*** 9761580 Tan This Phase I Small Business Innovation Research Phase I project will use a novel technique to process microcellular foams using a single-step operation and that does not use or release any hazardous chemicals/gases. The proposed foaming technique uses the principle of thermodynamic instability with nitrogen as the foaming gas. The proposer will foam both the unfilled and filled liquid crystalline and semicrystalline polymers (LCPs & PPS) which have excellent strength and stiffness to weight ratio, good solvent resistance, barrier properties, and high temperature stability. The blowing process will align the carbon/glass fibers along the struts of the foamed matrix. It has been demonstrated for amorphous polymers that the properties of microcellular foams are similar to their solid counterparts. Therefore, the low-density microcellular LCP and PPS foams will have tensile strength in the range of 20 to over 30 ksi. These microcellular foams will have much higher temperature stability and mechanical properties than those of the commercially available structural foams including Rohacell and Divinycell. Sandwich structures can be fabricated using these foams by heat pressing, thereby reduce manufacturing and assembling costs. Conventional processing techniques for rigid closed-celled) foams involve multiple steps and the blowing agent used is toxic. Some rigid foams give off hazardous gases during the post-processing steps. Low-density microcellular LCP & PPS foams are expected to have many commercial applications including sandwich structural materials for high speed aircraft, aerospace, outerspace vehicles, housing and support structures for rockets and propulsion components. Conventional applications of LCPs and PPS include various electronic connectors, electronic and audio-visual devices. They can be replaced by the proposed microcellular LCP and PPS foams with equivalent performance but much lighter in weight. On the ground applications, ladders an d bridges fabricated using these classes of microcellular foams would have extreme convenience of mobility because of much lighter weight. ***
