摘要:

AbstractThe polymerisation of N‐vinylcarbazole by mercuric chloride in chlorobenzene depends on the presence of co‐catalytic impurities contained in the monomer. These impurities can be partly removed by crystallisation and zone‐refining of the monomer, and these treatments reduce the polymerisation rate considerably, but not to zero; the residual reactivity is due to a co‐catalyst which was not removed by our

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320101

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY

摘要:

AbstractKinetics of pyrolysis of cotton cellulose and cellulose acetate with different degrees of substitution have been studied. The range of decomposition temperature of the cellulose samples was found to decrease with the increase in degree of substitution. However, the stability of the polymer increased as the degree of substitution increased. Probable mechanism of degradation of the test samples is discussed. Energy of activation and order of reaction for the decomposition of polymer samples as well as for the residual materials have been determined and correlated with DTA measurements.

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320102

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY

摘要:

AbstractIt has been shown that polysulphone is appreciably more stable to thermal and thermaloxidative breakdown than polycarbonate, the polyarylates, prepared from the condensation of terephthaloyl chloride/bisphenol A and terephthaloyl chloride/phenolphthalein, and polyphenylene oxide. The latter four polymers differ little in their thermal stabilities but regarding thermo‐oxidation, while the three polyesters are comparable, minor differences being attributable to the relative stability of the phenylene linking groups, polyphenylene oxide is markedly less stable. This has been explained as being due to the oxidisability of the pendant methyl groups in polyphenylene oxide. Also, it is noted that this polymer may be considered as being composed of potential antioxidant units and accordingly is liable to oxidative breakdow

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320103

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY

摘要:

AbstractOn a synthétisé à l'aide de la technique de polymérisation par voie anionique, des copolymères séquencés polystyrène/polyvinyl‐4 pyridine. On a opéré sous vide, en milieu tétrahydrofuranne qui est un mauvais solvant, sinon un précipitant, de la polyvinyl‐4 pyridine; l'initiateur utilisé était le cumylpotassium.Les échantillons ont été fractionnés par addition progressive d'heptane à leur solution dans le benzène. Les différentes fractions ont été caractérisées par diffusion de la lumière et analyse élémentaire. On a montré que les copolymères bruts ainsi préparés renfermaient très peu d'homopolymère et que les fractions recueillies avaient une polydispersité très faible, tant en masse qu'en composition.On a examiné par diffraction des rayons X aux petits angles de BRAGG, la structure des gels mésomorphes obtenus avec ces copolymères en présence d'octanol et de toluène, solvants sélectifs respectivement des séquences pyridiniques et styrèniques. On a mis en évidence deux types de structure, l'un correspondant à l'assemblage de sphères selon un réseau cubique, l'autre à un assemblage de cylindres selon un réseau hexagonal. On a déterminé la valeur des paramètres structuraux et on les a exprimés en fonction du degré de gonflement du gel et des dimensions respectives des séquences.L'emploi, comme solvant générateur de phases mésomorphes, d'un liquide polymérisable a permis d'obtenir, par polymérisation de ce dernier, des pol

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320104

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY

摘要:

AbstractThe results of the investigation on the oxidative coupling polymerization reaction of 2.6‐dimethylphenol in the presence of copper(II) chloride‐pyridine‐KOH complex (basic copper(II) complex) are reported. The yield of poly(2.6‐dimethyl‐4.4′‐phenylene oxide) which is the CO coupling product closely depends upon the copper(II) chloride concentration, the ratio of pyridine/copper(II) chloride, and the ratio of KOH/copper(II) chloride. However, the yield of 3.3′.5.5′‐tetramethyl‐4.4′‐diphenoquinone, the CC coupling product, scarcely changes with these reaction conditions.The rate of polymerization of 2.6‐dimethylphenol under oxygen was much larger than that determined in an air atmosphere.The basic copper(II) chloride complex catalyst showed the unusual property that the electron spin resonance‐detectable copper(II) ion in the basic copper(II) chloride complex was only 35 ± 5% using pure copper(II) chloride‐pyridine complex not containing KOH as a standard.It has been found by means of ESR measurements that the basic copper(II) complex had the function

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320105

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY

摘要:

AbstractIn order to examine the method of fractionation into summative fractions proposed by SPENCER, a complete mathematical fractionation was carried out by using an electronic computer according to the procedure of KAMIDE, OGAWA, and their coworkers. Various amounts of precipitates were separated from a 1.0% solution of a polymer having the most probable size distribution with the number‐average degree of polymerization (P)X̄ n0= 150. The solution theory by FLORY and HUGGINS was employed as the principle basis of the fractionation. The fractionation data obtained in this manner were analyzed according to the SPENCER'S method and the method revised by OKAMOTOto elucidate the integral P distribution in the initial polymer. The results were compared with the true distribution (i.e., the most probable distribution) and with the distribution evaluated from a simple successive precipitation method through use of the SCHULZ's procedure. It was found that the SPENCER's method has a tendency, more or less, to underestimate both the lower and higher regions of the molecular weight distribution. However, the SPENCER's method is sometimes preferable to the successive precipitational method to evaluate the P distribution. The OKAMOTO's method was found successful in a wide range of molecular wei

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320106

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY

摘要:

AbstractAnalytical expressions of the second and third virial coefficients obtained by vapor pressure osmometry were derived rigorously on the basis of the theory of KAMIDEand SANADA, previously developed. The apparent second virial coefficient A2,v′ in the following relation:\documentclass{article}\pagestyle{empty}\begin{document}$$ \left( {\rm T} - {\rm T} _0 \right )_s = {\rm K} _s \left( {\frac{{c_a}} {{\rm M_1}} + {A} _{{2},{ v}^\prime} {{c}_{a ^2}} + {A} _{{3},{v} ^\prime} {{c} _{a ^3}} + \ldots } \right) $$\end{document}is given by\documentclass{article}\pagestyle{empty}\begin{document}$${\rm A}_{2,{\rm v'}} = {\rm A}_{2,0} + \left( {\frac{{{\rm V}_0 }}{{{\rm M}_{1^2 } }}} \right)\left\{ {\left( {\frac{{{\rm RT}_0 }}{{\Delta {\rm H}}} - \frac{1}{2}} \right)\left( {\frac{{{\rm K}_{\rm s} }}{{{\rm K}_{\rm e} }}} \right)^2 + \frac{{{\rm K}_{\rm s} }}{{{\rm K}_{\rm e} }} - \frac{1}{2}} \right\} - \frac{{{\rm k}\left( {\rm t} \right)}}{{{\rm M}_1 }}$$\end{document}with\documentclass{article}\pagestyle{empty}\begin{document}$${\rm K} _{\rm e} = \frac{{{\rm RT} _{0 ^2} {\rm V} _0 }} {{\Delta {\rm H}}}$$\end{document}where T and T0represent temperature of a solution drop and a solvent drop, respectively, suffix s means that the measurements are made in the steady state, Ksa calibration parameter, cainitial concentration, M1the molecular weight of solute, A2,0and A3,0the osmotic second and third virial coefficients, V0the molar volume of solvent, R gas constant, ΔH the heat of condensation of solvent, k(t) a correction parameter due to a dilution effect, t time of measurement.Unexpectedly, A2,v′ differs significantly from A2,0, even if dilution effect can be neglected (i.e., k(t) = 0) for solute having M1<2ċ103, unless Ks/Ke= 1/{1 + (2 RT0/ΔH)1/2}. The numerical calculations and analysis of the experimental data show that the second term in the right‐hand side of the second equation approaches zero when M1becomes larger than (105/2)1/2V01/2. However, the third term due to a dilution effect can not be ignored i

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320107

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY

摘要:

AbstractAccording to the hypothesis that uncrystallizable units are excluded from the crystalline lattice into the surface of the crystals and concentrated in the folds, morphologies and textures of solution grown crystals of branched polyethylenes have been studied as functions of content and length of the branches by means of various techniques.Methyl, ethyl, and propyl branches were introduced into polyethylene chains by polymerization of mixtures of diazomethane and the corresponding higher diazoalkane. The crystals of these branched polymers grown from dilute solutions were treated with a selective oxidizing agent, fuming nitric acid. The degraded products were examined as regards the changes during the oxidation in molecular weight, weight‐loss, layer thickness (by low angle X‐ray studies), branch content (by IR analysis), unit cell dimensions, density and X‐ray crystallinities and morphology (by electron microscopy), with the aim of clarifying the nature of disordered material in polymer single crystals. It emerges that the thickness of the surface layer increases with the content and length of the branches and that the folds may be considered as irregular loose loops for crystals of polymers with a branch content beyondca.one per 100 carbon atoms. The results also revealed less perfect order of the crystal lattice for polymers with higher degree of branching. Thus, the branches seemed to be concentrated in the loose loops in the surface layer and within the crystal defects, both of which are accessible to oxidation. The concentration of the branches within the folds was discussed in terms of the content and the length of the branches. It was also found that the thicker the surface layer, the poorer the morphology of the cry

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320108

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY

摘要:

AbstractPoly‐4‐methylpentene‐1 was degraded in the temperature range 291–341°C. The decomposition products were determined and their rate of evolution followed. Their formation is explained on the basis of a free radical chain mechanism in which hydrogen transfer plays an important role. A free radical abstracts a hydrogen on a tertiary carbon atom by a “back‐biting” mechanism, although there is also evidence of the abstraction of secondary hydrogen atoms. A split in the chain follows and a volatile fragment is formed. Isobutene and propane are the main components of the fraction volatile at room temperature, which accounts for about 9% of the total loss of weight. The rest consists of higher molecular weight branched hydrocarbons and olefins. The energy of activation for the loss of weight was found to be

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320109

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY

摘要:

AbstractPoly‐4‐methylpentene‐1 was degradedin vacuoin the temperature range 294–355°C. The general mechanism of degradation is discussed on the basis of a free‐radical chain reaction including initiation, transfer and termination. The molecular weight of the polymer decreases sharply at the beginning of the reaction then more slowly. The rapid decrease is attributed to abnormal “weak” structures distributed at random along the chain. The introduction of oxygenated groups in the polymer increases the initial rapid decrease in molecular weight but does not vary the slower rate of reaction which seems to be characteristic of poly‐4‐methylpentene‐1. A unimolecular termination is then discussed. Although the function describing the rate equation provides a curve similar to the experimental curves, the resulting activation energy for termination is much higher than any reasonable guess. A smaller value of the activation energy for termination is obtained assuming a seco

ISSN:0025-116X    

DOI:10.1002/macp.1970.021320110

出版商:Hüthig&Wepf Verlag    

年代:1970

数据来源: WILEY