A comparative analysis of Kevlar-Derakane composites made from heat treated and as-received Kevlar-29

This analysis examines tensile and compressive strength testing of Kevlar-derakane composites. A total of 40 composites were tested in tension, 15 made with as-received Kevlar-29 fiber and the remaining 25 with Kevlar fibers that were previously heat-treated to enhance their compressive strength. As expected, the composites made from the heat treated Kevlar possesses slightly less tensile strength than those made from the as-received Kevlar (107.3 ± 2.8 MPa vs 117.3 ± 2.8 MPa). Forty-two additional composites were tested in compression (24 with asreceived fiber, 18 with heat-treated), but no statistically significant difference in the compressive strengths were observed (102.5 ± 13.7 MPa for the as-received compared with 98.4 ± 12.9) for the heat treated. Six control samples containing only resin and hardener provided a compressive strength of 83.6 ± 8.0 MPa, indicating that the fibers were serving a reinforcing role. Although the compressive strengths did not change between the composites made with as-received and heat-treated fibers, the dominant failure mechanism did. The composites made from as-received fibers failed primarily from fiber debonding and pull out, while those made with the heat-treated fibers shattered completely.