Cashewnut shell liquid: Characterization and studies of PVC degradation in solution

Abstract

AbstractCashewnut shell liquid (CNSL), which is basically a mixture of several alkyl substituted phenols was characterized using 1H and 13C‐NMR, FT‐IR, and mass spectroscopic techniques. The major constituent was found to be cardanol having one, two, or three double bonds in the alkyl side chain. Presence of one hydroxy group was confirmed by acetylation and 1H‐NMR studies. Distillation of CNSL under atmospheric conditions resulted in partial oxidation of the side chain. Such an oxidation was confirmed by elemental analysis and FT‐IR studies. Thermal degradation of poly(vinyl chloride) (PVC) in CNSL was studied in nitrogen atmosphere in the temperature range of 180–220°C. Rate of dehydrochlorination of PVC was found to be lower in CNSL in comparison to the degradation in ethyl benzoate. An induction period ranging from 23 min to 55 min was observed in CNSL and was found to depend on the concentration of PVC in solution and temperature of dehydrochlorination. Activation energy for dehydrochlorination of PVC in CNSL was found to be 43 ± kcal/mol. Compatibility studies of PVC in CNSL were done using differential scanning calorimetry (DSC). Good plasticization was observed by blending PVC up to 10% of CNSL. Overall thermal stability of PVC was not altered by the presence of CNSL in these low concentrations.