Compatibility of deproteinized natural rubber-grafted methyl methacrylate and regenerated cellulose in their composite fabricated by co-precipitation

Natural rubber (NR) and regenerated cellulose (RC) are valuable natural polymers, which are promising materials for a green future. They can be combined to fabricate a biocomposite, but incompatibility between them can result in undesirable properties. The objective of this work is to assess the compatibility between deproteinized NR-grafted methyl methacrylate (MMA) and RC in their composite fabricated by co-precipitation. Graft copolymerization of MMA onto deproteinized NR was carried out in the latex stage using tert -butyl hydroperoxide and tetraethylenepentamine as radical initiators at 30 °C. The composites were prepared from grafted NR latex and cellulose solution in urea/NaOH/water by co-precipitation method, followed by hot pressing. The chemical and crystal structures of two phases in the composites were characterized by attenuated total refection Fourier transform infrared radiation, proton nuclear magnetic resonance and X-ray diffraction. The improvement in thermal stability of the composite has been demonstrated by thermal gravimetric analysis. A reduction in RC phase size and a smoother interface of the MMA-grafted composites compared to ungrafted samples were observed via scanning electron microscopy. Differential scanning calorimetry showed glass transitions of the composites increased steadily with increasing RC contents, from − 63.47 to − 63.2, − 63.07 and − 62.82 °C at respective 0, 10, 20 and 30% RC. These results indicated that enhanced compatibility between NR and RC has been obtained after modifying NR by graft-copolymerization method.