The low-temperature thermal conductivity of a polyoxymethylene ’’crystal’’

The thermal conductivity κ of a polyoxymethylene (POM) ’’crystal’’ has been measured both parallel and perpendicular to the direction of fibers between 1.5 and 100 K. In the fiber direction κ∥ is very much less than might be expected from a single crystal but is instead very similar throughout the temperature range to the conductivity of extruded POM. Perpendicular to the fibers κ⊥ is rather less than in extruded material, particularly at the lowest temperatures where, even for polymers, the conductivity is unusually small. These observations lead to deductions about the specimen morphology that are substantiated by experiments involving x-ray diffraction.