TOTAL CURE SHRINKAGE OF CARBON-EPOXY COMPOSITES IN THREE PRINCIPAL DIRECTIONS

摘要

A method was developed for obtaining total shrinkage of carbon fiber-epoxy composite prepregsduring cure. A series of experimental work was also done to investigate the variation in totalcure shrinkage of two different prepreg systems. For this purpose, Cytec IM7/977-2unidirectional tape and Cytec T650/5320 8HS fabric were chosen as the primary materials.Prepared specimens were cured according to the manufacturer's recommended cure cycle(MRCC) for each material, and characteristic dimensional change of the specimens induced bycuring process was measured in three principal directions: longitudinal, transverse and throughthickness.Total cure shrinkage in longitudinal and transverse directions were measured usingdynamic mechanical analyzer (DMA) while for through-thickness direction, both DMA andthermomechanical analyzer (TMA) were used to obtain the shrinkage. Based on thisexperimental study, significant cure shrinkage was obtained for IM7/977-2 UD in transverse andthrough-thickness directions, whereas T650/5320 8HS showed such cure shrinkage only inthrough-thickness direction and for other directions cure shrinkage remains insignificant for bothmaterials. This experimental method effectively describes the variation in cure shrinkage fromdirection to direction, material to material.