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Biaxial Extrusion of Polyimide Larc—tpi and Larc—tpi Blends
Published online by Cambridge University Press: 22 February 2011
Abstract
Biaxial films of polyimide LARC—TPI and LARC—TPI/liquid crystal polymer Xydar® were extruded directly from the melt for the first time via an innovative new extrusion technique. Three types of films, neat LARC—TPI, LARC—TPI/lO wt percent and 30 wt percent blends were processed as a part of this NASA funded program. This new process offers an alternative technique to costly post—processing stretching of both solution cast and sheet extruded films. The post—processing step is often required to enhance certain properties. Processability was greatly enhanced by incorporating Xydar. The coefficient of thermal expansion was reduced from 34 ppm/ºC for the neat LARC—TPI to 15 ppm/º C for the 10 wt percent Xydar blend and ultimately down to I to 3 ppm/º C for the 30 wt percent blend films in the direction of extrusion. The maximum improvementin stiffness was realized by incorporating 10 wt percent Xydar (2.8 GPa up to 4.9 GPa). Tensile strength, however, experienced a drop as a result of Xydar addition, probably caused by inefficient mixing of the two phases.
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- Copyright © Materials Research Society 1990
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