RECYCLING OF MIXED EPS, PP AND HDPE WASTE PLASTICS AT FISH MARKET IN TAIWAN

摘要

The objective of this was to study the feasibility of mixed recovery EPS, HDPE and PP wasted plastic at fish markets by a polyblending method. Results from DSC measurements and SEM observations showed that EPS, PP, and HDPE at all blending ratios we tested were not well compatible. Tensile strength tests revealed that the Young's modulus (E) of polyblends of EPS and PP or EPS and HDPE decreased with the increase of PP or HDPE amounts. Our data also indicated that those relatively tough PP or HDPE decreased the brittleness of EPS while increasing its toughness. As a result, the mechanical properties of the polyblends reached the optimal values at approximately the mixture of 60% of EPS and 40% of PP and HDPE by weight. A most likely mechanism in which the improvement of such mechanical properties can be possible is that because HDPE has straight-chain molecular structure, enabling the carbon atoms of HDPE molecules to rotate easier so that HDPE molecules are less likely to fold. But when both PP and HDPE were present over 40%, HDPE and PP tend to twist and entangle, causing an increase of Young's modulus. The same phenomenon has been reported by other researchers as the "string-twisting effect".