Physical Property Relationships and Chemical Factors Affecting Flex Fatigue Characteristics of Flexible Urethane Foam

A statistical study of the standard flex fa tigue test methods to determine variations due to method and position of foam sample is reported. The effect of preflexing was also investigated. Certain physical properties of flexible urethane foams have been shown to have a significant bearing on the flex fatigue characteristics. Correlation between hystere sis loss, indentation load deflection, density, "Sac" Factor, etc., and load loss after flexing are discussed. A simple method of predicting flex fatigue characteristics of urethane foam is described.The relationship of chemical variables in the formulation and their effect on flex fa tigue is discussed in detail.