Influence of repeated recycling on the quality of molded finished products

Abstract

The main purpose of plastics recycling is to reduce the high rates of plastics pollution, and in the same time to reduce the need for raw materials (resins) needed to produce new parts. Sometimes, the above-mentioned goals are not attained for unpredicted reasons. During recycling process, and in special in the case of repeated (multiple) recycling, polymeric materials are subjected to a continuous process of degradation. It was found that, degradation and consequent the coloration of the molded parts from ABS is confined to the surface of the specimen and is controlled by the rate of oxygen diffusion through the polymer. In the case of molded parts obtained by multiple recycling, there is a significant difference between FTIR spectra of dark (colored) area samples and reference area samples, especially the peak absorbance value of the infrared spectra. Darkening, in the case of recycled ABS, is attributed to the butadiene degradation, pointed out by FTIR results. Within dark (colored) areas there were found deposits containing relatively high levels of carbon, oxygen, sodium, chlorine, potassium and trace amounts of other elements. The quality level of molded parts thus obtained is strongly affected by the presence of dark areas and mentioned deposits. This article presents some deficiencies encountered in recycling plastics and makes some suggestions for improving this process. Without analysis of the potential side effects of repeated recycling of plastics on the end user, the recycling of materials does not make sense because its main goal cannot be achieved.