Studies On Phenolic Resin/Vermiculite Nanocomposite And Its Application In Frictional Material

Phenolic resin is one of the widely used thermosetting resins because of its excellent ablative property, structural integrity and solvent resistance. Phenolic resin was modified in order to improve the properties of mechanical properties and thermal stabilities. In recent years there has been considerable interest in polymer-layered silicate nanocomposites because their use has resulted in unexpected improvement in physical and mechanical properties. Vermiculite (VMT), like the well-known MMT, is a micatype silicate and possesses a layered structure. VMT has much better properties of heat preservation and heat insulation in comparison with MMT. In this paper, phenolic resin/VMT nanocomposites were prepared.The interlayer structure of pristine vermiculite and expanded-vermiculite was modified respectively by hydrochloric acid, NaCl and hydrochloric acid/NaCl, and then organic-vermiculite was prepared by intercalation treatment with hexadecyl trimethyl ammonium bromide (CTAB). And the influence of different structure modification on organic intercalation of two kinds of vermiculite was discussed. The expanded-vermiculite was treated by intercalation agent with different structure, and investigated the influence of the intercalation agent style with different structure on organized expanded-vermiculite.The above organized vermiculite in various contents was introduced to the phenolic resin through in-situ polymerization and melt intercalation methods. The distribution of the organized vermiculite in the resultant materials, thermal stability and other corresponding properties were characterized. The results indicated that organized vermiculite was dispersed into PF matrices uniformly and the vermiculite layers were exfoliated fully. The flow distance and gelating time of the nanocomposites were shorter than that of the pure PF, which meet the standard of the PF used in frictional materials. Compared to the pure PF, the nanocomposites exhibited excellent thermal stability in air atmospheres. The thermal stability of nanocomposites affected by the content of interlayer water in vermiculite, interlayer spacing of vermiculite, intercalation agent style with different structure and the content of organized vermiculite.Moreover, the friction and wear performance of the brake pad based on the developed nanocomposites were also investigated. Compared to the brake pad based neat PF, the wear rate of the present one based with nanocomposites decreased obviously, especially in high temperature. Additionally, the brake pad based nanocomposites are also improved in the friction coefficient. A preferential stable friction was achieved for a brake pad based ODBA-OEVMT/PF nanocomposite, which can be served as a high performance of frictional materials.