This International Standard specifies a method of determining the behaviour of rigid cellular plastics materials when they are subjected to a tensile stress. It applies primarily to cellular materials having a compression resistance sufficient to permit suitable gripping of the test specimens. If it is impossible to grip the test specimen, the method is modified so that the ends of the specimen are reinforced with metal plates (see Clause 8). The relationship between cell size and test specimen size must be such that the test is realistic.