Post-consumer Polystyrene Research Articles

Recyclability of Post-Consumer Polystyrene at Pilot Scale: Comparison of Mechanical and Solvent-Based Recycling Approaches.

Solvent-based and mechanical recycling technology approaches were compared with respect to each process's decontamination efficiency. Herein, post-consumer polystyrene (PS) feedstock was recycled by both technologies, yielding recycled PS resins (rPS). The process feedstock was subjected to four recycling cycles in succession to assess the technology perennity. The physico-chemical and mechanical properties of the rPS were then evaluated to discern the advantages and drawbacks of each recycling approach. The molecular weight of the mechanically recycled resin was found to decrease by 30% over the reprocessing cycles. In contrast, the solvent-base recycling technology yielded a similar molecular weight regarding the feedstock. This consistency in the rPS product is critical for consumer applications. Further qualitative and quantitative analyses on residual organic compounds and inorganic and particulate contaminants were investigated. It was found that the solvent-based technology is very efficient for purifying deeply contaminated feedstock in comparison to mechanical recycling, which is limited to well-cleaned and niche feedstocks.

Recycling of Post-Consumer Polystyrene Packaging Waste into New Food Packaging Applications—Part 2: Co-Extruded Functional Barriers

Post-consumer polystyrene (PS) recyclates behind a functional barrier of virgin PS polymer is an attractive way to introduce post-consumer PS recyclates in packaging materials. However, until now, there has been no official guidance published on how to test the performance of a functional barrier. In addition, no threshold limits for the evaluation of post-consumer recyclates behind FBs have been published by competent authorities. This is a drawback in the food law compliance evaluation and novel technology notification of post-consumer recyclates behind a functional barrier. In this study, co-extruded yogurt cups with an artificially spiked core layer were investigated with respect to migration of the applied surrogates. The applied migration kinetic testing method into the gas phase was shown to be sensitive and suitable for the evaluation of the functional barrier performance. For consumer safety evaluation, two worst-case scenarios were used. As a result, due to the high processing temperatures used during co-extrusion, the virgin PS functional barrier layer was partly contaminated with the surrogates from the core layer. However, on the basis of the conditions, data, and the evaluation presented, the use of post-consumer recycled PS behind an FB of virgin PS can be considered as safe.

INFLUENCE OF SILICA NANOPARTICLES ON THE THERMOMECHANICAL PROPERTIES OF RECYCLED POLYSTYRENE

ABSTRACT Polystyrene from packing materials (rPS) was reinforced with 1, 3 and 5 % of silica prepared by the sol-gel method, through a blending process . The thermal, morphological and mechanical properties were compared with those of the virgin polystyrene (PS). The results show that the glass transition temperature (Tg), storage modulus (E’) and impact strength of the pure rPS and silica-rPS composites were higher than those of virgin PS. Thermogravimetric analysis revealed that the thermal stability of virgin PS was slightly greater than that of the rPS. The addition of silica to rPS increased their thermal stability to similar values of the virgin PS.SEM studies showed that the silica nanoparticles had an uniform size but its dispersion into the polymer matrix was not homogeneous.These results suggest that postconsumer PS can be used to obtain composite materials with good mechanical and thermal properties. Keywords: Polystyrene, nanocomposites, silica, thermal properties, morphology

Mechanical Properties and Effect of Coupling Agent in a Polystyrene/Flyash Composite

Composite samples were prepared consisting of up to 60 wt% flyash filler contained within a combined virgin and post-consumer polystyrene matrix. Mechanical testing was conducted, which included flexural, split tension and compression modes. As filler content increased, ultimate strengths and strains were compromised, especially under flexural and split tension loadings. These effects at a selected flyash level were largely reversed by incorporation of a silane coupling agent. The fracture behavior of these two-phase materials and the efficacy of the coupling agent are discussed, further supported by microscopic observation of fracture surfaces.