ISSN:0025-116X    

DOI:10.1002/macp.1960.020380101

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractIn Zusammenhang mit isotaktischen Polymeren werden die Struktur und die sterischen Regelmäßigkeiten einer neuen Serie von linearen Polymeren mit Kopf‐Schwanz‐Verknüpfung beschrieben und definiert. Diese Polymeren sind aus Monomeren mit Äthylen‐Doppelbindung, in denen beide Kohlenstoffatome der Doppelbindung substituiert sind, erhalten worden. Diese Polymeren mit sterisch regelmäßiger Struktur werden als di‐isotaktische Polymere bezeichnet; sie sind im allgemeinen kristallin und schmelzen bei hoher Temperatur.Um die gegenseitige sterische Lage der Substituenten in den Grundeinheiten zu charakterisieren, sind für die di‐isotaktischen Polymeren die Präfixe „erythro”︁ und “thero” eingeführt worden.Es wird gezeigt, daß es möglich ist, die Art der Öffnung der Doppelbindung beim Polymerisationsschritt zu bestimmen; es wurde nämlich gefunden, daß die Öffnung der Doppelbindung im Falle der stereospezifischen Polymerisation de

ISSN:0025-116X    

DOI:10.1002/macp.1960.020380102

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractTwo samples of highly isotactic polypropylene prepared by a NATTA's catalysis, have been fractionated by a column fractionation technique.Fractions having M̄w/M̄nratio very small (1.14 – 1.27) have been obtained and used for the determination of [η]−M̄nand [η]−M̄wrelations. Because of the small values of M̄w/M̄nratio, the [η]−M̄wrelation may be assumed also valuable as [η]−M relation. This relation is\documentclass{article}\pagestyle{empty}\begin{document}$$ \left[ \eta \right] = 0.80 \cdot 10^{ - 4} M^{0.80} $$\end{document}for molecular weight range of 40,000–650,000, where [η] is measured in tetralin at 135°C. Moreover values of\documentclass{article}\pagestyle{empty}\begin{document}$\sqrt {\overline {r_z^2 } }$\end{document}and of second virial coefficients A2are given in func

ISSN:0025-116X    

DOI:10.1002/macp.1960.020380103

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY

摘要:

Abstract[η] (Mn) functions are very, [η](Mw) functions less sensitive to differences in width of the molecular weight distribution. When [η](Mn) is known for different widths, the Mw/Mnratio of a sample can be estimated if its [η] and Mnvalues are known. A tentative graph is presented by means of which this can be done for low‐pressure polyeth

ISSN:0025-116X    

DOI:10.1002/macp.1960.020380104

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractIntrinsic viscosity and molecular weight data of fractions of low‐pressure polyethylene (LPPE) and polyvinyl acetate (PVAc) taken from literature and from our own experiments are analysed with observation of the molecular weight heterogeneity of the fractions. In general experimental data can be described by means of theories which do or do not make use of the excluded volume effect. The volume effect is reflected by a non‐linear relation between the z‐average mean square end‐to‐end distance 〈h2〉zand the z‐average molecular weight Mz.The deviation from linearity may be small and moreover Mzis sensitive to the type of molecular weight distribution (MWD). Therefore if Mzis calculated, the MWD should not be taken at will as is usually done.With PVAc and LPPE it was impossible to decide upon linearity or non‐linearity. For the first polymer the [η]‐data could be described by means of the theories of KURATAet al., BRINKMAN‐DEBYE‐BUECHE and KIRKWOOD‐RISEMAN. The value for the friction constant of the monomer unit found with the K.R.‐theory seems to be unreasonably low. The 〈h2〉zvalues calculated are reasonable, except those calculated with the B.D.B.‐theory. The value of the effective bond length found with this theory is too low to explain the experimental values of 〈h2〉z. For LPPE only the K.R. and B.D.B.‐theorys are applied. Also here the friction constant obtained with the K.R.‐theory is low. 〈h2〉zdata being not known at the moment, the values of t

