Study On The Preparation And The Properties Of Chlorobutyl Rubber Damping Materials

Damping materials have found numerous applications for the aircraft, automobile and machinery industries to reduce unwanted noise and to prevent vibrational fatigue failure. Polymer materials are widely used as damping materials because of its multilevel motion units. Damping materials of chlorobutyl rubber (CIIR) systems were prepared by blending. The effects of curing systems, fillers, plasticizer DOS and staple fibers on the vulcanization, mechanical and damping properties of damping materials were investigated. The vulcanization behaviors were characterized by curing curves. The mechanisms of vulcanization and damping were studied with FTIR. The mechanical properties were tested with multipurpose test machine and shore-A sclerometer. The damping properties were studied with DMA and impact bounce test machine. The main important conclusions are as follows:(1) In usual vulcanization systems, the time of optimum vulcanization of CIIR composite became short and the maximal torque large when the content of zinc oxide was increased, but the addition of accelerant into the system, the tensile strength was increased and the shore-A hardness were decreased. The sulfur vulcanization system shortened the time of premature vulcanization and heightened tensile strength markedly. Neither zinc oxide nor sulfur vulcanization system would shift the damping temperature range upwards effectively. The phenolic resin system lessened the times of premature and optimum vulcanization, the maximal torque and tensile strength of the composite were decreased while the hardness increased. The peak damping temperature of the composite shifted gradually towards high temperature, the maximal loss factor (tanδmax) decreased and the damping temperature range narrowed with the increase of phenolic resin. It implied that the temperature range of damping materials would be satisfied by changing the content of phenolic resin.(2) With the increase of petroleum resin, the times of premature and optimum vulcanization of the CIIR blends were extended, the tensile strength and elongation at break increased, the hardness and the bounce rate reduced, and the damping temperature range floated up and peak loss factor tanδmax increased. While the petroleum resin and phenolic resin were combined into the blends, the compatibility of the blends was poor and the twin peak damping temperatures appeared.(3) Carbon black (SRF and N330) both lengthened the times of premature and optimum vulcanization and magnified the maximal torque of CIIR blends; As far as vulcanization process was concerned, SRF gave longer premature time but shorter optimum time than those of the blends with N330, meanwhile SRF gave rise to higher maximal loss factor and wider damping temperature range. All other fillers had no much effect on the times of premature and optimum, however, the tensile strength of the blends presented a bell-shaped distribution and the glass transition temperature (Tg) moved to high temperature with the damping temperature range broadening when the increase of fillers was increased. Among the fillers, the mica and molecular sieves combination and the calcium carbonate and sepiolite combination both have shown positive effect on the damping properties .(4) The plasticizer DOS led to reduction of glass transition temperature and broadening the damping temperature range, but no change of peak loss factor.(5) Fibers generally enhanced the hardness of the CIIR blends much. The aspect ratio and the content of fibers affected the mechanical and damping properties. The smaller the aspect ratio was, the larger the tensile strength was. The maximal loss factor reduced, Tg moved to low temperature and the damping property of the CIIR blends became poor with the increase of PET staple fiber. The fiber-rubber layered structures showed high tensile strength. The tensile strength reached 18.59MPa with three layers of fabric inserted. (6) The damping element with optimum formula had good mechanical and damping properties, and gave perfect damping and reduced noise. The maximum and the average vibration level differences reached 54.1dB and 27.2dB, respectively.