Effect of pigmentation on the microstructure and properties of rotationally molded polyethylene

摘要

Rotational molding of plastics has experienced growth rates of about 12% per annum over the past decade. As a result, ever more demands are being placed on the quality of the moldings in terms of dimensional control and mechanical properties. With most molding methods for plastics, the use of pigments can have a significant effect on the quality of the product. This is particularly true for rotational molding because there are no stresses to assist with dispersion of the pigment, and the slow cooling rates encourage classic spherulite formation. This paper investigates the use of nucleating and non-nucleating pigments in a rotational molding grade of polyethylene. We demonstrate that the amount of work done on the plastic prior to molding affects the microstructure and the mechanical properties of the end product, often in a positive manner. Turbo-blending of pigments is shown to be problematic, particularly if the pigment is of the nucleating type. The amount of pigment used has little effect on strength but reduces toughness dramatically. (C) 1998 Kluwer Academic Publishers. [References: 16]