Abstract: Molded rheological property is a quite important process parameter for unsaturated polyester bulk molding compound (BMC) in the industrial process of pressing. Due to the poor performance of rheological molding process in traditional manufacturing process of BMC, the molding requires larger molding pressure and longer molding time. As a result, it not only increases the possibility of die loss, but also reduces the productivity of the plant. This article discusses systematically the influence of rheological behavior of chemical thickener Ca(OH)₂ in the molding process of BMC. On this basis, the crystalline resin was used to joint thicken BMC with Ca(OH)₂. Through tablet flow properties and spiral flow analysis of thickened BMC, the results show that the crystalline resin and Ca(OH)₂ as a complex thickening system will not affect the curing behavior of BMC. In fact, it can improve the molding flow properties of BMC and make the BMC be able to be molded under the low pressure.

Key words: crystalline resin, Ca(OH)₂, joint thickening, flow behavior, BMC