Effects of a chelating agent ‐ 2,4‐pentanedione on low temperature composite molding of vinyl ester and unsaturated polyester resins

Abstract

A major concern in low temperature composite manufacturing processes is how to design and control the mold filling and curing time. Inhibitors or retarders are often used to prevent premature gelation and provide a sufficiently long time to fill the mold completely. However, the addition of these chemical species tends to result in a low mold curing rate and a low final resin conversion. In this study, a chelating agent 2,4-pentanedione [2,4-P) was used to manipulate resin gelation and curing. This agent is known to affect the catalytic activity of the promoters (i.e. metal compounds such as cobalt carboxylates) in the decomposition of initiators. It can function as either a retarder or a co-promoter in the co-polymerization of styrene/polyester and styrene/vinyl ester resins depending on the acidity of the resin system. Based on this observation, an improved room temperature vacuumassisted resin transfer molding process was designed. This design allows 2.4-P to serve first as a retarder during mold filling to achieve a long gel time, it then as a co-promoter during curing to increase the curing rate. The 2.4-P also increases the resin conversion as the acidity of the resin increases.

Palm oil fuel ash as potential green micro-filler in polymer concrete

“…Both were mixed at low binder content of 12% by weight of resin and then mixed separately with methyl ethyl ketone peroxide (MEKP) as the catalyse (hardener) and cobalt naphthenate (CoNp) as the initiator. Polyester inhibitor of methyl methacrylate (MMA) was added into the polymer binder to prolong the working life [18]. The working life of both polymer binders is presented in Fig.…”

Control of shrinkage and final conversion of vinyl ester resins cured in low‐temperature molding processes

“…A substantially long gel time is very important for mold filling and fiber wetting. Recently, more effort has been given to the design of efficient curing systems to achieve desired performance (i.e., high final conversion, long pot life, and short cycle time) in low‐temperature molding processes 14, 15…”

“…Also, the function of 2,4‐P in UP and VE resins was found to be dependent on resin acidity 14, 19. For less acidic VE and UP resins, 2,4‐P functioned as a retarder in the redox initiation.…”

Unsaturated Polyester Resins: Chemistry and Technology

“…2,4-Pentanedione was applied as either a co-promoter in the copolymerization of a UP or a vinyl ester resin with styrene [169]. The activity of 2,4-pentanedione consists of the chelating of metal compounds, e.g.…”