On the viscometry of poly‐6‐caproamide

In the viscometric evaluation of poly-6-caproamide (6-PA), the following effects were studied in detail: influence of water in tricresol, influence of molecular weight, and influence of temperature. The water present in the tricresol lowers the measured value of [η] proportionately to the water content. The value of K in the Huggins equation ηsp/c = [η] + K[η]2C remains constant within the limits of experimental errors. The value of K in the Huggins equation was found to be influenced significantly by molecular weight. For low values of [η], the constant K increases manyfold. The constant K was, therefore, replaced by a function which takes account of the increase of K due to the molecular weight: where K1 = 0.26, K2 = 285.5, and x = 1.48. At higher temperatures, the measured value of [η] decreases, and the constant K in the Huggins equation remains constant within the limits of experimental error. The following equation was used to give the dependence of the viscosity of 6-PA on temperature: where the constant a is independent of [η], while b is a function of [η].