ISSN:0025-116X    

DOI:10.1002/macp.1960.020380105

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractThe methods of improving the dyeability of polyacrylonitrile are reviewed and classified, and the copolymerization of acrylonitrile with comonomers which introduce basic dye sites in the polymer chain is considered the most practical method. Comonomers containing the pyridine ring are especially effective in improving dyeability. To lower the basicity effect of the pyridine ring, comonomers based on diazine and triazine rings were synthesized. The basicity of the triazinyl comonomers can be varied greatly by substitution, and it is concluded that high basicity is not required to bind dyes and the ability of the comonomers to form complexes is also important with respect to dyeability.

ISSN:0025-116X    

DOI:10.1002/macp.1960.020380106

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractLatices of polyvinyl acetate polymerized under the influence of gamma‐rays have been used to initiate the polymerisation of methyl methacrylate. Extensive grafting occurred. If the conditions of preparation were suitable, discrete fractions of graft copolymer could be isolated. The structure of these graft copolymers has been discussed from the point of view of available rate constants for chain transfer of polymethyl methacrylate radicals.In systems where styrene is used in the second stage, little or no grafting could be detected‐the main product being pure polystyrene of high molecular wei

ISSN:0025-116X    

DOI:10.1002/macp.1960.020380107

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractThe bulk copolymerization reactions of 2‐methyl‐5‐vinylpyridine(MVP) with styrene(St), methyl methacrylate(MMA), methyl acrylate(MA), and acrylonitrile(AN) at 60°C. have been investigated. The copolymer compositions were estimated by means of electrometric titrations in a nonaqueous solvent mixture.The monomer reactivity ratios of the following systems were determined: St/MVP (r1= 0.812 ± 0.005; r2= 0.91 ± 0.02), MMA/MVP (r1= 0.46 ± 0.02; r2= 0.61 ± 0.08), MA/MVP (r1= 0.172 ± 0.007; r2= 0.88 ± 0.10), and AN/MVP (r1= 0.116 ± 0.003; r2= 0.27 ± 0.04). Moreover the Q‐ and e‐values were calculated for the methyl vinylpyridine and its behavior in copolymeriz

ISSN:0025-116X    

DOI:10.1002/macp.1960.020380108

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractPartition of a cationic dye between water and an organic solvent, the dye and the polymer being soluble in only water and the organic solvent respectively, has been utilized as a technique for detection of acid groups in a polymer. A coloration of the non‐aqueous layer takes place when anionic groups are present in the polymer. Detailed conditions for carrying out this test, to be called dye partition test, have been worked out for strong acid (sulphonate, sulphate, etc.) and COOH groups. The method has been extended for detection of OH groups. Some straightforward applications of this technique have been illustrate

ISSN:0025-116X    

DOI:10.1002/macp.1960.020380109

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractThe equilibrium conditions pertaining to reversible melt‐polycondensation in the polyethylene terephthalate system have been investigated at different temperatures and average DP's. Free ethylene glycol, end‐groups and monomer were determined quantitatively. The equilibrium constant K depends slightly on temperature but increases markedly with increasing extent of polycondensation, thus showing that polyethylene terephthalate does not obey the principle of equal reactivity. In addition, it appears that the monomer contents of various equilibrium products definitely exceed the theoretical contents given by the FLORY‐SCHULZ distribution function.By assuming as a first approximation, that only monomer does not fulfil the principle of equal reactivity, it is possible to describe both the abnormal monomer contents and the increase of K in terms of a ratio K0/K1= 1.8, where K0denotes the equilibrium constant for polymer molecules and K1that for monomer with polymer molecule.A detailed interpretation of the abnormal monomer reactivity will be given in a next paper dealing with the kinetics of reversible polycondens

ISSN:0025-116X    

DOI:10.1002/macp.1960.020380110

出版商:Hüthig&Wepf Verlag    

年代:1960

数据来源: WILEY