This International Standard specifies a method for the deter-mination of the compression stress-strain properties of vulcanized or thermoplastic rubber, using a specified test piece. Two procedures are given:
— A: With the metal plates, through which the com-pressive force is applied, lubricated.
— B: With the metal plates, through which the com-pressive force is applied, bonded to the test piece.
The two procedures do not give the same results. With lubricated test pieces, the results are dependent only on the modulus of the rubber and are independent of the test piece shape, provided that complete slip conditions are achieved. Ef-fective lubrication is sometimes difficult to achieve and it is pru-dent to inspect the variance in the test results from replicate test pieces for indications of erratic slip conditions. With bonded test pieces, the results are dependent on both the modulus of the rubber and the test piece shape. The dependence on test piece shape is strong and consequently the results will be markedly different from those obtained with lubricated test pieces.
Provision is made for the use of test pieces of different size and/or shape from the specified test piece but extrapolation of the results obtained to other sizes and shapes may not be poss-ible.
Guidance on the effect of size and shape of test piece and of bonding or lubricating is given in annex A.
The method is not suitable for materials that exhibit high set.
SIS SS-ISO 7743:1992 history
1992SIS SS-ISO 7743:1992 Rubber, vulcanized or thermoplastic — Determination of compression stress-strain properties