Comparison of Reinforcing Efficiency between Recycled Newspaper (RNP)/Carbon Black (CB) and Recycled Newspaper (RNP)/Silica Hybrid Filled Polypropylene (PP)/Natural Rubber (NR) Composites

Comparison was made between properties of recycled newspaper (RNP)/carbon black ( CB) and recycled newspaper (RNP)/silica hybrid filled polypropylene (PP)/natural rubber (NR) composites. The properties of composites consisting of processing characteristics, mechanical properties, thermal analysis via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), scanning electron microscopy (SEM) morphology and water absorption were studied. The results revealed that the incorporation of CB and silica in the weight ratio of RNP/CB and RNP/silica hybrid has increased stabilization torque of the composites. Certain mechanical properties of the composites such as tensile strength and elongation at break (E-B) were found increased, while Young's modulus decreased with increasing CB and silica content. The incorporation of CB in the weight ratio of RNP/CB hybrid shows higher stabilization torque, tensile strength, elongation at break (E-B) compared with RNP/silica hybrid of the PP/NR composites. However, RNP/silica hybrid exhibited higher Young's modulus than RNP/CB hybrid of the PP/NR composites. TGA and DSC results indicate that primary and secondary peak of DTG curve, initial degradation temperature (T-0), degradation temperature (T-deg), melting temperature (T-m), heat of fusion of composites (Delta H-f(com)), crystallinity of composites (X-com) and PP (X-PP) increased, while total weight loss and thermal degradation rate decreased for both hybrid composites. The RNP/silica hybrid is likely to be more thermal resistance and more crystalline than RNP/CB hybrid of the composites. A correlation between the increment of tensile strength and morphology of the composites was also studied. Results show that the presence of CB and silica has increased interfacial interaction between polymer and filler of the composites.