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2023 | Book

Recycled Polymer Blends and Composites

Processing, Properties, and Applications


About this book

This book presents an authoritative account of the potential of recycled polymer blends and composites such as recycled rubber, Polypropylene, Poly(Vinylidene Fluoride) (PVDF), polyhydroxybutyrate-3-valerate (PHBV), Polyethylene, and similar compounds, in polymer recycling industries. It highlights the latest research on fundamentals of recycled polymer blends and composites such as physical, chemical, mechanical and thermal properties and morphological studies. The book also provides a comprehensive state of the art review of recycling of polymer blends and composites for sustainability. Polymeric substances recycled from excess sludge in wastewater treatment plants, reinsertion of Poly(Vinylidene Fluoride) (PVDF), polyolefin and Polypropylene post-Industrial waste by primary recycling, as well as the recent development of biomass and COVID-19 plastic waste derived char filled natural starch biocomposite briquettes are also covered.

Table of Contents

Zooming into Recycling of Composites
The widespread use of plastic has led to an environmental crisis, with an estimated 6300 Mt. of plastic waste generated in 2018, of which only 9% was recycled, 12% burned, and 79% dumped in the environment or landfills. The production and disposal of plastics have a significant impact on the environment, with landfills and natural environments predicted to accumulate 12 billion tons of plastic waste by 2050. The COVID-19 pandemic has further increased plastic waste due to the use of personal protective equipment, disposable dinnerware, and plastic-wrapped food. To address this issue, a concerted global effort is needed to minimize plastic waste throughout the plastic lifecycle, including reducing waste output, increasing waste collection and recycling, and removing plastic pollution from the environment. Recycling plastic waste is critical, as it not only reduces the cost of garbage disposal but also helps recover energy from plastics and reduces the need for virgin materials. Composite materials, such as polymer–matrix composites, metal–matrix composites, and ceramic–matrix composites, offer superior quality, durability, and reduced energy usage, making them a popular choice in many engineering applications, particularly in the transportation industry. Good waste management systems are necessary for the proper disposal and recycling of composite materials. This chapter focuses on the recycling of composite materials as a way to address the growing issue of plastic waste and its impact on the environment.
Ilyas R. A., A. H. Nordin, H. S. N. Hawanis, J. Tarique, Sapuan S. M., M. R. M. Asyraf, M. Rafidah, Hanafi Ismail, M. Y. M. Zuhri
Recycling of Polymeric Membranes
Membrane separation process (MSP) is widely used in different industrial sectors, especially in the filtration and clarification of beverages, wastewater treatment, sterilization, among other applications. Commercial organic synthetic membranes are mainly produced by polymers. According to the membrane lifecycle, an appropriate destination must be designated for these materials. Correspondingly, this chapter includes topics about the recycling of the main polymers that comprise the polymeric membranes. Initially, the chapter presents the main polymers used and the types of recycling of these materials. The main areas of application of MSP, in which the use of polymeric membranes has intensified, are discussed, emphasizing the degradative processes that directly imply the lifecycle of the membranes. Finally, the main technologies applied to the membrane recycling context and the main challenges that involve the recycling of polymeric membranes are considered. At the end of the chapter, future outlooks on the subject are provided.
Maicon Sérgio Nascimento dos Santos, João Henrique Cabral Wancura, Carolina Elisa Demaman Oro, Rogério Marcos Dallago, Giovani Leone Zabot, Marcus Vinícius Tres
Composites Based on Polymeric Matrices Recycled from Different Wastes and Natural Fibers
The main advances developed during the last years on the preparation and characterization of composites based on recycled thermoplastics and natural fibers are reviewed. The main polymers used for this purpose are polyethylene terephthalate (PET) and polypropylene (PP), while a wide variety of natural fibers, such as woven flax, cotton fibers, sugar cane fibers, kenaf or rice straw fibers, among others, has been used for reinforcing the thermoplastics. The origin of components, together with the procedures used for composite preparation and the measured properties obtained by many authors in recent years, are presented and discussed.
Galder Kortaberria
Mechanical Properties of Recycled Polyolefin Composites
Over the years, there has been a growing interest among researchers to produce composite materials based on recycled thermoplastic matrices, which are available as waste materials in massive fraction. Evaluation of mechanical properties of these recycled or waste materials is one of the important scopes to be studied in the field of composite materials. The current book chapter reviewed the developments of recycled polyolefin matrix composite material, emphasizing their detailed mechanical performance such as tensile strength and elasticity modulus, flexural properties, impact strength, and so on. The focus was laid on the effect of blend composition, the effect of natural reinforcements such as rice husk fibers, wood flour fibers, the effect of artificial reinforcements such as glass fibers, and the effect of nano-sized filler such as nanoclay and carbon nanotubes in the recent development from 2015 to date.
Ruey Shan Chen, Mohd Nazry Salleh, Sinyee Gan
Polymeric Substances Recycled from Excess Sludge in Wastewater Treatment Plant
Recovery of resources from wastewater, e.g., bioplastics, cellulose, metals, and phosphorus, is one of the most important research objectives in wastewater treatment. Recently, the recovery of polymeric substances from excess sludge is gaining significant research interest in future wastewater treatment technologies, which can not only enhance the dewatering performance of sludge but also promote sludge reduction. Herein, extracellular polymeric substance (EPS) and typical polysaccharide alginate as recycled materials are discussed. First, membrane recovery of alginate was discussed, including ultrafiltration (UF) concentration of sodium alginate solution, filtration coefficient and recovery rate of alginate, forward osmosis recovery with useful reverse solute diffusion, and properties of recycled materials. Second, membrane recovery and properties of EPSs were described through the role of calcium ion, microfiltration separation of polysaccharides and proteins in EPS, and removal of heavy metal ion using UF with recovery of EPSs. Finally, the surfactant-enhanced ultrasonic extraction of PSs was proposed, in which the effect of surfactant on extraction efficiency, extraction mechanisms, characteristics of PSs, and adsorption properties of lead ion were shown.
Da-Qi Cao
Recycling of Ground Tire Rubber According to the Literature
The recycling of vulcanized rubbers, especially ground tire rubber (GTR), is a major challenge, even after years of research in the area. The three-dimensional structure and the large number of additives used in the formulation hinder the process. However, the recycling of end-of-life tires needs to be encouraged to reduce socio-environmental problems that they may cause when improperly disposed of in the environment and landfills. To verify the trends and hotspots related to the recycling of GTR according to the literature, bibliometric analysis was performed based on the results of a search in the Scopus database, with emphasis on the analysis of the keywords. The results showed an increase in the number of publications over the years, with publications in different areas and several applications, all aimed at solutions to the problem of the final disposal of end-of-life tires toward sustainable development.
Fabiula Danielli Bastos de Sousa
Polymer Processing Technology to Recycle Polymer Blends
Plastics recycling is a widely extended activity throughout the world, but still a complex process. However, nowadays, several parts are made from polymer blends or contain additives that require selecting an appropriate processing technology. In general, mechanical recycling is composed of several steps, including material separation (sorting), followed by washing (cleaning), size reduction (grinding), and extrusion (processing), where the pellets obtained can be used in a subsequent process. This review aims to perform a comparative analysis of the technology used in the recycling of polymer blends with respect to their final physical properties. This chapter includes a general introduction on the problems/limitations associated with the recycling of polymer blends based on the concepts of immiscible polymer blends. Then, recycling strategies for the processing of thermoplastic polymer blends are presented and discussed including blend formulation from recycled polymers with their advantages/applications. Finally, a comparison of the strategies used in the recycling of polymer blends is analyzed.
Daniel C. Licea Saucedo, Rubén González Nuñez, Milton O. Vázquez Lepe, Denis Rodrigue
Sustainable Materials from Recycled Polypropylene Waste and Green Fillers: Processing, Properties, and Applications
Sustainable materials made by manipulating sustainable resources spur the global community’s interest in creating next-generation feedstocks and goods. Polypropylene (PP) is among the most widely used thermoplastics in short product lifespan applications such as disposable containers. Only a tiny percentage of polypropylene-based products are recycled, and some end up in landfills. Due to their processability equipped with excellent physical and mechanical properties, recycled polypropylene would have added values if it is integrated with filler materials. A wide range of green fillers from animals, plants, minerals, and recycled goods, whether naturally occurring or manmade, have been used in plastic composites to reduce costs while improving strength, functionality, and biodegradability. For instance, the utilized green fillers in recycled polypropylene composites can be categorized as natural organic, natural inorganic, recycled fillers, and advanced fillers based on their origin and properties. This chapter, therefore, provides a comprehensive overview on types of green fillers and research and development work conducted on recycled polypropylene-based materials, especially those that incorporated various types of green fillers. Their mechanical, physical, thermal, and electrical properties are addressed by significant findings from the experimental studies and related mathematical models. The utilized processing methods and process parameters to produce recycled PP-based materials with their targeted application are also addressed.
Noraiham Mohamad, Hairul Effendy Ab Maulod, Jeefferie Abd Razak
Comparative Studies of Natural Rubber/Virgin Ethylene Propylene Diene Rubber and Natural Rubber/Recycled Ethylene Propylene Diene Rubber and Natural Rubber/Blends
This study focused on the blends of natural rubber (NR) containing virgin ethylene propylene diene rubber (EPDM) and recycled ethylene propylene diene rubber (R-EPDM). The blends’ properties ranged from 90/10, 80/20, 70/30, 60/40, and 50/50 (phr/phr) of NR/EPDM and NR/R-EPDM blends were observed. Results showed that both mixtures decreased tensile strength and elongation at break. In contrast, thermal stability showed an opposite trend as the weight ratio of EPDM or R-EPDM increased. The minimum torque (ML), maximum torque (MH), torque difference (MH–ML), scorch time (ts2), and cure time (tc90) of the blends exhibited increasing trend over the loadings of virgin EPDM or R-EPDM. This can be evidently seen from SEM micrographs showing a decrement in crack path especially when adding virgin EPDM or R-EPDM over 30 phr. This has led to less resistance to crack growth and thus lowering strength of the blends.
Nabil Hayeemasae, Hanafi Ismail
Optimization of Accelerators on the Properties of Natural Rubber/Recycled Ethylene Propylene Diene Rubber Blends
Due to the migration of sulfur from one rubber to another, a blend of natural rubber (NR) containing ground ethylene propylene diene rubber waste (w-EPDM) may cause cure incompatibility between these two rubbers. Therefore, accelerator optimization was formulated to see the curing incompatibility in NR/w-EPDM blends and increase curative dispersion. In this study, four types of rubber accelerators were chosen, these included N-tert-butyl-2-benzothiazole-sulfonamide (TBBS), N-cyclohexyl-benzothiazole-sulfenamide (CBS), tetramethyl thiuram disulfide (TMTD), and 2-mercapto benzothiazole (MBT). Using CBS has given the blend with the highest tensile strength. Furthermore, SEM images of CBS-vulcanized NR/w-EPDM blends showed more cracks and roughness, suggesting higher force needed toward the specimen. The results from damping characteristic and storage modulus verified TMTD-vulcanized blend provided a higher level of crosslinking followed by the CBS-, TBBS-, and MBT-accelerated blend, respectively.
