this energy varies between 80 and 220 kJ/mol in the same range of α. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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22 pages, 6121 KiB  
Article
Improvement of Chitosan Films Properties by Blending with Cellulose, Honey and Curcumin
by Noha G. Madian, Basant A. El-Ashmanty and Hadeel K. Abdel-Rahim
Polymers 2023, 15(12), 2587; https://doi.org/10.3390/polym15122587 - 6 Jun 2023
Cited by 7 | Viewed by 1543
Abstract
Chitosan is a natural biopolymer that can be used in biomedical applications, tissue engineering, and wound dressing because of its biodegradability, biocompatibility, and antibacterial activity. The blending of chitosan films with natural biomaterials such as cellulose, honey, and curcumin was studied at different [...] Read more.
Chitosan is a natural biopolymer that can be used in biomedical applications, tissue engineering, and wound dressing because of its biodegradability, biocompatibility, and antibacterial activity. The blending of chitosan films with natural biomaterials such as cellulose, honey, and curcumin was studied at different concentrations in order to improve their physical properties. Fourier transform infrared (FTIR) spectroscopy, mechanical tensile properties, X-ray diffraction (XRD), antibacterial effects, and scanning electron microscopy (SEM) were studied for all blended films. The XRD, FTIR, and mechanical results showed that films blended with curcumin were more rigid and compatible and had higher antibacterial effects than other blended films. In addition, XRD and SEM showed that blending chitosan films with curcumin decreases the crystallinity of the chitosan matrix compared to cellulose and honey blending films due to increased intermolecular hydrogen bonding, which reduces the close packing of the CS matrix. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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12 pages, 2173 KiB  
Article
Polypropylene Degradation on Co-Rotating Twin-Screw Extruders
by Matthias Altepeter, Volker Schöppner, Sven Wanke, Laura Austermeier, Philipp Meinheit and Leon Schmidt
Polymers 2023, 15(9), 2181; https://doi.org/10.3390/polym15092181 - 4 May 2023
Cited by 1 | Viewed by 1866
Abstract
Nowadays, usable plastic materials with defined properties are created by blending additives into the base polymer. This is the main task of compounding on co-rotating twin-screw extruders. The thermal and mechanical stress occurring in the process leads to a mostly irreversible damage to [...] Read more.
Nowadays, usable plastic materials with defined properties are created by blending additives into the base polymer. This is the main task of compounding on co-rotating twin-screw extruders. The thermal and mechanical stress occurring in the process leads to a mostly irreversible damage to the material. Consequently, the properties of the polymer melt and the subsequent product are affected. The material degradation of polypropylene (PP) on a 28 mm twin-screw extruder has already been studied and modeled at Kunststofftechnik Paderborn. In this work, the transferability of the previous results to other machine sizes and polypropylene compounds were investigated experimentally. Therefore, pure polypropylene was processed with screw diameters of 25 mm and 45 mm. Furthermore, polypropylene compounds with titanium dioxide as well as carbon fibers were considered on a 28 mm extruder. In the course of the evaluation of the pure polypropylene, the melt flow rates of the samples were measured and the molar masses were calculated on this basis. The compounds were analyzed by gel permeation chromatography. As in the previous investigations, high rotational speeds, low throughputs and high melt temperatures lead to a higher material degradation. In addition, it is illustrated that the previously developed model for the calculation of material degradation is generally able to predict the degradation even for different machine sizes by adjusting the process coefficients. In summary, this article shows that compounders can use the recommendations for action and the calculation model for the material degradation of polypropylene, irrespective of the machine size, to design processes that are gentle on the material. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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12 pages, 2760 KiB  
Article
Kinetic Analysis of Thermal Degradation of Recycled Polypropylene and Polystyrene Mixtures Using Regenerated Catalyst from Fluidized Catalytic Cracking Process (FCC)
by Paul Palmay, Leslie Pillajo, Mónica Andrade, Carlos Medina and Diego Barzallo
Polymers 2023, 15(9), 2035; https://doi.org/10.3390/polym15092035 - 25 Apr 2023
Viewed by 1863
Abstract
The pyrolysis process is a thermochemical recycling process that in recent years has gained importance due to its application in plastic waste, which is one of the biggest environmental problems today. Thus, it is essential to carry out kinetic and thermodynamic analyses to [...] Read more.
