摘要:

AbstractA procedure for photochemically detaching, isolating and characterising grafts (produced by a method developed previously by the authors) from glass surfaces is described. Preliminary results indicate that the molecular weights and molecular weight distributions can be varied through control of the kinetics of graft formation; our previous studies are seen to have produced a high surface coverage of grafts of high molecular weight. A thermodynamic argument is developed to explain the immiscibility of grafts with free homopolymer for high surface coverage by grafts from which it is seen that the immiscibility is entropy‐driven. Comparisons are drawn between our previous studies and relevant studies by other workers and apparent anomolies are explaine

ISSN:0007-1641    

DOI:10.1002/pi.4980160202

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe tacticities of poly(tri‐n‐butyl tin methacrylate)s prepared with radical initiators at various temperatures have been measured by13C n.m.r. As expected, the polymers are predominantly syndiotactic and this syndiotacticity decreases with an increase in temperature. The activation parameters governing the tacticity are similar to those published for poly(methyl methacrylate) but differ somewhat from values published for poly(trimethyl tin methacryla

ISSN:0007-1641    

DOI:10.1002/pi.4980160203

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractElectroinitiated cationic copolymerisation of α‐methylstyrene and β‐bromostryene has been studied at various applied potentials. The relationship between copolymerisation potential and resulting copolymer composition was investigated. The advantages of employing constant potential electrolysis over constant current electrolysis are discussed in terms of the reactivity ratios. The reactivity ratios of the monomers are calculated according to the integrated Lewis‐Mayo e

ISSN:0007-1641    

DOI:10.1002/pi.4980160204

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractPolymers are widely used as resists in electron beam lithography. This paper is concerned with theoretical modelling of the electron beam lithographic process and establishing criteria which need to be satisfied for a polymer to behave as a good positive resist. The effects of molecular weight, tacticity, solvent selection and sequence structure are discussed. Criteria are presented upon which the design of a new resist material may be based.

ISSN:0007-1641    

DOI:10.1002/pi.4980160205

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe composition and microstructure of a blend of bisphenol‐A polycarbonate (PC) and poly (butylene terephthalate) (PBT) have been established by a variety of physical methods. The composition was established by solvent extraction and infra‐red spectrophotometry, while the microstructure was determined by these and the additional methods of differential scanning calorimetry and dynamic mechanical thermal analysis. The PBT retained its crystallinity in the commercial blend, (Xenoy CL‐100), but blending reduced the main glass‐rubber transition of the PC from 147°C to approximately 100°C. Conditioning of the blend at high temperatures resulted in progressive transesterification: 3 minutes at 240°C gave a small but significant effect, while 30 minutes at 270°C yielded large changes in the structure. These findings are important in respect of processing the material, and the limitations which might be incurred in plant recycli

ISSN:0007-1641    

DOI:10.1002/pi.4980160206

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe amount of cationic soluble polymer fixed by cellulose fibres, whose specific surface area is increased by beating, was determined by a colloidal titration method. A linear relationship between the polymer uptake and the surface density of carboxyl groups was obtained up to a beating degree of 54°SR. For higher values, the uptake was found to be independent of surface carboxyl groups. These results are interpreted in terms of two mechanisms: a fixation of polycations through an ion‐exchange mechanism and an adsorption of polymer by Van der Waals interactions and/or hydrogenbondi

ISSN:0007-1641    

DOI:10.1002/pi.4980160207

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe tactic structure of PVAc synthesised by matrix polymerisation was reported. At temperatures below 0°C, for a ratio, matrix to monomer, equal to 3, a higher packing degree of the macromolecular chains was obtained. The third peak of the X‐ray diffraction spectra of matrix samples suggests the existence of isotactic polym

ISSN:0007-1641    

DOI:10.1002/pi.4980160208

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractAmine‐organic halide systems have been found to be good photo‐initiators for the polymerisation of vinyl monomers in a benzene medium. The n‐tertiary butylamine‐carbonte‐trachloride (TBA‐CC14) system is most suitable for the polymerisation of methyl meth‐acrylate (MMA) in the presence of light. The rate of polymerisation (Rp) and degree of polymerisation (P̄n) are found to be independent of incident light intensity (Io).Rp and 1/P̄n are linearly related to [TBA]0.5up to [TBA] = 0.108M, but above this concentration, TBA acts predominantly as a retarder.Rp and 1/P̄n are proportional to [CC14]0.5at low [CC14]. At [CC14]>0.099M it acts predominantly as a transfer agent. Furthermore,Rp is always proportional to [MMA]1.0Endgroup analysis by dye‐partition test shows that both amine bearing radicals and CC13radicals are the initiating species and an average of about one total endgroup per polymer molecule up to [CC14] = 0.099M indicates bimolecular termination of the poly (MMA) radicals through disproportionation. Higher chlorine endgroup and total endgroup incorporation at [CC14]>0.099M gives additional evidence of the preponderance of chain transfer under this condition. A suitable mechanism of polymerisation is suggested, based on kinetics and

ISSN:0007-1641    

DOI:10.1002/pi.4980160209

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA rapid method for the quantitative assay of alginate in solution over a wide concentration range (0.01–0.5 percent) has been developed using the polymetric cation poly(hexamethylenebiguandinium chloride) [PHMBH+Cl−]. The procedure consists of the addition of a known excess amount of PHMBH+Cl−to alginate solutions to precipitate the sample quantitatively and therafter measuring the u.v. absorption of residual PHMBH+C1−in the supernatant. The working range of the assay can be altered by simply adjusting the excess quantity of PHMBH+Cl−which is added during the assay. Assay response is easily reproducible and insensitive to variation in salt concentration (up to 2.5 per cent), pH (5.5–7.6) and temperature (10–60°C). The PHMBH+Cl−method shows good agreement with another recognised method for the assay of alginate solutions. The simplicity of this new method and the short time required to perform it, enhances its suitability as a quick analytical procedure for alginates. Preliminary evidence suggests that assay response is independent of the D‐mannuronic acid/L‐guluronic ac

ISSN:0007-1641    

DOI:10.1002/pi.4980160210

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractLiquid state radiation‐induced and electroinitiated polymerisations of epoxycyclopentane (ECP) have been investigated. Dichloromethane and tetrabutylammonium hexafluoro‐phosphate were employed as a solvent electrolyte couple. Temperature effects on the rate of electroinitiation were also studied. Apparent activation energy for the electroinitiated polymerisation was calculated from the Arrhenius plot. The propagation of the polymerisation for both methods was found to be through the opening of the epoxy ring, as verified by i.r. and n.m.r. spectra. Both methods of polymerisation yielded tacky, amorphous polym

ISSN:0007-1641    

DOI:10.1002/pi.4980160211

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY