摘要:

AbstractStyrene–acrylonitrile copolymer latices were prepared by emulsion polymerisation using sodium lauryl sulphate as emulsifier and potassium persulphate as initiator. The effect of polyoxyethylene nonyl phenyl ether on the stability of these copolymer latices has been investigated using magnesium chloride as a flocculating agent by measuring the rates of flocculation in the presence of various concentrations of surfactant. The values of the critical coagulation concentration (c.c.c.) were found to increase with increasing surfactant concentration for all latices. The rates of increase in c.c.c. with increasing surfactant concentrations were found to increase uniformly with increase in the content of acrylonitrile. The electrophoretic behaviour of these latices in the presence of surfactant has also been investigated. The values of mobilities at c.c.c. were found to decrease with increasein concentration of surfactan

ISSN:0007-1641    

DOI:10.1002/pi.4980070602

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractA series of poly(fluoroethers) has been studied by thermogravimetry, pyrolysisgas chromatography–mass spectrometry and fluoride ion analysis. The thermal stabilities are lower than those of a vinylidene fluoride/hexafluoropropene copolymer. Primary chain scission occurs at O—CH2links. Rearrangement processes giving rise to cyclic compounds are important for polymers containing aromatic or heterocyclic rings in the ch

ISSN:0007-1641    

DOI:10.1002/pi.4980070603

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractTwo perfluoroalkylene‐linked organosiloxane polymers have been studied by thermogravimetry, pyrolysis–gas chromatography–mass spectrometry and fluoride ion analysis. Fluorine transfer processes play an important part in the thermal brea

ISSN:0007-1641    

DOI:10.1002/pi.4980070604

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractPoly (1,3‐phenylenehexafluorotrimethylene) and perfluoroalkylene‐linked polyanhydride, polycarbonate and polyester have been studied by thermogravimetry, pyrolysis–gas chromatography–mass spectrometery and fluoride ion analysis. The thermal stability is governed by the ease of formation of specific cyclic degradation p

ISSN:0007-1641    

DOI:10.1002/pi.4980070605

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractGel permeation chromatography (g.p.c.) was used to monitor the degradation of polymeric viscosity index improvers in multigrade oils when subjected to mechanical shear using a Kurt Orbahn diesel injector rig. These tests are normally evaluated by measurement of viscosity of the oils before and after shear. For model systems of a base oil containing each of ten viscosity index improvers there is good correlation between viscosity and chromatography results. Tests on a multigrade oil subjected to sonic shear showed that g.p.c. can be used to follow qualitatively the degradation of one polymeric additive in the presence of another.

ISSN:0007-1641    

DOI:10.1002/pi.4980070606

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractVinyl acetate has been shown to polymerise during the electrolysis of its aqueous acidified emulsion. The stabilisation of the emulsion is difficult and sodium salts of ethoxylated fatty alcohols have been used as emulsifier. Polymerisation occurs only within a narrow, low pH range. Percentage conversion and molecular weight show a maximum at about pH = 1. Below this value, acid hydrolysis of monomer interferes with the polymerisation whilst at higher values a change in the electrode process may occur. Polymerisation is considered to occur through the presence of hydrogen radicals adsorbed on the mercury cathode.

ISSN:0007-1641    

DOI:10.1002/pi.4980070607

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe characteristics of the propagation process for the electroinitiated emulsion polymerisation of vinyl acetate are described when current is varied by a factor of 36 and emulsifier concentration by 128. The order with respect to current is 0.8, whilst with emulsifier concentration, two definite ranges are observed with exponents 0.26 and 1.12 at low and high concentrations respectively. A similar two range effect is observed using particle size measurements. Behaviour at low emulsifier concentration is similar to that described previously for vinyl acetate, involving particle formation mainly by precipitation from solution. At high emulsifier concentrations micelle formation appears to be of increased importance.

ISSN:0007-1641    

DOI:10.1002/pi.4980070608

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractOf the monomers studied, vinyl acetate and vinyl n‐caproate are the only ones capable of electroinitiated homopolymerisation in aqueous acidic emulsion. Water solubility does not appear to be the overriding consideration. Activity of the radical would seem to be most important. Copolymerisation with monomers not undergoing homopolymerisation in this system produces good yields of copolymers low in vinyl acetate concentratio

ISSN:0007-1641    

DOI:10.1002/pi.4980070609

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractPhase separations in condensed systems are reviewed on the basis of the still valid considerations of Gibbs, Van der Waals and Schreinemakers, formulated many years ago. Examples are taken from more recent data on mixtures containing macromolecules, which appear to obey phase‐rule theory in great detail and subtlety. The phase rule sets limits to the maximum possible number of phases, the actual number being governed by the precise dependence of the free enthalpy (Gibbs free energy) of mixing on temperature, concentration, molecular weight, etc. Accurate knowledge of the free enthalpy function allows prediction of phase behaviour with great precision. Methods are described which permit sufficiently accurate determination of the necessary parameter

ISSN:0007-1641    

DOI:10.1002/pi.4980070610

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980070611

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY