Effects of different testing conditions on tensile properties of carbon fiber yarn

Particular care has been always taken in the carbon fiber/resin composites, and the most critical parameters for engineering application are tensile strength and tensile modulus. ASTM D4018−11, JIS R7608-2007 and ISO 10618-2004 have shown a set of detailed instructions for tensile testing of resin-impregnated yarn. However, some problems still exist that the different sample preparation and testing conditions can generate a certain number of discrete data causing a great barrier to compare the results during my experiments. In this paper, the effects of different sample preparation and testing conditions on tensile properties of carbon fiber yarn, including T300B-3K, T700SC-12K and T800HB-6K supplied by Toray, have been investigated systematically based on types of resin and resin contents of impregnated yarn and tensile speeds. Thus the appropriate determination parameters for impregnated yarn have been got. The results showed that resin with high mechanical properties, good wettability, and low viscosity in room temperature could be employed, and the resin content of impregnated yarn should be controlled more than 30%. Furthermore, we suggest that tensile speed of 2mm/min and 5mm/min is suitable for the determination of tensile properties of impregnated yarn. As for the determination of modulus, strain range between 0.3% and 0.6% could be adopted for setting the strain parameters of extensometer.