Dynamic mechanical analysis of FRP composites based on different fiber reinforcements and epoxy resin as the matrix material

Three-ply composite laminates prepared from E-glass or N-glass chopped strand mats (CSMs) and jute (J) fabrics as reinforcing agents and amine-cured epoxy resin as the matrix material were subjected to dynamic mechanical thermal analysis at a fixed frequency of 1 Hz over a temperature range of 30-180 degrees C. The volume fraction of fibers ranged between 0.21 and 0.25. The reinforcing effect for the three fibers is in the order E-glass > N-glass much greater than jute. Glass-reinforced composites show a higher storage modulus (E') than that of jute-reinforced composites. The E' values of glass-jute hybrid composites lie between those of glass-reinforced and jute-reinforced composites. Odd trends in temperature variability of the loss modulus (E '') and the damping parameter, tan delta, and in the glass transition temperature (T-g) for the three different unitary and four different hybrid composites are interpreted and understood on the basis of odd differences in (1) the chemical nature and physical properties of the three different fibers (E-glass, N-glass, and jute), (2) the void content and distribution, (3) the thermal expansion coefficients of the main phases in the composites, (4) the degree of matrix stiffening at or near the fiber-matrix interface, and (5) the extents of matrix softening in the zone next to the interface. (C) 1997 John Wiley & Sons, Inc.