BS ISO 3384-1:2019 pdf free.Rubber, vulcanized or thermoplastic -Determination of stress relaxation in compression.
A test piece of vulcanized or thermoplastic rubber is compressed to a constant deformation and maintained at a predetermined test temperature. The decrease in counterforce is then measured. In method A, the compression is applied and all counterforce measurements are made at the test temperature. In method B, the compression is applied and all counterforce measurements are made at a standard laboratory temperature. The test pieces are stored at the test temperature. The test can be conducted in a gaseous or a liquid environment. The two measurement methods, A and B, do not give the same values ofstress relaxation, and comparison of values obtained from the two methods should be avoided. The method selected for use depends on the purpose of the test. Thus, for fundamental studies and in applications where sealing at elevated temperatures is a problem, method A might be preferred, and in applications where temperature cycling from normal to an elevated temperature is a problem, method B might be preferred. NOTE Other methods can be used for specific purposes, such as applying the compression at standard laboratory temperature and making all counterforce measurements at a different temperature.For ring test pieces, the plates shall have holes of at least 2 mm diameter drilled through their centre portions to allow equalization of pressure and circulation of fluid inside the ring-shaped test piece. It shall be possible to connect the compression device to suitable equipment for compressing the test piece to the specified compression at the specified speed and for measuring the counterforce exerted by the compressed test piece with an accuracy of 1 % of the measured value. The device shall be capable of setting the compression and maintaining it during the whole duration of the test, and it shall be possible to keep the device in an oven at the specified test temperature. Care shall be taken to ensure that there is no loss of heat from the test piece, for example by conduction through metal parts which are connected with the outside of the oven.BS ISO 3384-1 pdf download.