How to test the properties of raw materials?
Tensile Test – This test is performed to check the resistance of rubber against the outward force. When an external load is applied, depending upon the stretch ability of the sample, it ruptures at a certain point. To estimate the tensile strength, a tensile tester is used for this purpose. A dumb-bell shaped rubber sample is cut using a die, this sample is fixed in the vice grips attached to the movable plate.
The plate moves in an upward direction until sample fails. The force applied is displayed on the screen.
Environmental test – tyre are manufactured keeping different environmental conditions in mind. The sample should be able to withstand high and low temperature, humidity, UV, rain, and ozone exposure. Rubber tend to contract when used in low temperatures. This contraction may lead to rupture of the sample when bend. Rubber tyre are wrapped around the metal rim, upon contraction, they may exhibit cracks or may break. To avoid this, rubber samples are tested in the deep freezer and tested further to analyse any failure of the sample.
Similarly, for high temperatures, hot air oven is used. The sample is exposed to hot air of temperature up to 250°C. Further analysis is done to check the behaviour of sample.
The content left behind in crucible bowl is the remaining ash. The bowl is taken and weighed again. The difference in weight before and after the test is the weight of the sample.