Abstract: It takes about 7 days to mature in the ordinary bulk molding compound(BMC) before it can be used for production. This leads to large inventory, high production cost and low efficiency, and also limits the development of BMC production and applications. In this paper, physical thickener was used instead of calcium hydroxide thickeners to prepare BMC composite material and the performance of BMC was studied and analyzed. The viscosity of the BMC's resin paste was tested and characterized by the laminar viscometer, so the effect of physical thickener's amount on the properties of the BMC was studied. Plate Vulcanizing Press Machine, Universal Tensile Testing Machine, Breakdown Voltage Test, high resistance meter are used to measure and characterize the mechanical properties, electrical properties, and other related properties of BMC, to study the effects of physical thickener on the properties of BMC. The results show that the thickening effect of the physical thickener on BMC is prominent, which significantly reduces the time needed for achieving the molding viscosity. The thickening effect of BMC when the physical thickener accounts for 20% of the UP mass is perfect, its viscosity reaches the required viscosity for molding after 24 hours of kneading preparation. When the viscosity meet the need of the molding pressure, the fluidity D_min of bulk molding compound is increased by 6.4%, which is more conducive to molding. And the mechanical properties of BMC are only slightly reduced. So, physical thickener can improve the production efficiency of BMC and save the production cost.

Key words: bulk molding compound, composite material, laminar viscometer, gel time, bending strength