AN EXPERIMENTAL-STUDY OF ROTATIONAL MOLDING OF POLYPROPYLENE POLYETHYLENE COPOLYMERS/

The objectives of this work are to assess the rotomoldability of rubbe r toughened polypropylene resins and to investigate how resin properti es can influence the process of rotational molding and the final part quality. Four commercially available polypropylene/polyethylene copoly mers were tested. The chemical composition and the powder, rheological and thermal properties of the resins were determined. Rotational mold ing experiments were carried out in a laboratory scale uniaxial machin e which is capable of measuring internal mold temperature and which fa cilitates the visual observation of various transitions in the cycle. Impact and environmental stress clacking resistance tests, as well as thickness distribution and density measurements were performed on the rotomolded parts. It was found that increasing rubber content results in an improvement of the impact properties which is counteracted by di fficulties in processing, presence of bubbles and uneven surfaces.