ASTM D638 is used to generate Plastics Tensile Testing data including tensile strength, tensile modulus, and elongation for reinforced and unreinforced plastics. The generated data gives an idea of the force required to rupture a plastic component and the extent to which a plastic can be elongated.
Plastic Tensile Testing by ASTM D638 is done to calculate different tensile properties such as tensile strength, breaking strength, maximum elongation of reinforced and unreinforced plastics. The standard test samples are made in the form of dumbbell-shaped. The samples are tested under defined conditions of pretreatment, temperature, humidity, and testing machine speed. This test is used for measuring the force that is required to rupture a plastic sample and also helps to determine the extent to which the sample elongates to that of the breaking point.
For the ASTM D638 test, samples are mounted in the universal tester. Samples are placed in the tester in such a way that grips of the tester are at a specified grip separation and pulled until failure. The test speed of the material is determined as specified by ASTM D638. The elongation and tensile modulus are determined by the extensometer.
Elevated or reduced temperature test procedure:
The Universal Test machine is equipped with a thermal chamber. This chamber allows traveling across the top and bottom of the chamber on the foundation and the crosshead of the Universal Tester. Inside the chamber, standard measurement devices are mounted and the thermal monitored atmosphere is tested in the same way as it is at ambient temperature. The chamber has internal electric heaters to maintain high temperatures and external carbon dioxide is used as the coolant to lower temperatures. The ultimate elongation that is possible is limited by the size of the chamber. The extensometers here are usually limited to 200 °C or more.
The most common sample for ASTM D638 is a Type I tensile bar.