Evaluation of cure state of vinylester resins

The objective of this investigation is to characterize the effect of time and moisture on the degree of cure of two room temperature (RT)-curable vinylester resins (VE), VE8084, and VE510A. Both resins were cured at RT for 24 h. Following the initial cure, some specimens were cured at RT over an extended period of time; others were immersed in seawater or a humidity chamber (85% RH) at 50 degrees C, or post-cured (PC) at elevated temperatures. Dynamic-mechanic analysis (DMA) and differential scanning calorimetry techniques were performed to characterize the degree of cure. The degree of cure for 24 h RT-cured and seawater exposed specimens ranged from 83 to 86% for VE510A and from 86 to 93% for VE8084. After PC at elevated temperature, or exposure to 85% RH at 50 degrees C, the degree of cure of both resins increased to about 99100%. Analysis of the viscoelastic response of the resins by DMA revealed two heterogeneous transitions for partially cured VE resins and a single transition for fully cured resins. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013