Effects of additives and pre-heating temperature on interlayer shrinkage of polyamide-12 parts in Additive Manufacturing

Additive manufacturing (AM) processes, which require additives, fabricate polyamide-12 (PA12) parts. These additives can affect its physical appearance and mechanical properties in a single print job due to variations in thermal distribution. These properties are influenced by its crystallization behavior, which in turn is affected by the presence of additives of solvent due to low pre-heat temperature. From the Differential Scanning Calorimetry experiment, the remained DI-water affects the crystallization behavior of PA12. At low pre-heat temperature, the remained water vapor lowered the crystallization temperature and overall crystallinity of the PA12. The Thermomechanical Analysis results also suggested that samples with low pre-heat temperature exhibited higher shrinkage during the cooling process. Real-time optical images showed that the presence of additives reduced spherulite size and increased initiation rate. This investigation provided deeper insights into the influence of additives on the crystallization of PA12 for additive manufacturing.