Effect of nucleating agents and cooling rate on the microstructure and properties of a rotational moulding grade of polypropylene

摘要: Rotational moulding consists of coating the inside surface a metal mould with layer plastic by rotating mould, firstly in an oven and then cooling bay to induce solidification desired part shape. As rotational speeds are slow (typically about 10 rev/min), resulting hollow articles practically stress free. The primary material used for rotationally moulded parts is polyethylene but there increasing interest using polypropylene provide stiffer, higher temperature products. Unfortunately combined crystallisation rate results brittle mouldings coarse spherulites. Since inner contact air during moulding, degradation also likely occur. In order improve mechanical properties polypropylene, α β nucleating additives were added. effect faster rates was studied. It found that heterogeneous nucleation, both spherulites, did not ductility samples. However, when fast used, impact strength improved markedly, independent presence additives. parts, could only be applied outer which led asymmetric cooling. This resulted severe warpage, uneven morphology. problem should overcome on outside surfaces plastic.