Improved EB cured DGEBA systems by copolymerization with novel tetrahydrofuran functional comonomers

The overall objective of our work is the design of improved EB cured epoxy systems based on diglycidyl ether of bisphenol A (DGEBA). One method for designing such systems is the use of network modifiers. Herein we report the development of a new class of chain extenders based on the ring opening copolymerization of tetrahydrofuran (THF) with DGEBA. We report the successful copolymerization of THF with DGEBA induced by EB in the presence of an appropriate photoinitiator. THF was found to increase fracture toughness with a concomitant decrease in glass transition temperature. Additionally, THF presents practical processing difficulties associated with its high volatility. A series of novel THF functional comonomers was designed to mitigate the aforementioned drawbacks associated with THF. These include difunctional and trifunctional monomers possessing THF functionality. Methods of synthesis and the properties of DGEBA systems modified with these novel monomers are presented. It was found that the fracture toughness of EB cured DGEBA systems can be improved almost five fold with minimal loss of T_g. Moreover preliminary results indicate that composite properties can also be improved using these comonomers.