Thermal properties of thermoplastic natural rubber reinforced by microfibrillar cellulose

Thermoplastic natural rubbers (TPNR) based on natural rubber (NR) and polypropylene (PP) blends had been successfully prepared using dynamic vulcanization. The blends were reinforced with microfibrillar cellulose (MFC). The study aimed to evaluate the thermal properties of TPNR using thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses. MFC was derived from pineapple leaf fiber (PALF) through several treatments. Dynamic vulcanization was carried out using an internal mixer. PP was previously melt-mixed with MFC, then blended with NR compound. The ratio of NR/PP blend was maintained at 60/40, while MFC concentrations were varied ranging from 0, 1, 5, 10, 15 and 20 phr. The results showed that the degradation of TPNR samples occurred in two simultaneous stages. The onset of the degradation of TPNR started ranging from 346 °C to 361 °C. MFC concentration affected the thermal stability of the samples. The highest thermal stability was achieved by incorporating 1 phr MFC. DSC studies revealed that melting temperature (Tm) and heat of fusion (ΔHf) were independent of MFC concentration. Tm was in the 161-165 °C range, while ΔHf was around 24-31 J/mol. Keywords: thermoplastic elastomer, natural rubber, polypropylene, thermal properties, cellulose.