Influence of drawing and annealing on the structure and properties of bio‐based polyamide 56 fibers

The influences of drawing and annealing parameters on the structure and mechanical properties of melt spinning polyamide 56 (PA56) fibers were investigated and discussed in details. The as‐spun PA56 fibers have the relatively low crystallinity and rather low orientation. The crystalline phase in as‐spun PA56 fibers is mainly in γ phase. PA56 α‐like crystalline phase develops from the amorphous phase with the increase in chain orientation upon drawing of the as‐spun PA56 fibers. The crystallinity of PA56 fiber increases with rising draw ratio, which accompanies the increase in thickness of the crystalline lamella. The increase in draw ratio leads to the increase in tensile strength and the decrease in elongation at break of the resultant fibers. Tension annealing of the full‐drawn PA56 fibers at specific temperatures has obvious influences on the structure and properties of the fibers. The crystallinity and orientation increase with rising annealing temperature in the range of 150–210°C, during which the content of PA56 α‐like phase increases with the rising annealing temperature. Annealed the fibers at 230°C results in the increase in the content of PA56 γ phase with a tremendous decrease in the content of α‐like phase due to Brill transition. The optimum annealing temperature is around 170°C, at which the tenacity of the PA56 fibers is the highest. These results can provide valuable information for the production of PA56 fibers.