Rheological behavior of LDPE/CaCO₃blends containing EAA

Calcium carbonate (CaCO3) filler particles were surface treated with organic titanate (TTS), a coupling agent. The composites were prepared by blending low-density polyethylene (LDPE) with the surface-modified fillers at various weight ratios. Ethylene-acrylic acid copolymer (EAA) was added to improve the adhesion of LDPE to fillers. A capillary rheometer was used to evaluate rheological properties of the LDPE/CaCO3/EAA blends. The blends were shown to be pseudoplastic with shear thinning behavior. When CaCO3 was modified by TTS (<2 wt%), the viscosity of the blends decreased quickly, and, addition of a small amount of EAA (<6 wt%) could also decrease the viscosity of the blends. The thermal behavior of these materials is evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The addition of a small amount of EAA and TTS enhances the stabilization of the blends, which could be explained by the "ball belling" action. The effects of temperature, TTS content, CaCO3 granule size, and content on the rheological property were also studied. POLYM. COMPOS., 30:1212-1217, 2009. (C) 2008 Society of Plastics Engineers