Nabil Hayeemasae, Hanafi Ismail
Compatibilization of Natural Rubber/Recycled Ethylene Propylene Diene Rubber Blends
This work aimed to develop compatible blend between natural rubber (NR) and ethylene propylene diene rubber waste (w-EPDM). This was done by introducing third rubber matrix and electron-beam (EB) irradiation. As for the first method, natural rubber latex (NRL) was added where it was mixed with w-EPDM prior to blend with NRL on a two-roll mill. However, the latter route was prepared differently, EB-exposed to the samples in the presence of trimethylolpropane triacrylate (TMPTA) as cross-linking promoter. By applying these two methods, the compatible blends of NR and w-EPDM were successfully prepared. The blends exhibited good cure properties, solvent resistance, tensile, and dynamic mechanical properties. NR and w-EPDM were more entangled after introducing these two methods.
Nabil Hayeemasae, Hanafi Ismail
Effect of Metal Oxide Content on the Mechanical and Thermal Properties of Natural Rubber/Recycled Chloroprene Rubber Blends
Utilization of rubber waste and changing it into processable form are challenge for rubber material. An idea to blend rubber waste with virgin rubber is keen interest. This is to obtain compromising properties from both rubbers. In this chapter, natural rubber (NR) and chloroprene rubber waste (w-CR) were blended to synergistic properties of strength and solvent resistance provided by NR and w-CR. The focus was specifically on the action of metal oxide content on the overall properties of the blends. This was to enhance the final performance of the blends. The metal oxide used in the formulation was to be as curing activator, curing agent, and reinforcing filler. The results observed that introducing metal oxide has provided an excessive density of crosslinking and agglomeration which then reduced the overall performance of the blends. In summary, the content of metal oxide suggested for the NR/w-CR blend was 4 phr of MgO and 10 phr of ZnO.
Nabil Hayeemasae, Siti Zuliana Salleh, Hanafi Ismail
Chloroprene Rubber Waste as Blend Component with Natural Rubber, Epoxidized Natural Rubber, and Styrene Butadiene Rubber
An effective method to reduce rubber waste is to reuse it by blending with virgin rubber. There are many types of rubber that have been discarded, and chloroprene rubber is one of examples. Chloroprene rubber waste (w-CR) was used as blending component in this study where there are three types of virgin rubbers which were blended namely natural rubber (NR), epoxidized natural rubber with 50 mol% epoxidation level (ENR50), and styrene butadiene rubber (SBR). In this chapter, effects of blending ratio, i.e., 95/5, 85/15, 75/25, 65/35, and 50/50 (phr/phr) on properties, were studied. w-CR has lengthened the scorch and curing times of all blends due to their cure mismatch between two types of rubber. w-CR has also influenced the maximum torque (MH), minimum torque (ML), and torque difference (MH-ML) in all cases. This is simply because w-CR possesses the cross-linked precursor and its rigidity in nature. This further affected to increase in swelling resistance, overall cross-link density and thermal stability of the blends.
Nabil Hayeemasae, Siti Zuliana Salleh, Hanafi Ismail
Recycled Cellulose and Cellulose-Based Materials by Gamma Rays and Its Use as Reinforcement in Composites
In the last 50 years, large technological advances have contributed to the development of high-strength materials that provide excellent benefits. Nevertheless, in most cases, after a very short useful life, these materials become waste and contribute to environmental pollution. In efforts to solve such problems and to promote sustainable development, some investigations have focused on recycling by using innovative and clean technologies, such as gamma radiation, as alternative to conventional recycling processes, namely chemical, mechanical, and thermal. For such reasons, in this chapter, the usage of gamma radiation as novel tool for recycling of cellulose and cellulose-based materials is described. Special attention is focused on cotton, paper, cellophane, sisal, bamboo, wood, microcrystalline cellulose (MCC), cellulose nanocrystals (CNC), and cellulose/polylactic acid composites.
