Synthesis, fabrication, mechanical, electrical, and moisture absorption study of epoxy polyurethane-jute and epoxy polyurethane-jute-rice/wheat husk composites

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 135 degrees C 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 x 10(13), 1.84 x 10(13), and 1.91 X 1013 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. (C) 2007 Wiley Periodicals, Inc.