Published : 2022-09-19

Determination of volume changes during cure via void elimination and shrinkage of an epoxy prepreg using a quartz dilatometry cell

Abstract

Volumetric changes were eliminated in processing of a glass fiber reinforced epoxy prepreg; two components from void elimination and the crosslinking reaction itself were isolated. A quartz dilatometry cell inside a Thermomechanical Analyzer (TMA) was used to measure the volume changes. Compression was applied at a temperature higher than the resin glass transition temperature to isolate the void elimination volume change, whereas the change due to reaction shrinkage was observed at a longer time at the cure temperature. Uniaxial and biaxial composite prepregs were studied. Each sample exhibited an approximately 0.5% volume change due to crosslinking. Void elimination varied with temperature, pressure and fiber orientation. Several interesting trends are evident in the present results. Higher pressure results in higher void elimination. Lower cure temperatures produce higher void elimination, except that high temperatures show some increase due to low viscosity before curing locks in the structure. Bia-xially oriented fibers show higher void elimination than do uniaxial at low cure temperatures, but at higher temperatures the values are similar. The volume changes due to void elimination in the composites examined varied from 6% [biaxial, 100°C, 10 psi (ca. 0.07 MPa)] to 1% [uniaxial, 160"C, 5 psi (ca. 0.035 MPa)].


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Bilyeu, B., Brostow, W., & Menard, K. P. (2022). Determination of volume changes during cure via void elimination and shrinkage of an epoxy prepreg using a quartz dilatometry cell. Polimery, 46(11-12), 799–802. Retrieved from https://polimery.ichp.vot.pl/index.php/p/article/view/2135