Continuous polymer fractionation (CPF) -a new large-scale method -was applied to the technical poly(methy1 vinyl ether) (PVME) using toluene as solvent and petroleum ether as nonsolvent. TWO different devices served as fractionation apparatus, namely a column packed with glass beads and a set of mixer-settler extractors. Advantages and draw-backs of these devices are discussed. The experiments yielded numerous PVME fracti?ns, varying in molar mass from 22 to 87 kg/mol and in molecular non-uniformity U = (M,,,/M,) -1 from 0,25 to 0,41 according to gel-permeation chromatography as compared with ca. U = 1,30 for the starting material. The following Kuhn-Mark-Houwink relation was established for PVME in ethyl methyl ketone at 30 "C: [q]/(mL/g) = 2,6 * @,86.
Cloud point curves were measured turbidimetrically for blends (upper critical solution temperatures; UCSTs) of poly(ethylmethylsi1oxane) (PEMS) and four different samples of poly(dimethylsi1oxane) (PDMS); the weight average molar masses in kg/mol are 31.2 for PEMS and 10.4, 15.5, 18.1 and 24.0 for PDMS; all components have polydispersity indices D (= MJM") within the range from 1.82 to 2.67. Corresponding calculations on the basis of the Flory-Huggins theory (three adjustable parameters) account for the polydispersity; molecular weight distributions are represented by the generalized SchulzFlory equation. Calculated cloud point curves agree very well with those measured, if individual sets of parameters are admitted for each of the different mixtures. Even for an identical set of parameters the maximum deviations remain moderate. Realistic model calculations concerning the influences of D on cloud points and on critical points were performed with this set of parameters.For the present (only slightly endothermal) system, the precipitation threshold increases from 318 to 558.6 K as D , , , is raised from 1.87 to 4.00, keeping the number average degree of polymerization constant.--
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