UV Durability of Polyester/Glass Composites Exposed to Accelerated Weathering Simulating a South Florida Environment

摘要

Thermoset polyester matrix composites reinforced with continuous strand mat (CSM) were exposed to accelerated weathering of natural sunlight and moisture for six months simulating two years exposure in South Florida. Damage features were accessed using scanning electron microscopy (SEM). Tensile and flexural tests were conducted on exposed vs. non-exposed samples. All samples contained a UV inhibitor. Samples containing only alumina trihydrate (ATH) as filler showed little in any surface damage. A sample containing kaolin clay filler and a hindered-amine light-stabilized (HALS) surface veil also showed little if any surface damage. In comparison, samples containing primarily calcium carbonate (CaCO_3) filler with ATH. (68:34)_phr CaCo_3:ATH, displayed classicial weathering surface damage including matrix cracking, polymer erosion and fiber pop-out. The presence of neopentyl glycol resin (NPG) in samples containing CaCO_3 did not improve weatherability. A proposed mechanism for the corrosion is the formation of carbonic acid from reaction of CaCO-3 with moisture. Excess water, in the presence of the carbonic acid and UV energy, may have photohydrolyzed the ester functionalities causing polymer degradation. For damaged specimens, the depth of damage was determined to be 40 - 130 umm. Mechanical testing showed little change to strength, however, tensile modulus was decreased 25 - 45