A feasible way to modify microcrystalline cellulose powder and its reinforcing effect for NBR composites

It has attracted tremendous attention for replacing petroleum-based carbon black or mineral fillers with renewable, biology-based and low-cost cellulose. However, the reinforcing effect of cellulose, especially at the microscale, is still a great challenge in the polymer industry. In this work, a feasible surface modification method for microcrystalline cellulose powder (MCC) in all solid states is proposed by using rubber accelerators N-cyclohexyl benzothiazole-2-sulphenamidee (CBS) and 2,2'dibenzothiazoledisulfide (DM). These accelerators not only accelerate the sulfur crosslink of nitrile butadiene rubber (NBR), but also graft to rubber molecular chains and form hydrogen bonds with MCC, resulting in good interfacial interaction and good dispersion of MCC in the NBR matrix. As a consequence, the tensile strength and elongation at break of NBR/10MCC reach up to 20.12 MPa and 511%, respectively, which are the highest values of NBR/MCC or cellulose nanocrystals (CNCs) composites we can find in the world and are comparable to those of carbon black or mineral fillers. This provides a more effective and environmentally friendly way of using MCC or CNCs in the polymer industry.Highlights Microcrystalline cellulose powder can reinforce NBR. Hydrogen bonds have been established between accelerators and MCC. The tensile strength of NBR/10MCC composite reaches 20 MPa. The reinforcing mechanism is ascribed to the immobilized rubber layer.