THE EFFECT OF COMPOUND NUCLEATING AGENT ON THE CRYSTALLIZATION BEHAVIOR OF POLYPROPYLENE

A new type of nucleating agent (NA) compound nucleating agent made of ultra-fine rubber particles and organic phosphate, was applied to modify polypropylene (PP) resin. It is found that the new NA is a high efficiency nucleating agent. A small amount of organic phosphate NA can increase the crystallization rate and crystallization temperature of PP obviously. For example, a PP with crystallization temperature of 118.5 degrees C may have a crystallization temperature raised up to 125.6 degrees C while it is modified with 0.1% of this new NA containing only 0.02% organic phosphate NA. It is impossible to reach so high crystallization temperature if we use so small amount of pure organic phosphate NA. The morphology study showed that ultra-fine rubber particles acted as carriers of organic phosphate NA. The organic phosphate NA in compound NA could disperse better with the rubber particle dispersion in the PP matrix. Good dispersion of organic phosphate NA resulted in the high nucleating efficiency of new NA; therefore, PP modified with this new NA had high crystallization rate, high crystallization temperature and good mechanical properties while only a small amount of organic phosphate NA was used.