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SynopsisThe conductivity of dry poly(hexamethy1ene adipamide) (nylon 66) was measured as a function of time and temperature. Three temperature ranges were observed in which the time dependence of conductivity differed: (a) below 8OOC. the conductivity decreased continuously with time; ( b ) between 80°C. and 110'C. the conductivity remained constant over long periods; (c) above 120°C. a continuous decrease in conductivity was again observed. In other experiments the volume of gas evolved from the nylon film was measured under continuous potential and compared with the total current passed through the sample. It was observed that above 120°C. the gas evolved corresponded to about one-half the volume calculated if the conduction process involved only protons. Below 120°C. the gas evolved corresponded to an increasingly small fraction of the total current until below 90°C. no evolution of gas was observed. This suggests that at temperatures above 120°C. conduction involves the transport of both protons and electrons, whereas a t lower temperatures it is electronic. Mechanisms of conduction are discussed.

It has been possible in favorable cases to measure the intensities of the infrared bands of CO adsorbed on different ZnO an? .supp.orted Cu, CuO, and Pt catalyst surfaces. For weak, reversible adsorption at room te~perat?-re, gtvmg nse to the bands in the frequency region 2132-2212 em-I, a unique correlation between mtenslty and frequency was found which apparently holds for a number of chemically different substrates. Values for both gaseous and dissolved CO fit the correlation reasonably well. A tentative explanation in terms of small perturbations of the dipole moment of CO(£) was advanced. Measurements in the metal carbonyl region were complicated by the formation of multiple-surface species and volatile products [Ni(CO)4].

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A null-reading quartz spring microbalance is described which has been designed to measure the weight of gas adsorbed on thin pressed wafers suitable for infrared transmission studies. Its operation, calibration, and precision are discussed and special reference is made to the determination of integrated intensities of the infrared absorption bands of surface species.

The electrical conductivity of doubly oriented nylon 66 has been studied as a function of direction over the temperature range 23–150°C. Measurements were made (a) along the chain axes, (b) along the hydrogen‐bonded planes perpendicular to the chain axes, and (c) perpendicular to the hydrogen‐bonded planes. A complicated dependence of conductivity on pretreatment was found. In general the conductivity over the whole temperature range was anisotropic, being least along the chain axes and, after a number of thermal cycles, greatest along the hydrogen‐bonded planes perpendicular to the chain axes. Below 120°C. the activation energy of conductivity was also anisotropic. At temperatures higher than 120°C. the temperature dependence is isotropic. The anisotropy of the activation energy and conductivity are explained in terms of activated mobility and structural parameters. Water vapor had a pronounced effect on the conductivity. It lowered the activation energy of conductivity while increasing the overall conductivity in an anisotropic manner. The conductivity along the chain axes was again less than that parallel and perpendicular to the hydrogen‐bonded planes. The activation energy of conductivity along the chain axes was equal to that parallel to the hydrogen‐bonded planes. The increase in conductivity caused by the adsorption of water was greatest along the chain axes. Four factors may contribute to the observed effects: (a) increased dielectric constant, (b) increased carrier concentration, (c) increased charge carrier path length, and (d) plasticization.