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

Abstract

This paper describes the mechanical behaviour of castor oil based semi rigid polyurethane foams with relative density below 0.05moulded by varying isocyanate index (Isocyanate equivalent/hydroxyl equivalent) from 1:1 to 1:2. Mechanical properties of polyurethane foam mainly compressive strength is measured experimentally and the values were compared using three widely referred theoretical models namely: (i) the Empirical model (ii) Gibson and Ashby approach widely used for foam description and (iii) modified Gent Thomas model. Empirical model suggested that the synthesised polyurethane foam is closed-cell foams, which have cell walls that undergo stretching and struts that undergo bending. Experiment 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.