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Recycling, Volume 2, Issue 2 (June 2017) – 3 articles

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1306 KiB  
Article
Energy Payback Time of a Solar Photovoltaic Powered Waste Plastic Recyclebot System
by Shan Zhong, Pratiksha Rakhe and Joshua M. Pearce
Recycling 2017, 2(2), 10; https://doi.org/10.3390/recycling2020010 - 15 Jun 2017
Cited by 34 | Viewed by 11088
Abstract
The growth of both plastic consumption and prosumer 3-D printing are driving an interest in producing 3-D printer filaments from waste plastic. This study quantifies the embodied energy of a vertical DC solar photovoltaic (PV) powered recyclebot based on life cycle energy analysis [...] Read more.
The growth of both plastic consumption and prosumer 3-D printing are driving an interest in producing 3-D printer filaments from waste plastic. This study quantifies the embodied energy of a vertical DC solar photovoltaic (PV) powered recyclebot based on life cycle energy analysis and compares it to horizontal AC recyclebots, conventional recycling, and the production of a virgin 3-D printer filament. The energy payback time (EPBT) is calculated using the embodied energy of the materials making up the recyclebot itself and is found to be about five days for the extrusion of a poly lactic acid (PLA) filament or 2.5 days for the extrusion of an acrylonitrile butadiene styrene (ABS) filament. A mono-crystalline silicon solar PV system is about 2.6 years alone. However, this can be reduced by over 96% if the solar PV system powers the recyclebot to produce a PLA filament from waste plastic (EPBT is only 0.10 year or about a month). Likewise, if an ABS filament is produced from a recyclebot powered by the solar PV system, the energy saved is 90.6–99.9 MJ/kg and 26.33–29.43 kg of the ABS filament needs to be produced in about half a month for the system to pay for itself. The results clearly show that the solar PV system powered recyclebot is already an excellent way to save energy for sustainable development. Full article
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1716 KiB  
Article
Complete Recycling of Composite Material Comprising Polybutylene Terephthalate and Copper
by Fabian Knappich, Ferdinand Hartl, Martin Schlummer and Andreas Mäurer
Recycling 2017, 2(2), 9; https://doi.org/10.3390/recycling2020009 - 08 Jun 2017
Cited by 16 | Viewed by 9779
Abstract
Composite materials comprising plastic and metal parts generate a large amount of waste containing valuable components that are difficult to separate and recycle. We therefore developed an economical solvent-based process for the recovery of costly manufactured composite materials comprising several copper panels over-moulded [...] Read more.
Composite materials comprising plastic and metal parts generate a large amount of waste containing valuable components that are difficult to separate and recycle. We therefore developed an economical solvent-based process for the recovery of costly manufactured composite materials comprising several copper panels over-moulded with a polymeric matrix of polybutylene terephthalate (PBT). We applied the CreaSolv® Process, which uses proprietary formulations with a low risk to user and environment, in order to dissolve the polymer and retain the inert copper. After separating the metal from the solution, solvent recovery was achieved by means of vacuum distillation and melt degassing extrusion. The recovered solvent was collected and recycled while maintaining its original properties. We tested two candidate solvents with PBT, measuring their impact on the molecular weight (Mw) and polydispersity of the polymer at different residence times and dissolution temperatures. We found that increasing the temperature-time-load had a negative effect on the Mw. Both solvents we tested were able to dissolve the polymeric matrix within 30 min and with moderate energy consumption. Furthermore, we found that the exclusion of oxygen during dissolution significantly increases the quality of the recovered polymer and metal. We transferred the process from the laboratory scale to the small-technical scale and produced material for large analytical and mechanical quality evaluation, revealing no decline in the polymer quality by blending with new plastic. The recovered copper met virgin material properties. Therefore, both components of the original composite material have been recovered in a form suitable for reuse. Full article
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2658 KiB  
Article
Properties of Shredded Roof Membrane–Sand Mixture and Its Application as Retaining Wall Backfill under Static and Earthquake Loads
by Bennett Livingston and Nadarajah Ravichandran
Recycling 2017, 2(2), 8; https://doi.org/10.3390/recycling2020008 - 05 Apr 2017
Cited by 10 | Viewed by 5293
Abstract
About 20 billion square feet of Ethylene Propylene Diene Monomer (EPDM) rubber is installed on roofs in the United States and most of them will be reaching the end of their lifespan soon. The purpose of this study is to investigate potential reuses [...] Read more.
About 20 billion square feet of Ethylene Propylene Diene Monomer (EPDM) rubber is installed on roofs in the United States and most of them will be reaching the end of their lifespan soon. The purpose of this study is to investigate potential reuses of this rubber in Civil Engineering projects rather than disposing it into landfills. First, laboratory tests were performed on various shredded rubber-sand mixtures to quantify the basic geotechnical engineering properties. The laboratory test results show that the shredded rubber-sand mixture is lightweight with good drainage properties and has shear strength parameters comparable to sand. This indicates that the rubber-sand mixture has potential to be used for retaining wall backfill and many other projects. To assess the economic advantage of using shredded rubber-sand mixtures as a lightweight backfill for retaining walls subjected to static and earthquake loadings, geotechnical designs of a 6 m tall gravity cantilever retaining wall were performed. The computed volume of concrete to build the structural components and volume of backfill material were compared with those of conventional sand backfill. Results show significant reductions in the volume of concrete and backfill material in both static and earthquake loading conditions when the portion of shredded rubber increased in the mixture. Full article
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