Preparation And Characterization Of Phenolic Resin/Mineral Nanocomposites And Their Application In Friction Materials

In this paper, phenolic resin/mineral nanocomposites with excellent thermal properties were prepared with a certain proportion of nanometer and submicron barite minerals and nanometer SiO₂ that had good thermal stability as the filler and by mechano-chemical modification. The distribution of the nanometer-sized particles in the resultant materials, thermal stability and other corresponding properties were characterized. Moreover, the friction and wear performance of the brake pad based on the developed nanocomposites was also investigated. The results indicated that due to small particle size, large specific surface area, many non-paired surface atoms, and high surface chemical activity, the minerals have strong bonding with phenolic resin and have made special influence on the physicochemical properties of phenolic resin. Nanometer and submicron minerals can restrain thermal decomposition and raise the thermal decomposition temperature of phenolic resin substantially. The self-made nanometer and submicron mineral modified phenolic resin was used as the binder of the automobile frictional material. The nanocomposites meet the standard of the phenolic resin used in frictional materials. Compared to the brake pad based on phenolic resin, the wear rate of the present one with phenolic resin/mineral nanocomposite decreased obviously, especially at high temperature. In addition, the wear performance of the brake pad based on phenolic resin/mineral nanocomposites was also improved. A preferential stable friction was achieved for a brake pad based on nanocomposites, which can be used as a high performance frictional material.In this paper, different from the preparation methods of polymer/clay nanocomposites including intercalation polymerization,polymer solution-intercalation and polymer melt-intercalation, high-pressure method was used for the first time to produce phenolic resin/rectorite clay nanocomposites. In the mean time, the microstrutures of the clays and the nanocomposites were characterized by XRD, FT-IR, TEM, AFM and TGA techniques. The results show that the polymer molecules entered the interlayers of the clay under high pressure, resulting in intercalated nanocomposites under ralatively lower pressure and exfoliated nanocomposites under higher pressure. When the proportion of rectorite was 4% or 20%, nanocomposites can form under high pressure. On the other hand, without polymerization solidification reaction, the preparation of polymer/clay nanocomposites made the polymer molecules enter the interlayers of the clay under high pressure. Socomposites were still powder material, which has offered an effective way for further studies on the structure of clay layers. Because the thermal property of nanocomposites has been improved greatly, it is obvious that nanocomposites have greater thermostability. It provides possibility of application of phenolic resin in the fields of high temperature.