Research On The Modification Of Low-density Bulk Moulding Compound

Be called Bulk molding compound premix, BMC is a kind of matrix of fiber reinforced composite material basics on the thermosetting resin, Representative BMC plastics is made by unsaturated polyester resin,which has added some low shrinkage additives, besides, glass fiber, filler, release agent, initiator, thickening and some other components also must be joined. This BMC is the most widely used varieties. As comparison with general engineering thermoplastics, BMC has a good tensile strength, impact strength, bending strength and resistance to creep and fatigue properties, high heat resistance, molding products with good dimensional accuracy and stability and so on. At the same time, in order to obtain the performance requirements of a special production, It can also be regulated component type and content based on need. All of these excellent comprehensive properties make BMC widely used in electrical, chemical, transportation, manufacturing industry and other fields. As its application requirements increase, BMC has been put higher requirements forward in the field of lightweight, low shrinkage performance of products. The study on the modification of BMC becomes the composite research hotspot.Through the study of molding process of rheology and unsaturated polyester resin mechanical properties and surface quality, we determine the optimal parameters, the paper do the discussion of BMC molding performance. This paper select150degrees as forming temperature,7MPa as molding pressure,60min as molding time by experimental parameters. As contrast, when the glass fiber length is6mm, fiberglass filler mass ratio of35/35, overall performance is better. BMC get the best mechanical properties. To meet some of the areas of the lightweight high strength BMC products, we try to join the hollow ceramic beads to reduce its density, which is selected the isostatic strength of17-21MPa, the particle density of0.7-0.95g/cm3, the packing density of0.4-0.5g/cm3,particle size range of45-355μm beads were tested, do distribution by SEM analysis of microspheres. Experiments show that by adding the relative filler content of40%beads, the density of the products can be reduced to1.19. To ensure that the modified BMC has good mechanical properties, After selecting the proper ratio, temperature, pressure, we test mechanical properties and density. Initially selected cenospheres content of20-30%to get good mechanical performance under the low density products.The paper used the orthogonal experiment method to determine the best process parameters, and through the burning loss of weight loss method for the determination of glass fiber content, we discussed glass fiber length, content of filler type on the effect of viscosity through the Torque rheometer, besides, Through a large number of experimental data, we do analysis of influence factors on performance of BMC material, Do observation of BMC material section morphology by scanning electron microscopic, to understand glass fiber and filler in the distribution of BMC materials.