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Intercrystalline links in polyethylene have been revealed by crystallizing from the melt mixtures of fractionated polymer and the linear hydrocarbon n‐C32H66, the latter constituent being removed later by washing at room temperature in an organic solvent. These fibrous links measure up to 15,000 A. in length and are 30–300 A. in thickness. Molecular chains are oriented parallel to the lengths of the links, and apparently nucleate on tie molecules formed by the simultaneous crystallization of different parts of the same molecule on the surfaces of different, and often widely separated, crystals. The maximum length of the links found in a given polymer varies as the square root of molecular weight, and there are indications that molecules in the melt are much more extended than is predicted by conventional configurational statistics. The links are under tension and presumably exert a significant influence on physical properties.

When operated at the current densities in excess of 10 mA/cm2 that are typical of efficient solar‐irradiated photovoltaic cells, normaln‐normalCdSe/1MNa2S‐1MS‐1MnormalNaOH/C semiconductor‐liquid junction cells deteriorate with time. In normalCdSe electrodes that have lost activity, formation of a normalCdS‐normalenriched film has been detected by means of Auger spectroscopy and electron beam‐induced luminescence. Such a layer is a barrier to the flow of holes to the surface. The rate of deterioration increases with light flux, usually decreases with stirring, and depends on the crystal face exposed to the solution. Addition of small amounts of elemental selenium to the solution substantially improves the stability by preventing excessive sulfide enrichment of the surface. For example, with 0.5M Se added, the output of <112̅0> face electrodes run at 35 mA/cm2 is essentially unchanged beyond 2×104C/cm2 charge passage.

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Difficulties previously encountered in the growth of chain‐folded single crystals of isotactic polystyrene suitable for study by electron microscopy and electron diffraction have been overcome using very poor solvents (including atactic polystyrene of low molecular weight). The hexagonal lamellar crystals produced are relatively stable under electron bombardment and, as a consequence, dark‐field moiré patterns produced by double diffraction from overlapping layers are easy to study. These patterns show no evidence of differences in lattice spacing between fold and nonfold planes such as have been reported in single crystals of several other polymers. Such differences were attributed to congestion at fold surfaces and their absence in polystyrene, for which the surface energy of fold surfaces is small, supports this interpretation. A comparison of crystallization kinetics of polystyrene crystals grown from good and from poor solvents reveals differences in growth rates of three or more orders of magnitude at comparable supercoolings. This disparity cannot be accounted for by acceptable adjustments of thermodynamic parameters in current theories of crystallization with chain folding. The role of molecular conformation in solution appears to exert an unexpectedly large influence on crystallization rate.