Preparation And Application Of Phenolic Resins For Friction Material Matrix Modified By Boron And Linseed Oil

In today's society, with the rapid development of science, the requirements of material performance are needed to be improved everyday in every industry field. As friction material matrix, the performance of phenolic resin is also needed to be improved. The heat resistance and the flexibility become important indicators to affect the application of phenolic resin. Therefore, it becomes an urgent problem to improve the heat resistance and flexibility.Using chemical methods, with phenol and formaldehyde as raw materials, the boron modified phenolic resin, linseed oil modified phenolic resin and boron-linseed oil bi-modified phenolic resin were prepared with hydrochloric acid, sodium hydroxide and ammonia as catalyst, respectively. Based on a large number of experiments, the optimum preparation conditions of raw material ratio, reaction temperature and time, catalyst dosage were obtained for the modified phenolic resins.The boron modified phenolic resin is prepared under the optimum conditions with mole ratio of phenol, boric acid and formaldehyde of 1:0.4:1.3. The catalysis of the reaction for phenol with boric is sodium hydroxide with mass 3% dosage of phenol at the reaction temperature of 90-100? for 2h. The reaction temperature for boric acid reaction of phenolic resin and formaldehyde is 100-110? for 3h, and the dehydration temperature is 120?for 45 min.The linseed oil modified phenolic resin is prepared under the optimum conditions with mass ratio of phenol, linseed oil and methyl benzene sulfonic acid of 1:0.5:0.01. The catalyst of the reaction for phenol with linseed oil is methyl benzene sulfonic acid at the temperature of 130-140? for 3h. The reaction of linseed oil-phenol product with formaldehyde is under the catalysis of ammonia(25%) with mole ratio of phenol and ammonia of 1:0.06 at temperature of 100-110? for 2h, and the dehydration temperature is 100? for 45 min.The boron-linseed oil bi-modified phenolic resin is prepared under the optimum conditions with mole ratio of phenol, boric acid, linseed oil, formaldehyde of 1:0.4:0.06:1.3 under the catalysis of NaOH with mass 3% dosage of phenol. The reaction temperature of phenol and boric acid is 90-100? for 2-3h. The reaction temperature of boric acid phenol grease, formaldehyde and linseed oil is 100-110? for 3h, and the dehydration temperature is 140? for 30 min.The properties of modified resins were determined by infrared spectrometer, thermal analyzer, universal tensile testing machine to investigate the modifying mechanism. The results show that the introduction of boron in modified phenolic resin molecules can generate B-O bond with high bonding energy to obtain crosslinking structure of boron, and the thermal stability of resin can be significantly improved. The flexibility performance can be improved by the introduction of linseed oil flexible long chains. The mechanical properties test of the modified phenolic resin showed that:Impact strength and tensile strength linseed oil-modified phenolic resin of the largest, respectively, than ordinary phenolic resin improved 3.9 times and 1.5 times. Hardness boron modified phenolic resin of the largest, 5.4% higher than ordinary phenolic resin.With modified phenolic resins as matrix materials, the friction materials were prepared with a certain amount of strengthening agent and fillings. The friction and wear performance was determined on the friction test machine. The results show that under 50 N load, the average friction coefficients of ordinary phenolic resin matrix friction materials, boron modified phenolic resin matrix friction materials, linseed oil modified phenolic resin matrix friction materials, and boron-linseed oil modified phenolic resin matrix friction materials are 0.421, 0.513, 0.487 and 0.513, respectively. Under 50 N load, the wear rates are 0.62x10-7, 0.49x10-7, 0.21x10-7 and 0.18x10-7cm3(N·m), respectively. The average friction coefficient and the friction stability of the modified phenolic resin matrix friction material are higher than those of ordinary phenolic resin matrix friction materials, and the wear rate is low.