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An impor- tant principle of behavior in plastic materials and in many other types of materials is that as strength and stiffness increase, ductility decreases. In a tensile test, the property of elongation at break, or ultimate elongation, is considered to be a relative measure of ductility. While Fig. 1 does not show the full scale of the tensile tests, it was observed that at the slowest crosshead speed of 5 mm/min the ultimate elongation was more than 300%, while at 50 mm/min the value at rupture was 125%, and at 500 mm/min it was reduced further to 30%. increase. The material appears to be stronger and stiffer simply due to the increase in strain rate, an effect that can also be achieved by keeping the strain rate constant and incrementally reducing the test temperature. FIG 2 This shows a rapid increase in load in a period of about 3 millisec. As soon as the test achieves a maximum value, the load drops off very quickly, signaling the occurrence of a brittle failure. Impact Test Result on PVC at High Velocity Here, the load builds up more gradually, partly due to the lower speed of the initial impact. Compared with the high-velocity test, when the peak load is reached the material does not fail immediately but continues to manage the energy of the event. FIG 3 4.0 3.0 2.0 1.0 0.0 -1.0 4.0 3.0 2.0 1.0 0.0 -1.0 35.0 28.0 21.0 14.0 7.0 0.0 35.0 28.0 21.0 14.0 7.0 0.0 -3.0 -1.5 0.0 1.5 3.0 4.5 -10.0 0.0 10.0 20.0 30.0 40.0 Load, kN Load, kN Energy, J Energy, J Time, msec Time, msec Impact Test Result on PVC at a Lower Velocity AUGUST 2016 28 Plastics Technology PTonline.com K now How