Tensile properties and color and mass variations of GFPR composites under alkaline and ultraviolet exposures

The objective of the present study was to evaluate the influence of two different environmental conditions on the quantitative change of color and mass, tensile strength and modulus of elasticity of glass fiber reinforced polymers (GFRP) produced in Brazil. For this purpose, specimens were taken from pultruded composite profiles with two different matrices (vinylester and phenolic resins) reinforced with glass fibers. The first condition consisted of exposing them to cycles of ultraviolet radiation followed by water spray. In the second environment, the specimens were continuously exposed to alkaline solution at a constant temperature of 40 degrees C. After the exposure, both vinylester and phenolic composites were characterized according to the following parameters: variation of mass, tensile strength and modulus of elasticity. The CIE 1976 L*a*b* color system was used to determinate the color variation of the specimens after degradation using a spectrophotometer. Results indicated significant reductions in tensile strength values for both composites, in addition to expressive variations of mass and color. However, the color variation was not directly related with the loss of mechanical strength.