Influence of Reprocessing in the formation of functional groups during low density polyethylene aging

Abstract

Abstract:In recent years, the interest in polymer recycling has increased. However, in every reprocessing step the material undergoes shear stress and is affected by temperature and oxygen. The aim of this paper is to investigate the influence of multiple extrusion in the generation of functional groups, namely hydroperoxide, carbonyl, and transvinylene. Low density polyethylene was reprocessed three times in a single screw extruder. In each recycling step hot pressed films were prepared. These films were submitted to a heat treatment in an oven with air circulation and renovation to proceed with aging tests at different times and temperatures. The results obtained showed that all functional groups had their concentration increased with the increase in number of reprocessing, the aging time and temperature of the heat treatment. The factorial design was applied to verify the influence of these parameters. All the parameters had significant effects, since their regression coefficients had the same order of magnitude, with the most influential parameter being the aging temperature, followed by the aging time and number of extrusions. Most of the interactions were influential, indicating that the formation of functional groups depends upon their interaction, and not only on their isolated effects.

Development and characterization of post-consumer rubber tire powder, high density polyethylene and ethylene-octene-1copolymer ternary mixtures

“…When rubber tire is ground it can be added to polymeric matrix to produce composites. This is considered an interesting strategy for reusing this waste because the process is relatively simple and involves only mechanical mixing [9,10] . However, the incorporation of rubber tire powder (RTP) can result in materials with poor mechanical properties due to the lack of interfacial adhesion between polymer and RTP [9][10][11][12] .…”

“…This is considered an interesting strategy for reusing this waste because the process is relatively simple and involves only mechanical mixing [9,10] . However, the incorporation of rubber tire powder (RTP) can result in materials with poor mechanical properties due to the lack of interfacial adhesion between polymer and RTP [9][10][11][12] . Several techniques are employed to improve the interfacial properties between these components: partial devulcanization of rubber tire, treatment with peroxides to create reactive sites in the RTP surface, functionalization of the waste tire rubber, and the addition of non-reactive copolymers with chemical affinity with composite components [9,[13][14][15][16][17] .…”