Abstract: In this paper, the effects of different contents of the phenolic hollow microspheres on the mechanical properties, thermal insulation and microstructure of the hybrid composites were investigated. Quartz fiber, phenolic fiber and phenolic hollow microspheres were used as reinforcing materials by physical mixing for the production of hybrid composites. Experimental results show that the porosity of composites is increased by the incorporation of phenolic hollow microspheres, and the air bubbles in the pores provids better heat insulation performance. With the increase of the mass fraction of phenolic hollow microspheres, the density and mechanical properties of the composites were all reduced. The addition of phenolic hollow microspheres can obviously improve the thermal insulation property. Through the SEM photographs of fracture surfaces, it was found that when the phenolic hollow microsphere content was 6%, the phenolic hollow microspheres dispersed uniformly. The composites′ thermal insulation increased clearly and their specific tensile strength and compression strength reached maximum, realizing the best effects.

Key words: polymer composites, phenolic hollow microspheres, mechanical properties, thermal insulation, microstructure