Thermal and Mechanical Properties of Unsaturated Polyester Composites Containing Microballoons

The purpose of this study is to develop the thermal insulation material having function like watervaporproof, light-weight and very high strength. By preparing the cast moldings of unsaturated polyester composites filled with several kinds of microballoons of 50 to 150μm in the diameter. The investigation was performed on the effect of the filler content about the density, thermal conductivity and mechanical strength of the castings. Furthermore, a way to estimate the thermal conductivity of these composites by empirical formula was discussed. The result shows that the density of the materials are extremely reduced by containing microballoons. The thermal conductivity of composites containing such fillers as silica (FMB), glass (GMB) and plastic (PMB) microballoons was decreased with increasing filler contents, and was also decreased depending on the temperature. Their thermal conductivity estimated by the formula (2) was found to closely resemble the measured data, and it appeared that the thermal conductivity of water absorbed composites estimated by the formula (3) increased in proportion to water absorbing capacity. In the composites containing silica (FMB) or metallized silica (AFMB) microballoons, the Young's modulus was about 1. 5 times higher as compared with that of matrix itself. Whereas, the mechanical properties such as tensile, compressive, bending and Izod impact strengths of these composites, generally decreased with the increaseing of filler content. From the above evidence, it is concluded that the material containing 60v% of plastic microballoon (PMB) can use as a light weight and strong thermal insulant with humidity resistance.