摘要:

AbstractThe monomer sequence distributions of three types of aryl ether sulphone copolymers have been determined by13C n.m.r. spectroscopy. Two amorphous aryl ether sulphone copolymers were shown to have transetherified (or ether interchanged) during polymerisation to become random copolymers. The residues in these copolymers were (i)—OøOøSO2øS—and (ii)—OøSO2øøSO2ø—‐where ø denotes 1,4‐phenylene. Copolymers of 50:50 aryl ether sulphone and aryl ether ketone made from different combinations of monomers were found to have different solubilities in dimethyl sulphoxide, and from13C n.m.r. data this was shown to correlate with the amount of transetherification which had taken place during the polymerisations. The13C n.m.r. chemical shifts for some of the carbon nuclei in these polymers were sensititive to functional groups situated even as far away as three or four aromatic nuclei alon

ISSN:0007-1641    

DOI:10.1002/pi.4980200402

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe cloud point curves for the ternary solutions non‐solvent/dimethyl‐formamide/polyethersulphone and non‐solvent/dimethylformamide/polysul‐phone were determined by a titration technique, at 303 K. In both systems the following order of increasing non‐solvent content at the cloud point was obtained: water

ISSN:0007-1641    

DOI:10.1002/pi.4980200403

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPoly (vinyl chloride), PVC, and poly(vinylidene fluoride), PVDF, are incompatible polymers. Poly(neopentyl glycol adipate), PDPA, is miscible with both PVC and PVDF. With PDPA acting as a compatibilizer between PVC and PVDF. compatible PVC/PDPA/PVDF blends can be formed at PVDF content of about less than 50wt%. Above 50wt% PVDF the ternary blends exist in two phases exhibiting two glass transition temperatures,Tg, PVC is the main contributor to the mechanical strength while PDPA and PVDF contribute to the elastic properties of these blends. A compatible blend of 55/22.5/22.5 wt% PVC/PDPA/PVDF exhibiting one singleTgappears to show an interesting balance of the properties of the blend components.

ISSN:0007-1641    

DOI:10.1002/pi.4980200404

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSome oligomeric species (condensates) in a melamine‐formaldehyde adduct mixture have been isolated by preparative high performance liquid chromatography (h.p.l.c.) and partly identified by high field1H and13C nuclear magnetic resonance (n.m.r.) spectroscopy. The oligomers are shown most likely to be largely dimers, trimers and tetramers and to contain both methylene and methylene ether linkages. Some cured melamine‐formaldehyde resins are shown by solid‐state cross‐polarisation magic angle sample spinning (c.p./m.a.s.)13C and15N n.m.r. to contain linear and branched methylene and methylene ether linkages but few free methylol groups. The relative proportions of the various linkages in both the oligomers and the cured resins appear to be controlled mainly by the melamine: formaldehyd

ISSN:0007-1641    

DOI:10.1002/pi.4980200405

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe following aspects of the manufacture, properties and applications of biaxially oriented poly(vinyl alcohol) (PV‐OH) films are discussed: selection of starting PV‐OH; method of production by successive biaxial orientation: technical aspects of production; characteristics and applications of the film. Biaxially oriented PV‐OH films have good antistatic properties, good thermal resistance, oil and solvent resistance, and excellent gas barrier properties, and are used in food packaging applications.The following aspects of the manufacture, properties and applications of poly(vinyl alcohol) film produced by a blown film technique are discussed: selection of starting PV‐OH; process for the production of hot‐water‐soluble (HWS) film; technical aspects of film production; characteristics and applications of the film. Blown films, which are hot‐water‐soluble, are produced in tubular form, for conversion into disposab

ISSN:0007-1641    

DOI:10.1002/pi.4980200406

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPoly(vinyl alcohol) (PV‐OH), prepared from poly(viny) acetate), is used widely in many industries. Various grades have been produced, with different degree of polymerization and degree of hydrolysis. Recently, novel modified (PV‐OH)s with anion, cation, silanol or hydrophobic groups have been studied and developed. They have new properties in addition to those of ordinary PV‐OH and have new applications. The methods of modification and the characteristics and some applications of the modified polymers are desc

ISSN:0007-1641    

DOI:10.1002/pi.4980200407

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe requirements for PVC suspension resin have changed considerably in the last few years, so much so that few companies have products on their ranges that are more than 4 or 5 years old. The suspending agent has a crucial influence on the morphology of the resin, so the changes in resin characteristics have largely been achieved by changes in the suspending agent systems.After a brief review of the mechanism of PVC suspension polymerisation, the properties of polymers made using PVOH suspending agents are related to changes in the latter. The effect of variations in PVAc degree of hydrolysis and viscosity are related to changes in surface tension. Methods of achieving higher porosity by using low hydrolysis co‐suspending agents are described. It is shown that higher bulk densities can be achieved by delayed addition of the PVOH. Levels of conjugated unsaturation and copolymer distributions are also shown to have important influence

ISSN:0007-1641    

DOI:10.1002/pi.4980200408

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe thermoreversible gelation of solutions of poly(vinyl alcohol) in ethylene glycol was investigated by calorimetric and optical observations, X‐ray scattering techniques and rheological measurements. The gelation that occurs on cooling to room temperature results from a liquid‐liquid demixing, followed by a crystallization of the polymer in the concentrated domains. As a consequence of the two‐phase morphology, practically no molecular orientation is observed when the gels are stretched. Gelation at high temperature, above the region of liquid‐liquid demixing, originates from a slow crystallization from solution. On stretching these gels, the crystallites orient their molecular axis perpendicular to the stretching direction and the (101) plane either parallel or perpendicular to the same direction. Rheological observations show that under no circumstances is a real network formed. The different gels studied resemble much more a stable colloidal dispersion with thixotropic pro

ISSN:0007-1641    

DOI:10.1002/pi.4980200409

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA trend in the inhibition period of vinyl acetate monomer (VAM), using benzoyl peroxide (Bz2O2), azobisisobutyronitrile (AIBN) and potassium peroxy disulphate (K2S2O8), during suspension, emulsion and bulk polymerizations, with change in pressure from 730 mm Hg to 760 mm Hg, is reported.

ISSN:0007-1641    

DOI:10.1002/pi.4980200410

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980200412

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY