Bisphenol-C-formaldehyde-toluene-2,4-di isocyanate polyurethane (PU) has been synthesized at room temperature and used for the fabrication of jute and jute-rice husk/wheat husk hybrid composites. PU-jute and PU-jute-RH/WH composites were prepared under pressure of 30.4 MPa at room temperature for 8 h, while PU-jute-RH/WH composites were prepared under same pressure at 110°C for 5 h. PU-jute composite has good tensile strength and flexural strength (50 -53 MPa), while PU-jute-RH/WH hybrid composites have moderate tensile strength (9 -11 MPa) and a fairly good flexural strength (15-31 MPa). Composites possess 1.1-2.2 kV electric strength and 0.94 -1.26 ϫ 10 12 ohm cm volume resistivity. Water absorption in PU-jute composite is different in water (9.75%), 10% HCl (12.14%), and 10% NaCl (6.05%). Equilibrium water uptake time in salt environment is observed 96 h, while in pure water and acidic environments it is 192 h. In boiling water equilibrium water content and equilibrium time are found to be 21.7% and 3 h, respectively. Water absorption increased 2.2 times in boiling water, whereas equilibrium time reduced 64 times. Thus, PU-jute composite has excellent hydrolytic stability against boiling water, 10% HCl, and 10% NaCl solutions. Fairly good mechanical and electrical properties and excellent hydrolytic stability of composites signify their usefulness for low cost housing units and in electrical and marine industries.

Bisphenol-C-epoxy-toluene diisocyanate polyurethane (PEBCT) has been synthesized and used for the fabrication of jute, jute-rice husk (JRH), and jute-wheat husk (JWH) composites. The composites have been fabricated by hand lay-up technique under a hydraulic pressure of 30.4 MPa at 1358C for 2.5 h. PEBCT-J, PEBCT-JRH, and PEBCT-JWH possess respectively, tensile strength of 37.4, 9.5, and 14.7 MPa, and flexural strength of 39.6, 12.9, and 21.3 MPa, electric strength of 1.3, 1.8, and 1.9 kV/mm and volume resistivity of 1.40 Â 10 13 , 1.84 Â 10 13 , and 1.91 Â 10 13 ohm cm. Tensile strength and flexural strength have decreased, while electric strength and volume resistivity are improved upon hybridization. PEBCT-JWH has better interfacial bond strength and stiffness as compared to PEBCT-JRH. Moisture uptake behavior of PEBCT-J in water, 10% HCl and 10% NaCl at room temperature is quite different. Equilibrium moisture content of PEBCT-J in 10% NaCl (5.5%) is almost half of those in water (11.3%) and 10% HCl (13.6%) environments. Equilibrium time for saline environment is also comparatively low. Equilibrium moisture uptake in boiling water has increased 1.84 times, while equilibrium time has decreased 15.3 times. The composites may be useful for low load bearing in construction industries and for marine applications.

Polyester polyols of epoxy resins of bisphenol-A and bisphenol-C were synthesized by reacting corresponding 0.02 mol epoxy resin, and 0.04 mol ricinoleic acid by using 1,4-dioxane (30 ml) as a solvent and 0.5 g triethyl amine as a catalyst at reflux temperature for 4-5 hr. Polyurethanes have been synthesized by reacting 0.0029 mol of polyester polyols with 0.004 mol toluene diisocyanate at room temperature and their films were cast from solutions. The formation of polyester polyols and their polyurethanes are supported by IR spectral data (1732.9-1730.0 cm À1 ester and urethane and 3440.8-3419.6 cm À1 OH and NH str). The densities of polyurethane of bisphenol-A (PU-A) and polyurethane of bisphenol-C (PU-C) were determined by a floatation method. The observed densities of PU-A and PU-C are 1.2190 and 1.2308 g/cm 3 , respectively. Slightly high density of PU-C is due to structural dissimilarity of two bisphenols. The tensile strength, electric strength, and volume resistivity of PU-A and PU-C are 34.7, 18.7 MPa; 80.7, 44.4 kv/mm; and 1.7 3 10 15 , 2.2 3 10 15 ohm cm, respectively. PU-A and PU-C are thermally stable up to about 182-187 C and followed three step degradation. Incorporation of cyclohexyl cardo group in polyurethane chain did not impart any change in thermal properties but it caused drastic reduction in tensile and electric strength due to rigid nature of PU-C chains. PU-C has excellent chemical resistance over PU-A. Both polyurethanes possess good resistance against water, 10% each of aqueous acids (HCl, HNO 3 , and H 2 SO 4 ), alkalis (NaOH and KOH) and NaCl. Good thermo-mechanical, excellent electrical properties, and good chemical resistance of polyurethanes signify their usefulness in coating and adhesive, electrical and electronic industries.