Effects of Injection Molding and Storage Conditions on Polypropylene Copolymer

Abstract

Abstract This work focused on studying the effects of injection molding parameters (cooling time and melt temperature) and storage conditions (annealing versus cooling) on the thermal, mechanical, and optical properties of an ethylene-propylene copolymer made with and without nucleating agents. Preform properties (optical, crystallinity) affect the consistency of the preforms’ reheating via infrared lamps before stretch blow molding. The analysis of detailed preform properties as a result of both injection molding processing and postmolding treatment or preform storage conditions was lacking to correlate with the blow molding performance. This study confirmed that postmolding aging is a significant factor that affects material properties and therefore suggested subsequent blow molding. It also suggested that shorter injection molding cooling time helps to minimize the effects of aging and storage conditions. As expected, with the inclusion of the nucleating agent, clarity, yield strength, and density of the material improved.