Synthesis and Charaterization of Polyurethane Composite Materials Derived from Hydroxy Terminated Polyepichlorohydrins

Abstract

Hydroxy terminated polyepichlorohydrins (PECH) of different molecular weights were synthesized using a novel catalyst and co-catalyst combinations. Different polymerization conditions like temperature, time and monomer addition rates exhibited pronounced effect on the molecular weight, polydispersity and functionality of the products. After optimization of the conditions, polyepichlorohydrins of three different molecular weights i.e., 1045, 2497 and 3521 daltons were selected for the preparation of their polyurethane elastomers (PUE). The DSC studies of the polyol displayed linear increase in glass transition temperature (Tg) with the increase in its molecular weight (-35.6 to -28.3 oC). In second part of the present study two series of polyurethane elastomers were prepared by prepolymer method from polyepichlorohydrins (polyols) of three different molecular weights, aromatic (TDI) and cycloaliphatic (IPDI) diisocyanates and three chain extenders (1,4-butadiol, 1,6-hexanediol and cyclohexanedimethanol). The structural elucidation of PECH and its elastomers was carried out by FT-IR and NMR spectroscopic techniques. The change in molecular weight (polyol), type of diisocyanate, nature of chain extender and amount of chain extenders engendered significant effect on the surface morphology and thermo-mechanical properties of the resulting PUEs. Aromatic diisocyanate based elastomer (P25TDIDM10) exhibited optimum UTS (8.11 MPa) and elongation at break (511.7%) whereas cycloaliphatic diisocyanate elastomer (P10IPDIDM10) showed 8.58 MPa UTS and elongation at break (511.7%). All the polyurethane elastomers were stable up to 200 °C and were degraded without melting to constant mass above 450 °C. Tg of TDI based PUE was increased to -16 oC while in IPDI series it was further shifted to 7.98 oC. In the third part of this research work, selective polyurethane elastomer P10IPDIDM10 was used, due to its superior properties, as a matrix for the synthesis of polymer based composites. Graphite, aluminium flakes and aluminium powder were used in different proportions (5-15%) as fillers in the polymer matrix composites. Incorporation of fillers enhanced the UTS with corresponding decrease in elongation at break, whereas in case of graphite, electrical properties of the composite were also improved. The present study revealed that the synthesized PUEs and composites were found promising candidates for various advanced applications.