STP873

    Hygrothermal Degradation of Sheet Molding Compounds

    Published: Jan 1985


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    Abstract

    Environmental variables such as moisture and temperature degrade fiber-reinforced polymer composites to various levels. This paper characterizes the hygrothermal degradation of a sheet molding compound (SMC) containing 65% by weight of E-glass fibers. Six different environments were chosen for the study: room temperature (RT)/65% relative humidity (RH), RT/98% RH, RT/water, 75°C/65% RH, 75°C/65% RH, 75°C/98% RH, and 75°C/water. The extent of degradation was evaluated using visual, microscopic, and chemical analysis techniques. From this study, distinct color changes and blistering on the specimen surfaces were evident. Degradation was manifested in the ultrasonic attenuation and in the reduction of short beam strength and stiffness.

    Keywords:

    hygrothermal environments, degradation, swelling, sheet molding compounds, composite materials, moisture, strength, stiffness, ultrasonic attenuation, blisters


    Author Information:

    Hosangadi, AB
    Graduate student and professor of mechanical engineering, Washington University, St. Louis, MO

    Hahn, HT
    Graduate student and professor of mechanical engineering, Washington University, St. Louis, MO


    Paper ID: STP34018S

    Committee/Subcommittee: D30.03

    DOI: 10.1520/STP34018S


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