DYNAMIC-MECHANICAL ANALYSIS OF PULTRUDED GLASS-GRAPHITE EPOXY HYBRID COMPOSITES AT ELEVATED-TEMPERATURES/

In this paper the dynamic performance characteristics of pultruded gla ss-graphite/epoxy hybrid samples at elevated temperatures are presente d. In previous research the dynamic mechanical properties of the hybri d composites have been characterized at room temperature but the wide application range of these pultruded products necessitates their chara cterization at high temperatures and over longer periods. The dynamic mechanical analysis technique has been employed to characterize pultru ded glass-graphite/epoxy hybrid composite materials over a wide temper ature range. At elevated temperatures, the rate of degradation in flex ural modulus and variation in loss factor were found to be dependent o n the fiber lay-up sequence. Results indicate that the width of the gl ass transition zone, an important design criterion, can be effectively broadened by judicious incorporation of the glass fibers. Tests repea ted on post-cured pultruded products demonstrate a significant shift i n the glass transition temperature towards higher side along with an i ncrease in the onset temperature of glass transition. The frequency mu ltiplexing technique used in conjunction with the time-temperature sup erposition principle proved to be an effective method for predicting t he long-term behavior of these hybrids.