Miscibility of a series of nylons-6, with poly(hexamethylene isophthalamide), abbreviated 61 nylon, was investigated. Four polyamides (nylon-6,5, nylon-6,7, nylon-6,8, and nylon-6,9) were found miscible, on a DSC scale, with 61 nylon. A series of nylon-, which had the same number of CHs groups as nylon-6,7 was also studied; no miscible blend with 61 nylon was found. This was taken as direct evidence of the importance of average interamide distances for miscibility. Negative deviations from linearity in Tg-composition behavior of the blend are proposed to stem from conformational changes leading to weaker van der Waals interactions. These weak interactions are counterbalanced, in terms of energy, either by more ordered hydrogen bond networks or by entropy effects. For nylon-6,8/61 nylon blend, an S-shaped curve was observed, which is attributed to the occurrence of variations of chain morphologies with blend composition.

Summary. Using a new mathematical treatment, the nature and stability constants of the simple and mixed complex-species of copper(I1) with hydroxyde and ammonia as ligands have been determined. The solubility curves of CuO in heterogeneous equilibrium have been identified in function of pH only and in function of pH and pNH,,,, a t 25 "C and unit ionic strength (NaClO,).The predominent species in the relatively dilute system limited by the ionic strength are [Cu2+]

No abstract

From the solubility of precipitated Co(OH)2 (s) determined radiometrically as a function of pH and ammonia content of the heterogeneous systems, the formation constants have been obtained for the following mononuclear hydroxo‐, ammine‐ and mixed hydroxo‐ammine‐complexes: Co(OH)2, Co(OH)3−, Co(NH3)22+, Co(NH3)32+, Co(NH3)42+ and Co(OH)2 (NH3)2. The solubility of cobalt(II) hydroxide has also been calculated. The medium was 1M NaClO4 and the temperature 25° C.