The changes of polypropylene staple fiber after drying and setting:

1. After setting, the boiling water shrinkage of polypropylene fiber can tend to zero.

2. Polypropylene fiber shrinks greatly after setting, domestic resin shrinks about 15%, imported resin can reach about 18%, polypropylene fiber has high resilience and large shrinkage.

3. After setting, the elongation decreases. After the setting, the strength of the polyester fiber decreases and the elongation increases. The reason is that the de-orientation occurs. However, after the setting of the polypropylene staple fiber, the strength change is not obvious, while the elongation is significantly reduced. It can be reduced by 10-15% before setting.