Effect of side-chain length of succinic anhydride on coefficient of thermal expansion behavior of epoxy resins

The effect of an alkenyl side-chain of succinic anhydride (SA) on the thermal behavior and the coefficient of thermal expansion (CTE) of diglycidylether of bisphenol A (DGEBA) epoxy resins was studied. The number of carbons in the side-chain of SA was varied from 6 to 14 and N,N-Dimethylbenzylamine was used as an accelerator. As a result, the reactivity of SA with epoxide groups was decreased on increasing the length of the alkenyl side-chain of SA. The thermal stabilities of cured DGEBA/SA samples were approximately constant with varying alkenyl side-chain of SA. Also, the CTE of the systems was increased as the length of the alkenyl side-chain of SA increased. This could be attributed to the increased motion of the chain segments in the epoxy network structure induced by the longer alkenyl side-chain of SA. The effect of amount anhydride, thermoplastics, and fillers on the CTE of the epoxy resins was also discussed.