Deflection of Plastic Beams at Elevated Temperatures

The objective of this investigation was to study the behaviour of plastics exposed to elevated temperatures. Tests were conducted measuring the deflection of Polypropylene and Acrylic rods subjected to three point bending while being exposed to either 150, 200, 250, 300, or 350°F. Rods with three different diameters were tested. For each rod a failure deflection was defined and the time required to reach this failure was measured. In addi tion the temperatures at the centers of 1 inch diameter rods were recorded. The latter data were used to determine the thermal diffusivities of the plastics. Data are presented show ing the failure times as functions of load and exposure temperature. The results are given in terms of dimensionless parameters so that they can be applied to geometries, materials, and temperatures not covered in the present tests.