Foam Properties and Testing Methods

Foam Properties and Testing Methods. In general, most physical properties of foams, both flexible and rigid, are proportional to the foam density. Therefore, at all times, the first physical property to be determined is foam density. Foam density can be calculated fi om the following equation  

Representative test methods of flexible foam properties, as defined by the ASTM D-3574 are density, IFD (indentation force deflection), CFD (compression force deflection), sag factor, compression set, tensile and tear strengths, elongation, resilience, dry-heat aging and steam autoclave aging. 

Flame retardance is another important property and is defined by different test methods. Some of the small-scale methods include horizontal flame spread (FMVSS 302, ASTM D-1692) vertical flammability (ASTM D-3014, so-called Butler Chimney Test), limiting oxygen index (ASTM D-2863), and smoke density (ASTM D-2840). 

Very recently, stricter regulations in flame-retardant seatings for furniture have been issued. Representative testing methods are California Technical Bulletins 117 and 133, Boston Fire Department Chair Test, BS 5852 Part I and Part 2. 

Sag factor (or comfort factor or support factor) is the ratio of the 65% compression force divided by the 25% compression force, and is used for evaluating cushioning ability. The sag factors of three kinds of flexible foams are shown below  

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