摘要:

AbstractThermal degradation of sodium alginate was investigated in its dependence on the ionic strength of the solution. Degradation was carried out at 100°C. The molecular weight was determined viscosimetrically at 25°C.The degree of degradation, which provides a measure for the rate of the reaction, depended on the concentration of sodium chloride and on that of sodium alginate.With increasing NaCl concentration, the rate of the reaction of degradation diminishes. In the range of 0–0.1NNaCl the decrease in rate is steep, whereas above 0.1NNaCl concentration the decrease is slow.The rate of the reaction of degradation of sodium alginate decreases with increasing concentration of the latter.This effect cannot be explained by invoking the laws of chemical kinetics. Albeit, it was found that the curves representing the dependence of the degree of degradation on the NaCl concentration for various concentrations of the alginate (Fig. 2) can be reduced to a single curve, provided the degree of degradation is expressed as a function of the sum of the concentrations of sodium chloride and alginate (Fig. 3). Herein, however, the concentration of the alginate has to be multiplied by a coefficient of 0.9.This coefficient, termed the correlation coefficient of concentrations, is found to be identical with the coefficient of isoionic dilution introduced into the chemistry of polymers by Palsand Hermans. Indeed, the numerical value of concentration correlation coefficient, when substituted into the Pals‐Hermansequation to replace the coefficient of isoionic dilution, yields a linear shape of the functionnsp/C =

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660101

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractRefractive index increments were determined very accurately for polydimethylsiloxane in toluene for the wavelengths 436 and 546 mß at five different temperatures from 15° to 35°C. Solutions of concentrations ranging from 0.005 to 0.05 g./ml. were used. the temperature and concentration dependence of the increment was obtained. The observed values are compared with those calculated from a Gladstoneand Daleexpression and the agreement is found to be very go

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660102

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractDie Polymerisation von Acrylnitril mit AgNO3in Substanz und in Lösung wird untersucht. In orientierenden Kinetischen Versuchen wird gefunden, daß die Reaktion nach einem radikalischen Mechanismus abläuft; sie wird durch Licht katalysiert. Außerdem wird die Aktivität einer Reihe anorganischer Salze und organischer Nitratebei der Initiierung der Polymerisation geprüft. Die Reaktionsmöglichkeiten werden disk

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660103

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe dehydrochlorination of polyvinylchloride in ethyl benzoate solution has been studied over the temperature range 178° to 212°C in an atmosphere of nitrogen. Over this temperature range the expression for the rate in moles HCl liberated/litre. sec., is 5.7·107e‐22,800/R.T.cn, where cnis the polymer concentration in polymoles/litre. Thus, for a fixed weight concentration of polymer, the rate is inversely proportional to the number average degree of polymerisation of the polymer.The presence of oxygen does not affect the rate of dehydrochlorination, but it causes a more rapid blackening of the polymer solution, and is accompanied by chain scission. The addition of free radical initiators increases the rate somewhat while quinone type compounds have no inhibiting effect. The addition of a commercial stabilizer (Stanclere 70) containing a dialkyl tin salt resulted in a retarded rate for a period proportional to the amount added. This was followed by the normal unretarded rate. The results, however, still leave undecided the mechanism of the dehydrochlorination reac

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660104

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe cross‐linking of polyvinylchloride in ethyl benzoate solution was studied over the temperature range 178 to 212°C. in an atmosphere of nitrogen. The effects of variation in polymer concentration and in molecular weight of the polymer on the time taken for the polymer solution to gel were observed, and the rate of crosslinking was calculated from such data by applying Flory's theory of gelation. Over the above‐mentioned temperature range the expression for the rate of crossbond formation was found to be 2.0·103e‐23,000/RT cw2crossbonds/1.·sec., where cwis the polymer concentration in monomoles/1. This expression applies to polymer samples with number average degrees of polymerization varying from 192 to 905, and may well apply to an even wider range.The addition of free radical initiators and free radical inhibitors had little effect on the time of gelation whereas oxygen retarded or prevented gel formation. The results in general support the view that the crosslinking process proceeds by a non‐radical mechanism, and involves a random condensation reaction between two structural units in different polymer molecules with the eliminat

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660105

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractDimensionen und Staudinger‐Indices einer Polystyrol‐Probe (Mw= 335 000) wurden in verschiedenen Θ‐Lösungsmittelgemischen bei 25°C gemessen. Entgegen den bisherigen Annahmen der Literatur sind beide Größen nicht unabhängig vom Θ‐System. In erster Näherung nehmen mit steigenden Dimensionen auch die Staudinger‐Indices zu, wobei die ersteren im Bereich zwischen 218 und 302 Å, die letzteren zwischen 39,1 und 69,9 ml/g variieren. Ein Einfluß der Polarität des Θ‐Gemisches ist nach Messungen der Kohäsionsenergie‐Dichte nicht feststellbar. Die Hugginskonstante kHnimmt mit steigenden Werten der Staudinger‐Indices ab und erreicht bie [η] ∼ 50 ml/g den Wert 0,5. Die Messungen können durch die Raumaufweitung der Knäuel durch den Raumbedarf der solvati

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660106

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe synthesis of a series of model compounds related to poly[2,2‐propanebis(4‐phenyl)‐carbonate] is described. Exposure of these compounds to electron beam irradiation and analysis of the products showed that degradation occurs predominantly at the carbonate grouping; reaction schemes are proposed for the products isolated. On the basis of these results and earlier work the radiation stability of the polymer is attributed mainly to its aromatic character, but it is suggested that radical recombination reactions are an important factor in reducing the degree of chain sci

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660107

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractDie bekannte Zweikernverbindung, 6,6′‐Dihydroxy‐3,3′‐dimethyl‐benzophenon (I), wurde nach einer geeigneteren Methode hergestellt. Die Darstellung der Dreikernverbindung, 4‐Hydroxy‐1‐methyl‐3,5‐bis(6‐hydroxy‐3‐methyl‐benzoyl‐(1))‐benzol (IV), gelang mittels einer Friedel‐CRAFTS‐Synthese. Die Strukturen von I und IV wurden durch Reduktion der Carbonylgruppen und Identifizierung der bekannten, Methylengruppen enthaltenden Zwei‐ bzw. Dreikernverbindung bewiesen. Einige Vierkernverbindungen mit drei Carbonylgruppen je Molekel konnten durch die FriesscheVerschiebung ent

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660108

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractWith the object of clarifying the kinetics of addition reaction between organic isocyanates and alcohols, the rate of reaction between phenyl isocyanate and 1‐butanol in benzene was examined in the presence of butyl phenylurethan, butyl butylurethan, and tributylamine at 20, 30, and 40°C. by the method of differential calculi on the graph of conversion against reaction time, and the effect of these added compounds on the reaction has been investigated. The mechanism and the rate equation for the reaction of organic isocyanates with alcohols, which had been studied by Bakeret al.2and Sato7, were re‐examined and discu

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660109

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractAnalysis of thermogravimetric weight loss data from the literature indicated correlations between the overall energietics of decomposition and characteristics of the thermogravimetric curves for measurements made under nitrogen. Such correlations provide a means for comparing relative thermal stabilities of polymers from easily obtained weight loss data.

ISSN:0025-116X    

DOI:10.1002/macp.1963.020660110

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY