Papers by Keyword: Polymer Recycling

Abstract: Improper disposal and management of plastic and rubber waste pose significant environmental and health risks, while also contributing to resource depletion. With the increasing demand for polymeric materials, it is crucial to develop more sustainable solutions for recycling and reutilizing waste into sustainable and eco-friendly products. This study explores the development of composite material made from recycled polyvinylchloride (rPVC) sourced from carpet backing material and waste rubber particles from two different sources namely LeHigh (cryogenically ground truck tire rubber) and ALUM (scrap rubber from scuba diving products). The composites were melt mixed using a Brabender internal mixer at 165°C, with filler content ranging from 0–30 wt%. The study evaluates the impact of LeHigh and ALUM as fillers in rPVC composites, aiming to meet performance standards for car floor mats. Processability data showed that the saturation point for both fillers in rPVC was at 20 wt%, beyond which the composites became immiscible and sticky. Properties evaluation revealed that LeHigh offered better tensile strength, compatibility and overall performance as compared to ALUM. The optimal formulation, with 20 wt% LeHigh and 10 wt% ALUM, met the performance requirements for car floor mat application, including a minimum tensile strength of 5 MPa, a minimum elongation at break of 25%, water absorption of less than 2.5%, and shore A hardness of 90 ± 5. Beyond 20 wt% filler, agglomeration and increased processing torque led to poor processability and reduced performance. This work highlights the importance of selecting the right materials and compounding formulations for recycling plastic and rubber waste into valuable, sustainable composites, contributing to industrial innovation, environmental sustainability, and the circular economy.

Abstract: Throughout the combination of unique approaches on innovative polymer composites and rotational moulding plastics processing technique, we developed a building block using a mix of recycled and virgin plastic. This block was a technical case study from a multidisciplinary approach - comprising materials science, polymers processing and design - to reinsert recycled plastics in the Circular Economy. The aim was to produce a three-dimensional interlockable block, combining unique design and unconventional materials to create an emblematic building element. We investigated the composition and availability of local plastic waste, as well as other waste-stream materials – concrete waste, red mud, hemp fibre, sugarcane bagasse. We prepared a range of composites and blends to test their prospective aspect and processability. To simulate the end-result of a rotationally-moulded part, we prepared samples of the blends in an oven. The thermal analysis showed that all materials were thermally stable at the processing temperature of the virgin polymer in rotomoulding, around 200 °C. There were an evident LLDPE continuous-phase and a recyclate dispersed-phase. We also explored the aesthetic effect of scattering particles of colour in the mixes. The impact test showed better results for the polyethylene-based recyclates if compared to polypropylene and poly (ethylene terephthalate) ones. We concluded that waste materials could be revalued into something practical and reproducible, produced by rotational moulding plastics processing. And we developed a viable and innovative potential product for the Circular Economy, requiring minimal fixing and no further external finishing.

Abstract: The paper presents the extruder functioning point changing, resulted as the intersection of screw and extrusion head functional characteristics curves, during the processing of a polymeric material recycled many times, in comparison with the same polymeric material - first time extruded. The recycling could modify the slope of the screw characteristic curve. In the paper it is shown the modification of the screw characteristic, at the same screw speed, for a sort of HDPE, at a certain extruding temperature. Similar, there are modifications of the extruder head characteristics curves. So the extruder functioning point becomes quite different as the number of recycling increases, but it has to be situated in the head optimal working field.