Microcrystalline cellulose as reinforcing agent in silicone elastomers

Cellulose is commonly used as filler for the reinforcement of polymer materials but data in the case of silicones remain rare. In this work we report the modification of microcrystalline cellulose (MCC) fibers from cotton linters by propargyl bromide, in aqueous medium without alteration of the crystalline domains. The analysis evidenced the efficient grafting of alkyne functions at the surface of the fibers, the DS being 0.5. The resulting MCC-Alkyne fibers were introduced within a bi-component reactive silicone formulation (up to 20wt%), allowing the formation of network through hydrosilylation reaction in which MCC-Alkyne played the role of a reactive fillers. Comparison between the properties of composites prepared with unmodified MCC and MCC-Alkyne highlighted a densification of the network and an enhancement of mechanical and thermal properties when coupling reactions occurred. Mechanical properties of silicone elastomers were better if the load of MCC-Alkyne remains low.