Polypropylene/CaCO₃ Nanocomposites Fabricated Using Masterbatch: Effect of Nano-CaCO₃ Loadings and Re-Processing on the Melting Properties

Abstract

Polypropylene filled calcium carbonate (CaCO3) nanocomposites were fabricated by employing melt blending/compounding method using masterbatch. To investigate the efffect of reprocessing on the melting properties of PP/CaCO3 nanocomposites, the melt compounding process was conducted twice (two cycles). The effect of nano-CaCO3 loadings (i.e. 5, 10 and 15 wt%) on the melting properties of PP/CaCO3 nanocomposites were also studied. The meling properties of the nanocomposites were analyzed by using a DSC (Differential Scanning Calorimetry). Additionally, the nanocomposites samples were also analyzed by an SEM (Scanning Electron Microscopy). The SEM analysis results revealed that at higher nano-CaCO3 loading (i.e. 15 wt%), the nano-CaCO3 particles in the 2nd cycle were more well distributed/dispersed in the polypropylene matrix as compared to the 1st cycle. Whereas, the DSC test results showed that the crystallinity of the nanocomposites samples were similar to that of neat PP for the 1st cycle of melt blending process, which was about 41%. In the other hand, for the 2nd cycle, the crystallinity of the samples slightly increased wtih increasing nano-CaCO3 loadings, which were about 39.6; 43; 44% for nano-CaCO3 loadings of 0, 5, 10 wt%, respectively. Nevertheless, at the highest nano-CaCO3 loadings (i.e. 15 wt%), the crystallinity of the nanocomposites (i.e. NCC-15-II) decreased again and lower than that of neat PP, which was about 37.7%.