摘要:

AbstractThe formation of cokes and graphites proceeds via the creation from the isotropic fluid phase of carbonization of pitch and coal, of lamellar nematic liquid crystals or mesophase. This anisotropic fluid, deformable mesophase, develops as spheres within which constituent molecules are stacked parallel to an equatiorial plane. This type of structure facilitates coalescence to a coherent mass which eventually forms a graphitisable carbon. The ‘onion‐skin’ structure of mesophase spheres cannot so coalesce. Different optical textures of cokes and graphites owe their origin to different chemical reactivities and fluidities of mesophase, the lower the fluidity the smaller the size of the optical texture. Mesophase from lameller molecules is compared with conventional rod‐like nematic liquid crystals. Structures in needle‐cokes, metallurgical coke, coke from solvent refiend coal and carbon fibre from pitch are discussed in terms of formation and properties of lamellar nematic liquid

ISSN:0007-1641    

DOI:10.1002/pi.4980130102

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThermotropic behaviour is observed in a number of aromatic polyesteramides containingp‐phenylene or substitutedp‐phenylene groups. In such polymers, a substantial proportion of co‐polymerised units lacking rigid rod structure can be tolerated without loss of thermotropic behaviour. Anisotropic melts can be formed at very short average chain length. The upper temperature limit of stability of the anisotropic phase is lower the shorter the average chain length and the greater the proportion of relatively flexible units. Some polyesteramides formally derived fromp‐N‐methylaminophenol also exhibit thermotropic

ISSN:0007-1641    

DOI:10.1002/pi.4980130103

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractAqueous gels can be made by heating concentrated solutions of the globular protein BSA above its unfolding temperature, around 60°. The effect of such factors as length of heating, protein concentration, pH and ionic strength on the small deformation shear modulus of the gel is determined. The results may be rationalised qualitatively in terms of the effect of these factors on the homogeneity and of the microstructure of the gel, but a quantitative description of the rheological properties in such a complex system remains to be found

ISSN:0007-1641    

DOI:10.1002/pi.4980130104

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe effects of particle size and concentration of calcium carbonate fillers on the critical oxygen index and the evolution of hydrogen chloride during pyrolysis of PVC have been examined. Both retention of hydrogen chloride in the condensed phase and critical oxygen index chloride in the condensed phase and critical oxygen index depend not only on concentration but also on particle size of the calcium carbonate. Efficiency of retention of hydrogen chloride increases with decreasing particle size and approaches 100% at particle sizes below 0.1 micron. Critical oxygen index is not appreciably affected by calcium carbonates of particle size around one micron. Coarser calcium carbonates increase critical oxygen index, while finer calcium carbonates decrease it up to concentrations at which all the hydrogen chloride is retained in the condensed phase, after which it is steadily increased with increasing concentration.

ISSN:0007-1641    

DOI:10.1002/pi.4980130105

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe kinetics of Ziegler‐Natta polymerisations can be described in terms of a spectrum of active sites, each with differing propagation rates and stereospecificity. It is therefore necessary to use complementary methods of measuring active centres to get the whole picture. Higher activity in polymerisation of propylene using TiCl3‐ Et2AlCl systems can be achieved by varying the catalyst preparation so that the effective surface area is increased or by removing inhibitors. When Et3Al is used as activatior in place of Et2AlCl higher activity is due to a combination of increase in number of centres per mole TiCl3and of increase in their propagation r

ISSN:0007-1641    

DOI:10.1002/pi.4980130106

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980130107

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe tensile and compressive strengths and the elastic moduli of sand and asbestos filled polymer cements, based on the aluminosilicate/poly(acrylic acid) (ASPA) system, have been measured. A progressive decline in property with increasing volume fraction of filler (in the range 5 to 12%) was observed. The decline is interpreted in terms of dilution, lack of matrix‐filler interaction and void conten

ISSN:0007-1641    

DOI:10.1002/pi.4980130108

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractIn this paper, the general expressions of average molecular weights for condensation polymerisation involving eliminat species are derived in the pre‐gel region especially for systems composed of monomers endowed with both A and B coreactive functional groups. The weight average molecular weights are calculated directly according to a new method using the propagation expectatio

ISSN:0007-1641    

DOI:10.1002/pi.4980130109

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980130110

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980130101

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY