Paper number 626


Yang Zhong and Jianren Zhou

Department of Mechanical Engineering
Prairie View A&M University
Prairie View, TX 77446 USA

Summary Hygrothermal freeze/thaw cycling exposures were performed on glass/vinyl ester composites to simulate the harsh temperature and moisture conditions the composites might encounter during their lifetime in services. Moisture absorption of the composite during the exposures and hygrothermal effects on the glass transition, thermal stability, and mechanical properties of the composite were investigated. It was found that moisture absorption of the composite showed a cyclic increasing, within the freeze duration, and decreasing in the thaw period, while glass transition temperature of the composite exhibited a steady increase with an increase in hygrothermal cycling duration and leveled off beyond 1000 hours of the exposure. Thermal stability of the composite was only slightly influenced by the hygrothermal exposures at 80C. By comparison, it was also found that the degradation in compression property of the composite was less significant for the composite experienced the cyclic exposures than that with simply isothermal holding at the same temperature and with the same exposure duration. Upon compression tests, microstructural observations revealed that the matrix resin at fractured surface region showed a more fragmented feature for both the cyclic exposed and isothermal held samples.
Keywords Vinyl ester composite, hygrothermal aging, environmental durability.

Theme : Durability and Ageing

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