Effects of degree of cure, direction of heat flow and temperature on thermo-physical properties of out-of-autoclave carbon fiber-epoxy prepreg

Abstract

Thermal conductivity is an essential parameter considered by engineers when selecting composite materials for aerospace applications. It mainly is a function of temperature, direction of heat flow and degree of cure (DOC). In this study, thermo-physical properties of 5320-8HS carbon fiber-epoxy prepreg and samples with DOC of 95%, 83%, 67%, 33% and 2% were determined by the Laser flash technique. Measurements were taken along 0, 90 and through-the-thickness (TT) directions and the effects of DOC, temperature and direction of heat flow on thermo-physical properties was studied. Thermal conductivity along t-t direction remained constant regardless of temperature change while it increased in 0 and 90 directions. Conductivity along 0 direction is 4.8 times that of TT direction whereas the diffusivity is 5.5 times that of TT direction. The diffusivity in 0 direction can approximately be equated with 90 direction. Further, thermal conductivity and diffusivity increased with an increase in DOC.