Michael O Wells
Reynolds Polymer Technology, USA
Title: Use of combination crp-thermal cure in free radical bulk polymerization systems
Biography
Biography: Michael O Wells
Abstract
In a series of studies carried out several years ago, some papers were presented covering the research efforts involved with using Controlled Radical Polymerization techniques in radically cured thermosetting resins. Among the positive attributes that were shown are: improved stability of initiated resins, longer potlife, the ability to create b-staged polyester materials, and most interestingly, the ability to drastically improve mechanical properties. The most noticeable ability of these unique molecules is that property of developing a two-way, reversible, “on-off” type of complex with a growing polymer chain. Since this property is dependent upon the monomeric composition and the processing temperature of the application technique, this particular technology can be used to tailor initiator systems to particular applications and conditions. The overriding question in the middle of these findings is, “what characteristic of these systems causes such changes in mechanical properties?” In this paper, an attempt is made to look mechanistically at the resins created and correlate these improvements to: molecular weight changes, changes in the molecular weight between crosslinks, changes in free volume within the matrix, changes in order/crystallinity within the resin matrix, and changes in crosslink density. It is assumed that through these studies, a better understanding of why radical controllers used in small quantities can make such profound differences in radically cured resins.