Preparation and properties of flame-retardant epoxy prepreg yarn for dry winding

AbstractThe winding tension of the dry-wound forming process is uniform, the process is easy to control and the structure and performance of the prepared vehicle-mounted hydrogen composite pressure vessels are stable. Since the vehicle-mounted hydrogen pressure vessels must be subjected to rigorous fire experiments, the flame-retardant epoxy prepreg yarn technology is currently monopolized by foreign countries. The development of flame-retardant prepreg yarn with good processing properties is of great significance to the promotion and application of hydrogen pressure vessels. Here, a flame-retardant additive hexaphenoxy cyclotriphosphazene (HPCTP) was synthesized and dissolved in epoxy resin of prepreg yarn named P/N-EP. Then, the flame-retardant prepreg yarn was made by the solution impregnation method. Curing behavior, thermal analysis combustion behavior and mechanical properties of P/N-EP and tensile properties of flame-retardant prepreg yarn were investigated. Experimental results showed that the LOI value reached 36.4% at 10 phr and reached the V-0 level of the UL-94 test. The results about thermal stability of the P-N/EP resin system showed that with the increase of P-N content, T5% (temperature at 5% weight loss) and CY600 (carbon residue rate) both increased. The microstructure of carbon residue after UL-94 test was studied by electron microscope and laser Raman spectrometer. The results showed that with the increase of P-N content, the carbon layer structure became denser and the ID/IG decreased significantly, to achieve the flame-retardant effect by the condensed phase mechanism.Keywords: Flame-retardantepoxy prepreg yarndry windingmechanical properties Disclosure statementNo potential conflict of interest was reported by the authors.Additional informationFundingThis work was supported by Jilin Province intelligent manufacturing major science and technology project (20210301004GX).