LARC-TPI/LIQUID CRYSTAL POLYMER BLENDS

NASA'S GROWING DEMAND FOR SPACECRAFT STRUCTURES, SUCH AS THEPRECISION SEGMENTED REFLECTOR, TRUSS TUBES, AND SOLAR CELL ARRAY PANELS, REQUIRES THE DEVELOPMENT OF LOW COEFFICIENT OFTHERMAL EXPANSION (CTE) POLYMERS WITH EXCELLENT PROCESSIBILITY. WE PROPOSE TO BLEND NOVEL LIQUID CRYSTAL POLYMERS (LCPS) WITH NASA'S HIGH PERFORMANCE THERMOPLASTIC POLYIMIDE, LARC-TPI TO OBTAIN MATERIAL PROPERTIES THAT MEET NASA'S FUTURE MISSION REQUIREMENTS FOR SPACECRAFT. RECENT WORK SHOWS THAT SUCH BLENDS CAN REDUCE CTE BY MORE THAN A FACTOR OF 10 AND CAN INCREASE MODULUS BY MORE THAN THREE TIMES AT VOLUME RATIOS OF 30 TO 50 PERCENT FOR THE LCP. ALSO, THE BLEND IS MUCH EASIER TO PROCESS BECAUSE VISCOSITY IS REDUCED BY TWO ORDERS OF MAGNITUDE. SUCH IMPROVEMENTS WILL MAKE LARC-TPI/LCP BLENDS FULLY COMPETITIVE WITH FIBER-REINFORCED COMPOSITES, BUT AT LOWER COST. THESE HIGH TEMPERATURE, HIGH STIFFNESS, LOW DENSITY, NEAR-ZERO CTE FILMS AND MOLDED PARTS WILL MAKE IDEAL MATERIALS FOR A VARIETY OF APPLICATIONS, SUCH AS HIGH STRENGTH, HIGH STIFFNESS THIN-WALLED SPACE STRUCTURES, PRECISION SEGMENTED REFLECTORS FOR SOLAR COLLECTORS, AND ENGINE PARTS. THE BLENDS HAVE THE POTENTIAL TO BE AS STRONG, STIFF AND DIMENSIONALLY STABLE AS FIBER-REINFORCED COMPOSITES, BUT WITHOUT THE DRAWBACKS OF DISTINCT FIBER AND MATRIX PHASES (MICROCRACKING, POOR TRANSVERSE STRENGTH, ETC.). ALSO, SINCE THE BLENDS CAN BE DIRECTLY FABRICATED INTO PARTS SUCH AS TUBES AND STRUCTURAL SHEET, THEY WILL BE CHEAPER TO FABRICATE THAN MULTI-STEP FIBER COMPOSITES (PREPREG, WEAVING, LAY-UP, CURING, CUTTING, BONDING. ETC.). THE PERFORMANCE/COST ADVANTAGES SHOULD BE SUBSTANTIAL FOR NASA'SSPACECRAFT MISSIONS.