Study of cryostructuration of polymer systems. XV. Freeze–Thaw-induced formation of cryoprecipitate matter from low-concentrated aqueous solutions of poly(vinyl alcohol)

✍ Scribed by Lilija G. Damshkaln; Irina A. Simenel; Vladimir I. Lozinsky

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 137 KB
• Volume: 74
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19991121)74:8<1978::aid-app11>3.0.co;2-l

✦ Synopsis

Freeze-thaw treatment of low-concentrated (ϽC*) aqueous solutions of poly(vinyl alcohol) (PVA) results in the formation of a cryoprecipitate fraction. It is shown that the efficiency of such a process (the yield of PVA cryoprecipitation) depends on the initial polymer concentration in the solution to be frozen and the conditions of a cryogenic influence. The key factor is defrostation dynamics: The slower the thawing rate, the higher the cryoprecipitation yield. The iodine-staining method is employed for the quantitative analysis of PVA concentrations in the solutions under study and the necessity of the use of reduced (0 -2°C) temperatures throughout such a PVA quantification is demonstrated. Observation of the kinetics of the freeze-thaw-induced formation of cryoprecipitate matter reveals the extreme character of the temperature dependence of the efficacy of PVA macromolecule aggregation, the extreme point being situated in the vicinity of Ϫ2°C.