ملخص: This work describes the e.ect of the molecular weight on the viscosimetric parameters of poly(4-vinylpyridine) (P4VP) polymers in ethanolic solution. Numerous studies concerning this question have been reported in very separate intervals of molecular weight. We have observed a discordance (discontinuity) in the variation of the intrinsic viscosity as a function of the molecular weight of these polymers ?½g ¼ f ?Mw??. In order to establish a general relationship between viscosimetric parameters andMw,we have considered 10 P4VP samples in a wide interval of molecular weights: 0:75  104 to 153  104. These results have been compared and completed with that of the literature. We have observed that: ii(i) All viscosimetric parameters (intrinsic viscosity [g],Huggins constant kH,second virial coe.cient,viscosimetric expansion coe.cient ag,and critical concentration) change according to a continuous function without a break. i(ii) The lower is the molecular weight of P4VP; the higher are the variations of the expansion coe.cient and the interaction e.ects. (iii) The variation of the intrinsic viscosity versus the molecular weight follows a unique relation in the whole Mw range. In fact,the Berkowitz equation (1), described for a limited range of relatively high Mw (105 to 18:5  105) is extended for all Mw interval values. (iv) Empiric laws for [g], kH, A2 and C and variations as a function of molecular weight were proposed for the P4VP in ethanol.

لغة: إنجليزية