EFFECTS OF ENVIRONMENTAL EXPOSURE ON FIBER-REINFORCED PLASTIC (FRP) MATERIALS USED IN CONSTRUCTION

A major hindrance to the acceptance of polymer composites in civil eng ineering applications is the susceptibility of the polymeric matrix to weathering. The polymer matrix is prone to degradation initiated by u ltraviolet (UV) radiation, moisture, temperature, and high pH environm ents. The objective of this study was to characterize chemical and phy sical changes in polymeric matrix resins following exposure to these e nvironments. The ultimate goal is to identify factors that contribute to matrix resin degradation under environmental and mechanical stresse s. Resin systems studied included vinyl ester and isophthalic polyeste r, both of which are commonly used in construction applications. Neat polymer films were exposed to UV radiation, moisture, alkaline, and sa line environments. Diffusion of water, alkali, and saline solution int o the polymers was calculated from gravimetric measurements. Changes i n strength, viscoelastic response, and thermal properties were evaluat ed through tensile testing, dynamic mechanical thermal analysis (DMTA) , and differential scanning calorimetry (DSC). Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were also used for d etecting changes in the polymer surface following UV exposure.