Radical-induced cationic frontal polymerisation for prepreg technology

In this study, a new type of prepreg technology has been established using a dual curing system consisting of 1,6-hexanediol diacrylate (HDDA) and frontally polymerisable components based on the epoxide resin. The study of the polymerisation of HDDA revealed (tert-butylcyclohexyl)peroxydicarbonate (BCPC) as the most suitable radical thermal initiator. The presence of BCPC resulted in a fast radical polymerisation of HDDA and no cationic ring-opening reaction of the epoxy, which was observed by monitoring the double bond and epoxy group conversion in real time-NIR rheology measurement. The formed prepreg can subsequently be cured by radical-induced cationic frontal polymerisation of the epoxy resin. Effects of HDDA amount on the radical polymerisation, stiffness of the gel, frontal parameters and thermal mechanical properties of final polymers were investigated. With 10 wt% HDDA, the formed prepreg has very good storage stability, which was proved by monitoring the epoxy group conversion during 4 months of storage at 50 degrees C while still a stable front can be obtained. Furthermore, the RICFP-prepregs with different fibre contents were prepared and polymerised by RICFP. Then, a snowflake composite was successfully produced using RICFP-prepreg. Graphic abstract

Automated summary

A new prepreg technology was established using a dual curing system, with HDDA and frontally polymerisable components based on epoxide resin. The study focused on the polymerisation of HDDA using BCPC as the radical initiator, without cationic ring-opening reaction of the epoxy. By investigating the effects of HDDA amount on radical polymerisation, stiffness of the gel, and thermal mechanical properties, the study successfully produced snowflake composite using RICFP-prepregs.