Recycling of Polypropylene Recovered from a Composting Plant: Mechanical Behavior of Compounds with Virgin Plastic

Abstract

The recycling of polypropylene recovered from waste discarded by a composting plant was investigated. The recovery involved a sorting step carried out by means of an optical infrared separator and a subsequent washing treatment. This method of processing allowed us to obtain polypropylene that was only slightly contaminated by other polymeric and inorganic materials. As many tens of tons of polypropylene could be recovered every year in this plant, recycling could be convenient from the economic point of view and beneficial for the protection of the environment. In fact, the landfill of this waste could be reduced in this manner. A possible mechanical recycling route was developed for the recovered plastic. The recycling was carried out by pelletizing the recovered polypropylene, mixing it with a commercial polypropylene feedstock, and manufacturing items by injection molding. In this way, tensile specimens containing different amounts of recycled polypropylene were processed and tested. Their tensile features were compared with those of a commercial polypropylene that was used as a reference. The elastic modulus and tensile strength were slightly worsened when using the recycled plastic, while the strain at failure significantly increased. Nonetheless, the tensile properties of compounds made by mixing recycled and virgin polypropylene were consistent with the characteristics that are expected for polypropylene-based plastics.

Improvement of Thermal Protection in Recycled Polyolefins through Hybrid Mesoporous Silica–Antioxidant Particles

“…A single melting process is noticed in the curve for the virgin PP, which is located at about 165 • C, while two endothermic events are exhibited by the PPR, at around 160 • C and 128 • C, respectively. The existence of these two meltings indicates that PPR is not a bare recycled PP, but rather it contains a fraction of polyethylene (PE) from cross contamination [37,38]. Thus, the peak at the highest temperatures is related to the polypropylene component in PPR, which might be composed, due to its recycled nature, of a mixture of different grades including homopolymers and copolymers, while the peak at low temperature is attributed to PE.…”

An Experimental Approach to Determining the Average Diffusion Coefficient of Volatile Components in Polymer Waste Materials

“…Although legislative pressure on the plastics industry has recently increased, the proportion of recycled plastics in the EU stagnates at roughly 8% [1]. If the above targets are to be achieved, the recycling of plastics will become increasingly important, and plastic as a material must be shifted into a sustainable circular economy [3]. Life-cycle analyses (LCAs) have shown that beverages multi-packaged in post-consumer recycled plastic cause 73% less greenhouse gas emissions and consume 90% less energy than their cardboard counterparts [4].…”