We have studied the homogeneous hydrogenation of a series of unsaturated polymeric substrates with diimide formed from the thermal decomposition of p ‐toluenesulfonylhydrazide (TSH) at elevated temperatures (110 to 1...
We have studied the homogeneous hydrogenation of a series of unsaturated polymeric substrates with diimide formed from the thermal decomposition of p ‐toluenesulfonylhydrazide (TSH) at elevated temperatures (110 to 160°C) and in aromatic solvents. At a TSH/olefin ratio of 2.0, homopolymers of butadiene, polycyclohexadiene, and polyisoprene were quantitatively hydrogenated as were two styrene/butadiene copolymers. Alkyl branching at or near the residual polymer double bond, as in methyl rubber and poly‐2.5‐dimethyl‐2.4‐hexadiene, gave less than 50% hydrogenation. Polychloroprene was not hydrogenated by diimide (conversions less than 10%) which is in agreement with the behavior previously observed for low molecular weight olefins. The unsaturated polymers which were successfully hydrogenated were soluble and, hence, showed no excessive crosslinking. Polycyclohexadiene and polyisoprene, the only samples evaluated for molecular weight changes, exhibited no chain degradation. Some qualitative kinetic data were obtained using per cent conversion vs. time data. Under the conditions of toluene reflux and TSH/olefin ratios of 1.5, the relative rates of hydrogenation for cis, trans and vinyl butadiene units was k cis ≃ k trans < k vinyl. Byproducts from the diimide generation resulted in the introduction of 0.2 to 1.0% of p ‐CH 3 C 6 H 4 SO 2 ‐groups into the polymer based upon 100% of the double bonds originally present. Die homogene Hydrierung einer Serie ungesättigter polymerer Substrate mit Diimid, dargestellt durch Thermolyse von p ‐Toluolsulfonylhydrazid (THS) bei 110–160°C, wurde in aromatischen Lösungsmitteln untersucht. Bei einem TSH/Olefin‐Verhältnis von 2,0 wurden sowohl die Homopolymeren des Butadiens, das Polycyclohexadien und das Polyisopren, als auch zwei Styrol/Butadien‐Copolymere quantitativ hydriert. Bei Alkylverzweigung an oder in Nachbarschaft der Doppelbindung des polymeren, wie im Poly‐2.5‐dimethyl‐2.4‐hexadien, verlief die Hydrierung zu weniger als 50%.
Temperature dependent infrared studies have been carried out on three series of poly-urethanes previously synthesized and characterized. The repeat units of the three series may be schematically represented as follows...
Temperature dependent infrared studies have been carried out on three series of poly-urethanes previously synthesized and characterized. The repeat units of the three series may be schematically represented as follows: In each case n varies from 2 to 10. The H and DP series are partially crystalline while the 4M series is entirely amorphous. It was possible to draw several conclusions concerning the hydrogen bonded NH and Cbond;O groups in these polymers. These conclusions are: (1) The aromatic polyurethanes of the DP and 4M series are hydrogen bonded in the amorphous phase below the glass transition temperature, (T g ) , to the extent of 75% or less whereas the aliphatic H series is completely hydrogen bonded below T g . (2) Both the DP and H series are completely hydrogen bonded in the crystalline phase below the melting point, ( T m ), regardless of the value of n . (3) A temperature dependent equilibrium between free and hydrogen bonded NH groups occurs in the amorphous phase above T g in all three series. (4) The temperature dependences of the total area of the NH stretching bands exhibit transitions corresponding to T g , T m , and, in the case of the H series, to a first order crystal-crystal phase transition, T t . (5) The temperature dependences of the frequencies of the hydrogen bonded NH stretching vibration also exhibit transitions corresponding to T g and T m .
Dynamic mechanical study has been made of ethylene-methacrylic acid copolymer containing 4.1 mol% of methacrylic acid units and its sodium, lithium, and calcium salts;it is proposed that structures of ionized copolyme...
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Dynamic mechanical study has been made of ethylene-methacrylic acid copolymer containing 4.1 mol% of methacrylic acid units and its sodium, lithium, and calcium salts;it is proposed that structures of ionized copolymers consist of three distinct phases -- crystalline polyethylene phase, amorphous polyethylene phase, and ionic phase consisting of ionic domains;it is further proposed that unionized acid copolymer consists of two phases -- crystalline polyethylene phase and amorphous phase consisting of polyethylene crosslinked with hydrogen bonded, carboxylic acid dimers.
An improved self‐beat spectrometer has been used to study the spectrum of light, from a He–Ne laser, scattered by solutions of poly‐γ‐benzyl‐l‐glutamate (PBG). From the observed spectral broadening, the transla...
An improved self‐beat spectrometer has been used to study the spectrum of light, from a He–Ne laser, scattered by solutions of poly‐γ‐benzyl‐l‐glutamate (PBG). From the observed spectral broadening, the translation diffusion constants of the solvated polymer were calculated. Diffusion constants were measured also as a function of solvent composition. A change in the diffusion constant at about 76% dichloroacetic acid (at 25°C) reflected the well‐known helix–coil transition of PBG.
Mechanical and thermal properties of a polyphosphonic acid based on low density polyethylene. Incorporation of the phosphonic acid groups results in considerable broadening of the spectrum as well as the introduction ...
Mechanical and thermal properties of a polyphosphonic acid based on low density polyethylene. Incorporation of the phosphonic acid groups results in considerable broadening of the spectrum as well as the introduction of several new bands.
Ethyl α-chloroacrylate was polymerized by anionic and free radical initiation under a variety of conditions to yield polymers of differing tacticities ranging from predominantly syndiotactic to slightly isotactic on ...
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