Blending Techniques Affecting Mechanical and Morphological Properties of Fly Ash/Ldpe and Caco ₃ /LDPE Composites

The effects of blending methods on mechanical and morphological properties of CaCO ₃ /LDPE and fly ash/LDPE composites were investigated as a function of filler loadings. The CaCO ₃ /LDPE and fly ash/LDPE composites considered in this work were prepared by dry blending (high-speed mixer) and melt blending (using single- and twin-screw extruders). It was found that as the CaCO ₃ or FA loading was increased, the modulus and hardness for all blending techniques were increased, due to rigidities of the fillers and increased crystallinity level of the composites. Increasing the CaCO ₃ and FA loadings decreased the ultimate mechanical properties (tensile strength, elongation at break and impact strength) due to poor dispersion and interfacial defects of the composites. Composites prepared by the twin-screw extruder had the best mechanical properties as compared to those prepared by the dry blending or single-screw extruder, except for the impact strength. The overall mechanical properties of LDPE composites with CaCO ₃ were similar to those with FA particles, but the changes in the composite properties with CaCO ₃ particles were more sensitive than those with FA particles, this being associated with the differences in particle characteristics and dispersion level of CaCO ₃ or FA fillers.