Damping properties of para-phenylene terephthalamide pulps modified damping materials

A series of para-phenylene terephthalamide pulp modified damping materials were prepared. The dynamic mechanical properties, differential scanning calorimetry, vibration damping properties, vulcanization property, tensile strengths as well as scanning electron microscopy micrographs of the damping materials were studied theoretically and experimentally. The dynamic mechanical properties of para-phenylene terephthalamide pulp modified damping materials were also compared with aramid short-cut fiber, E-glass staple fiber and carbon fiber powder modified damping materials. The results showed that para-phenylene terephthalamide pulp modified damping materials exhibited the best damping property and highest modulus in comparison with the other types of fibers. The storage modulus ( E′), loss modulus ( E″) and tensile strength of the materials were all increased significantly with increasing pulp content, and this trend was significantly greater in machine direction rather than in cross-machine direction. The second, third and fourth modes modal loss factors (η) of the steel beams coated with para-phenylene terephthalamide pulp modified damping materials increased substantially up to a maximum, and then became stable with increasing pulp amount. The optimal η in machine direction was achieved as the mass ratio of butadiene-acrylonitrile rubber to para-phenylene terephthalamide pulp was 100:30. Excellent damping property was mainly attributed to the extremely high interfacial contact area which significantly improved the efficiency of energy dissipation of internal friction, interfacial sliding and dislocation motion between para-phenylene terephthalamide pulps and butadiene-acrylonitrile rubber chains. Since para-phenylene terephthalamide pulp modified damping materials offer a high E′, excellent vibration damping properties, broad damping temperature and frequency ranges, it is ideal for free-damping structures which are widely utilized in industrial vibration and noise control applications.