ISSN:0007-1641    

DOI:10.1002/pi.4980080102

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractFree cationic polymerisations were initiated in bulk by field ionisation with a positive tip. Dilatometric measurements obtained with ‘dry’ and ‘ultra‐dry’ styrene,a‐methylstyrene and isobutylvinylether were in agreement with kinetic equations derived by assuming that in the absence of deactivating impurities the space charge is built up only by growing macromolecules.Determination of the space charge by independent physical methods suggests that the kpvalues of the literature need to be re‐evaluated. It was also shown that charge injection enhances the degree of dryness (measurable by this process) and is therefore useful in ultimate purificatio

ISSN:0007-1641    

DOI:10.1002/pi.4980080103

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractDynamic mechanical properties of substituted polypentenamers having thioglycolate side groups and their hydrogenated derivatives have been studied. Methyl esters, acids and salts were investigated at two concentrations, 5.5 mole (%) and 9.2 mole (%). In the un‐hydrogenated derivatives one principal relaxation, labelled β, exists in the temperature range from‐160 to 100°C. This relaxation arises from microbrownian segmental motion accompanying the glass transition. Its temperature is affected by the concentration of substituent but not the chemical nature of the substituent. A ‘rubbery plateau’ region exists in the acid and salt derivatives and in the latter the salt groups act as reinforcing fillers in this plateau region, consistent with the ionic domain model for their structures.In the hydrogenated derivatives, three relaxations occur in the temperature range from −160 to 120°C and these are labelled α, β, and γ in order of decreasing temperature. The α relaxation arises from motions associated with the crystal phase except in the case of the 9.2 mole (%) sodium salt derivatives where it arises from motions occurring within ionic domains. The β relaxation arises from microbrownian segmental motions accompanying the glass transition, and the γ relaxation arises from localised motions which may involve both amorphous and crystallin

ISSN:0007-1641    

DOI:10.1002/pi.4980080104

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractUsing the Gibbs free energy of mixing relation of Flory and Huggins with a concentration‐dependent interaction parameter one can calculate quasi‐binary phase diagrams for solvent‐polymer systems. If the polymer has a very asymmetric molecular weight distribution, separation into three‐liquid‐phases occurs which may result in a cloud‐point curve without stable critical point. In the latter case the spinodal does not touch the stable branches of the cloud‐point curve and the coexistence curves show marked bends and kinks. These phenomena could be qualitatively verified by experiments on the system cyclohexane‐polystyrene. The phase‐volume ratio method for the determination of consolute states itself clearly indicates when situations prevail precluding

ISSN:0007-1641    

DOI:10.1002/pi.4980080105

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractElectric birefringence studies have been made on a sample of high molecular weight cellulose trinitrate in acetone. The molecule is shown to have only a permanent dipole moment and no significant anisotropic polarisability in this solvent. Both the rotary relaxation times obtained from transient time dependent effects and the amplitudes of the observed birefringence have been analysed in terms of theories for rigid rods, weakly bending rods, worm‐like chains and both flexible and stiff random coils. The study indicates that (a) electric birefringence data are sensitive to molecular flexibility and (b) that in this solvent, nitrocellulose of 12% nitrogen content appears to be a stiff, non free draining coil with a dipole moment of the order of a few debye (i.e. ⋍ 10−29C m) per monomer

ISSN:0007-1641    

DOI:10.1002/pi.4980080106

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980080107

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980080108

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980080101

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY