1,721,028 research outputs found
Evaluation of the quality of postconsumer plastics obtained from disassembly-based recycling strategies
No full textThe focus of the presented research is on the mechanical recycling of postconsumer plastics from Waste Electrical and Electronic Equipment (WEEE). Currently only a limited number of these plastics are mechanically recycled on an industrial scale while the majority is thermally treated for energy recovery. Since there is a significant potential for value recovery and to lower the environmental impact of plastics, the aim of this research is to develop new mechanical recycling processes based on the disassembly of plastic components and the sorting of these plastics based on identification by spectroscopic methods. This study will present this distinct recycling process based on a case study of the recycling of Acrylonitrile Butadiene Styrene terpolymer (ABS) from Liquid Crystal Display (LCD) TVs. The quality of the recyclates is evaluated by mechanical testing and injection molding of thin-walled products. Results showed that with direct reapplication of the obtained ABS without compounding, high mechanical properties could be achieved when compared to postshredder recycled ABS. However, remaining impurities in the polymer matrix limit the applicability of the recycled plastics to components without neither structurally critical nor aesthetical requirements. POLYM. ENG. SCI., 58:485-492, 2018. (c) 2017 Society of Plastics EngineersFlemish Environmental Technology Platform (MIP); Flanders Innovation & Entrepreneurship (VLAIO
Towards a more circular economy for WEEE plastics – Part A: Development of innovative recycling strategies
No full textThis two paper series describes a method to develop and evaluate innovative recycling strategies for WEEE plastics. Part A presents a SWOT analysis of a new dismantling based recycling process of plastic components and the integration in an existing post-shredder separation recycling facility. Subsequently, recycling strategies are developed and the economic potential is evaluated. Part B investigates the technical feasibility of the recycling strategies. Asa case study the dismantling of LCD TV plastic back cover housings is taken. First, the advantages and disadvantages of the new process and the main external factors based on the market for recycled plastics and the waste material input are discussed on industrial level. Subsequently, five recycling strategies are developed: Strategy (1) produces recycled granulates with the dismantling process for direct reapplication in electronic products, strategy (2) recycles plastics for the use as carrier materials for flame retardant masterbatches, strategy (3) blends the recycled plastic with post-shredder recyclates for material upgrading, strategy (4) recycles the plastics with the post-shredder process and strategy (5) thermally treats plastics. Finally, the economic evaluation shows that the special engineering plastics used for LCD TV back covers have very high virgin prices up to 5 (sic) per kg. The implementation of the new process indicates a significant potential for value recovery based on plastics that would otherwise be incinerated or downcycled. (C) 2019 Elsevier Ltd. All rights reserved
Experimental analysis of conformal cooling in SLM produced injection moulds: Effects on process and product quality
No full textIn an injection moulding process, the cooling step takes up to 50% or more of the total cycle time. Therefore, any reduction of the cooling time directly results into an increase of the production rate. Furthermore, products are often rejected because of defects such as warpage or sink marks. The cause of these defects is often an unevenly distributed cooling in the mould due to complex product or mould shapes. A solution for both problems is Conformal Cooling, a technique in which the cooling channels are designed to follow the contour of the mould cavity to obtain an optimal cooling. These often curved cooling channels are difficult or even impossible to produce with conventional techniques such as milling, drilling and EDM. The recent development of the Selective Laser Melting (SLM) 3D printing technology can be used to overcome these limitations. In a previous work [1] the cooling channels of an existing mould to produce sorting trays were assessed and redesigned to achieve a conformal cooled mould. A mould cavity and insert were provided with these cooling channels by means of the SLM technique. In this work the performance of the conformal cooled mould is compared with the original mould based on process characteristics and product measurements. In particular the start-up losses, mould temperature during the cycle, cycle time and product warpage are assessed
A novel method for the prediction of adhesive strength for two-component injection molding of thermoplastics with thermoset rubbers
No full textTwo component injection molding is a widespread technique to produce polymer products that consist of two materials. This technique is commonly used to combine various material properties, or functionalities in one product. The `hard-soft' combination where a stiff material is over-molded by a soft layer, is one example, often seen in valve like products where the soft part is used as a seal. Thermoplastic elastomers (TPE's) are commonly used is this case. However, TPE's have only limited properties for chemical and temperature resistance. For such applications it would be beneficial to use a thermoset rubber as EPDM, NBR, NR, etc. Although injection molding of thermoset rubbers is not that uncommon, using it in an over molding process is rather rare and not much is known about the final properties of the over molded product. One of the most important parameters is the adhesion between the two materials. Recommendations for good adhesion can be found in literature for specific material combinations, but data on predicting the strength of adhesion in thermoset rubber over molding in function of material and process settings does not exist. This paper presents a novel, empirical method to predict the strength of adhesion in function of material and process settings
Prediction of interfacial strength of HDPE overmolded with EPDM
No full textMulticomponent injection molding often combines a stiff thermoplastic material with a thermoplastic elastomer or thermoplastic vulcanite. Recently, for high-demanding applications, a novel process has been developed to replace these thermoplastic elastomers or vulcanite with a thermoset rubber, for example, NBR or EPDM. One of the most important properties of a two component product is an adequate adhesion between both components. This paper describes a method, which combines experiments and numerical simulations to predict the adhesion strength between a thermoplastic, semicrystalline HDPE, and an EPDM thermoset rubber. This method uses numerical simulations of the interfacial temperature and the local degree of cure. The local interface temperature is combined with the results of DSC measurements to predict the degree of melting, subsequently linked to the ability to develop adhesive strength. The degree of cure is used to determine the local rubber strength. The combination of the given data will be used to predict interfacial strength. The results obtained by proposed numerical strategy have been successfully validated with experimental data on a simple plate product. POLYM. ENG. SCI., 59:1489-1498 2019. (c) 2019 Society of Plastics Engineer
Effect of co-agents on adhesion between peroxide cured ethylene– propylene–diene monomer and thermoplastics in two-component injection molding
No full textTwo-component (2K) injection-molded products combining ethylene–propylene–diene monomer (EPDM) with polar or nonpolar
thermoplastics require strong interfacial bonding. To optimize the adhesion, co-agents trimethylolpropane trimethacrylate (TMPT) and triallylcyanurate (TAC) are compared and concentrations were varied between 0 and 12 parts per hundred rubber (phr). Changes inmaterial compatibility were characterized by contact angle measurements at high temperature, the adhesion was evaluated by tensile testing, and physicomechanical properties of the EPDMbulk were analyzed. Results show that with polypropylene, the adhesion increases to an optimum (3 phr TAC or 6 phr TMPT) independent of the co-agent type, while for polyethylene only TAC (1.5 phr) effectively boosts adhesion. It is surmised that these optimal concentrations promote crosslinking reactions at the interface. For polycarbonate and acrylonitrile–butadiene–styrene, increasing TAC concentration causes higher adhesion due to improved compatibility. Furthermore, physicomechanical bulk properties change significantly with co-agent concentrations, making the optimal curing composition application dependent.sponsorship: B. Laing acknowledges Research Foundation - Flanders (FWO) for funding this PhD Fellowship strategic basic research (1SB0319N). The authors also acknowledge the company Hercorub NV for providing the uncured rubber material. (Research Foundation - Flanders (FWO)|1SB0319N)status: Published onlin
Optimization and development of processing aids for PVC foam applications
No full textKaneka Belgium develops and produces additives for PVC to improve its properties. Processing aids are added to improve fusion of the PVC resulting in better processability. PVC has poor processability characteristics other than slow fusion such as melt fracture, poor melt strength and extensibility. Processing aids improve melt rheology thanks to their high molecular weight chains. This master's thesis aims to improve the production process of a processing aid as well as develop a new processing aid. Properties of former processing aid should remain the same whilst production efficiency increases. Development of a processing aid resulting in a low-density PVC foam product with good surface finish is a desired outcome.
Processing aids are produced via free radical emulsion polymerization. Changes in recipe such as solid content, emulgator type, reaction time and post-initiation methods aim to improve the production process. To ensure properties remain within range, evaluation of parameters such as molecular weight, particle size distribution and shear viscosity are performed. In attempt to develop a new processing aid, parameters such as chain transfer agent, monomer composition and functional groups are changed along with blending of processing aids. Die swell and Brabender tests are performed to evaluate melt rheology of the new processing aid.
Alterations to the former processing aid resulted in an improved production efficiency. First developments towards the new processing aid were conducted
Development and evaluation of an acrylic lubricant for PVC formulations.
No full textOne of Kaneka Belgium's activities is the development and production of additives for PVC in order to improve its properties. Lubricants, for instance, are added to the PVC formulation to reduce friction and melt viscosity in order to improve processing. However, current lubricants tend to display plate-out, which is an uncontrolled deposition on machinery parts. Therefore, this master's thesis aimed to develop a low molecular weight acrylic lubricant that is sufficiently compatible with the PVC matrix to avoid plate-out.
The acrylic lubricant was synthesized via free radical suspension polymerization. Parameters of the polymerization process, such as temperature, initiator type, initiator concentration, emulsifier type, emulsifier concentration and addition of chain transfer agents were methodically adapted. As a result, a recipe was achieved that produces low molecular weight acrylic polymers. From the different polymerization tests, promising acrylic polymers were evaluated on their lubricating properties by Brabender gelation and shear viscosity measurements. Results of these tests were compared to the lubricating properties of standard lubricants.
A recipe to produce low molecular weight lubricating acrylic polymers was successfully developed. The acrylic polymers displayed similar lubricating properties compared to current lubricants according to Brabender gelation and shear viscosity measurements
Development and evaluation of an acrylic lubricant for PVC formulations.
No full textOne of Kaneka Belgium's activities is the development and production of additives for PVC in order to improve its properties. Lubricants, for instance, are added to the PVC formulation to reduce friction and melt viscosity in order to improve processing. However, current lubricants tend to display plate-out, which is an uncontrolled deposition on machinery parts. Therefore, this master's thesis aimed to develop a low molecular weight acrylic lubricant that is sufficiently compatible with the PVC matrix to avoid plate-out.
The acrylic lubricant was synthesized via free radical suspension polymerization. Parameters of the polymerization process, such as temperature, initiator type, initiator concentration, emulsifier type, emulsifier concentration and addition of chain transfer agents were methodically adapted. As a result, a recipe was achieved that produces low molecular weight acrylic polymers. From the different polymerization tests, promising acrylic polymers were evaluated on their lubricating properties by Brabender gelation and shear viscosity measurements. Results of these tests were compared to the lubricating properties of standard lubricants.
A recipe to produce low molecular weight lubricating acrylic polymers was successfully developed. The acrylic polymers displayed similar lubricating properties compared to current lubricants according to Brabender gelation and shear viscosity measurements
Two-component injection moulding of thermoplastics with thermoset rubbers: The effect of the mould temperature distribution
No full textIn a previous study [1] a novel two-component injection moulding process was proposed for combining thermoplastics with thermoset rubber. This process requires moulds in which the cavities for the thermoplastic and the rubber are thermally separated making it possible to use different mould temperatures for both materials. The process starts by first injecting the thermoplastic part. Afterwards the thermoset rubber is injected and vulcanised. The goal of two-component injection moulding is to combine materials within a single product without assembly. Therefore the adhesion strength between the two materials is an important property that detennines the product quality for a two-component injection moulded product. A second important property for every injection moulding process is the cycle time. The cycle time for this specific process is mainly determined by the time required to sufficiently vulcanise the rubber. In this paper the effect of the mould temperature on both the adhesion strength and the vulcanisation time arc investigated experimentally. Products are produced using different mould temperature distributions. Afterwards the adhesion strength is examined using tensile tests. The vulcanisation time is detennined by using hardness measurements to verify the vulcanisation degree of the rubber. Results indicate that higher mould temperatures for the thermoplastic part lead to higher adhesion strength and lower vulcanisation time
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