How to do rubber tensile test?

When stretching the rubber specimen, the universal testing machine can automatically draw the tensile stress-strain curve of the rubber. The initial stage of the curve in the figure will be a curved line, which is caused by the sliding of the sample head in the fixture and the gap in the testing machine. During the analysis, the straight line segment in the figure should be extended and the abscissa to intersect at point O as the origin of its coordinates. The stretching of rubber has only the elastic stage. The tensile curve can intuitively and more accurately reflect the deformation characteristics of the rubber when it is stretched and the relationship between the force and the deformation. When the rubber is stretched, it basically satisfies Hooke's law, and it is roughly a straight line on the stress-strain curve, so the elastic modulus E can be represented by the slope tanα of this straight line. In order to calculate the value of the elastic modulus more accurately, Matlab can be used to fit the data within the proportional limit with a straight line, and the slope of the fitted straight line can be obtained, which is the value of the elastic modulus.