Irna Zukeyt Garduño-Jaimes, Gonzalo Martínez-Barrera, Enrique Vigueras-Santiago, Julián Cruz-Olivares
Tensile, Thermal Properties, and Biodegradability Test of Paddy Straw Powder-Filled Polyhydroxybutyrate-3-Valerate (PHBV) Biocomposites: Acrylation Pretreatment
The mechanical, thermal, and biodegradability properties of paddy straw powder (PSP)-filled polyhydroxybutyrate-3-valerate (PHBV) biocomposites were investigated. The impacts of chemical alteration of PSP via acrylic acid treatment were examined as well. The outcomes of the study portrayed a decrease in the elongation at break and tensile strength when the filler loading increased; however, the modulus elasticity of composites could be seen to increase. Chemical alteration of PSP via acrylic acid enhanced modulus elasticity of the biocomposites and tensile strength; nevertheless, the elongation at break was decreased. Thermogravimetric analysis demonstrated the enhancement of thermal stability of the biocomposites via PSP compared to neat PHBV. The thermal stability of the biocomposites was positively affected by chemical alteration of PSP. Meanwhile, DSC analysis proved that the melting temperature (Tm) of the biocomposites was not altered when the filler was added. Treated biocomposites demonstrated higher crystallinity (30.18%) compared to the untreated composites (26.24%). Biodegradability test showed the strains from both Aspergillus species have the potential to degrade PHBV/PSP biocomposites. The weight loss of biocomposites after undergoing fermentation with Aspergillus fumigatus strain SGE57 and Aspergillus niveus isolate A17 was 2.42% and 3.65%, respectively.
Noorulnajwa Diyana Yaacob, Hanafi Ismail, Sam Sung Ting
Comparison Between Natural Rubber, Liquid Natural Rubber, and Recycled Natural Rubber as Secondary Matrix in Epoxy/Natural Rubber/Graphene Nano-platelet System
A comparison is made between the effects of natural rubber (NR), liquid natural rubber (LNR), and recycled natural rubber (rNR) in the filled epoxy systems on the physical, mechanical, thermal, and electrical performances of filled epoxy systems. The results show that flexural strength and modulus values were improved. The toughness properties of the filled epoxy system were enhanced with NR phases (72 MPa, 2317 MPa, 4.2 MPa.m½), as compared to those with LNR (55 MPa, 2100 MPa, 3.2 MPa.m½) and rNR (52 MPa, 2000 MPa, 2.3 MPa.m½) at 5 vol.%. Scanning electron micrograph (SEM) analysis revealed that the particle sizes of NR phases dispersed within the epoxy matrix were smaller and more uniform (0.29–1.65 μm) as compared to those with LNR (0.64–3.57 μm) and rNR (≥250 μm) phases. The incorporation of NR, LNR, and rNR phases improved the thermal stability of the filled system. This is attributed to more heat energy being needed to overcome good interfacial bonding between epoxy matrices and the small NR phases. X-ray diffraction analysis results showed that the filled epoxy/NR/GNP system has higher 2θ values, indicating that d-spacing in GNP nano-fillers has the closer distance. Electrical bulk conductivity values of filled epoxy/NR/GNP systems were the highest, 4.50 × 10−3 1/Ω.cm at 20 vol.%. Small NR phases acted as elastomer spacers, which provided better GNP packing efficiency and realigned the GNP nano-fillers to form more effective conductive pathways for electron transport.
K. W. Kam, P. L. Teh, C. K. Yeoh
Recycling of Commonly Used Waste Plastics to Fabricate Membranes for Filtration Applications
Among the several waste management methods developed for the plastic solid waste (PSW) disposal, the route via recycling is considered as the best as it is economic and environmetal friendly. Waste plastics are nowadays being recycled and reused for energy generation, mechanical recycling, filtration membrane manufacturing, etc. Here, we briefly present the use of selected recycled polymers like polyethylene terephthalate (PET), polyvinyl chloride (PVC), polystyrene (PS), polycarbonate (PC), and few other polymers as membrane filter material and establish the casting formulation parameters to achieve the final membranes with improved eco-efficiency characteristics and technical performance toward filtration applications like water purification and gas separation. The challenges involved on extending the recycling of more polymer wastes into useful filtration membrane developments and future research directions on this area are also discussed.
