No abstract

Many of the outstanding physical properties that characterize elastomeric Polyurethans have been realized in a soluble, thermoplastic variety, Polyurethan VC, which displays the superficial properties of a rubbery vulcanizate at room temperature and so is considered to be virtually crosslinked. High tensile strength as well as good tear, abrasion, solvent, oil, and ozone resistance characterizes this polymer. Since these properties are realized in the unvulcanized state, many useful applications of the readily processable polymer can be made, avoiding the complications which attend the use of conventional (vulcanizing) urethan elastomers. Outdoor exposure and indoor accelerated weathering studies demonstrated a deficiency in the weather resistance of the raw polymer. Weather-induced changes, believed to be due to ultraviolet-initiated autoxidation, have been estimated by noting changes in the stress-strain properties as well as the ultraviolet and infrared absorption spectra of the polymer on exposure to natural and artificial weather conditions. The beneficial effects of certain carbon blacks, conventional antioxidants, and ultraviolet absorbers on the weather resistance of the polymer have been described.

No abstract

The line source technique for determination of thermal conductivity has been modified to allow measurement to higher temperatures than previously attained. This required the addition of a high-temperature tube furnace to the standard experimental equipment. The modified device was used to measure the temperature-dependent thermal conductivities of a glassand talc-filled phenol-formaldehyde(pheno1ic) resin and a glass-and fiberglass-filled acrylonitrile-butadiene (AB) copolymer. Thermal conductivities of the virgin material were measured from room temperature to the onset of thermal decomposition. The char material thermal conductivities were measured from room temperature to approximately 900°C. A least-squares fit of the data yielded a linear-curve fit for the virgin material and a third-order fit for the char material.

The line source technique for determination of thermal conductivity has been modified to allow measurement to higher temperatures than previously attained. This required the addition of a high‐temperature tube furnace to the standard experimental equipment. The modified device was used to measure the temperature‐dependent thermal conductivities of a glass‐ and talc‐filled phenol‐formaldehyde(phenolic) resin and a glass‐ and fiberglass‐filled acrylonitrile‐butadiene (AB) copolymer. Thermal conductivities of the virgin material were measured from room temperature to the onset of thermal decomposition. The char material thermal conductivities were measured from room temperature to approximately 900°C. A least‐squares fit of the data yielded a linear‐curve fit for the virgin material and a third‐order fit for the char material.