Experimental study of foamed polyethylene in rotational molding

Rotational molding of foamed polyethylene has increasingly become an important process in industry because of its thicker walls, low sound transfer, high stiffness and good thermal insulation. However, the foaming process of polyethylene during rotational molding has not been well studied. The focus of this article is to assess the rotomoldability of foamed polyethylene and to investigate how blowing agents can influence the process of rotational molding and the final product quality. Rotational molding experiments were carried out in a laboratory scale uniaxial machine capable of measuring internal mold temperature in the cycle. Mechanical property tests, as well as thickness distribution and density measurements, were performed on the rotationally molded parts. Differential scanning calorimetry and optical microscopy have also been employed to identify the material and structural parameters. It was found that the presence of blowing agent results in an improvement of the impact properties, which are counteracted by longer cycle times and uneven surfaces.