Understanding the differences in how each melts is crucial to obtaining melt uniformity. Semi-crystalline polymers have a structure or ordered pattern of chain alignment. With amorphous polymers, chains are random—meaning they have no specific order or alignment, something like tangled pieces of string. The solid break-up that can occur when processing semi-crystalline materials lead to some partially unmelted pellets getting through the transition and metering zones of the screw. These partially unmelted pellets can wind up in the part. The solid break-up that can occur when processing semi-crystalline materials lead to some partially unmelted pellets getting through the transition and metering zones of the screw.
Read more: Injection Molding: Melting Amorphous vs. Semi-Crystalline Plastics
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