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(1)聚己內醯胺試樣在85％甲酸溶液中加水分級沉澱,得到分子量不同的級份,經羧基滴定,並於40％硫酸溶液中,在25°時测定粘度,得到下面的特性粘數分子量關係式: [η]=5.92×10~(-4) M~(0.686)或 [η]=2.44×10~(-5) M+0.080濃度單位是克/分升,分子量範圍是3000-13000。 (2)聚己內醯胺的40％硫酸溶液的粘度數據,試用了三種外推公式: lnη_r/c=[η]-β[η]~(2)c (1) η_(sp)/c=[η]+k′[η]~(2)c (2) logη_(sp)/c=log[η]+k[η]c (3) 用式(1)和式(3)得到的[η]值相同,式(2)得到的略小1-2％。β和k′值隨分子量的减小而顯著地增大,這和一般的高聚物——溶劑體系的行為相反。當高分子與溶劑分子間的氫鍵作用是高聚物溶解的主要因素時,用k′值來做溶劑能力的估計,是完全沒有意義的。 (3) 聚己內醯胺在40％硫酸裏,溶液粘度的切變速度依賴性是可以忽略的。我們認為40％硫酸是測定聚己內醯胺的粘均分子量的最合適溶劑。 (4) 從粘度數據依照Debye和Bueche的特性粘數理論,算出聚己內醯胺分子在40％硫酸裏的等效Stokes半徑,說明聚己內醯胺分子在40％硫酸溶液裏的形態,可以看作是無規則的線團。
(1) polycaprolactam samples in 85% formic acid solution by water-level precipitation, to obtain different molecular weight fractions, the titration of the carboxyl group, and in 40% sulfuric acid solution, the viscosity was measured at 25 ° to obtain the following properties Viscosity number molecular weight relationship: [η] = 5.92 × 10 ~ (-4) M ~ (0.686) or [η] = 2.44 × 10 -5 M + 0.080 Concentration unit is g / 3000-13000. (2) Viscosity data of polycaprolactam in 40% sulfuric acid solution were tested using three extrapolation formulas: ηη (η) = [η] + k ’[η] ~ (2) logη_ (sp) / c = log [η] + k [η] c (3) The value of [η] is the same, and the formula (2) is slightly smaller than 1-2%. The β and k ’values increase significantly with decreasing molecular weight, in contrast to the general polymer-solvent system behavior. When the hydrogen bonding between a polymer and a solvent molecule is a major factor in the dissolution of the polymer, it is totally pointless to use the k ’value to estimate the solvent capacity. (3) polycaprolactam In 40% sulfuric acid, the solution viscosity shear rate dependence is negligible. We consider 40% sulfuric acid as the most suitable solvent for determining the viscosity average molecular weight of polycaprolactam. (4) Calculate the equivalent Stokes radius of polycaprolactam molecule in 40% sulfuric acid according to the intrinsic viscosity theory of Debye and Bueche from the viscosity data, indicating the morphology of polycaprolactam molecule in 40% sulfuric acid solution, Can be seen as a random coil.