Waste electrical and electronic equipment (WEEE) have attracted attention due to their high pollutant potential and increasing volume produced in recent years as function of the modernization and ...continuum substitution of the current equipment that quickly become obsolete. Among polymeric materials that make up the WEEE, acrylonitrile-butadiene-styrene (ABS) and high-impact polystyrene (HIPS) copolymers are the most important materials. However, it is not always possible the complete segregation of ABS and HIPS during the processes for mechanical recycling of these polymers. Thus, the formation of ABS/HIPS blends is often unavoidable. In this report, the relationship between morphology and mechanical/rheological properties of ABS/HIPS blends produced from WEEE recycling was investigated. Although the component polystyrene (PS) and polybutadiene (PB) are present in the composition of both ABS and HIPS, the blends ABS/HIPS are immiscible, showing complex morphology that directly affect the mechanical and rheological behavior of the material. On the other hand, the production of the ABS/HIPS blends is an interesting alternative for properties control of the recycled polymers from WEEE.
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•ABS and HIPS are the main polymers of the waste electrical and electronic equipment (WEEE) from computer devices.•ABS/HIPS blends are often generated during WEEE recycling.•ABS/HIPS blends present a complex phase morphology.•Recycled ABS/HIPS blends show sufficient mechanical performance for new electrical and electronic equipment.
Carbon fiber composites are used in several industries such as, aerospace, automotive, civil engineering, sports goods and technical applications due to its low-weight, strength and stiffness. ...However, the technology of recycling of these thermosetting polymer composites remains an engineering challenge because of their cross-linked structures that impede their reprocessing by simple heating. The aim of this work was to study the influence of the amount and dimensions of carbon fibers arising from composite waste into a new composite of polypropylene matrix. In order to carry out the study, the carbon fiber composite waste has been mechanically processed for the production of chopped fibers with two different lengths (4.5 mm and 3.0 mm). Thermoplastic composites made of chopped carbon fiber/ polypropylene at proportions 1%, 5% and 7% in fiber weight content were obtained by extrusion and injection process. Then, a series of laboratory test (mechanical, thermal and morphological) were performed in order to characterize the composite material obtained. The results showed that the fibers were capable of causing a reinforcing, even though the new composite presents a complex phase system with low adhesion between the recycled carbon fibers and the polypropylene matrix.
Microwave devulcanization has been studied as a method for elastomer recycling, which is based on the conversion of the reticulated and infusible structure of thermosetting rubbers in free polymeric ...chains able to be remolded by thermomechanical processing in recycling operations for the manufacture of other products. Elastomeric wastes are often irregularly discarded in nature, producing serious environmental damage, and their mechanical recycling is still considered a challenge. Thus, the development of alternatives for elastomer recycling is directly related to the actions of sustainable development and economic benefits to companies that pay to discard their wastes. The aim of this work is to evaluate the chemical modifications occurring in styrene–butadiene rubber (SBR) after microwave devulcanization. Compounds of SBR were vulcanized in the presence of vulcanization agents and variable amounts of carbon black, and then the rubbers were milled and submitted to microwave treatment. Only the SBR with high carbon black content shows some portion of devulcanized material. However, the rubber with lower content of carbon black which was devulcanized by microwave radiation shows an increase in cross-link density. The microwave treatment also causes cross-link breaks mainly in polysulfidic bonds as well as decomposition of chemical groups containing sulfur attached to the chemical structure of SBR, while the chemical bonds of higher energy such as monosulfidic bonds remain preserved. The improvement of the microwave method for rubber devulcanization represents a way for viable recycling of thermosetting rubbers.
The commingled technology is a promising technique for the manufacture of composites reinforced with natural fibers. This study presents the development, processing and basic characterization of a ...long fiber Jute/Polypropylene (Jute/PP) commingled composite. The Jute/PP fabric was produced in a handloom and the composite was consolidated by compression molding. The PP matrix was chemically and thermally characterized to certify its chemical composition and define its melting and crystallization temperatures. The degradation behavior of jute fibers was also studied by Friedman’s kinetic isoconversional model using thermogravimetric analyses (TGA). The mechanical properties of jute reinforcement and Jute/PP composite were characterized by tensile strength tests and by fractographic study of the fracture surfaces. Its tensile strength (44.62±6.02 MPa) and elasticity modulus (7.10±2.34 GPa) are approximate to the ones obtained by other processing techniques, suggesting that the developed commingled process can work as a low cost and practical alternative methodology for manufacturing of more sustainable composites in industries.
Polymeric materials constitute a considerable fraction of waste computer equipment and polymers acrylonitrile-butadiene-styrene and high-impact polystyrene are the main thermoplastic polymeric ...components found in waste computer equipment. Identification, separation and characterisation of additives present in acrylonitrile-butadiene-styrene and high-impact polystyrene are fundamental procedures to mechanical recycling of these polymers. The aim of this study was to evaluate the methods for identification of acrylonitrile-butadiene-styrene and high-impact polystyrene from waste computer equipment in Brazil, as well as their potential for mechanical recycling. The imprecise utilisation of symbols for identification of the polymers and the presence of additives containing toxic elements in determinate computer devices are some of the difficulties found for recycling of acrylonitrile-butadiene-styrene and high-impact polystyrene from waste computer equipment. However, the considerable performance of mechanical properties of the recycled acrylonitrile-butadiene-styrene and high-impact polystyrene when compared with the virgin materials confirms the potential for mechanical recycling of these polymers.
Waste electrical and electronic equipment (WEEE) are currently constituted by a considerable fraction of polymers, mainly acrylonitrile–butadiene–styrene (ABS) and high‐impact polystyrene (HIPS). ...Despite the increasing interest for ABS and HIPS recycling from WEEE, some factors, such as intrinsic mixture between polymeric components, are barriers to the advancement of the polymeric WEEE recycling. In present study, ABS and HIPS from WEEE were combined each other and with virgin ABS and HIPS in presence of the compatibilizers styrene–butadiene–styrene (SBS) and styrene–ethylene–butylene–styrene/styrene–ethylene–butylene (SEBS/SEB), generating recycled ABS/HIPS blends in different compositions. The materials were evaluated by mechanical tests, morphological analysis, dynamic‐mechanical‐analysis, and melt flow rate. The presence of compatibilizers SBS and SEBS/SEB affects significantly the morphological structure of ABS/HIPS, changing the shape and size of the dispersed phases of styrene–acrylonitrile or polystyrene, which leads to modifications of the mechanical properties of the materials. The presence of virgin polymer in the blends also affects the material morphology. Thus, ABS and HIPS waste from WEEE can be recycled as ABS/HIPS blends and their mechanical properties controlled by use of compatibilizers SBS and SEBS/SEB and incorporation of virgin polymers, avoiding processes for segregation of the polymers during mechanical recycling.
Since the early development, the sectors where the composite materials are being used have been growing gradually. Nowadays, these materials have extensive application in the structural components in ...the aerospace, defense, transportation, civil, and energy industries. The composites, especially carbon fabric/epoxy resin, have excellent in-plane properties. However, the susceptibility to delamination from out-of-plane loads, due to the lack of fibers oriented through the thickness, is still one of the weaknesses of this kind of materials. The introduction of reinforcement through the thickness has the potential to increase out-of-plane properties of composite materials. This can be accomplished by different reinforcement methods, such as Z-pinning, stitching, and tufting. This work aimed to develop and implement a simplified method of through-the-thickness reinforcement, based on tufting reinforcement. The experimental methodology was developed in a CNC router machine where glass fiber and polyamide were used as the main reinforcement materials in different square patterns (5 × 5 and 7 × 7) and applied in laminated carbon/epoxy composites manufactured by vacuum resin transfer molding process. Then, efficiency of the reinforcement was evaluated by means of mechanical testing, i.e., tensile and end-notched flexure testing in order to evaluate the ability to improve the interlaminar fracture strength. Results showed that the presence of the reinforcements provided around 27% increase in the delamination resistance compared to the non-reinforced composites in the thickness direction.
