Effect of Nano-CaCO3 on Properties of PP/TLCP/CaCO3in-situ Hybrid Materials

Abstract

In this thesis, to reinforce and soften PP plastics, thermotropic liquid crystalline polymer (TLCP) and nano-CaCO3 were used. The PP/TLCP/CaCO3 in-situ hybrid materials were prepared in a twin-screw extruder respectively by one-step and two-step method. The effect of nano-CaCO3 adding method on PP/TLCP/CaCO3 in-situ hybrid materials was investigated. Polarization optical microscope (POM) and differential scanning calorimeter (DSC) measurements showed that: nano-CaCO3 play an important role in PP/TLCP system heterogeneous nucleation, and CaCO3 particles can increase the crystal growth rate of PP matrix more than the contribution of the improvement of crystallinity. Field emission scanning electron microscope (FESEM) observation revealed that the nano-CaCO3 enriched in the PP matrix though one-step method, which helped to promote the TLCP forming fibrils, therefore the tensile strength of one-step preparation sample was higher relatively. Mechanical measurements revealed that under the condition of the same proportion of PP/TLCP/CaCO3/PP-g-MAH=85/5/4/6, the mechanical properties of the hybrid materials prepared by one-step method were better than which of two-step method, the tensile strength of the one-step sample was 36.62 MPa, increased 2.95% more than which of two-step sample, the elongation at break of one-step method sample was 35.12%, increased 76.4%: the impact strength was 3.86 kJ/m2, and increased 4.9%.