Study of the thermal behavior of carbon/epoxy laminates exposed to multiple thermal cycles

Abstract

In this study, the thermal behavior of three families of carbon fiber/epoxy resin laminates, exposed to multiple thermal cycles, were evaluated. Thermogravimetric (TGA) and dynamic mechanical (DMA) analyses were used. This paper aims to consider the use of carbon fiber/epoxy prepreg scraps - a noble material in the aircraft industry, by comparing the thermal behavior of one laminate manufactured with prepreg scraps (laminate R), a laminate manufactured with commercial prepreg (Laminate A) and a third one produced with wet hand lay-up materials (Laminate B). The cured laminates were exposed to multiple thermal cycles: 40, 100 and 300 h of exposure at the maximum temperature of 180 °C. TGA results show that laminates exposed to the multiple thermal cycles present thermal stability at 180 °C, with relative mass loss due to humidity absorbed by the laminates. DMA curves show that the multiple thermal cycling has almost no effect on the thermal behavior and even raises the glass transition temperatures of the epoxy resin systems studied. With these results, it can be affirmed that the laminates submitted to multiple thermal cycling have thermal stability enough to be used on composite curing jigs.

Keywords:
epoxy resin; carbon /epoxy composites; thermal cycling; TGA; DMA