Effect of Processing Method on Morphological and Rheological Properties of PC/CaCO₃ Nanocomposites

Abstract

The focus of this work is to investigate the effect of different manufacturing methods on nanoparticles dispersion and rheological properties of polycarbonate (PC) filled nano-calcium carbonate (CaCO₃) nanocomposites. Two methods were used to prepare the PC/CaCO₃ nanocomposites through twin-screw extruder: one was compounding PC with CaCO₃ nano-powder, named PC-CP; another was compounding PC with CaCO₃ aqueous suspension, named PC-CAS. The relationship between the processing method and the particle dispersion, matrix molecular weight and rheological properties of the nanocomposite was discussed. Morphological observation showed that nanoparticles were dispersed more homogeneously in PC-CAS. Gel permeation chromatography (GPC) test showed that molecular weight drop of PC-CAS was smaller than PC-CP when CaCO₃ content under 2.2 wt%. Melt flow rate (MFR) and capillary rheological behavior indicated the change of rheological property of PC-CP was larger than PC-CAS while CaCO₃ content under 2.6 wt%. In general, both the dispersion and rheological property of PC-CAS were better than PC-CP under a reasonable CaCO₃ content.

Keywords:

• Aqueous suspension
• Dispersion
• Polycarbonate
• Rheology

ACKNOWLEDGMENTS

The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China (Grant No. 10590351), and Sichuan University Youth Science Foundation (Grant No. 06007). We also are heavily indebted to Mr. Zhu Li from the Center of Analysis and Test of Sichuan University for the careful SEM measurements.