Composites of Pet and PBT/PP with Bentonite
The need for solid-waste management has pushed the development of alternative systems for recycling and revalue used plastic containers. Poly(ethylene terephthalate) (PET) is being widely used as raw material for beverage bottles. However, as has been widely reported, PET undergoes degradation and hydrolysis when reprocessed. On the other hand, poly(butylene terephthalate) (PBT) is another thermoplastic polyester with easy processability but high brittleness and cost. Hence, it has been blended with other polymers such as polypropylene to overcome its disadvantages. In this work, bentonite was incorporated into recycled PET and PBT/polypropylene blends by extrusion. Rheological and tensile properties and processability of the composites thus prepared were studied. Results showed a strong newtonean character of extrudates of recycled PET and higher viscosities and a more pseudoplastic behavior and improved reprocessability when bentonite was added to PET. Furthermore, inclusion of the filler increased its initial degradation temperature, as observed during rheological testing. All composites displayed a brittle behavior. However, the tensile properties of PET composites were not strongly deteriorated. There was a slight increase in the Young’s modulus values and in the tensile strength, with unnoticeable effects on the elongation at break. The Young’s modulus values of PBT/PP composites were not significantly affected.
Alan K.T. Lau, J. Lu, Vijay K. Varadan, F.K. Chang, J.P. Tu and P.M. Lam
R. Perera et al., "Composites of Pet and PBT/PP with Bentonite", Advanced Materials Research, Vols. 47-50, pp. 1019-1022, 2008