摘要:

AbstractSolid‐phase pyrolysis directly integrated with gas chromatography has been further developed in the field of polymer studies. The use of the technique applied to polymer structure is reviewed critically, and the application to a range of styrene copolymers is described. The yield of the depolymerising species, styrene, under operating conditions giving reproducible and quantitative results is found to be in qualitative agreement with the structures expected from copolymerisation parameters.In the extreme cases of random and block copolymers, exemplified by commercial butadiene‐styrene copolymers, pyrolysis/gas chromatography is shown to be capable of distinctive differentiat

ISSN:0007-1641    

DOI:10.1002/pi.4980010501

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractA brief investigation has been carried out into the nature and quantity of the toxic gases evolved during the thermal decomposition of polyurethane, urea‐formaldehyde, nylon and acrylonitrile in air and in nitrogen. The weight fractions of the polymers evolved as hydrogen cyanide are given, together with the lowest temperatures at which hydrogen cyanide, carbon monoxide, ammonia and nitrogen oxides are evolved. Apparent activation energies for the evolution of hydrogen cyanide and carbon monoxide have been determined. A brief discussion of the experimental data is give

ISSN:0007-1641    

DOI:10.1002/pi.4980010502

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe equations relating to gas transmission rate given in some published specifications are considerably in error, particularly at large values of mercury displacement. The exact integrated expression applying to an extended interval is cumbersome to use, however, and a good approximation to it would be acceptable in most cases. An equation has been derived which is both theoretically justified and empirically satisfying and, within the limit of the specifications as at present laid down, would be in error by no more than 5 %.

ISSN:0007-1641    

DOI:10.1002/pi.4980010503

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractBF2‐chelates are powerful polymerisation catalysts for epoxy resins; derivatives of β‐diketones and of β‐ketoamides are especially interesting as ‘latent’ hardeners. Comparison of these metal halide chelates with BF3‐amine complexes in various epoxy systems has shown the chelates to be superior in several respects. Particular advantages are the ease with which reactivity can be varied by choice of chelate structure and by addition of moderators, and the reduced sensitivity to atmospheric moisture during cure. Use of BF2‐Chelates also gives cured products with better electrical properties, and in many cases better mechanical properties, than with BF3

ISSN:0007-1641    

DOI:10.1002/pi.4980010504

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractFilms of unstabilised PVC have been exposed to xenon‐arc irradiation at various levels of intensity within a limited temperature range, and the rates of photo‐oxidation have been determined by infra‐red spectroscopy. It has been found that the rate of reaction is directly proportional to radiation intensity measured in absolute units, and that transposition of time and radiation intensity is valid. The consequences of this finding have been discussed in terms of reaction mechanism and acceleration of the time scale for oxidation of PVC under artificial exposures to the xenon‐arc, compared with outdoors exposure to solar radiation at Melbourne and

ISSN:0007-1641    

DOI:10.1002/pi.4980010505

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractSynthesis of α‐(aminoalkyl) acrylates has proceeded along the conventional malonic ester route. The amino structure was protected by the use of phthalimido derivatives with subsequent removal of the phthalate moiety to produce the desired esters. Ethyl α‐alkyl acrylates with phthalimido, phthalimidoethyl and phthalimidobutyl groups as the α‐substituent were prepared together with the phthalimidoethoxyethyl derivative. The esters were prepared in substantial purity but with some difficulty owing to their ease of polymerisation. Infra‐red spectra and polymerisability studies were carried out on the new α‐phthalimidoalkyl acrylates and are presented here. Hydrolysis (with hydrazine hydrate) of these intermediate esters to their corresponding α‐(aminoalkyl) acrylates was shown qualitatively using a modified ninhydrin test. It was necessary to develop a modified test procedure since excess hydrazine from the hydrolysis was found to interfere with the ninhydrin

ISSN:0007-1641    

DOI:10.1002/pi.4980010506

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractHot‐melt adhesives based on ethylene‐vinyl acetate (E‐VA) copolymer resins are compared with other important classes of adhesive products, and reasons for the prominence of E‐VA copolymer resins in this field are discussed. Particular emphasis is placed on the influence of the randomly distributed vinyl acetate content on the structure and properties of E‐VA copolymers. Molecular structure is the factor which most strongly influences compatibility of the E‐VA resin with other hot‐melt ingredients.A procedure for tackling the problem of hot‐melt adhesive formulation is described, and emphasis is placed on the importance of having available simple test procedures for the complete and reliable assessment of adhes

ISSN:0007-1641    

DOI:10.1002/pi.4980010507

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractCopolymers of ethylene and vinyl acetate (E‐VA) of a certain composition can be used for the improvement of impact properties (elasticisation) of PVC as well as under certain conditions (grafting) for the preparation of flexible PVC (plasticisation). Products of interesting properties are prepared by blending E‐VA (up to ∼ 12%) with PVC or more advantageously by grafting vinyl chloride on special E‐VA types. Graft copolymerisation by the suspension method allows the synthesis of E‐VA/PVC systems in all ratios (up to 80% E‐VA); these polymers are compatible over the whole range in contrast to the blends.Studies on the grafting efficiency of some monomers show that vinyl chloride can be grafted readily on E‐VA.The grafting process is performed on a technical scale to give PVC types with E‐VA contents up to 50%. Products with 6–8% E‐VA should be classified as impact‐modified suspension PVC. Flexible types (40–60% E‐VA) have properties of flexible PVC with the plasticiser chemically incorporated, but may also be blended with unmodified PVC to give impact‐improved formulations.The properties of the elasticised PVC (8% E‐VA) mainly depend on the vinyl acetate (V‐OAc) content of the E‐VA and its molecular weight. Levapren® 450 P (45% V‐OAc; mol. wt. ∼ 100,000), a solution process copolymer, has good elasticising efficiency in blends and graft copolymers with PVC.PVC/E‐VA products may be processed with or without addition of uncombined PVC into rigid or flexible PVC by the usual methods of PVC technology, e.g. extrusion, injection moulding, blow‐moulding and calendering.Competitive modifiers, such as acrylonitrile‐butadiene‐styrene copolymers, methacrylate‐butadiene‐styrene copolymers, acrylates or chlorinated polyethylene, are compared with E‐VA. Levapren® 450 P shows high efficiency as an impact modifier even in low concentration, giving good processability and ageing behaviour. Glass‐clear high‐impact PVC cannot be obtained by E‐VA modification.Some electron microscopy studies to characterise the distribution of E‐VA in the resin phase (PVC) a

ISSN:0007-1641    

DOI:10.1002/pi.4980010508

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe function of ethylene as a plasticising comonomer for vinyl acetate is reviewed from the historical standpoint and in relation to alternative methods of plasticisation. Both chemical and physical effects are considered. Emulsion polymerisation and the use of aqueous dispersions are covered in some detail, and methods of polymer characterisation are summarised, with particular reference to i.r. and n.m.r. spectroscopy.

ISSN:0007-1641    

DOI:10.1002/pi.4980010509

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980010510

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY