Gérard Bauduin

Poly(vinylidene fluoride)/poly(vinyl alcohol-co-vinyl acetate) blends : 1. compatibility study by differential scanning calorimetry (DSC)

Abstract Blends of poly(vinylidene fluoride) (PVDF) and some poly(vinyl alcohol–co-vinyl acetate) copolymers (PVAAc) with various molecular weights and acetate contents are studied by differential scanning calorimetry. First, two sets of blends of PVDF with two different PVAAc at various concentrations are analysed. Then, 50/50 (wt/wt) blends of each copolymer with PVDF are studied. Even though the glass transitions of both polymers are not observable, the PVDF melting and crystallization data give some indications about these blends: (1) the amorphous phases of both polymers seem to be, in any case, immiscible; (2) the crystallization of PVDF is modified by mixing with the copolymers (PVAAc), the most crystalline of them (with low acetate contents) improving its crystallinity ratio.

Etude de la télomérisation de C2F4 avec les iodures de perfluoroalkyle Partie I. Télomérisation radicalaire

Abstract The remomerization of C 2 F 4 with C 6 F 13 F by various initiators has been achieved. These results have shown the effect of the temperature on the mechanism of the reaction. With t -butylperoxide (DTBP) at 130°C, we have observed that the apparent relative reactivity of C 8 F 17 I (monoadduct) is constant versus time. On the contrary, with cyclohexyl percarbonate(CHPC) at 47°C, it decreases continuously. On the other hand the ratio of the initial rates of consumption of monomer to telogen is close to 1 at high temperature while it is near to 2 at low temperature. These results clearly demonstrate that the mechanism proceeds by monoaddition in the first case (DTBP) while it is by propagation in the second case (CHPC). Secondly, we have proposed a mathematical simulation of these two kinds of reaction and discussed the validity of these laws.

Calcul a priori des deplacements chimiques en RMN du 19F. 1. Modele previsionnel adapte aux composes aliphatiques fluores lineaires

Abstract A new empirical model for the a priori calculation of the chemical shifts in 19 F NMR spectroscopy for fluorinated linear aliphatic compounds is described. In contrast to previous models, it takes into account the influence of distant atoms (up to 5 bonds). Comparison between measured and calculated chemical shifts in linear saturated molecules containing hydrogen and halogen atoms shows a significantly increased accuracy for the present model with regard to that described previously. Perfluorinated linear saturated carboxylic acids are also studied using the model described.

A priori calculation of chemical shifts in 19F NMR spectroscopy. 4. Testing our model with new experimental values

Abstract This paper deals with the application of the previously presented model and computer program for predicting 19 F NMR chemical shifts to a set of essentially new experimental values recently published in this journal.

Copolymerization of chloromethylstyrene and maleic anhydride: an example for testing a new method to determine reactivity ratios

Abstract The reactivity ratio r of chloromethylstyrene copolymerized with maleic anhydride (reactivity ratio is assumed to be zero) is determined using a new previously described integrated method. A methodology is presented to select the experimental conditions. The value of r is found to be in the range 0.835–1.12 with a 95% confidence level.

Calcul à priori des deplacements chimiques en RMN du 19F.2. Amelioration et extension du modèle prévisionnel pour les molécules saturées

Abstract The quality of the earlier described model for predicting the chemical shifts of 19F nuclei in linear saturated molecules is appreciably improved by using as reference some 19F nuclei selected according to the objective criteria of optimization. The model is extended to non-perfluorinated linear carboxylic acids and to branched molecules.

Copolymerization of glycidyl methacrylate and N-vinyl pyrrolidone: An example for testing a new method to determine reactivity ratios

Abstract A new method based on the measurement of maximum conversion rate of the least reactive monomer ( N -vinylpyrrolidone; NVP) was used to determine the reactivity ratio of glycidyl methacrylate (MAG), that of NVP being considered to be zero. Despite a peculiar experimental difficulty due to the occurrence of NVP homopolymerization, the monomer reactivity ratio of MAG was found to be between 2.87 and 4.05 (at a 95% probability level), in good agreement with data from the literature.

A priori calculation of chemical shifts in 19F NMR spectroscopy. 3. Data treatment for saturated molecules Calcul a priori des déplacements chimiques en RMN du 19F. 3. Traitement informatique pour les molécules saturées

Abstract This paper presents two programs which allow the ready empirical calculation of fluorine chemical shifts. The first program deals with the management of paramagnetic increment files and the second with the calculation itself.

Poly(vinylidene fluoride)/poly(vinyl alcohol-co-vinyl acetate) blends: 2. Study by infrared spectroscopy

Abstract Blends of poly(vinylidene fluoride) (PVDF) and some poly(vinyl alcohol-co-vinyl acetate) copolymers (PVAAc) with various molecular weights and acetate contents are studied by Fourier transform infrared spectroscopy (FTIR). First, two sets of blends of PVDF with two different copolymers at various concentrations are analysed. Then, 50/50 (wt/wt) blends of seven PVAAc with PVDF are studied. Two carbonyl bands are observed corresponding to free and bonded carbonyls. The rate of bonded carbonyls and the interaction enthalpies are determined. The results are in good agreement with the occurrence of a rather strong interaction between the carbonyls of the residual acetate groups and the hydroxyl groups of the copolymers. No interaction between the carbonyls and PVDF were observed. The experimental results are in a good agreement with the foresights of the Coleman–Graf–Painter interaction model.