Today's KNOWLEDGE Share : CNSL for Brake Pads

Today's KNOWLEDGE Share

Development of Refined Natural Resin based Cashew Nut Shell Oil Liquid (CNSL) for Brake Pads Composite

Development the composite-based brake pads aim to reduce the damage of train wheels and sparks during braking continually. Cashew Nut Shell Liquid (CNSL) is an oil composed from a complex phenolic compounds with long carbon chain branched and unsaturated. CNSL extraction that's done using hot water, which is then dried to remove water from the extract of physical separation by centrifugation.The main structure CNSL is 90% anarcadic acid and 10% cardol, but in detail components in the CNSL separated will depend on the treatment path will be executed.

The increase in the levels of cardanol done through extraction using semi-polar and non-polar solvent. Raw CNSL has a high relative density because it has anarcadic acid as the major fraction, there is intermolecular attraction between the electronegative oxygen atom and the partially positive hydrogen atom of the phenol core as a result the molecules are closely packed together. The structure of anacardic acid, cardol, cardanol and 2-methyl-cardol were founded in crude CNSL. CNSL compound was added as a resilience in the binder system and reduces brake noise. 

FTIR analysis of technical CNSL and decarboxylated CNSL result were shown. Infrared spectra absorption were in the regions of 3424 cm-1, 2700-2900 cm-1, 1615 cm-1, 1200-1600 cm-1, and 500-700 cm-1 representing as -OH hydroxyl, C-H stretching, C-O, C=C aromatic stretching, and aromatic ring respectively. The presence of –OH hydroxyl has a role as a reactive group which will react with other components of composite material, so that CNSL can be used as an alternative of phenolic resin. But, raw CNSL still content impurities so that needed decarboxilation procedure to remove the impurities.

Simulant Thermal Analysis (STA) for the determination of thermal resistance of materials. Based on thermal analysis using STA indicated that the CNSL has high stability in temperature under 400 ºC, proved by the small decrease of its mass in the temperature range of 0 - 350 ºC. Nevertheless, when the temperature up to 400 ºC, the more mass loss because of the decomposition of the CNSL coumpound.

Cashew nut shell liquid (CNSL) have been used as a substituent of phenolic resin. The CNSL compound of cardanol, acid cardanol and cardol can act as a binder in the brake pads composite preparation due to the functional group in their compound. Infrared test showed the presence of hydroxyl groups belong Cardanol. The CNSL has high stability in temperature under 400 ºC, proved by the small decrease of its mass in the temperature range of 0 - 350 ºC. The addition of CNSL resin also improve mechanical properties of brake pads composites proven by higher tensile strenght, elongation and excellent pressure strength of formula 2, 900 N, 2,59 MPa and 20.000 N respectively.

source: S Wahyuningsih et al 2017 IOP Conf.