EFFECT OF CONCENTRATION VARIATION OF HYDROXYL AND ISOCYANATE MOIETIES ON MECHANICAL PROPERTIES OF FLY ASH REINFORCED POLYURETHANE COMPOSITES AT CONSTANT INDEX RATIO

Abstract

Polyurethane (PU) based foams/composites shows versatile utility and are designed as per the end use by varying Index ratio (IR; NCO/OH), or the filler functionalities or its concentration thereof. The present research work focuses on the study of extent of polymerization of PU system by varying the weight ratios of binary components of cross linking agents (Tepanol and castor oil) in their homogenous mixture and is found to be independent of their weight ratios but depends on the weight of homogenous mixture of cross linking agents, as revealed by the SEM images of fly ash reinforced polyurethane composites. Variations in mechanical properties of PU foam/composites can be studied by varying IR. In present study, fly ash reinforced polyurethane composites designed at IR 1.1 keeping higher concentration of curing agent (2,4- Toluene diisocyanate) shows better mechanical properties (TS;26MPa 8 YM;13GPa) compared to, when binder (polyethylene glycol-600,) concentration was decreased at constant IR i.e 1.1 (TS;13MPa 8 YM;6.5GPa) or lowering the concentration of cross linking agents (TS;11MPa 8 YM5.5GPa) at same IR i.e 1.1. The study also reveals that composites designed at IR0.9 shows better mechanical properties (TS;22MPa 8 YM;11GPa) at higher concentration of cross linking agents as compared to composites designed at same IR but with higher concentration of binder (TS;10MPa 8 YM;5GPa) or lower concentration of curing agent (TS;8MPa 8YM;4GPa).