Abstract
This study consisted of an investigation of the thermo-mechanical properties of post-consumer high impact polystyrene (HIPS) through five consecutive injection moulding steps to simulating the recycling cycles. The selectively collected HIPS residue was ground, washed only in water, dried, agglutinated and then moulded as a set of mechanical test specimens before the first step. The melt flow index (MFI), glass transition temperature (Tg), complex viscosity (η*), deflection temperature under flexural load (HDT), tensile, flexural and impact strength tests were determined at each reprocessing cycles. The results revealed that the degradative effect of consecutive recycling on the material's thermal properties was low and may be considered negligible. After five reprocessing cycles, the results showed an ∼8°C decrease of Tg in DSC, an increase of MFI, a decrease in viscosity and a slight decrease of HDT, which could be attributed to chain scission caused by consecutive cycles of exposure to shear stresses and high temperature. The material became slightly more rigid and fragile, as indicated by the mechanical tests.
Get full access to this article
View all access options for this article.