论文部分内容阅读
作者用毛細管粘度計,在外加水柱壓力下,測定了聚甲基丙烯酸甲酯的四個經分級的試樣(M=4×10～5-5×10～6)和一個未經分級的試樣(M=5×10～6)在25°時苯溶液粘度的切變速度依賴性。在毛細管管壁的切變速度D_R,變化在500-8000秒～(-1) 的範圍內。對實驗數據首先試用了冪函數形式的流變函數來處理,除M=4×10～5的一個試樣外,溶液粘度都有切變速度依賴性。作者也依照Weisenberg的方法,從實驗數據作出了流變曲線。同時把非Newton溶液對Newton溶劑的相對粘度(η_r)′(在毛細管管壁切變應力S_R下)下定義為:(η_r)′=D_R(溶劑)/D_R(溶液)這樣得到的(η_r)′,除M=1.5×10～(-6)的一個試樣外,In(η_r)′可向D_R→0作線性外推外。對其他數據來說,這樣的外推都是不可能的,因為在D_R值愈小時,離線性的偏差愈大。有切變速度依賴性的高分子溶液,可以有二種方式來給特性粘數下定義:(1)在給定D_R值時,(?);(2) 在給定S_R值時,[η]_S=。祇有Newton液體,以這二種不同方式定義的特性粘數是等值的。作者得到的實驗數據在給定D_R值時,In(η_r)′/C對C的圖,線性是好的;但((η_r)′-1)/C對C的圖是彎曲的。在給定S_R值時,ln(η_r)′/C或((η_r)′-1)/C對C的圖都呈線性, 而且其外推值相同。[η]_D和[η]_S都隨D_R或S_R的增加而減少,向D_R→0或S_R→0的外推,都是不可能的;因為在低D_R或S_R值時,變化更大。根據這些結果,我們建議用D_R=3000秒～(-1)時的[η]_(D=3000) 或用S_R=25達因/厘米～2時的[η]_(S=25)來做粘度平均分子量的量度。在應用[η]_(S=25) 的數據時,假若用t_r=t/t_0。來代替(η_r)′(t_r與(η_r)′在溶液的非Newton程度不大時,相差很小),那末祇要在一個給定外加壓力下測定,可以達到快捷的要求。
The authors used a capillary viscometer to measure four graded samples of polymethylmethacrylate (M = 4x10-5-5x10-6) and an unscreened test at an applied water column pressure The shear rate dependence of the viscosity of the benzene solution at 25 ° (M = 5 × 10 ~ 6). The shear rate D_R at the capillary wall changes within the range of 500-8000 seconds -1. The experimental data first tried the rheological function of the power function to deal with, in addition to a sample of M = 4 × 10 ~ 5, the solution viscosity shear rate dependence. According to Weisenberg’s method, the authors also made rheological curves from the experimental data. The relative viscosity (η_r) ’of the non Newtonian solution to Newton’s solvent (under capillary shear stress S_R) is defined as: (η_r)’ = D_R (solvent) / D_R (solution) In addition to a sample of M = 1.5 × 10 -6, In (η_r) ’can be linearly extrapolated to D_R → 0. For other data, such extrapolations are not possible because the smaller the D_R value, the greater the deviation from the linearity. There are two ways to define the intrinsic viscosity: (1) at a given D_R value (?); (2) at a given S_R value, [η ] _S =. With Newton’s liquid, the intrinsic viscosities defined in these two different ways are equivalent. The experimental data obtained by the author is good for the plot of In (η_r) ’/ C for plot C given a value of D_R; however, plot of (η_r) -1 - / C for plot C is curved. Given a S_R value, either ln (η_r) ’/ C or ((η_r)’ - 1) / C is linear with respect to C and its extrapolation is the same. Both [η] _D and [η] _S decrease as D_R or S_R increases, and extrapolation to D_R → 0 or S_R → 0 is not possible; as the change is greater at low D_R or S_R values. Based on these results, we propose to use [η] _ (S = 25) when D_R = 3000 seconds -1 (D = 3000) or S_R = 25 dynes / cm_2 A measure of the viscosity average molecular weight. When applying [η] _ (S = 25) data, use t_r = t / t_0. Instead of (η_r) ’(t_r and (η_r)’ when the degree of non-Newton solution is small, the difference is very small), so long as a given applied pressure measured, you can achieve fast requirements.