Y. Pietrasanta

Study of morphological and mechanical properties of PP/PBT blends

SummaryThe synthesis of emulsifiers has been performed by the condensation of terephthaloyl chloride, butanediol and hydrogenated α-ω hydroxy polyisoprenes. The products are carefully characterized by 1H-nuclear magnetic resonance (NMR), infra-red spectroscopy and size exclusion chromatography.The PP/PBT blend, in a 60:40 ratio, was prepared with, and without, emulsifiers by melt-blending. The effect of these emulsifiers on mechanical properties and morphological studies of the PP/PBT blend was examined.

Recycling of PET and PVC wastes

A method for recycling mixed PET and PVC wastes is described. Glycolysis of PET leads to oligomers that are polycondensed with caprolactone. The obtained diols are extended with hexamethylene diisocyanate. In certain conditions the polyurethanes are totally miscible with PVC, leading to acceptable mechanical characteristics for the blend. A relation between the structure of the polyurethane and miscibility with PVC is described. The mechanical characteristics of the blend depends on the polyurethane chemical structure.

Synthese de polysiloxanes fluores. Partie II. Addition de thiols fluores sur des silanes insaturees

Abstract The addition of fluorinated thiols such as C 6 F 13 CH 2 CH 2 SH to silanes having an allylic or vinylic unsaturated group is described. A previous study on vinyl trimethylsilane and on chlorotrimethylsilane shows that the thiols react in a selective way, with the double bonds but not with the Si-Cl group. The addition compounds with chlorodimethyvinylsilane, dichloromethylvinylsilane, dichloromethylallylsilane and tetramethyltetravinylcyclotetrasiloxane are studied and identified by 1 H and 13 C NMR. This new method of obtaining monomer silanes through a monoaddition reaction of fluorinated thiols gives the expected compounds with an excellent yield.

Etude de la réactivité du fluorure de potassium sur des esters polyhalogénés

Abstract Reactions of polyhalogenated esters with potassium fluoride in polar solvents have been studied. Two kinds of reactions are possible depending on the starting compound: the hydrochlorinated esters RCCl 2 CH 2 CHR′CO 2 CH 3 (R=Cl, -CF 3 ; R′=H, -CH 3 give the corresponding α-β unsaturated derivatives. Moreover when using ethylene glycol as a solvent, a transesterification reaction occurs after the dehydrohalogenation. From perhalogenated esters, mainly decarboxylation products are formed; for example in DMSO as a solvent, the fluorination of the telomers Cl-(CFClCF 2 ) n -CO 2 CH 3 yields the corresponding perfluoroalkenes C 2n F 4n . Some mechanistic interpretations are given in order to explain the formation of the different compounds.

Synthèses de diols fluorés a partir de dérivés des télomères du chlorotrifluoroéthylène et du tétrachlorure de carbone

Abstract Synthesis of fluorinated diols using telomers as starting compounds was studied. Thus chemical transformation of difunctional telomers RO2CCF2(CFClCF2)nCO2R (I,n) (n = 1,2 ; R = H or CH3) leads to the following series of diols: (II,n) HOCH2CF2(CFXCF2)nCH2OH (n = 1,2 ; X = H or Cl) (III,n) et (IV,n) RCOCF2(CFClCF2)nCOR (n = 1,2 ; R = OCH2CH2OH, NHCH2CH2 Addition of 1,1,1,3,3,3 hexachloro 2,2 difluoro propane by redox catalysis on functionalized alkenes of general formula CH2CHG (G = OCOCH3, CH2OCOCH3, CO2CH3, CH2OH, CO2CH2CH2OH) leads to the corresponding difunctional products GCHClCH2CCl2CF2CCl2CH2CHClG (V). Kinetic study shows that the reaction proceeds in two steps: formation of the monoadduct which then reacts with the monomer to give the difunctional compound. Reduction (when G = CH2OCOCH3, -OCOCH3, CO2CH3) or hydrolysis (when G = CH2OCOCH3) of compounds (V) leads to the two following diols: HOCH2CHClCH2CCl2CF2CCl2CH2CHClCH2OH HOCH2CH2CCl2CF2CCl2CH2CH2OH

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.

Telomerisation du tetrafluoroethylene avec le tetrachlorure de carbone par catalyse redox

Abstract The redox telomerization of tetrafluoroethylene with carbon tetrachloride using the FeCl3/benzoīn complex as catalyst has been studied. The CnFe transfer constants of this reaction are measured and compared to the results obtained under other conditions, especially under radical catalysis. We can also evaluate the Ki constant of the reaction rate between telogen and the metal at its lowest oxidation state. The DP n on the reaction conditions, the structure of low molecular weight telomers being established by mass spectrometry and the conditions to obtain the telomers of C2F4 with CCl4 are specified.

Fluoration de telomeres polyhalogenes par le fluorure de potassium: synthese d'olefines perfluorees

Abstract Action of potassium fluoride on chlorofluorinated telomers of general formula Cl-(CFCl-CF 2 ) n -CCl 3 leads to a mixture of perfluorinated cis isomers of internal olefins with the more substitued isomer being preponderant. The influence of temperature and solvant has also been studied. Only reactions carried out in tetramethylene sulfone or preferably in dimethylsulfoxide lead to perfluorinated alkenes. We suggest a mechanism with elimination followed by fluorination.

Synthese de materiaux polymeres transparents. Partie I Synthese du trifluoroacrylate de trideuteromethyle

Abstract The acrylic ester F 2 CCFCO 2 CD 3 is prepared from a mixture of difluorotetrachloroethanes CFCI 2 CFCI 2 and CF 2 CICCI. The dehalogenation of these Freons, followed by the addition of CFCI 3 by means of AICI 3 leads to a mixture of chlorofluoropropanes. The hydrolysis with oleum gives the acid chlorides which are then esterified by CD 3 OD. The dehalogenation of the mixture by the zinc stirred in oxalic acid enables isolation of the expected ester by distillation. This compound, the refractive index of which n 20 D =1.3667 does not show a major absorption in the near infra-red between 0.6 and 1.4 μm. Thus the corresponding polymer is likely to provide a good material for the core of optical fibers.

Synthese de polysiloxanes fluores. Partie III addition de thiols silicies sur des olefines fluorees

Abstract Fluorinated silanes are prepared by reaction of the siliciated telogen thiol (OCH 3 ) 2 (CH 3 ) Si-(CH 2 ) 3 SH upon various fluorinated olefines. The reaction upon the ether C 6 F 13 (CH 2 ) 2 OCH 2 CH = CH 2 gives the monoaddition compound whereas the reaction of the thiol upon the pentafluorostyrene and the methacrylate gives polyaddition compounds as well. The monoaddition compounds which are obtained are systematically identified by 1 H and 13 C NMR through a comparison between these products and various model molecules prepared for this purpose.