The pyrolysis process is a thermochemical recycling process that in recent years has gained importance due to its application in plastic waste, which is one of the biggest environmental problems today. Thus, it is essential to carry out kinetic and thermodynamic analyses to understand the thermocatalytic degradation processes involved in plastic waste mixtures. In this sense, the main objective of this study is to analyze the degradation kinetics of the specific mixture of polypropylene (25%) and polystyrene (75%) with 10% mass of regenerated FCC catalyst which was recovered from conventional refining processes using 3 heating rates at 5, 10 and 15 K min−1 by thermogravimetric analysis (TGA). The obtained TGA data were compared with the isoconversional models used in this work that include Friedman (FR), Kissinger Akahira Sunose (KAS), Flynn–Wall–Ozawa (FWO), Starink (ST) and Miura–Maki (MM) in order to determine the one that best fits the experimental data and to analyze the activation energy and the pre-exponential factor; the model is optimized by means of the difference of minimum squares. Activation energy values between 148 and 308 kJ/mol were obtained where the catalytic action has been notorious, decreasing the activation energy values with respect to thermal processes. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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21 pages, 5944 KiB  
Article
Effect of LNR-g-MMA on the Mechanical Properties and Lifetime Estimation of PLA/PP Blends
by Kraiwut Wisetkhamsai, Weerawat Patthaveekongka and Wanvimon Arayapranee
Polymers 2023, 15(7), 1712; https://doi.org/10.3390/polym15071712 - 29 Mar 2023
Viewed by 1526
Abstract
Polylactide (PLA) polymer, polypropylene (PP) polymer, and a PLA/PP (70:30 wt%) blend, with liquid natural rubber−graft−methy methacrylate (LNR−g−MMA) of 0.0, 2.5, 5.0, and 10.0 phr as compatibilizers, were prepared by internal mixing and compression molding. The effect of LNR-g-MMA content on the morphology, [...] Read more.
Polylactide (PLA) polymer, polypropylene (PP) polymer, and a PLA/PP (70:30 wt%) blend, with liquid natural rubber−graft−methy methacrylate (LNR−g−MMA) of 0.0, 2.5, 5.0, and 10.0 phr as compatibilizers, were prepared by internal mixing and compression molding. The effect of LNR-g-MMA content on the morphology, mechanical properties, water absorption, thermal degradation, and a lifetime of blends based on PLA and PP was investigated. Scanning electron microscopy (SEM) revealed that the PLA/PP blend underwent phase separation, and the presence of LNR−g−MMA in the PLA/PP blend showed a more homogenized and refined blend morphology. Hence, the addition of LNR−g−MMA was used as a compatibilizer to induce miscibility in the PLA/PP blend. The values of tensile strength, elongation at break, and impact strength of the polymer blends increased, whereas water absorption values decreased with increased LNR−g−MMA content. Thermal degradation kinetics was studied over a temperature range of 50–800 °C with multiple heating rates. The results demonstrated that the thermal stability of blends without LNR-g-MMA was greater than that of blends with LNR−g−MMA and that the thermal stability decreased with increasing LNR−g−MMA content. The activation energy (Ea) was calculated by using the Kissinger–Akahira–Sunose method. The Ea value of PLA was much lower than that of PP, and incorporating PP in the PLA matrix increased the Ea. The addition of LNR−g−MMA to the PLA/PP blend decreased the Ea. The lifetime of PLA/PP blends was reduced with the addition of LNR−g−MMA. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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17 pages, 5120 KiB  
Article
The Effect of Accelerated Aging on the Molecular Weight and Thermal and Mechanical Properties of Polyester Yarns Containing Ceramic Particles
by Gabriela Mijas, Marta Riba-Moliner and Diana Cayuela
Polymers 2023, 15(6), 1348; https://doi.org/10.3390/polym15061348 - 8 Mar 2023
Cited by 3 | Viewed by 1601
Abstract
The accelerated aging of polyethylene terephthalate (PET) multifilament yarns containing nano or microparticles of titanium dioxide (TiO2), silicon carbide (SiC), or fluorite (CaF2) at a maximum percentage of 2% has been studied. For this, the yarn samples were introduced [...] Read more.
The accelerated aging of polyethylene terephthalate (PET) multifilament yarns containing nano or microparticles of titanium dioxide (TiO2), silicon carbide (SiC), or fluorite (CaF2) at a maximum percentage of 2% has been studied. For this, the yarn samples were introduced into a climatic chamber at 50 °C, 50% relative humidity, and an ultraviolet A (UVA) irradiance of 1.4 W/m2. They were then removed from the chamber after periods of between 21 and 170 days of exposure. Subsequently, the variation in weight average molecular weight, number molecular weight, and polydispersity was evaluated by gel permeation chromatography (GPC), the surface appearance was evaluated using scanning electron microscopy (SEM), the thermal properties were evaluated using differential scanning calorimetry (DSC), and the mechanical properties were evaluated using dynamometry. The results showed that, at the test conditions, there was degradation in all of the exposed substrates, possibly due to the excision of the chains that make up the polymeric matrix, which resulted in the variation in the mechanical and thermal properties depending on the type and size of the particle used. This study provides insight into the evolution of the properties of PET-based nano- and microcomposites and might be helpful when selecting materials for specific applications, which is of great interest from an industrial point of view. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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17 pages, 6111 KiB  
Article
Effect of Aging on Unidirectional Composite Laminate Polyethylene for Body Armor
by Amy Engelbrecht-Wiggans, Zois Tsinas, Ajay Krishnamurthy and Amanda L. Forster
Polymers 2023, 15(6), 1347; https://doi.org/10.3390/polym15061347 - 8 Mar 2023
Cited by 2 | Viewed by 1565
Abstract
The construction of ballistic-resistant body armor is experiencing an increasing use of flexible unidirectional (UD) composite laminates that comprise multiple layers. Each UD layer contains hexagonally packed high-performance fibers with a very low modulus matrix (sometimes referred to as binder resins). Laminates are [...] Read more.
