Studies on Modelling of Mechanical Properties of Polyester-based Semi-rigid Polyurethane Foams

This study describes the mechanical behaviourof castor oil based semi-rigid polyurethane foams with relative density below 0.05, moulded by varying isocyanate index (Isocyanate equivalent/hydroxyl equivalent) from 1:1 to 1:2. Mechanical properties of polyurethane foam, mainly compressive strength,were measured experimentally and the values were compared using three widely referred theoretical models namely: (i) the Empirical model (ii) Gibson and Ashby approachwidely used for foam description and (iii) modified Gent Thomas model. Empirical model suggested that the synthesised polyurethane foam is closed-cell foam, which has cell walls that undergo stretching and struts that undergo bending. Experimental values showed variation from Gibson and Ashby model and Gent Thomas model, since both these models are based on the deformation of a simple cubic or rectangular structure, which is not representative of a real foam structure.