TABLE OF CONTENTS There are many tests used to measure the properties of FPF. The most significant methods are formalised under ASTM D3574 [52] and D3453 [53] and BS EN ISO 1798 [54]. In 1994, the Polyurethane Foam Association (USA) published the Joint Industry Foam Standards and Guidelines [55] which relates the test data to foam performance and value, particularly in the furniture industry. Of course, there are many tests that are specific to a particular customer, manufacturer or application. Some of the more important tests are summarised in the next section.
Density and hardness are sometimes thought to be similar, but these are completely different properties, and surprisingly, there is only a weak relationship between them [56]. Adding water to reduce density also increases the amount of urea in the polymer which makes it harder. Many flame retardants increase density while softening the foam, and copolymer polyols will stiffen the foam without affecting density.
Density is important to the performance and economics of a foam because it measures how much of a foam is air and how much is polymer. The density is simply the mass divided by the volume and is commonly measured in kilograms per cubic meter (kg/m 3) [57]. Most conventional grades of slabstock foams range from about 12 to 40 kg/m 3. Foams with fillers, flame retardants and copolymer or polyester polyols usually have a higher density and range from 25 to 100 kg/m 3. Flexible moulded foams can be...
