Study On The Effect Of Supercritical Carbon Dioxide On The Characteristics Of Resin Matrix Composites

Resin matrix composites have been widely used because of its excellent mechanical, physical, chemical properties. The supercritical carbon dioxide (SC-CO₂) was used into fiber-reinforced composite materials in this paper.Firstly E-51 epoxy resin was used as the matrix material and glass fiber was used as the reinforce material. The suitable amount of curing agent triethylene tetramine was determined. The viscosity of pure epoxy resin and resin matrix was studied. Secondly the effect of the pressure, temperature and time of supercritical carbon dioxide on glass fiber, resin matrix and the composites were discussed. The results show that the tensile strength of glass fibers treated by SC-CO₂ has little decrease. Resin cured at the pressure 7.5MPa, the temperature 70℃and the treatment time 30min in SC-CO₂ has better characteristics, with the flexural strength 124.8 MPa and the impact strength 19.2kJ·m-2. The flexural strength of resin matrix cured in SC-CO₂ is worse than which isn't treated in supercritical carbon dioxide, but the impact strength better. The mechanical properties of composites after fabricating in supercritical carbon dioxide is the best one when the pressure is 7.5MPa, the temperature is 40℃and the treatment time is 30min, with the flexural strength 331.8 MPa and the impact strength 104.3kJ·m-2 and it decreases along with temperature increasing and time lengthening.The curing temperature of resin was observed by DSC. The exothermic peak is most at 80℃.After fabrication, samples were analyzed by optical microscopy FTIR and SEM. As a result, 2362.64cm^-1 and 663.47cm^-1 as CO₂ absorption peak appeare after fabricating in SC-CO₂ by FTIR. The fracture pattern of glass fiber, cured resin and the composites were observed by SEM. SEM photographs show that the appearance of treated glass fiber is smooth, the fracture pattern of cured resin is regular and the fibriform structure forms, and the adhesion is good between the fiber and the resin when the composites is treated in SC-CO₂.