Hydroxyl Boron Nitrid e/Natural Rubber Composites with Enhanced Mechanical and Thermal Conduction Properties: Implications for Heat Dissipative Tires or Conveyor Belts

Abstract

For its significant technological interest, a systematic investigation on mechanical and thermal conduction properties of natural rubber reinforced by functionalized hexagonal boron nitride nanosheets is highly desirable. We herein first demonstrate a unique synthesis of hydroxyl-functionalized boron nitride nanosheets (OH-BNNSs) via a simple one-pot reduction reaction. This involves negative charging by treating BNNSs with lithium in liquid ammonia and subsequent bubbling of oxygen into dispersion of BNNS salts. Subsequently, a series of functionalized boron nitride nanosheets/natural rubber (NR) composites were fabricated by latex mixing and co-coagulation. Co-coagulating a stable aqueous suspension of OH-BNNSs with natural rubber latex afforded a weblike morphology consisting of platelet networks between the latex particles. Compared to pure rubber, the tensile strength and storage modulus at 25 °C for OH-BNNSs/NR (5 wt %) are increased by 466% and 1 order of magnitude, respectively. Benefiting from the unique structure, the composite at 5 wt % shows a 40% improvement in thermal conductivity relative to pure rubber. This latex-based method provides a facile and effective strategy to design and fabricate advanced functional BNNS-based polymeric nanocomposites with a segregated filler network morphology and considerable property enhancements in direct competition with graphene sheets. The composites could be potentially used in heat dissipative tires or conveyor belts.