Abstract The curing reactions of epoxy resins are a complex process that defines thermosets final properties and are affected by any additive present on its formulation. Considering this, the aim of ...this study was to analyze the influence of the solvent addition on the curing kinetics of an epoxy system. The epoxy samples were prepared using different percentages by weight of acetone: 0, 2, 5 and 10 wt.%. From DSC and DMA tests, followed by the Borchardt-Daniels kinetic analysis it was reported that the addition of acetone can decrease the reactions rate, activation energy, Tg and elastic modulus. The presence of solvent, even in small amounts, can affect the curing mechanisms of epoxy resins. The changes on the curing behavior and the low quality of the final properties for the sample with 10 wt.% of solvent indicates that this may be a limit for acetone addition on the epoxy formulations.
O crescimento na geração de rejeitos de equipamentos elétricos e eletrônicos (REEE), legislações mais rigorosas e o valor agregado destes materiais incentivam o desenvolvimento de tecnologias de ...reciclagem. Contudo, a reciclagem dos componentes poliméricos dos REEE (CP-REEE) precisa superar desafios como a degradação durante o uso e reprocessamento, a presença de diferentes aditivos nos rejeitos e a depreciação de propriedades causada pela mistura não controlada de polímeros. Assim, o objetivo deste trabalho foi desenvolver um estudo sobre a reciclagem mecânica na forma de blendas poliméricas de rejeitos do copolímero acrilonitrila-butadieno-estireno (ABS) e do poliestireno de alto impacto (HIPS), empregando agentes compatibilizantes. No desenvolvimento do trabalho foram realizadas a caracterização dos CP-REEE, análise das propriedades mecânicas, químicas, térmicas e morfológicas dos polímeros e das blendas de ABS/HIPS nas proporções de 1:3, 1:1 e 3:1 com variações na composição dos polímeros reciclados e virgens e por fim, realizado um estudo do envelhecimento foto-oxidativo acelerado de uma blenda ABS/HIPS. Os resultados mostraram que os polímeros ABS e HIPS reciclados ainda apresentam boas propriedades mecânicas e que a presença de agentes compatibilizantes provoca o aumento da tenacidade nas blendas ABS/HIPS. A incorporação de polímeros virgens nos materiais reciclados não promove ganho significativo nas propriedades mecânicas das blendas. Blendas com até 50% de ABS demonstraram ter propriedades próximas às do HIPS, enquanto as blendas com altos teores de ABS não alcançaram valores de propriedades mecânicas similares aos do ABS virgem. O comportamento das propriedades das blendas virgens e recicladas frente ao envelhecimento fotoquímico foi similar, indicando que o material reciclado apresenta grande potencial para aplicações. O estudo de blendas ABS/HIPS de CP-REEE demonstra que o controle da composição das blendas definem a sua aplicação.
The growth in waste electrical and electronic equipment (WEEE) generation, directives more stringent and the aggregate value presents in these waste are encouraging the development of recycling technologies. However, recycling of polymeric components from WEEE (PC-WEEE) must overcome challenges such as degradation during use and reprocessing, the presence of various additives in the waste and the depreciation of properties caused by uncontrolled polymers mixture. The aim of this work was to develop a study of the mechanical recycling in the form blends with of polymeric waste of acrylonitrile-butadiene-styrene copolymer blends (ABS) and high impact polystyrene (HIPS) using compatibilizers. During the study was carried out the characterization of the PCWEEE and mechanical, chemical, thermal and morphological analysis of the polymers and the ABS / HIPS blends in proportions of 1:3, 1:1 and 3:1 with recycled and virgin polymers, as well as a study of the accelerated photo-oxidative aging of the ABS/HIPS blends. The results showed that ABS and HIPS recycled polymers still have good mechanical properties and the presence of compatibilization agents leads to increased toughness in ABS/HIPS blends. The incorporation of virgin polymers in recycled materials does not promote significant gain in the mechanical properties of the blends. Blends with up to 50% ABS have demonstrated to be closer to the HIPS, while blends with high content of ABS did not reach values of mechanical properties similar to the virgin ABS. The mechanical properties of virgin and recycled blends during the photochemical aging were similar, indicating that the recycled material has great potential for applications. The study of ABS/HIPS blends from PC-WEEE demonstrated that control of the blend composition establish their applications.
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