Study On The Properties And Molding Theory Of Low Pressure Molding Compounds

Low Pressure Molding Compounds (LPMC) is a new material product with higher mobility, lower molding pressure, less production cost and processing equipment cost, which can be used to produce SMC. These products have advanced electrical performance, mechanical properties, heat resistance, chemical resistance and dimensional stability, which can be widely used in many fields. In this paper, the LPMC thickening mechanism, the fiber immersional ability, the mechanical and electrical properties were investigated. The effects of the LPA (LPA), glass fiber content and length, LPMC crystalline resin content and other factors on the mechanical and electrical properties of LPMC were investigated. Furthermore, the Theological characteristics and embossing flow theory of LPMC were studied. Torque Rheometer was used and combined with the determination of LPMC concentric fiber glass content. The flow properties of premix in molding process were studied. The factors which can effect on the flowing viscosity and the distribution of glass fiber in LPMC were analyzed, including temperature, content and length of the glass fiber, filler particle size and crystalline resin content.In this paper, Matlab software was introduced to simulate the flow and heat conduction of LPMC. The molding process of LPMC was divided into two parts, a filling mold process during the ascending temperature stage and a curing process during the closed mold stage. LPMC samples were analyzed under the same environment and molding conditions. It can be found that result of the computer simulation test coincided with that of the actual flow test, which indicated that Hele-Shaw model also matched the LPMC. The relationship between temperature and time of LPMC in the mold can be studied using mathematical simulation of the heat conduction process. Therefore, the curing reaction could be avoided by adjusting the thickness of film and the initial temperature of mold, or adding the polymerization inhibitor, which can satisfy the technical demands. According to the thermal analysis of mold surface, it can be concluded that most heat came from the region covered by the initial materials rather than the filled area. This paper conducted a preliminary study, which is significant and valuable for the final decision of the mold design, paving method of LPMC and pressing parameters.