Load-deflection diagram. Plot of load vs corresponding deflection.

Loss factor. Ratio of the real and imaginary components of complex modulus. Term is used in connection with dynamic tests to determine damping capacity of materials and combinations of materials. An alternate term is loss tangent.

Loss modulus. Imaginary component of complex modulus. It takes into account mechanical energy dissipated as heat during deformation of a material under dynamic loading.

Loss tangent. An alternate term for loss factor.

Low temperature brittleness test. A method for measuring the resistance of rubbers and rubber-like materials to brittle cracking at low temperatures. Specimens are exposed to a specified temperature for 4 hr and flexed. Results are reported as failure or non-failure at specified temperatures. (ASTM D-736).

Low temperature compression set. Measure of the ability of vulcanized rubber loaded at room temperature and subsequently subjected to prolonged exposure at low temperatures to recover from deformation at the low temperature. It is the % compressive deformation retained by a specimen subjected to the standard test set out in ASTM D-1229. The test simulates conditions encountered by seal and gasket materials used in aircraft and submarines.

Low temperature stiffening. Measure of the effect of temperature change on the stiffness of rubber and rubber like materials. It is usually reported as the temperature at which a material has a specified relative modulus. (ASTM D-1063). See also Gehman torsional test.