The β‐crystalline form of wollastonite‐filled polypropylene

Abstract

Abstract A study has been made of the thermal, X‐ray diffraction, and dynamic mechanical characteristics of polypropylene (PP1330, a copolymer containing 22% ethylene) filled with wollastonite. Various levels of β‐form crystallinity were produced in the PP by mixing in varying amount of wollastonite. It has been found that all the wollastonite‐filled samples contain both the α‐and the β‐forms, and four melting transitions were observed instead of only two of the unfilled PP on the DSC scan. The conversion of the β‐to the β‐form on heating has been observed. The relative amount of the β‐form in the samples was measured from WAXS data by the K value. The K value obtained increases with increasing wollastonite content. Dynamic mechanical measurements showed an increase in the magnitude of the damping in the high‐temperature region for the wollastonite‐filled PP and the contribution from the filler‐matrix boundary. Wollastonite acted as both a reinforcement and a β‐nucleator for PP.