The construction of ballistic-resistant body armor is experiencing an increasing use of flexible unidirectional (UD) composite laminates that comprise multiple layers. Each UD layer contains hexagonally packed high-performance fibers with a very low modulus matrix (sometimes referred to as binder resins). Laminates are then made from orthogonal stacks of these layers, and these laminate-based armor packages offer significant performance advantages over standard woven materials. When designing any armor system, the long-term reliability of the armor materials is critical, particularly with regard to stability with exposure to temperature and humidity, as these are known causes of degradation in commonly used body armor materials. To better inform future armor designers, this work investigates the tensile behavior of an ultra-high molar mass polyethylene (UHMMPE) flexible UD laminate that was aged for at least 350 d at two accelerated conditions: 70 °C at 76% relative humidity (RH) and 70 °C in a desiccator. Tensile tests were performed at two different loading rates. The mechanical properties of the material after ageing demonstrated less than 10% degradation in tensile strength, indicating high reliability for armor made from this material. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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11 pages, 1284 KiB  
Article
Microplastic Removal from Drinking Water Using Point-of-Use Devices
by Ashlyn G. Cherian, Zeyuan Liu, Michael J. McKie, Husein Almuhtaram and Robert C. Andrews
Polymers 2023, 15(6), 1331; https://doi.org/10.3390/polym15061331 - 7 Mar 2023
Cited by 9 | Viewed by 4373
Abstract
The occurrence of microplastics in drinking water has drawn increasing attention due to their ubiquity and unresolved implications regarding human health. Despite achieving high reduction efficiencies (70 to >90%) at conventional drinking water treatment plants (DWTPs), microplastics remain. Since human consumption represents a [...] Read more.
The occurrence of microplastics in drinking water has drawn increasing attention due to their ubiquity and unresolved implications regarding human health. Despite achieving high reduction efficiencies (70 to >90%) at conventional drinking water treatment plants (DWTPs), microplastics remain. Since human consumption represents a small portion of typical household water use, point-of-use (POU) water treatment devices may provide the additional removal of microplastics (MPs) prior to consumption. The primary objective of this study was to evaluate the performance of commonly used pour-through POU devices, including those that utilize combinations of granular activated carbon (GAC), ion exchange (IX), and microfiltration (MF), with respect to MP removal. Treated drinking water was spiked with polyethylene terephthalate (PET) and polyvinyl chloride (PVC) fragments, along with nylon fibers representing a range of particle sizes (30–1000 µm) at concentrations of 36–64 particles/L. Samples were collected from each POU device following 25, 50, 75, 100 and 125% increases in the manufacturer’s rated treatment capacity, and subsequently analyzed via microscopy to determine their removal efficiency. Two POU devices that incorporate MF technologies exhibited 78–86% and 94–100% removal values for PVC and PET fragments, respectively, whereas one device that only incorporates GAC and IX resulted in a greater number of particles in its effluent when compared to the influent. When comparing the two devices that incorporate membranes, the device with the smaller nominal pore size (0.2 µm vs. ≥1 µm) exhibited the best performance. These findings suggest that POU devices that incorporate physical treatment barriers, including membrane filtration, may be optimal for MP removal (if desired) from drinking water. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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13 pages, 5720 KiB  
Article
Microscopic Mechanism of Electrical Aging of PVDF Cable Insulation Material
by Zhiyi Pang, Yi Li, Hanbo Zheng and Rui Qin
Polymers 2023, 15(5), 1286; https://doi.org/10.3390/polym15051286 - 3 Mar 2023
Viewed by 1701
Abstract
In this study, the quantum chemical method was used to investigate the microscopic characteristics of α-poly viny difluoride (PVDF) molecules under the influence of an electric field, and the impact of mechanical stress and electric field polarization on the insulation performance of PVDF [...] Read more.
In this study, the quantum chemical method was used to investigate the microscopic characteristics of α-poly viny difluoride (PVDF) molecules under the influence of an electric field, and the impact of mechanical stress and electric field polarization on the insulation performance of PVDF was analyzed through the material’s structural and space charge characteristics. The findings reveal that long-term polarization of an electric field leads to a gradual decline in stability and a reduction in the energy gap of the front orbital, resulting in the improved conductivity of PVDF molecules and a change in the reactive active site of the molecular chain. When the energy gap reaches a certain value, a chemical bond fracture occurs, with the C-H and C-F bonds at the ends of the backbone breaking first to form free radicals. This process is triggered by an electric field of 8.7414 × 109 V/m, which leads to the emergence of a virtual frequency in the infrared spectrogram and the eventual breakdown of the insulation material. These results are of great significance in understanding the aging mechanism of electric branches in PVDF cable insulation and optimizing the modification of PVDF insulation materials. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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17 pages, 5608 KiB  
Article
Sustainable Engineered Design and Scalable Manufacturing of Upcycled Graphene Reinforced Polylactic Acid/Polyurethane Blend Composites Having Shape Memory Behavior
by Busra Cetiner, Gulayse Sahin Dundar, Yusuf Yusufoglu and Burcu Saner Okan
Polymers 2023, 15(5), 1085; https://doi.org/10.3390/polym15051085 - 21 Feb 2023
Cited by 8 | Viewed by 1931
Abstract
Material design in shape memory polymers (SMPs) carries significant importance in attaining high performance and adjusting the interface between additive and host polymer matrix to increase the degree of recovery. Herein, the main challenge is to enhance the interfacial interactions to provide reversibility [...] Read more.
Material design in shape memory polymers (SMPs) carries significant importance in attaining high performance and adjusting the interface between additive and host polymer matrix to increase the degree of recovery. Herein, the main challenge is to enhance the interfacial interactions to provide reversibility during deformation. The present work describes a newly designed composite structure by manufacturing a high-degree biobased and thermally induced shape memory polylactic acid (PLA)/thermoplastic polyurethane (TPU) blend incorporated with graphene nanoplatelets obtained from waste tires. In this design, blending with TPU enhances flexibility, and adding GNP provides functionality in terms of mechanical and thermal properties by enhancing circularity and sustainability approaches. The present work provides a scalable compounding approach for industrial applications of GNP at high shear rates during the melt mixing of single/blend polymer matrices. By evaluating the mechanical performance of the PLA and TPU blend composite composition at a 9:1 weight percentage, the optimum GNP amount was defined as 0.5 wt%. The flexural strength of the developed composite structure was enhanced by 24% and the thermal conductivity by 15%. In addition, a 99.8% shape fixity ratio and a 99.58% recovery ratio were attained within 4 min, resulting in the spectacular enhancement of GNP attainment. This study provides an opportunity to understand the acting mechanism of upcycled GNP in improving composite formulations and to develop a new perspective on the sustainability of PLA/TPU blend composites with an increased biobased degree and shape memory behavior. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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25 pages, 9096 KiB  
Article
Effects of Bamboo Leaf Fiber Content on Cushion Performance and Biodegradability of Natural Rubber Latex Foam Composites
by Keavalin Jitkokkruad, Kasama Jarukumjorn, Chaiwat Raksakulpiwat, Saowapa Chaiwong, Jutarat Rattanakaran and Tatiya Trongsatitkul
Polymers 2023, 15(3), 654; https://doi.org/10.3390/polym15030654 - 27 Jan 2023
Cited by 5 | Viewed by 3963
Abstract
Bamboo leaf fiber (BLF) was incorporated into an eco-friendly foam cushion made from natural rubber latex (NRL) to enhance the biodegradation rate. The objective of this work was to investigate the effects of BLF content on the foam structure, mechanical properties, cushion performance, [...] Read more.
Bamboo leaf fiber (BLF) was incorporated into an eco-friendly foam cushion made from natural rubber latex (NRL) to enhance the biodegradation rate. The objective of this work was to investigate the effects of BLF content on the foam structure, mechanical properties, cushion performance, and biodegradability. The NRL foam cushion nets with and without BLF were prepared using the Dunlop method along with microwave-assisted vulcanization. BLF (90–106 µm in length) at various loadings (0.00, 2.50, 5.00, 7.50, and 10.00 phr) were introduced to the latex compounds before gelling and vulcanizing steps. Scanning electron microscopy (SEM) showed that the BLF in a NRL foam caused an increase in cell size and a decrease in the number of cells. The changes in the cell structure and number of cells resulted in increases in the bulk density, hardness, compression set, compressive strength, and cushion coefficient. A soil burial test of 24 weeks revealed faster weight loss of 1.8 times when the BLF content was 10.00 phr as compared to the NRL foam without BLF. The findings of this work suggest the possibility of developing an eco-friendly cushion with a faster degradation rate while maintaining cushion performance, which could be a better alternative for sustainable packaging in the future. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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11 pages, 2183 KiB  
Article
The Effect of Shear on the Properties of an Associated Polymer Solution for Oil Displacement
by Guoying Jiao, Shijie Zhu, Zhongbin Ye, Zheng Shu, Xijin Wang and Daming Wang
Polymers 2023, 15(3), 616; https://doi.org/10.3390/polym15030616 - 25 Jan 2023
Cited by 4 | Viewed by 1602
Abstract
Polymer flooding is one of the techniques used to enhance oil recovery from depleted hydrocarbon reservoirs. Although this technology is popular for this application, the shearing effect in the injection process causes poor performance, which is an obstacle to meeting the needs of [...] Read more.
