The Measurement of Thermal Conductivity of Plastics at Cryogenic Temperatures — A Discussion of Contact Resistance and One’s Naiveté
A computer-controlled method that minimizes thermometric and radiation errors for the measurement of thermal conductivity of materials is presented. Initial runs with G-11 to “qualify” the apparatus brought us face to face with our naiveté when large contact resistance errors were observed. Various methods that failed to maintain good thermal contact from room to liquid-helium temperature are examined, and the solution to the problem is discussed. Thermal conductivity curves for G-10/11CR (NIST), Amodel 33% glass, Noryl SEIGFN3, and 3 types of Ultem are presented. The thermal properties of Vectra, a liquid-crystal polymer, are also mentioned because its properties are unique.
KeywordsContact Resistance Support Plate Good Thermal Contact Cryogenic Engineer Mold Flow
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