SYNTHESIS OF POLYURETHANE FROM CASHEW NUT SHELL LIQUID (CNSL), A RENEWABLE RESOURCE

A novel thermoplastic polyurethane was prepared from cardanol, a renew able resource and a waste of the cashew industry. Cardanol was recover ed from cashew nut shell liquid (CNSL) by double vacuum distillation. It was characterized by CHN analysis and IR, H-1-NMR, and C-13-NMR spe ctroscopy techniques. Cardanol is a meta-substituted long chain phenol . The long aliphatic chain unit substituent was found to be a monoene. The monomer, 4-[(4-hydroxy-2-pentadecenylphenyl)diazenyl] phenol was prepared from cardanol. It was a dihydroxy compound as characterized b y CHN analyzer, UV, and 1H-NMR spectroscopy. The polyurethane was synt hesized from this dihydroxy compound by the treatment with 4,4'-diphen ylmethane diisocyanate (MDI) in dimethylformamide (DMF) solvent at 80- 90 degrees C under nitrogen atmosphere. The polymer was characterized by 1H-NMR, FTIR, and UV spectroscopy. The elemental analysis was done for determining the percentage content of C, H, and N, and the intrins ic viscosity [eta] Of polymer showed 1.85 dL/gm. Thermogravimetric inv estigations (TGA) of the cardanol, the dihydroxy compound, and the pol yurethane were performed to study their decomposition. The semicrystal line nature of the PU was confirmed by differential scanning calorimet ry (DSC) and dynamic mechanical thermal analyzer (DMTA). The wide-angl e X-ray diffraction (WAXS) study of PU shew a broad amorphous halo ind icative of absence of crystallinity in the polymer, which has been exp lained as due to strong hydrogen bonding in the hard phase. PU may pos sibly be useful as a telecommunication and as a nonlinear optical mate rial. (C) 1998 John Wiley & Sons, Inc.