Polymer flooding is one of the techniques used to enhance oil recovery from depleted hydrocarbon reservoirs. Although this technology is popular for this application, the shearing effect in the injection process causes poor performance, which is an obstacle to meeting the needs of the formation. An experimental evaluation of the rheological properties, viscoelasticity, hydrodynamic size, static adsorption, and seepage characteristics of the associated polymer solution before and after shearing was conducted to determine the influence of shearing on the polymer solution. The results show that the effect of shear on the polymer was irreversible, and the properties of the polymer solution damaged by shear were attenuated. After the critical associating concentration, the associated polymer can recover its solution properties through hydrophobic association, which can improve the shear resistance of the polymer solution and make its own rheological law and reduce the viscoelastic change. Although the hydrodynamic size, viscoelasticity, and adsorption capacity of the polymer solution after shear failure decreased, strong flow resistance during porous media seepage and mobility control was achieved. Improving the shear resistance of the polymer solution by increasing the intermolecular force is proposed to develop new polymer systems for subsequent oil displacement. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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16 pages, 3086 KiB  
Article
Insight into Degrading Effects of Two Fungi on Polyurethane Coating Failure in a Simulated Atmospheric Environment
by Xiangping Hao, Kexin Yang, Dawei Zhang and Lin Lu
Polymers 2023, 15(2), 328; https://doi.org/10.3390/polym15020328 - 9 Jan 2023
Cited by 3 | Viewed by 1755
Abstract
Two different fungi, Talaromyces funiculosus (T. funiculosus) and Phanerochaete chrysosporium (P. chrysosporium), were collected from the Xishuangbanna atmospheric corrosion site and incubated on a polyurethane (PU) coating at 30 °C for two weeks under 95% relative humidity (RH). The biodegrading [...] Read more.
Two different fungi, Talaromyces funiculosus (T. funiculosus) and Phanerochaete chrysosporium (P. chrysosporium), were collected from the Xishuangbanna atmospheric corrosion site and incubated on a polyurethane (PU) coating at 30 °C for two weeks under 95% relative humidity (RH). The biodegrading effects of these fungi on the coating failure were investigated from aspects of metabolism and electrochemistry. The results showed that T. funiculosus contributed more to the degradation of the PU coating failure than P. chrysosporium, and two factors played dominant roles. First, the weight of the T. funiculosus mycelium was nearly 3 times more than that of P. chrysosporium, indicating there was more substrate mycelium of T. funiculosus deep into the coatings to get more nutrition in atmospheric during colonization. Second, T. funiculosus secreted carboxylic acids, such as citric, propanoic, succinic, and tartaric acids, and accelerated the hydrolysis of the ester and urethane bonds in the PU coatings. As a result, the mycelium of T. funiculosus readily penetrated the interface of the coating and substrate resulting in a rapid proliferation. Thus, the |Z|0.01Hz value of the coating decreased to 5.1 × 104 Ω·cm2 after 14 days of colonization by T. funiculosus while the value remained at 7.2 × 107 Ω·cm2 after colonization by P. chrysosporium. These insights suggest that the biodegradation process in simulated atmospheric environments would provide theoretical guidance and directions for the design of antifungal PU coatings. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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16 pages, 4168 KiB  
Article
Catalytic Pyrolysis of Polystyrene Waste in Hydrocarbon Medium
by Konstantin I. Dement’ev, Stanislav P. Bedenko, Yulia D. Minina, Aniya A. Mukusheva, Olga A. Alekseeva and Timur A. Palankoev
Polymers 2023, 15(2), 290; https://doi.org/10.3390/polym15020290 - 6 Jan 2023
Cited by 5 | Viewed by 1988
Abstract
The fast catalytic pyrolysis of polystyrene in the hydrocarbon medium (light and heavy cycle oil) over zeolite catalysts at 450–550 °C was investigated. The influence of reaction conditions (medium, temperature, vapor residence time, polystyrene concentration) on polymer conversion and product distribution was studied. [...] Read more.
The fast catalytic pyrolysis of polystyrene in the hydrocarbon medium (light and heavy cycle oil) over zeolite catalysts at 450–550 °C was investigated. The influence of reaction conditions (medium, temperature, vapor residence time, polystyrene concentration) on polymer conversion and product distribution was studied. It was found that the polymer conversion is close to 100%, while ethylbenzene, benzene, and toluene are the main products of its transformation. The maximum yield of ethylbenzene (80%) was achieved at 550 °C, vapor residence time 1–2 s, polystyrene concentration 10%, and heavy cycle oil as the medium. The influence of zeolite topology on product distribution was explored. The possible mechanism of polystyrene pyrolysis was proposed. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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15 pages, 3739 KiB  
Article
Improvement in Acid Resistance of Polyimide Membranes: A Sustainable Cross-Linking Approach via Green-Solvent-Based Fenton Reaction
by Srinath Ravi, Woo-Seok Kang, Hyung-Kae Lee, You-In Park, Hosik Park, In-Chul Kim and Young-Nam Kwon
Polymers 2023, 15(2), 264; https://doi.org/10.3390/polym15020264 - 4 Jan 2023
Cited by 2 | Viewed by 1956
Abstract
In this study, we present a facile surface modification method using green solvents for a commercial polyimide (PI) nanofiltration membrane to exhibit good acid stability. To enhance acid stability, the PI organic solvent nanofiltration membrane was modified using Fenton’s reaction, an oxidative cross-linking [...] Read more.
In this study, we present a facile surface modification method using green solvents for a commercial polyimide (PI) nanofiltration membrane to exhibit good acid stability. To enhance acid stability, the PI organic solvent nanofiltration membrane was modified using Fenton’s reaction, an oxidative cross-linking process, using environmentally friendly solvents: water and ethanol. The surface properties of the pristine and modified PI membranes were investigated and compared using various analytical tools. We studied the surface morphology using scanning electron microscopy, performed elemental analysis using X-ray photoelectron spectroscopy, investigated chemical bonds using attenuated total reflectance-Fourier transform infrared spectroscopy, and studied thermal stability using thermogravimetric analysis. The acid resistances of the pristine and modified membranes were confirmed through performance tests. The pristine PI nanofiltration membrane exposed to a 50 w/v% sulfuric acid for 4 h showed an increase in the normalized water flux to 205% and a decrease in the MgSO4 normalized rejection to 44%, revealing damage to the membrane. The membrane modified by the Fenton reaction exhibited a decline in flux and improved rejection, which are typical performance changes after surface modification. However, the Fenton-modified membrane exposed to 50 w/v% sulfuric acid for 4 h showed a flux increase of 7% and a rejection increase of 4%, indicating improved acid resistance. Furthermore, the Fenton post-treatment enhanced the thermal stability and organic solvent resistance of the PI membrane. This study shows that the acid resistance of PI membranes can be successfully improved by a novel and facile Fenton reaction using green solvents. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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15 pages, 2393 KiB  
Article
Studying the Physical and Chemical Properties of Polydimethylsiloxane Matrix Reinforced by Nanostructured TiO2 Supported on Mesoporous Silica
by Sari Katz, Noa Lachman, Nir Hafif, Lilach Rosh, Alexander Pevzner, Amir Lybman, Tal Amitay-Rosen, Ido Nir and Hadar Rotter
Polymers 2023, 15(1), 81; https://doi.org/10.3390/polym15010081 - 25 Dec 2022
Cited by 6 | Viewed by 3100
Abstract
In this study, a reactive adsorbent filler was integrated into a polymeric matrix as a novel reactive protective barrier without undermining its mechanical, thermal, and chemical properties. For this purpose, newly synthesized TiO2/MCM/polydimethylsiloxane (PDMS) composites were prepared, and their various properties [...] Read more.
In this study, a reactive adsorbent filler was integrated into a polymeric matrix as a novel reactive protective barrier without undermining its mechanical, thermal, and chemical properties. For this purpose, newly synthesized TiO2/MCM/polydimethylsiloxane (PDMS) composites were prepared, and their various properties were thoroughly studied. The filler, TiO2/MCM, is based on a (45 wt%) TiO2 nanoparticle catalyst inside the pores of ordered mesoporous silica, MCM-41, which combines a high adsorption capacity and catalytic capability. This study shows that the incorporation of TiO2/MCM significantly enhances the composite’s Young’s modulus in terms of tensile strength, as an optimal measurement of 1.6 MPa was obtained, compared with that of 0.8 MPa of pristine PDMS. The composites also showed a higher thermal stability, a reduction in the coefficient of thermal expansion (from 290 to 110 ppm/°C), a 25% reduction in the change in the normalized specific heat capacity, and an increase in the thermal degradation temperatures. The chemical stability in organic environments was improved, as toluene swelling decreased by 40% and the contact angle increased by ~15°. The enhanced properties of the novel synthesized TiO2/MCM/PDMS composite can be used in various applications where a high adsorption capacity and catalytic/photocatalytic activity are required, such as in protective equipment, microfluidic applications, and chemical sensor devices. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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13 pages, 3400 KiB  
Article
Selective Solvolysis of Bio-Based PU-Coated Fabric
by David De Smet, Jente Verjans and Myriam Vanneste
Polymers 2022, 14(24), 5452; https://doi.org/10.3390/polym14245452 - 13 Dec 2022
Cited by 3 | Viewed by 2209
Abstract
Polyurethane (PU) coatings are widely applied on high performing textiles due to their excellent durability and mechanical properties. PUs based on renewable resources were developed to improve the environmental impact of coatings by decreasing the carbon footprint. However, at the end-of-life, PU-coated textiles [...] Read more.
Polyurethane (PU) coatings are widely applied on high performing textiles due to their excellent durability and mechanical properties. PUs based on renewable resources were developed to improve the environmental impact of coatings by decreasing the carbon footprint. However, at the end-of-life, PU-coated textiles still end up as landfill or are incinerated since PUs are not biodegradable and are not being recycled at this moment. Therefore, the recycling of PU-coated substrates needs to be examined. This study reports the selective solvolysis of a polyester (PET) fabric coated with a bio-based PU using a 70% ZnCl2 aqueous solution. This method allowed the easy separation of the coating from the fabric. The thermal, chemical and mechanical characteristics of the virgin PET and recycled PET were examined via tensile strength tests, IR, TGA, DSC and GPC. Analysis of the fractions after solvolysis revealed that the PU was converted into the original polyol and an amine, corresponding to the isocyanate used for PU synthesis. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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13 pages, 3357 KiB  
Article
Large-Scale Preparation of Uniform Millet Bread-like Durable Benzoxazine-Phthalonitrile Foam with Outstanding Mechanical and Thermal Properties
by Wenwu Lei, Dengyu Wang, Qi Liu, Kui Li, Ying Li, Fei Zhong, Qiancheng Liu, Pan Wang, Wei Feng and Xulin Yang
Polymers 2022, 14(24), 5410; https://doi.org/10.3390/polym14245410 - 10 Dec 2022
Cited by 5 | Viewed by 1516
Abstract
It is essentially important to develop durable polymer foams for services in high-temperature conditions. The current study reported the preparations and properties of a high-performance benzoxazine-phthalonitrile (BZPN) foam by utilizing azodicarbonamide and tween-80 as the blowing agent and stabilizer, respectively. Rheological and curing [...] Read more.
It is essentially important to develop durable polymer foams for services in high-temperature conditions. The current study reported the preparations and properties of a high-performance benzoxazine-phthalonitrile (BZPN) foam by utilizing azodicarbonamide and tween-80 as the blowing agent and stabilizer, respectively. Rheological and curing studies indicated that the appropriate foaming temperature for BZPN foam is below 180 °C, and its foaming viscosity window is below 20 Pa·s. Guided by these results, uniform millet bread-like BZPN foams with decimeter leveling size were successfully realized, suggesting the high prospect of large-scale production. The structural, mechanical, and thermal properties of BZPN foams were then investigated in detail. BZPN foam involves a hierarchical fracture mechanism during the compressive test, and it shows a high compression strength of over 6 MPa. During a burning test over 380 °C, no visible smoke, softening, or droplet phenomena appeared and the macroscopic structure of BZPN foam was well maintained. Mechanically robust, flame-retardant, and uniform large-size BZPN foam are promising light durable materials with high service temperatures, i.e., as filling materials even in a very narrow pipette. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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13 pages, 10225 KiB  
Article
Analysis of Erosion Characteristics and Erosion Mechanism of Polypropylene Fiber Tailings Recycled Concrete in Salt Spray Environment
by Xiuyun Chen, Tao Li, Meng Zhan, Yijie Ding, Faguang Leng and Jia Sun
Polymers 2022, 14(23), 5137; https://doi.org/10.3390/polym14235137 - 25 Nov 2022
Cited by 2 | Viewed by 1088
Abstract
Economic development and infrastructure improvement will inevitably lead to the accumulation of construction waste and tailings, which has not only a huge impact on the environment but is also a waste of resources. Recycling these resources and making green concrete is an effective [...] Read more.
Economic development and infrastructure improvement will inevitably lead to the accumulation of construction waste and tailings, which has not only a huge impact on the environment but is also a waste of resources. Recycling these resources and making green concrete is an effective way to solve these problems. In this study, the salt spray erosion characteristics and erosion mechanism of tailings recycled concrete (TRC) with polypropylene fibers were studied through macro and micro methods. The results showed that its compressive strength and splitting tensile strength increased at first and then decreased, with the optimum content of 0.6–0.9%, and the strength increase coefficient reached its maximum value at the erosion period being 14 d to 28 d. Under the same erosion cycle, when the fiber content was low (≤0.6–0.9%), the erosion depth hardly fluctuated. While the fiber content changed from 0.6% to 1.2%, the erosion depth and curing ability (erosion for 90 days) increased by 16.29% and 11.20%, which implied that its erosion resistance decreased sharply. Through SEM microscopic analysis, it could be observed that when the fiber content was low, the matrix structure and porosity had little change; while the fiber content was excessive, the porosity increased greatly. The longer the erosion period was, the greater the cumulative expansion of salt crystals was, and the larger the porosity was, whose results were in good agreement with the experimental results. This research provides a significant theoretical basis for the application of TRC in engineering. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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15 pages, 5776 KiB  
Article
Analysis of Wear Phenomena Produced by Erosion with Abrasive Particles against Fluoropolymeric Coatings
by Guillermo Guerrero-Vaca and Oscar Rodríguez-Alabanda
Polymers 2022, 14(21), 4617; https://doi.org/10.3390/polym14214617 - 31 Oct 2022
Cited by 7 | Viewed by 1847
Abstract
To date, PTFE, PFA, and FEP-based fluoropolymer coatings have proven unbeatable in many services due to their excellent chemical inertness, very low wettability, thermal resistance, high non-stick properties, and good applicability. In use, these coatings usually suffer service cycles with consequent deterioration, and [...] Read more.
