Investigation of thermal decomposition and thermal oxidative degradation of a composite of cellulose nanofibers and deproteinized natural rubber grafted methyl methacrylate ☆

Natural rubber (NR) is a polymer that has many applications in daily life. However, the traditional rubber industry relies heavily on petroleum-based materials, causing environmental pollution problems. Therefore, to reduce environmental challenges, products created from NR are combined with ecologically safe chemicals and natural fillers such as cellulose nanofibers (CNF). This study presents the effect of CNF on the thermal properties of novel composites made from CNF and deproteinized natural rubber grafted methyl methacrylate (DPNR-g-MMA) under air and nitrogen atmosphere. Graft copolymerization of MMA onto DPNR to produce DPNR-g-PMMA was performed in the latex phase. The CNF/DPNR-g-PMMA composite was created by dispersing CNF in DPNR-g-PMMA at concentrations of 0.5%, 1%, and 1.5% using ultrasonic waves. DPNR-g-PMMA was employed as the composite's matrix and CNF served as its reinforcing phase. Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy (1H NMR) were used to confirm the success of the graft copolymerization. The thermal properties of materials were studied by Thermalgravimetric analysis (TGA) and Differential scanning calorimetry (DSC). In which, the thermal stability of composites was examined via TGA under air and nitrogen atmosphere. The obtained data illustrate that, in comparison to DPNR and DPNR-g-PMMA, thermal stability increases for all CNF/DPNR-g-PMMA composites, especially at CNF concentrations of 1%. After reinforcing CNF to DPNR-g-PMMA, the decomposition temperatures of CNF/DPNR-g-PMMA 1% increased by nearly 2 °C in nitrogen atmosphere and by 5.27 °C in air atmosphere. These results prove that the CNF is a key role in the thermal stability of DPNR-g-PMMA.