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Identification and thermomechanical characterization of polymers recovered from mobile phone waste
Abstract
The plastic components from waste mobile phones were sorted and characterized using visual, spectroscopic and thermal methods. The sustainable strength of the recovered plastics was investigated by comparing their mechanical and thermal properties with commercially used reference materials. The results revealed that the recovered polymers have significant potential to be reused. However, some properties, such as impact strength and tensile modulus, are significantly low compared to virgin materials and need further improvement. The samples were also tested for brominated flame retardants (BFRs) using gas chromatography–mass spectrometry technique, and the results indicated the absence of BFR in recovered plastics; hence, these can be processed without any risk of BFR toxicity.
... More than 80 percent of the total polymers used in the production of a mobile phone are made of polycarbonate (PC) and PC/ABS blends. In comparison to these plastics, the shares of other polymers are insignificant (Forti et al. 2018;Sarath et al. 2017). The various stages for recovering Polymers from mobile wastes are illustrated in Figure 5. ...
... Most items are made with PC, followed by PC/ABS blends. Melt-mixing and FTIR analyses were used to identify a significant portion of the recovered pieces that lacked generic markings (Gu et al. 2019;Sarath et al. 2017). ...
Mobile phones are among the most widely used devices worldwide, but they also present a serious environmental contamination issue. Mobile phones often contain dangerous materials that, if not properly handled and disposed of, will leak into the environment. To ascertain the level of contamination, risk assessment techniques must be developed. In this research, national and international scenarios and regulating measures have been discussed for the harmfulness and management of mobile waste materials. The various characteristics of mobile wastes and materials flow for the processing of mobile related wastes have been elaborated. The different types of frameworks for the indicating systems, selection criteria, and risk assessment indication systems were also illustrated. The various stages of mobile waste handling and processing to recover polymers have also been represented.
... More than 80 percent of the total polymers used in the production of a mobile phone are made of polycarbonate (PC) and PC/ABS blends. In comparison to these plastics, the shares of other polymers are insignificant (Forti et al. 2018;Sarath et al. 2017). The various stages for recovering Polymers from mobile wastes are illustrated in Figure 5. ...
... Most items are made with PC, followed by PC/ABS blends. Melt-mixing and FTIR analyses were used to identify a significant portion of the recovered pieces that lacked generic markings (Gu et al. 2019;Sarath et al. 2017). ...
The rapid technological advancement of the manufacturing sector over the past few decades inevitably led to the rise of Industry 4.0. It has the potential to significantly alter how globalisation is practiced in the production and consumption of products and services across international markets. In this chapter, we'll take a closer look at the rise of Industry 4.0 and the new technical architecture that underpins it, as well as the benefits it's expected to bring.In addition, how we may use technology to fortify a company's competitiveness and shield it from the perils of this transformation. The new global division of labour, the worldwide supply chain, and the global value chain will all be profoundly affected by this multifaceted technology, as evidenced by a thorough examination of the relevant literature. It will alter the competitive landscape by shifting the advantage away from large corporations and toward small and medium-sized enterprises (SMEs) in emerging markets and developed markets. As human and technological skills advance quickly, businesses may be able to profit.
... More than 80 percent of the total polymers used in the production of a mobile phone are made of polycarbonate (PC) and PC/ABS blends. In comparison to these plastics, the shares of other polymers are insignificant (Forti et al. 2018;Sarath et al. 2017). The various stages for recovering Polymers from mobile wastes are illustrated in Figure 5. ...
... Most items are made with PC, followed by PC/ABS blends. Melt-mixing and FTIR analyses were used to identify a significant portion of the recovered pieces that lacked generic markings (Gu et al. 2019;Sarath et al. 2017). ...
Waste management represents a challenge due to the rapid increase in waste production and the emerging of new waste types. Overcoming the issue involves using innovative technologies such as nanotechnology. Nanotechnology uses nanomaterials, which are materials that have at least one dimension less than 100 nm. Due to their small size, these materials increase reactivity in processes such as adsorption and oxidation/reduction. The application of nanotechnologies is significant in the production of new materials to replace current raw materials, and in providing novel solutions for waste recycling and disposal. Furthermore, nanofiltration is effective in the treatment of metals, toxic waste, and nonbiodegradable materials of leachate. Nanomaterials, however, represent a safety risk for the environment, and a serious threat to human health due to their small size and long suspension time. This chapter deals with the use of nanotechnology in waste management, including reduction, recycling, treatment, and disposal phases.
... As can be seen in Figure 2, from 2018 onwards, an increasing trend in the number of publications was recorded. A deep analysis indicates that the focus was on topics such as circular economy [25,[56][57][58][59][60][61], as well as the recycling of contaminated plastics (e.g., from e-waste and agricultural packaging) [15,24,[62][63][64][65][66][67][68][69][70][71][72]. to the literature review is to target some, yet not all, of the published scientific articles and online reports on the main topics of plastics recycling, circular economy of plastics, and challenges to plastic waste recycling. ...
... As can be seen in Figure 2, from 2018 onwards, an increasing trend in the number of publications was recorded. A deep analysis indicates that the focus was on topics such as circular economy [25,[56][57][58][59][60][61], as well as the recycling of contaminated plastics (e.g., from e-waste and agricultural packaging) [15,24,[62][63][64][65][66][67][68][69][70][71][72]. Analysing the topics "plastic recycling" and "circular economy" combined during the same lifespan in the Web of Science Core Collection resulted in a total of 337 publications. ...
The increasing consumption of plastics and plastic products results in correspondingly substantial volumes of waste, which poses considerable environmental burdens. With the ongoing environmental actions, the application of circular economy on this waste stream is becoming inevitable. In this paper, the topics of plastics recycling, circular economy on plastics, and challenges to plastic waste recycling are critically reviewed. In the first part of this paper, the development of research on plastic recycling was viewed from 1950 until 2020 using the scientific database Web of Science, and 682 related studies were found and used to assess the changing research priorities along that timeline. The following sections discuss the potentials and requirements to enhance the quality of the produced recycled plastic, in connection with the factors that currently limit it. In conclusion, the quality of recycled plastic is generally determined by the homogeneity of the recovered plastic feed. There are various strategies which could be implemented to overcome the hindrances identified in the paper and to improve the quality of the recycled plastic, such as working on enhanced product designs for minimised waste heterogeneity and controlling the materials’ degree of contamination by applying advanced sorting.
... Plastics make up over 10% of the total weight of mobile phones (Yamane et al., 2011;Liu et al., 2019b). However, due its low economic value (Liu et al., 2019b) and inferior mechanical performance once recovered (Sarath et al., 2016), plastics in WMPs are seldomly recycled. Monteiro et al. (2007) and Kasper et al. (2011b) recovered PC/ABS blends from WMPs, shredding the plastic scraps and then prepared test samples using injection molding. ...
Due to the vast consumption and shortened lifespan of mobile phones, waste mobile phones (WMPs) have become one of the fastest-growing global waste electrical and electronic equipment (WEEE) streams. Although the recycling potential of WMPs is well-recognized, the current recycling rate remains low, jeopardizing the sustainability of both the environment and mobile phone industries. With the objective of identifying limitations in the current method developments that hinder WMP recycling, we review the material recovering technologies for WMP recycling, published in academic journals and/or conferences between Jan 2005 and Feb 2019. Most WMP recycling processes have been developed to recover precious metals (such as gold and silver) from mobile phone printed circuit boards (PCBs), via acid leaching processes. However, pre-treatment and separation steps required to concentrate the waste stream for efficient extraction are often overlooked. In addition, to separate the individual components of the WMP, most recycling methods use manual disassembly as their first step, a practice which is not suitable for scale-up. Generally, particle size ranges used in laboratory trials are smaller than those used in current industrial practice, as it is not economically feasible to acquire such small particle sizes industrially. There is a current trend to replace the inorganic acids used for metal leaching with more environmentally-friendlier lixiviants, however, industrialization of these approaches is not economically viable. This review serves as a guidance for future research and development in this area, providing information to facilitate WMP management.
... But here the result tells us that plastics have at least comparable economic potential to that of silver and are worthy of attention. In addition, studies have revealed that the mechanical performance of recovered plastics make it possible for their use in new products (Kasper et al., 2011;Monteiro et al., 2007;Sarath et al., 2016). ...
Incomplete recovery of materials in mobile phones results in a significant economic loss. Many studies have focused on improving the situation by characterizing metals within printed circuit boards (PCBs) to identify where losses occur. Our work focuses on the evolving composition of mobile phones and particularly the flow of materials located within components outside of PCBs. In this study we quantify the appreciable economic potential of non-PCB derived metals and provide suggestions for optimization of different preprocessing steps to recover these materials. These opportunities can be categorized as recovering both high value and high volume materials. We therefore recommend that preprocessors pay special attention to precious metals in fine shredding and develop strategies for plastics recycling based on our demand and supply forecasts of postconsumer plastics in phones. We have performed this work based on a case study of Portugal.
The growing concern over the management of e-wastes has generated an interest in the recovery of resources from these wastes under the concept of urban mining and circular economy. However, in the absence of accurate knowledge of the physico-chemical compositional structure of these wastes makes the recycling process difficult. Thus, the present study conducted a recycling-oriented characterization of waste mobile phones (WMPs) for the identification of secondary materials and estimated their recycling potential. The characterization was performed using ICP-OES and FTIR techniques after dismantling WMPs for the determination of elemental composition and the polymeric fractions respectively. Dismantling of the WMPs revealed that enclosures, batteries, display modules, and PCBs consist of 35.33 wt%, 28.9 wt%, 19.44 wt%, and 16.31 wt% respectively. Of these components, PCBs constitute the highest economic recovery potential with an estimated potential revenue generation of more than 50,000 US /ton of WPCBs followed by Sn (27.37 tons/year) and Ni (24.64 tons/year). Among different precious metals, Au was found to have the highest percentage of economic value (76.22%) followed by Pd (8.16%) and Ag (3.13%). The display modules and enclosures were found to have relatively lower contributions than WPCBs in the overall recycling potential due to lower metal contents and mixed polymeric fractions. The findings in the study indicate that WMPs could serve as a promising new source for sustainable secondary mining of rare and valuable metals. Further, the study will help the policymakers in designing effective e-waste management strategies through the promotion of sustainable recovery of materials.
Separation and characterization studies were carried out on end-of-life mobile printed circuit boards (EoL Mobile PCBs). The raw material has been subjected to a hammer mill to reduce the particle size. A series of comminution experiments were conducted to produce different size particles, which indicates that a number of crushing stages are needed to generate finer products. Comminution products consist of fine hydrophilic metals and hydrophobic nonmetal particles. Further, flotation studies were conducted to separate metals and nonmetals. The experimental results indicated that the product grade of 84–90% metals could be achieved from the feed containing 48% metals and recovery values varying between 44 and 66%. Characterization of the feed and flotation products was carried out following stereomicroscope and scanning electron microscope. The stereomicroscopic investigations show that the metallic particles were irregular in shape and the majority of them were liberated and few interlocks observed with the plastic/nonmetallic materials. The scanning electron microscope studies showed the presence of different metallic phases in the flotation products.
In the recycling of polymer e-waste, there is a pressing need for rapid measurement technologies for the simple identification and classification of these materials. The goal of this work was to instantly identify e-waste polymers by laser-induced breakdown spectrometry (LIBS). The studied polymers were acrylonitrile-butadiene-styrene (ABS), polystyrene (PS), polyethylene (PE), polycarbonate (PC), polypropylene (PP), and polyamide (PA). Emission lines were selected for C (247), H (656), N (742 + 744 + 747), and O (777), as well as the molecular band of C2 (516), and the theoretical ratios of the emission lines and molecular band were utilized. Classification models, k-nearest neighbors (KNN) and soft independent modeling of class analogy (SIMCA), were used to rank the polymers. Both constructed models gave satisfactory results for the validation samples, with average accuracies of 98% for KNN and 92% for SIMCA. These results prove the predictive analytical capabilities of the LIBS technique for plastic identification and classification.
Two kinds of BFRs in three WEEE plastics(cell phone shells, computer housings and TV housings) and PCBs were detected with GC/MS. The results showed the plastics used as mobile phone shells had no BFRs. TBBPA was only found in computer housings. Among PBDEs, congeners of heptabromodiphenyl ether, octabromodiphenyl ether and nonabromodiphenyl ether were frequent ones, and detected in both TV housings and computer housings. But the contents of N9BDE were lower than the other two, only 180 mg/kg and 5.3 mg/kg in computer housings and TV housings respectively, while pentabromodiphenyl ether and hexabromodiphenyl ether were determined in PCBs.
The subscribers base of mobile phones is increasing globally with a rapid
rate.The sale of mobile phones has exceeded those of personal computers.India
is the second largest telecommunication network in the world in terms of number
of wireless connections after China.Telecom companies are ready to tap a large
unexplored market in India with lucrative offerings.Smart phones sale are at
its peak.3G technology is also ready to play a lead role in mobile
revolution.Due to the low average life of the mobile phones,lack of awareness
among users and in absence of government policies,mobile waste is accumulating
in vast amount in India.Without a proper system of recycling,the unsafe
disposal is causing a variety of environmental and health problems.This paper
discusses the various issues related to the worldwide growth of mobile
phones,the insecure methods of disposal and the regulations and policies in
India.We intend to put forward some challenges and advices.
This paper examines the policy trends of electronic waste (e-waste) management in Asia. E-waste is a rapidly growing waste stream in the world today and is estimated to be growing at 3-5 % per annum. Fast paced obsolescence in the electronic sector has resulted in the generation of e-waste. There are concerns that e-waste generated in developed countries is ending up in developing countries especially in Asia resulting in adverse environmental and health impacts. Consequently, a number of countries in Asia are developing policy instruments to ensure the proper management of e-waste. These include e-waste regulatory frameworks, data and inventories, and infrastructure and capacity building. These trends indicate a positive development path towards sustainable e-waste management in Asia. Nevertheless, potential limiting obstacles for e-waste management in Asia may also include an over-reliance on legislation to drive e-waste management or the simplistic adoption of policies from developed countries without taking into context the local political, cultural and socio-economic waste management issues. Consequently, this paper suggest that e-waste policy development may require a more customized approach where, instead of addressing e-waste in isolation, it should be addressed as part of the national development agenda that integrates green economy assessment and strategic environmental assessment as part of national policy planning. In conclusion, policy trends of e-waste management in Asia appear promising provided there is a paradigm shift from an e-waste perception of an environment problem to a e-waste perception of a potential opportunity as sustainable national green growth strategy in Asia. © 2013 Springer Japan.
The cell phone market is developing at a rapid speed. Today there are more than 1.6billion consumers in the world, and the
lifetime of a cell phone is less than 2years. As a consequence, there is an increase in the waste associated to this product,
and many alternatives to the disposal of the cell phones are being studied, such as recycling which shows to be the most important.
It is crucial to know what materials constitute the cell phone in order to carry out recycling and determine environmental
and economical issues. This work presents an evaluation of the cell phone components, characterizing the raw materials and
some properties of the recycled materials.
An attempt has been made to establish an approach and a methodology to quantify electronic waste (e-waste) in India. The study
was limited to personal computers (PCs) and televisions (TVs) within the state boundaries of Delhi and in selected areas in
the National Capital Region (NCR). Material flow analysis was used to establish an e-waste trade value chain, where cathode
ray tubes (CRTs) were tracked in the e-waste dismantling stream of the CRT regunning process. The market supply method was
used to estimate the theoretical amount of e-waste for each item. Sensitivity analysis was carried out for PCs, using 5 years
and 7 years as the average life, and for TVs, using 10 years and 12 years as the average life. Externalities such as e-waste
entering the study area from outside were factored into the final e-waste analysis. Sensitivity analysis on the average life
also factored in elements of active usage, reuse, and storage of electronic items and consumer behavior into assumptions about
the obsolescence rate in market supply method. A primary survey indicated an output of 1800–2100 CRTs per day from all regunning
units in the study area. This range validated the theoretical output for an average life of 7 years for a PC and 12 years
for a TV. Using this approach, e-waste was estimated to reach 2 million units from the domestic market by 2010.
Bangalore figures prominently in the world map for its contribution in Information Technology (IT), Business Process Outsourcing, Research and Development (R&D) outsourcing and Bio-Technology. This phenomenal growth over the past decade, has given rise to the generation of lot of Electronic Waste. E-waste thus generated contains many recoverable metals and non metals along with hazardous wastes and their improper disposal may cause environmental problems. The main issue of E-Waste is that there are backyard recyclers who are practicing E-waste recycling by adopting crude methods resulting in inefficient recovery, besides causing health and environmental hazards.
There is an enormous growth in mobile phone consumption worldwide which leads to generation of a large volume of mobile phone waste every year. The aim of this review is to give an insight on the articles on mobile phone waste management and recycling, published in scientific journals, major proceedings and books from 1999 to 2015. The major areas of research have been identified and discussed based on available literature in each research topic. It was observed that most of these articles were published during the recent years, with the number of articles increasing yearly. Material recovery and review on management options of waste are found to be the leading topics in this area. Researchers have proved that economically viable refurbishing or recycling of such waste is possible in an environmentally friendly manner. However, the literatures indicate that without proper consumer awareness, a recycling system cannot perform to its maximum efficiency. The methodologies followed and analytical techniques employed by the researchers to attain their objectives have been discussed. The graphical representations of available literature on current topic with respect to year of publication, topics and location have also been explored.
Because of their short life span and high production and consumption rates, mobile phones are one of the contributors to WEEE (waste electrical and electronic equipment) growth in many countries. If incorrectly managed, the hazardous materials used in the assembly of these devices can pollute the environment and pose dangers for workers involved in the recycling of these materials. In this study, 144 polymer fragments originating from 50 broken or obsolete mobile phones were analyzed via laser-induced breakdown spectroscopy (LIBS) without previous treatment. The coated polymers were mainly characterized by the presence of Ag, whereas the uncoated polymers were related to the presence of Al, K, Na, Si and Ti. Classification models were proposed using black and white polymers separately in order to identify the manufacturer and origin using KNN (K-nearest neighbor), SIMCA (Soft Independent Modeling of Class Analogy) and PLS-DA (Partial Least Squares for Discriminant Analysis). For the black polymers the percentage of correct predictions was, in average, 58% taking into consideration the models for manufacturer and origin identification. In the case of white polymers, the percentage of correct predictions ranged from 72.8% (PLS-DA) to 100% (KNN).
This study characterizes the composition of plastic frames and printed circuit boards from end-of-life mobile phones. This knowledge may help define an optimal processing strategy for using these items as potential raw materials. Correct handling of such a waste is essential for its further "sustainable" recovery, especially to maximize the extraction of base, rare and precious metals, minimizing the environmental impact of the entire process chain. A combination of electronic and chemical imaging techniques was thus examined, applied and critically evaluated in order to optimize the processing, through the identification and the topological assessment of the materials of interest and their quantitative distribution. To reach this goal, end-of-life mobile phone derived wastes have been systematically characterized adopting both "traditional" (e.g. scanning electronic microscopy combined with microanalysis and Raman spectroscopy) and innovative (e.g. hyperspectral imaging in short wave infrared field) techniques, with reference to frames and printed circuit boards. Results showed as the combination of both the approaches (i.e. traditional and classical) could dramatically improve recycling strategies set up, as well as final products recovery.
The world's waste electrical and electronic equipment (WEEE) consumption has increased incredibly in recent decades, which have drawn much attention from the public. However, the major economic driving force for recycling of WEEE is the value of the metallic fractions (MFs). The non-metallic fractions (NMFs), which take up a large proportion of E-wastes, were treated by incineration or landfill in the past. NMFs from WEEE contain heavy metals, brominated flame retardant (BFRs) and other toxic and hazardous substances. Combustion as well as landfill may cause serious environmental problems. Therefore, research on resource reutilization and safe disposal of the NMFs from WEEE has a great significance from the viewpoint of environmental protection. Among the enormous variety of NMFs from WEEE, some of them are quite easy to recycle while others are difficult, such as plastics, glass and NMFs from waste printed circuit boards (WPCBs). In this paper, we mainly focus on the intractable NMFs from WEEE. Methods and technologies of recycling the two types of NMFs from WEEE, plastics, glass are reviewed in this paper. For WEEE plastics, the pyrolysis technology has the lowest energy consumption and the pyrolysis oil could be obtained, but the containing of BFRs makes the pyrolysis recycling process problematic. Supercritical fluids (SCF) and gasification technology have a potentially smaller environmental impact than pyrolysis process, but the energy consumption is higher. With regard to WEEE glass, lead removing is requisite before the reutilization of the cathode ray tube (CRT) funnel glass, and the recycling of liquid crystal display (LCD) glass is economically viable for the containing of precious metals (indium and tin). However, the environmental assessment of the recycling process is essential and important before the industrialized production stage. For example, noise and dust should be evaluated during the glass cutting process. This study could contribute significantly to understanding the recycling methods of NMFs from WEEE and serve as guidance for the future technology research and development.
Electric and electronic equipment (EEE) is
swiftly growing in volume, level of sophistication, and
diversity. Also, it evolves briskly, moved by innovation
and technical change, and draws on numerous and at times
rare resources. Waste EEE (WEEE) has evolved into an
important societal problem. Recycling and treating WEEE
implies occupational as well as environmental hazards that
are still incompletely documented. Still, second hand EEE
has been exported and treated in Africa, China, and India in
a precarious informal context. In developed countries, EEE
recycling has been sustained by a wide range of initiatives
and motives, such as sustainability, creating jobs, and the
value of precious or rare metals. Current EU Directives
require a steep reduction of WEEE plastics (WEEP) going
to landfill. Mechanical, thermal, and feedstock recycling of
WEEP are analysed and some options confronted. Plastics
recycling should be weighed against the eventual risks
related to their hazardous ingredients, mainly legacy brominated
fire retardants and heavy metals. Another paper is
related to a somewhat similar problem, yet involving a
different mix of plastics:
This study shows the application of laser induced breakdown spectroscopy (LIBS) for waste electrical and electronic equipment (WEEE) investigation. Several emission spectra were obtained for 7 different mobiles from 4 different manufacturers. Using the emission spectra of the black components it was possible to see some differences among the manufacturers and some emission lines from organic elements and molecules (N, O, CN and C2) led to the highest contribution for this differentiation. Some polymeric internal parts in contact with the inner pieces of the mobiles and covered with a special paint presented a strong emission signal for Cr. The white pieces presented mainly Al, Ba and Ti in their composition. Finally, this study developed a procedure for LIBS emission spectra using chemometric strategies and suitable information can be obtained for identification of manufacturer and counterfeit products. In addition, the results obtained can improve the classification for establishing recycling strategies of e-waste.
During processing of recycled ABS and ABS/HIPS blends, voiding defects can occur within the resulting material which can result in deterioration of mechanical properties. The voids were previously thought to be caused by the evolution of volatile substances during processing. This study investigated the recycling of post-consumer ABS from a variety of types of WEEE. The mechanical properties of the processed material were assessed and a combination of visual observation during processing and optical microscopy was used to identify the extent of voiding. It was found that flexural strength and ductility in particular decreased with increased levels of voids. The gases emitted during heating and processing were analysed using Gas Chromatography with Mass Spectroscopy (GCMS) and were found to be breakdown products of the original polymers. These seem to be present in the WEEE, either as polymerization residuals or as products of degradation during the initial service life rather than degradation products from reprocessing. The amounts of volatiles liberated were quantified, which showed that the volatile emissions from post-consumer material were of a similar magnitude to those seen with virgin material. More intensive or longer processing led to a reduction in the emissions and voiding and an improvement in strength, suggesting that there is a finite potential for volatile liberation, and that the problem could be overcome by the use of suitable processing conditions.
Polystyrene intercalated graphite oxide (GO) nanocomposite was prepared by emulsion polymerization reaction and characterized by X-ray diffraction (XRD), high resolution electron microscopy (HREM), and thermogravimetric analysis (TGA). It was shown that polystyrene can be intercalated into the interlayer space of GO and form exfoliated and intercalated nanocomposites. The thermal analysis demonstrated that the presence of GO enhances the char residue of the nanocomposite.
The compositions of three WEEE plastic batches of different origin were investigated using infrared spectroscopy, and the metal content was determined with inductively coupled plasma. The composition analysis of the plastics was based mainly on 14 samples collected from a real waste stream, and showed that the major constituents were high impact polystyrene (42wt%), acrylonitrile-butadiene-styrene copolymer (38wt%) and polypropylene (10wt%). Their respective standard deviations were 21.4%, 16.5% and 60.7%, indicating a considerable variation even within a single batch. The level of metal particle contamination was found to be low in all samples, whereas wood contamination and rubber contamination were found to be about 1wt% each in most samples. In the metal content analysis, iron was detected at levels up to 700ppm in the recyclable waste plastics fraction, which is of concern due to its potential to catalyse redox reactions during melt processing and thus accelerate the degradation of plastics during recycling. Toxic metals were found only at very low concentrations, with the exception of lead and cadmium which could be detected at 200ppm and 70ppm levels, respectively, but these values are below the current threshold limits of 1000ppm and 100ppm set by the Restriction of Hazardous Substances directive.
The effect of three types of silicas with varied loading and the loading of hydroxyl terminated silicone oil on the mechanical and thermal properties of silicone rubbers (SRs) were investigated. Mechanical properties were affected by the silica loading because of the interaction between fillers and polymer and the filler dispersion. Fumed silica filled SRs showed higher tanδ, tensile strength, and elongation at break compared to those containing two types of precipitated silicas. With increasing silicone oil loading, the tensile strength, tear strength, hardness, and tanδ of SRs first increased and then decreased.
The pyrolysis and flame retardancy of a bisphenol A polycarbonate/silicon rubber/bisphenol A bis(diphenyl
phosphate) (PC/SiR/BDP) blend were investigated and compared to those of PC/BDP and PC/SiR. The impact modifier SiR consists mainly of poly(dimethylsiloxane) (PDMS> 80 wt %). The pyrolysis of PC/SiR/BDP was studied by thermogravimetry (TG), TG-FTIR to analyze the evolved gases, and a Linkamhot stage cellwithin FTIR aswell as 29SiNMR and 31PNMRto analyze the solid residue. The fire performance was determined by PCFC, LOI, UL 94, and a cone calorimeter under different external irradiations. The fire residues were studied by using ATR-FTIR as well as the additional binary systems PC + PDMS, PC + BDP, and BDP + PDMS, focusing on the specific chemical interactions. The decomposition pathways are revealed, focusing on the competing interaction between the components. Fire retardancy in PC/SiR/BDP is caused by both flame inhibition in the gas phase and inorganiccarbonaceous residue formation in the condensed phase. The PC/SiR/BDP does not work as well superimposing the PC/SiR and PC/BDP performances. PDMS reacts with PC and BDP, decreasing BDP’s mode of action. Nevertheless, the flammability (LOI > 37%, UL 94 V-0) of PC/SiR/BDP equals the high level of PC/BDP. Indeed, SiR in PC/SiR/BDP is underlined as a promising impact modifier in flame-retarded PC/impact modifier blends as an alternative to highly flammable impact modifiers such as acrylonitrile� butadiene�styrene (ABS), taking into account that the chosen SiR leads to PC blends with a similar mechanical performance.
The silicone rubber vulcanizate powder (SVP) obtained from silicone rubber by mechanical grinding exists in a highly aggregated state. The particle size distribution of SVP is broad, ranging from 2 µm to 110 µm with an average particle size of 33 µm. X-ray Photoelectron Spectroscopy (XPS) and Infrared (IR) Spectroscopy studies show that there is no chemical change on the rubber surface following mechanical grinding of the heat-aged (200°C/10 days) silicone rubber vulcanizate. Addition of SVP in silicone rubber increases the Mooney viscosity, Mooney scorch time, shear viscosity and activation energy for viscous flow. Measurement of curing characteristics reveals that incorporation of SVP into the virgin silicone rubber causes an increase in minimum torque, but marginal decrease in maximum torque and rate constant of curing. However, the activation energy of curing shows an increasing trend with increasing loading of SVP. Expectedly, incorporation of SVP does not alter the glass-rubber transition and cold crystallization temperatures of silicone rubber, as observed in the dynamic mechanical spectra. It is further observed that on incorporation of even a high loading of SVP (i.e., 60 phr), the tensile and tear strength of the silicone rubber are decreased by only about 20%, and modulus dropped by 15%, while the hardness, tension set and hysteresis loss undergo marginal changes and compression stress-relaxation is not significantly changed. Atomic Force Microscopy studies reveal that incorporation of SVP into silicone rubber does not cause significant changes in the surface morphology.
The feasibility of reprocessing has been investigated as a possible alternative of polycarbonate recycling. The effect on thermal and mechanical properties of polycarbonates after up to 10 reprocessing cycles and the effect of the combined reprocessing and accelerated weathering were analyzed. Measurements collected after each molding cycle revealed a slight decrease of thermal properties. The same behaviour was observed from accelerated weathering tests. Neither the modulus of elasticity nor the tensile strength was affected in the first seven reprocessing cycles, whereas the impact strength decreased sharply. However, accelerated weathering showed that only after the first reprocessing cycle there was an important influence of the number of reprocessing cycles on the mechanical properties.
Acrylonitrile–butadiene–styrene (ABS) and high-impact polystyrene (HIPS) are two of the plastics most frequently used as outer casings for computer equipment such as monitors, keyboards, and other similar components. We assessed the effects of the recycling and blending of ABS and HIPS on mechanical properties. We found that the effects of recycling on ABS and HIPS were similar, in that changes in glass-transition temperatures, tensile strengths, and tensile moduli were negligible, but strains to failure and impact strengths were reduced considerably. Blending proportions of ABS and HIPS caused no more deterioration in properties than occurred as a result of the recycling process, and the presence of small proportions of one material in the other actually restored significant amounts of ductility, as seen by increases in the strains to failure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 572–578, 2002
An ABS-material has been subjected to a series of six combined cycles of extrusion and ageing in air at an elevated temperature. Each cycle consisted of conventional extrusion processing followed by ageing in air at 90 °C for 72 h. Large changes in the tensile and flow properties were observed. From the second to the sixth cycle, the elongation at break decreased markedly due to the ageing and increased as a result of the extrusion step. Further analysis showed that the large reductions in elongation at break could be attributed to physical ageing of the SAN-phase and to thermo-oxidative ageing of the polybutadiene phase, as shown by further tensile measurements and infrared spectroscopy. SEM-measurements indicated no significant changes in the size and shape of the polybutadiene particles. No significant changes in the molar mass of the SAN-phase were observed.
This paper describes a direct analysis study carried out in a recycling unit for waste electrical and electronic equipment (WEEE) in Portugal to characterize the plastic constituents of WEEE. Approximately 3400 items, including cooling appliances, small WEEE, printers, copying equipment, central processing units, cathode ray tube (CRT) monitors and CRT televisions were characterized, with the analysis finding around 6000 kg of plastics with several polymer types. The most common polymers are polystyrene, acrylonitrile-butadiene-styrene, polycarbonate blends, high-impact polystyrene and polypropylene. Additives to darken color are common contaminants in these plastics when used in CRT televisions and small WEEE. These additives can make plastic identification difficult, along with missing polymer identification and flame retardant identification marks. These drawbacks contribute to the inefficiency of manual dismantling of WEEE, which is the typical recycling process in Portugal. The information found here can be used to set a baseline for the plastics recycling industry and provide information for ecodesign in electrical and electronic equipment production.
Pyrolysis and combustion runs at 850°C in a horizontal laboratory furnace were carried out on different parts of a mobile phone (printed circuit board, mobile case and a mixture of both materials). The analyses of the carbon oxides, light hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), polychlorodibenzo-p-dioxin, polychlorodibenzofurans (PCDD/Fs), and dioxin-like PCBs are shown. Regarding semivolatile compounds, phenol, styrene, and its derivatives had the highest yields. In nearly all the runs the same PAHs were identified, naphthalene being the most common component obtained. Combustion of the printed circuit board produced the highest emission factor of PCDD/Fs, possibly due to the high copper content.
Electronic scrap is part of a universally wide range of obsolete, defective, or used materials that need to be disposed of or recycled in an ecologically friendly manner. The present study focused on the polymers present in mobile phone scrap. In mobile phones, polymers are found in frames and in printed circuit boards (PCBs). The frames are mainly made of polymers whereas PCBs use a variety of material (polymers, ceramics, and metals) which makes recycling more difficult. As a first step, mobile phones were collected, separated by manufacturer/model, and weighed, and the principal polymer types identified. The frames and PCBs were processed separately. The metals in PCBs were separated out by an electrostatic separation process. The resulting polymeric material was identified and mixed with the polymers of frames to fabricate the samples. Two types of samples were made: one with polymeric frames, and the other with a mixture of frames and polymeric fraction from the PCBs. Both kinds of sample were fabricated by injection moulding. The samples were evaluated by mechanical tests (tensile, impact, and hardness) to verify the feasibility of recycling the polymers present in mobile phone scrap. The results demonstrated the technical viability of recovering polymers using mechanical processing followed by an injection process.
There is an increasing interest in the end-of-life management of polymers present in waste electrical and electronic equipment (WEEE). This is mainly due to high recycling and recovery quotas set by the European WEEE directive, which can only be fulfilled by including the plastic fraction in recycling and recovery approaches. Previous studies identified a high material diversity and various contaminants in WEEE plastics, including heavy metals, polybrominated biphenyls (PBB), diphenyl ethers (PBDE), as well as polybrominated dibenzodioxins and dibenzofurans (PBDD/F). These substances are regulated by European directives that limit their levels in marketable products. Consequently, both material diversity and contaminants are strong arguments against material recycling and point to hazardous waste treatment. However, recent developments in the production of flame retardants and electrical and electronic goods aimed to reduce contaminants and material diversity. Thus, the present study summarises updated contaminant levels of plastic fractions of European WEEE, as well as data on materials in waste housing polymers. Material characterisation revealed housing fractions to be interesting sources for polymer recycling, which however has to implement potent material separation and/or bromine elimination techniques. With respect to contaminants, our data indicate an effective phase-out of PBB, but still high levels of PBDE and PBDD/F are found. Sources and implications for the material recycling and thermal recovery approaches are discussed in detail.
Initiative White Paper (2014) One global definition of e-waste. From StEP initiative. http:// www. stepinitiative. org/ files/ step
- E-Waste Solving The
- Problem
The global e-waste monitor—2014. From United Nations University
- Cp Balde
- F Wang
- R Kuehr
- J Huisman
Thermal analysis of silicone rubber. From Hitachi Hightech Science Corporation
- Hitachi Hightech
In: Damanhuri E (ed) Postconsumer waste recycling and optimal production
- P Tanskanen
Tanskanen P (2012) In: Damanhuri E (ed) Postconsumer waste recycling
and optimal production. Intech, Finland, pp 129-150
The global ewaste monitor— 2014
- Cp Balde
- F Wang
- R Kuehr
- J Huisman
Balde CP, Wang F, Kuehr R, Huisman J (2015) The global ewaste monitor—
2014. From United Nations University, IAS—SCYCLE, Bonn, Germany.
http://i.unu.edu/media/unu.edu/news/52624/UNU1stGlobalEWasteMonitor
2014small.pdf. Accessed 15 May 2015
TA No. 18, Thermal analysis of silicone rubber
- Hitachi Hightech
Hitachi Hightech (1985) TA No. 18, Thermal analysis of silicone rubber.
Ewaste assessment methodology and validation in India
- A Jain
- R Sareen
Jain A, Sareen R (2006) Ewaste assessment methodology and validation in
India. J Mater Cycles Waste Manag 8:40-45. doi:10.1007/s1016300501452
Electronic waste management in the United States through
United States Environmental Protection Agency (2011) Electronic waste
management in the United States through 2009. From USEPA.
Characterization and recycling of polymeric components present in cell phones
- M R Monteiro
- Dgg Moreira
- M A Chinelatto
- Pap Nascente
- N G Alcantara
Monteiro MR, Moreira DGG, Chinelatto MA, Nascente PAP, Alcantara NG
(2007) Characterization and recycling of polymeric components present in cell
phones. J Polym Environ 15:195-199. doi:10.1007/s1092400700609
Preparation and characterization of polystyrene/graphite oxide nanocomposite by emulsion polymerization
- R Ding
- Y Hu
- Z Gui
- R Zong
- Z Chen
- W Fan
Ding R, Hu Y, Gui Z, Zong R, Chen Z, Fan W (2003) Preparation and
characterization of polystyrene/graphite oxide nanocomposite by emulsion
polymerization. Polym Degrad Stabil 81:473-476. doi:10.1016/S0141
3910(03)001320