COMPARATIVE-STUDY OF WARPAGE, GLOBAL SHRINKAGE, RESIDUAL-STRESSES, AND MECHANICAL-BEHAVIOR OF ROTATIONALLY MOLDED PARTS PRODUCED FROM DIFFERENT POLYMERS

A comparative study of warpage, global shrinkage, and residual quench stresses developed in rotational molding is made for a series of thermoplastics including various polyethylenes, polypropylene, polyamide-6, polycarbonate, and polystyrene. The influence of rate of quench on uniaxial stress strain and impact behavior of rotomolded parts was also studied. Generally, warpage, global shrinkage, and residual stresses increase with increasing quench rate for all the polymers. Further, the levels of warpage and global shrinkage increases with extent of crystallization, i.e., products from glassy polymers exhibit little warpage and those from highly crystalline polymers are highly warped. Increasing rate of quench tends to increase elongation to break and impact strength.