To date, PTFE, PFA, and FEP-based fluoropolymer coatings have proven unbeatable in many services due to their excellent chemical inertness, very low wettability, thermal resistance, high non-stick properties, and good applicability. In use, these coatings usually suffer service cycles with consequent deterioration, and it is of great interest to determine the intensity and type of wear caused in addition to the deterioration that occurs in their properties. In this work, the response of three polymeric coatings of interest applied to aluminum substrates, after being subjected to the action of abrasive particles of aluminum corundum, glass, and plastic projected under pressure, has been studied. During the application of a given wear cycle, the hardness, surface roughness, surface texture, and thickness of the coating have been measured, in addition to the slip angle and surface transmittance to analyze the evolution of each type of coating. The results allowed a concise evaluation of the performance of three fluoropolymeric coatings of great interest, differentiating the induced erosive wear phenomena and contributing complete information to facilitate the correct selection for users with practical application purposes and as a basis for future research work focused on advancements in this field. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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Review

Jump to: Research

21 pages, 497 KiB  
Review
Hydrothermal Ageing of Glass Fibre Reinforced Vinyl Ester Composites: A Review
by James Thomason and Georgios Xypolias
Polymers 2023, 15(4), 835; https://doi.org/10.3390/polym15040835 - 8 Feb 2023
Cited by 9 | Viewed by 2480
Abstract
The use of glass fibre-reinforced polymer (GFRP) composites in load-carrying constructions has significantly increased over the last few decades. Such GFRP composite structures may undergo significant changes in performance as a consequence of long-term environmental exposure. Vinyl ester (VE) resins are a class [...] Read more.
The use of glass fibre-reinforced polymer (GFRP) composites in load-carrying constructions has significantly increased over the last few decades. Such GFRP composite structures may undergo significant changes in performance as a consequence of long-term environmental exposure. Vinyl ester (VE) resins are a class of thermosetting polymers increasingly being used in such structural composites. This increasing use of VE-based GFRPs in such applications has led to an increasing need to better understand the consequences of long-term environmental exposure on their performance. The reliable validation of the environmental durability of new VE-based GFRPs can be a time- and resource-consuming process involving costly testing programs. Accelerated hydrothermal ageing is often used in these investigations. This paper reviews the relevant literature on the hydrothermal ageing of vinyl ester-based GFRP with special attention to the fundamental background of moisture-induced ageing of GFRP, the important role of voids, and the fibre-matrix interface, on composite mechanical performance. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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20 pages, 1065 KiB  
Review
Methods of Analyses for Biodegradable Polymers: A Review
by Siti Baidurah
Polymers 2022, 14(22), 4928; https://doi.org/10.3390/polym14224928 - 15 Nov 2022
Cited by 20 | Viewed by 7821
Abstract
Biodegradable polymers are materials that can decompose through the action of various environmental microorganisms, such as bacteria and fungi, to form water and carbon dioxide. The biodegradability characteristics have led to a growing demand for the accurate and precise determination of the degraded [...] Read more.
Biodegradable polymers are materials that can decompose through the action of various environmental microorganisms, such as bacteria and fungi, to form water and carbon dioxide. The biodegradability characteristics have led to a growing demand for the accurate and precise determination of the degraded polymer composition. With the advancements in analytical product development, various analytical methods are available and touted as practical and preferable methods of bioanalytical techniques, which enable the understanding of the complex composition of biopolymers such as polyhydroxyalkanoates and poly(lactic acid). The former part of this review discusses the definition and examples of biopolymers, followed by the theory and instrumentation of analytical methods applicable to the analysis of biopolymers, such as physical methods (SEM, TEM, weighing analytical balance, etc.), chromatographic methods (GC, THM-GC, SEC/GPC), spectroscopic methods (NMR, FTIR, XRD, XRF), respirometric methods, thermal methods (DSC, DTA, TGA), and meta-analysis. Special focus is given to the chromatographic methods, because this is the routine method of polymer analysis. The aim of this review is to focus on the recent developments in the field of biopolymer analysis and instrument application to analyse the various types of biopolymers. Full article
(This article belongs to the Special Issue Durability and Degradation of Polymeric Materials II)
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