Abichal Ghosh, Anirban Roy, A. K. Ghosh
Recycled Polymer Bio-based Composites: A Review of Compatibility and Performance Issues
The production of biocomposite materials based on recycled plastic polymers and agro-residues has been accelerated since it meets significant ecological and circular economic requirements. However, manufacturers are still facing many challenges related to the preparation, production, and performance of these materials. Improving the performance of the final biocomposites is drastically influenced by the fiber pretreatment and the functionalization of recycled polymers. They enhance the efficient crosslinking and bonding between the two main components of biocomposites. Therefore, we investigate compatibility problems linked to using natural fillers as reinforcement material for recycled plastic polymers. Furthermore, we provide comprehensive analyses related to mechanical, morphological, physical, and thermal properties of several types of recycled-based biocomposites. After that, we conclude the chapter by providing enriched discussions of the present hurdles and potential future approaches that interested researchers may take in order to fill the gap between exploration and application of this class of materials.
Khalid Alzebdeh, Nasr Al Hinai, Mahmoud Al Safy, Mahmoud Nassar
Production and Recycling of Biocomposites: Present Trends and Future Perspectives
Biocomposite has been a trending topic in the field of polymer composites and is observed to be attracting the attention of numerous researchers and industrial practitioners. It is a type of composite that uses polymer resin as the matrix and reinforcement filler in the form of natural materials which are mostly natural fibers derived from plants. These components are preferred due to their advantages such as low cost, low density, easy to separate, nontoxic, biodegradability, and sustainability. Biocomposites have been widely studied and used in practical applications because they are eco-friendly. Therefore, this chapter focuses on discussing the recent trends in the production of biocomposites, their subsequent contributions as an alternative material in engineering, application of Life-Cycle Analysis (LCA) to analyze their environmental effects, and an overview of the recycling technologies.
Venitalitya A. S. Augustia, Achmad Chafidz
Recycled Polyethylene Blends and Composites: Current Trend, Technology, and Challenges
Thermoplastics being a modern material had provided significant contribution to human civilization. Polyethylene (PE) being the highest consumed thermoplastic is gaining more momentum in production for application in the field of automotive, electrical, and food packaging. Environmental issues with single-usage trend of PE products had catalyzed various initiative to recycle PE specially to produce recycle PE blends and composites. Even though various laboratory-based development been successfully carried out to produce recycled PE blends and composites but its commercialization is still at infancy. Thus, in this chapter the current PE recycling methods, products, and its applications are being discussed and the challenges faced by industry for full-scale adaption of findings in laboratories are highlighted. Critical analysis on the production and products of recycled PE blends and composites are reported to provide the reader with future trends for practical approach in PE recycling at industrial scale.
Yamuna Munusamy, Zunaida Zakaria, Hanafi Ismail, Nor Azura Abdul Rahim
Recycled Polyethylene Terephthalate Blends and Composites: Impact of PET Waste, Engineering Design, and Their Applications
Polyethylene terephthalate (PET) is one of the major polymers produced and has been widely used in downstream industries, such as the production of textile fibers, packaging bottles, and films. The increased use of PET is associated with its excellent properties, which include thermal resistance, lightweight, high transparency, good impact, and relatively low cost. This indirectly contributes to a large amount of PET solid waste, which is detrimental to human life and exacerbates environmental issues. As a result, conversion to new PET blends and composites is an efficient method to recycle PET and reduce waste. While research in this area is ongoing and improving with the development of new materials for various applications, its commercialization has yet to begin. This chapter focuses on the designation of recycled PET and its performance as new blends and composites. Among the other topics discussed are PET waste sources, recycling methods, and applications, as well as the challenges of recycling PET and converting this solid waste into value-added products.
Zunaida Zakaria, Hakimah Osman, Nor Azura Abdul Rahim, Yamuna Munusamy, Hanafi Ismail
Recycled Polymer Blends and Composites
Hanafi Ismail
Sapuan S. M.
Ilyas R. A.
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