Towards sustainable rubber compounds: The use of waste raw materials

This article aims to realize a sustainable rubber compound made in large percentage of secondary raw materials. Waste chewing gum (WCG) has been studied as source of rubber and added in 25% by weight in an ethylene propylene diene monomer based compound in view of a circular economy and eco-friendly rubber manufacturing. Biobased CaCO3 extracted from waste eggshells was used as extender agent and waste cooking oil from potato chips frying was employed as processing aid. The rubber extracted from WCG resulted to be polyisobutylene (PIB) whereas the main component of the WCG is polyvinyl acetate (PVAc). The addition of the WCG modifies the rheological properties of the rubber compound leading to a better filler-filler and filler-matrix interaction. On the other hand, the presence of both PVAc and PIB leads to lower mechanical properties (max torque 6 vs 10 dNm in curing test) but also higher elongation at break (600% vs 500%). The WCG also increases the self-adhesion of the rubber and decreases the glass transition temperature allowing for the use of these compounds at lower temperatures thanks to its good tack behavior.