摘要:

AbstractThe reaction between poly(ethylene oxide) glycol (α‐hydro‐ω‐hydroxypoly(oxyethylene)) and methylenebis(1,4‐cyclohexylene) diisocyanate was studied at 70, 80 and 90°C. The course of the reaction was followed by determining the isocyanate content of the reaction mixture at appropriate time intervals. The data thus obtained were analyzed by taking into consideration the glycol‐ and urethane‐catalyzed reactions separately. It was found that although the urethane‐catalyzed reaction was faster in the temperature range studied, its relative importance decreased with increa

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790111

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractThe solvent effect on radical Polymerization of methyl methacrylate initiated by copper(II) 2‐aminoethanolate (Cumea) or by the system Cumea‐reducing agent (H2NCH2CH2OH, CCl4) is discussed. In the first case, where the initiating radical is formed from a Cumea‐MMA complex, the solvent influences the equilibrium of the complex‐forming reaction and thus also the initiation reaction. Further, in this system also primary radical termination and degradative chain transfer are operative. In the initiation by the system Cumea‐reducing agent, the non‐ideal course of polymerization is due to primary radical termination and degradative cha

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790112

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractPoly(p‐vinylbenzophenone), (poly[1‐(4‐benzoylphenyl)ethylene]), (PVB) has been synthesized for the first time directly from its monomerp‐vinylbenzophenone (VB) the preparation of which was improved. In a second step, copolymers containing blocks of photosensitive VB units separated by isolated quenching vinylferrocene (VF) units have been prepared. PVB and the VB‐VF copolymers were irradiated in the presence of isopropyl alcohol in benzene solutions. The benzophenone groups inserted in these macromolecular chains obey the same reaction scheme as the photoreduction of the small molecule of benzophenone. However, recombination of the radicals located along the polymeric chain leads to intra‐ and intermolecular reactions changing drastically the macromolecular morphology by the formation of cycles and networks and by chain scissions. The quantum yields of the photochemical transformations were measured, but they could not be related quantitatively to morphological parameters. In all cases the ferrocene group inhibits strongly the photochemic

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790113

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractUsing a new general formulation of Flory's gelation criterion, a critical transition equation is derived for polyol/polyacid systems having hydroxyl groups of unequal reactivity. The reaction probabilities of various hydroxyl groups are formulated from kinetic calculations. The gelation equation shows that the inclusion of monomers having groups of unequal reactivity significantly increase the extent of reaction necessary for the gelation. The theoretical forecasts are confirmed by the experimental study of some polyester systems.

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790114

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractA sample from commercially available polyisobutylene with a viscosity average molecular weight ofM̄v= 320 000 is fractioned according toBaker‐Williams. 9 Fractions are recovered and are characterized by viscometry and gel permeation chromatography (GPC). Molecularly very homogeneous fractions with an inhomogeneityU= (M̄w/M̄n)−1 ≈ 0,05 can be obtained in the range of molecular weights up toM̄v= 600 000. Inversion of molecular weight occurs in the last three fractions. A 3 wt.‐% portion withM̄v>106is lost during the f

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790115

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractCationic polymerizations ofN‐vinylcarbazole (NVC) in methylene dichloride containing approximately 1% nitromethane were studied by adiabatic calorimetry at temperatures between −40 and −70°C. Tropylium salts containing AsF 6−, SbF 6−and SbCl 6−counterions were used as initiators. Reaction halflives ranged from 2 to 80 seconds and first‐order plots displayed induction periods. Evidence indicated that the majority of the initiator was consumed, permitting estimation of propagation rate constants. For polymerizations involving the SbF 6−counterion, these rate constants were found to be relatively insensitive to the concentration of initiator or excess anion and the conclusion is drawn that paired and unpaired PNVC+SbF 6−ions have similar reactivities at low temperatures. Correlation of the present results with those from previous work at 20 and 0°C yielded an Arrhenius exponential factor for propagation by unpaired ions of 30±9 kJ mol−1. The degree of polymerization approached the ratio [M]0/[1]0at −70°C. At higher temperatures, molecular weights appeared to be governed by transfer reactions. The absence of significant chlorine content in polymer samples precluded the possi

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790116

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractThe effect of polyanions on the formation of mixed dimers of methylene blue (1) and trypaflavine (2), methylene blue (1) and phenosafranine (3), and methylene blue (1) and pyronine G (4) was investigated spectrophotometrically. The following polyanions were used: poly(potassium styrenesulfonate) (PSS), poly(potassium vinyl sulfate) (PVS), and poly(sodium acrylate) (PAA). On addition of polyanions, the formation of mixed dimers was enhanced largely. Thermodynamic parameters inferred that the enhancement of the formation of mixed dimers in the presence of polyanions resulted from an entropic factor.

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790117

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractPolystyrene containing benzophenone, present either as an additive or linked to the polymer chain has been irradiated at 365 nm at room temperature and the ESR spectra were analyzed. When benzophenone is linked to the chain, equal proportions of the “ketyl macroradical”2and of the “polystyryl radical”3resulting from abstraction of the tertiary H‐atom of the styrene unit are detected. These decay on warming the sample and at 410K only about 20% of the ketyl radicals is still present. Very fast radical decay occurs at room temperature on addition of oxygen to samples where radicals2and3are trapped as pairs. In samples annealed at 410K, the isolated ketyl radicals decay slowlier by second order kinetics under the same conditions. If benzophenone is present as an additive, only a small amount of isolated polystyryl radical3is trapped at room temperature since most of the polymer radicals have reacted with the mobile ketyl radicals. These isolated radicals3decay by second order kinetics on addition

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790118

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

Abstract1‐(9‐Anthryl)ethyl methacrylate (9AEMA) was prepared by condensation of 1‐(9‐anthryl)ethanol with methacryloyl chloride. The rate of AIBN initiated polymerization of 9AEMA in benzene at 60°C was intermediate between the polymerization rates of styrene and methyl methacrylate. 9AEMA/styrene copolymerization studies at 60°C resulted in the copolymerization parametersr9AEMA= 0,42±0,07 andrst= 0,37 ± 0,08. Charge transfer complexes are formed betweenp‐ chloranil and the 9AEMA homo‐ and copolymers. The absorption maxima of the CT‐complexes shifted to higher wavelengths with increasing 9AEMA content of the copolymers, whereas the equilibrium constant of the CT‐complex formation was independent of copolymer composition. Both the complex formation enthalpies and entropies decreased with increasing 9AEMA conten

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790119

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractThe dynamic mechanical behaviour of polyamide systems containing different degrees of unsaturation was analyzed. The results do not show any simple relation between unsaturation and mechanical response. Particular attention was given to the α‐transition, that is a glass transition, and experimental data suggest that the generally accepted mechanism for this transition requires a more extensive stu

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790120

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY