Production of low-density LLDPE foams in rotational molding

This paper describes plastic foam processing for the manufacture of LLDPE f oams in rotomolding. In order to better understand the mechanisms of foamin g, a fundamental study on the foaming process in rotomolding has been condu cted. First, the decomposition behavior of the chemical blowing agents was studied by a thermogravimetric analyzer (TGA). The zero-shear viscosity of LLDPEs was measured using a rotational stress rheometer. Also, an optical m icroscope with a hot stage was used to study cell nucleation, growth, coale scence, and coarsening in LLDPE melts, which provide an improved understand ing of the foaming dynamics with a chemical blowing agent in rotational mol ding. Finally, the actual foaming behavior in rotomolding has also been stu died. The experimental results indicate that the amount of blowing agent, t he heating time, and the processing temperature play important roles in det ermining the cell morphology in rotational foam molding.