摘要:

AbstractNous avons étudié les propriétés rhéologiques des matériaux à l'état fondu au moyen d'un viscosimètre à capillaire.Nous avons essayé de relier les valeurs des énergies d'activation, à vitesse et tension de cisaillement constantes, avec les valeurs de l'indice d'écoulement.Les valeurs de l'indice d'écoulement obtenues selon l'approche mathématique ne coincident pas avec les valeurs obtenues expérimentalement. L'énergie d'activation de LDPE est supérieure à celle du HDPE en raison du volume libre de LDPE

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730101

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractBased on the newly proposed instrumental spreading shape function (ISF) of Omorodion and Hamielec1and the new theoretical developments on peak dispersion phenomenon2, the present study reported herein deals with some of the non‐inherent contributing sources to peak dispersion phenomenon in SEC. Despite when the choice of a suitable mobile phase has been accomplished for a particular polymer/packing material system3–5, the need to optimize the system for minimum peak broadening is still very important. The major contributing sources discussed here are the roles of pore dispersion (large pores) and polymer/small pore‐size surface area interactions resulting from the traditional method of column arrangements. The systems employed in the study are dextran/mostly CPG systems. Other packing materials employed included Bio‐glass (BG) and EM‐gel (EM), both of large pore s

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730102

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of organic pigments on the supermolecular structure of mass coloured PA fibres has been investigated by means of small‐angle and wide‐angle X‐ray scattering methods. It has been found that the dye molecules introduced in polymer melt before the fibre is formed take part in the formation of the supermolecular structure of the fibres. The presence of these molecules causes changes of the weight fractions of the polymorphic forms of the polyamide, the increase of the crystallinity index of the fibres and the increase of the thickness of the transition layers between crystalline and amorphous regions. Changes which have been observed are dependent both on the content of pigments and on their chemical n

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730103

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractCrosslinking of polyethylene (PE) photoinitiated by some benzoquinones and naphthoquinones has been studied. The quantum yields (φ) of the initiator reactions in PE under UV irradiation were measured. The φ‐values for benzoquinone, tetrachlorobenzoquinone, tetrabromobenzoquinone, tetrafluorobenzoquinone, naphthoquinone, and 2,3‐dichloronaphthoquinone were equal to 0.23, 0.18, 0.14, 0.26, 0.09, and 0.11, respectively. Naphthoquinones were more effective as initiators in photocrosslinking of polyeth

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730104

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractTerpolymer resins (SBT) were synthesized by the condensation of salicylic acid and biuret with trioxane in the presence of acid catalyst and using varied molar ratios of reacting monomers. Terpolymer resin compositions have been determined on the basis of their elemental analysis and the number average molecular weights of these resins were determined by conductometric titration in non‐aqueous medium. The viscosity measurements carried out in DMF indicate normal behaviour. IR spectra were studied to elucidate the structure. TGA data were analysed to estimate the characteristic thermal parameters. The terpolymer resins have been further characterized by reflectance spectra in solid state, absorption spectra in non‐aqueous medium, X‐ray diffraction and electrical conductivity. Chelation ion‐exchange properties have also been studied employing the batch equilibration

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730105

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractMit Hilfe einer neuartigen Untersuchungsmethode wurden die Diffusionskoeffizienten von Ammoniak (NH3) in 22 transparenten filmbildenden Polymeren bei Raumtemperatur bestimmt. Die Methode beruht auf der UV‐VIS‐spektroskopisch verfolgbaren reversiblen Reaktion von Ammoniak mit 4‐Nitrophenol zu einem 4‐Nitrophenolat‐Ammoniak‐Meisenheimer‐Komplex.Die Farbbildungsreaktion im Polymerfilm wurde untersucht und anhand einer einfachen Näherung der Diffusionsgleichung ausgewertet. Die erhaltenen Diffusionskoeffizienten stimmen sehr gut mit den wenigen verfügbaren Literaturwerten überein.Die Abhängigkeit der NH3‐Diffusionskoeffizienten von der Polymerstruktur ist weitgehend der für permanente Gase bekannten analog.Die beschriebene Methode erlaubt problemlos, Diffusionskoeffizienten zu messen, die sich bis zu drei Größenordnungen unterscheiden (Ethylcellulose: 1,07 · 10‐7cm2· s‐1; Polyvinyla

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730106

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe orientation mechanism of cold‐drawn, partially crystalline polyoxymethylene (ULTRAFORM) samples was studied by performing wide angle X‐ray scattering (WAXS) measurements. The anisotropic samples were prepared in uniaxial tensile tests around 130°C, in a temperature range between the glass transition and the melting point. The process of the plastic deformation is discussed for different degrees of anisotropy. The orientation distribution of the crystalline lamellae was qualitatively characterized by performing pole figure intensity calculations from the measured WAXS intensities. The degree of orientation was quantitatively described by calculating the orientation factors for the [100] normal vector of the unit cell. The texture of the necked samples with high orientation degrees was a mixture of axial and uniplanar‐axial textures. An explanation for the formation of this kind of orientation is proposed assuming an influence of the sample geometry on the orientation p

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730107

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractPolystyrene (PS) was reinforced/filled with grafted thermomechanical pulp (TMP) of aspen and birch. The dependence of tensile properties of composites on different loadings of filler, on polymer loading in grafted fiber, on the presence of homopolymer in grafted fiber, and on impregnation of fibers with PS were studied. PS filled with grafted aspen and birch (lower polymer loading) showed a significant increase in tensile strength and modulus. Fracture energy and elongation of the composites decreased with an increase in the concentration of filler.

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730108

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe thermal expansibility of high density polyethylene is calculated within the framework of the composite model which has already been found useful in describing its mechanical properties and thermal conductivity. The orientational changes of the units of which the bulk of the polymer is supposed to be composed has been derived from a two parameter empirical relation proposed by the authors. A comparative study of the variation of the orientational parameters with processing conditions has also been included.

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730109

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractA poly(quaternary ammonium) salt, 2,4‐ionene, has been immobilized on a macroporous chloromethylated poly(styrene‐divinylbenzene) resin (XAD‐2). The ionene content of the resin, determined by CHN elemental analysis, was 50.2 g/kg resin. The most important side effect of the modified resin, catalyst (2,4‐ionene) bleeding, can be detected by a spectrophotometric method capable of determining extremely low concentrations of free ionene in the supernatant of the resin.The activity of these immobilized 2,4‐ionene/cobalt(II)phthalocyanine‐tetrasodiumsulfonate (CoTSPc) complexes towards the oxidative coupling of thiols is much lower than in the homogeneous case, but still considerably higher than for the polymer free system. The observed decrease in reaction rate does not originate from the considerable mass transfer resistances but predominantly from catalyst properties like a very low local N+/Co ratio. The active sites appear to be present in the outer shell of the resin par

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051730110

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY