Effects of Water, Salt Solution and Simulated Concrete Pore Solution on the Properties of Compostie Matrix Resins Used in Civil Engineering Applications

摘要

One of the obstacles hiI1cdering the acceptance of polymer composites in civil en- gineering applications is the susceptibility of the polymeric matrix to degradation that is initiated by moisture, temperature, and corrosive chemical environments. The objective of this study was to characterize chemical and physical changes in polymer matrix resins following exposure to these environments. Resin systems studied were vinyl ester and isophthalic polyester, both of which are proposed for use in construction applications. Unreinforced free films were exposed to water, al- kaline and saline environments at ambient and elevated temperatures for extended periods of time. Changes in strength and thermophysical properties were evaluated through tensile testing, dynamic mechanical thermal analysis (DMrA) and thermo- gravimetric analysis (TGA) .Chemical degradation of the polymers was character- ized using Fourier transform infrared (FTIR) spectroscopy. Energy dispersive X-ray (EDX) analysis of specimens following exposure was carried out to determine if ion diffusion into the bulk polymer occurred. Only minor changes in the glass transi- tion temperatures of the polymers were observed after prolonged exposure at ele- vated temperature, but more substantial changes were noted in tensile strength, particularly in the case of the isophthalic polyester. Examination of the polymers following immersion in salt solution and alkaline solution showed essentially no ionic penetration into the bulk, with the exception of specimens that were visibly degraded. Spectroscopic analysis of chemical structure prior to and following expo- sure revealed varying degrees of ester hydrolysis.