Catalytic effect of natural clays on properties and chemical structure of recycled polyethylene

Montmorillonite clays such as bentonites are often studied and used as reinforcement to thermoplastics, since it can generate nanostructures, improving the material performance mainly when the mechanical properties are considered. The low cost of the montmorillonite clays is other important characteristic, which awakens also interest for application in polymer recycling for the purpose of minimizing loss of polymer properties due to the degradation effects. In addition to the mechanical reinforcement on polymer matrices, the montmorillonite clays can also catalyze chemical changes in polymer chains that are not yet well-understood. In present study, the catalytic action of five different bentonite clays on degradation of post-consumer low-density polyethylene waste (LDPE waste) was evaluated after thermal treatment on controlled conditions at temperatures next to the polymer decomposition. A distinct catalytic activity was noted between the five clays, which showed be dependent of their interlayer spacing. An appropriated control of the conditions for thermal treatment and thermomechanical processing of the polymer can conduce to desirable changes in their structure, improving the related performance of properties.