Radical-induced cationic frontal polymerisation for prepreg technology

Abstract

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 °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

Frontal Polymerizations: From Chemical Perspectives to Macroscopic Properties and Applications

“…The primary initiators employed in cationic FP are photoacid generators (PAGs), 34,59,61,77,80,[176][177][178][179][180][181][182][183][184][185] amine-boron trifluoride adducts, 71,80,131 or crosslinking polyamines. 79,186,187 While the mode of propagation with these curing agents matches that of the general mechanism in Scheme 4, several differences in monomer activation and initiation exist.…”

“…Specifically, successful FP with diaryliodonium PAGs exploits the thermolysis of added benzoyl peroxide (BPO) 77 or 1,1,2,2-tetraphenylethylenediol (TPED). 34,59,61,177,179,[181][182][183]190 Amine-boron trifluoride initiated FP occurs by background reaction with residual moisture. These adducts react readily with water (Scheme 5B) to form a transient, solvent separated species, [RNH3][BF3OH].…”

Photoinitiating systems and kinetics of frontal photopolymerization processes – the prospects for efficient preparation of composites and thick 3D structures

“…Nevertheless, in recent years, the composites with fillers such as zinc oxide and carbon fibres, 131 multiwalled carbon nanotubes, 107 glass fibres, 132 glass microspheres and graphite powder 133 were successfully prepared using the RCIFP method. This self-sustaining frontal polymerisation system was also successfully used in prepreg technology 134 and interpenetrating phase composites. 135 The convenience and versatility of this method will undoubtedly result in more applications in the future.…”

Frontal‐Photopolymerization of Fully Biobased Epoxy Composites

“…The composite could be obtained in a second time by activating the RICFP of the DGEBA. [60] However, the applicability of RICFP on fully biobased natural fiber composite systems is still to be demonstrated. To fill this gap, we investigated the RICFP of an epoxidized vanillinresin matrix reinforced with either linen or cellulose fabrics.…”