膜渗透计测定低分子量聚合物

本文用小体积膜渗透计及动态渗透压法测定了聚苯乙烯标准样品(分子量1000—17000)和一系列主链含-5氟尿嘧啶聚酯的分子量(低于9000)。同时研究了再生纤维素玻璃纸制备的半透膜的渗透性和选择性。该膜在丙酮中具有较高的选择性,可测定1000分子量。 低分子量聚苯乙烯的第二维利系数A_2依从A_2=常数·(?)关系。

DETERMINATION OF LOW MOLECULAR WEIGHT POLYMERS BY USING MEMBRANE OSMOMETER

The molecular weights of standard polystyrenes (1000 ≤M ≤ 17000) and a series of polyesters containing 5-fluorouracil in the mate chain (M <9000) have been determined satisfactory by a small-volume membrane osmometer and dynamic osmometry. The selectivity and permeability of the membrane, prepared from a home-made regenerated cellulose with different treatments have been investigated in acetone and DMF at various temperatures. It has been found that the membrane used in acetone gives higher selectivity and the measurement for the sample with M=1000 is possible.The second virial coefficient A2 of low molecular weight polystyrenes increases rapidly as the molecular weight decreases. The relationship between A2 andMn is A2 = const An-1.40. This suggests that polymers of low molecular weights in dilute solution are fully extended.