Polypropylene blends: Impact of long chain-branched polypropylene on crystallization of linear polypropylene

Abstract

This study compares the efficiency of commercially available sorbitol-based clarifying agent (NA) and varying amounts of long chain-branched polypropylene (LCBPP) acting as a specific α-nucleating agent for linear polypropylene (PP). The sorbitol-based clarifying agent, 1,3;2,4-bis(3,4-dimethyl benzylidene)sorbitol (Millad 3988), in concentration 0.2 wt%, and LCBPP in the concentration of 1, 2, 5 and 10 wt% were mixed into PP. The comparison of the effect of NA and long branches under isothermal conditions on the crystallization process, crystallinity and polymorphic composition was realized by differential scanning calorimetry and wide-angle X-ray scattering. The addition of long chain-branched polypropylene, even at the lowest concentration, performs better at higher crystallization temperatures and has a superior effect on the crystallization process, crystallization rate and overall crystallization than the addition of NA.

Keywords

• crystallization
• morphology
• polyolefins
• blends
• crystal growth