摘要:

AbstractParmi les nombreuses méthodes permettant de suivre la circulation de l'eau libre dans un matériau, les méthodes diélectriques (région des micro‐ondes) semblent à la fois particulièrement sensibles et appropriées.A 9 GHz nous avons pu étudier et déterminer, au moyen d'une technique de perturbation d'une cavité résonnante, les coefficients de diffusion de films de polyuréthanne. Des mesures simultanées de perméabilité à la vapeur d'eau ont aussi été entreprises.Les résultats mettent en évidence d'une part un faible comportement Fickien et d'autre part une augmentation du coefficient de diffusion et de perméabilité avec l'épaisseur. Le caractère hydrophile des constituants du film et le manque d'aération de la surface sont pris en compte com

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300101

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractRadiation and thermal curing of unsaturated polyester resins with styrene were investigated by combining differential thermal analysis with electric and mechanical relaxation techniques. A microprocessor controlled combined relaxation equipment of special construction was used. By radiation initiated curing the reaction was interrupted at different stages and the products were analyzed. Relaxation and simultaneous differential thermal measurements were also made during the course of gamma radiation and peroxide initiated thermal curing. By this way the shift of the characteristic transitions of the resin as a function of conversion could be studied. Also the change of the phase‐structure of the resin caused by the reaction was monitored. By deconvolution of the dielectric spectrum band the physical structure was found to become heterogeneous by crosslinking.Besides the shift of the transition temperatures the oscillator strength of the dielectric transition was found to decrease with conversion. Electrical polarization and depolarization studies were also performed. A special intermittent load thermomechanical technique was used for separating elastic from viscous response of the sample subjected to external mechanical force. The transitions exhibited by the thermomechanical curves were found to shift to higher temperatures by crosslinking and the compliance plateaus decrease

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300102

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractEine Probe eines Styrol‐Acrylnitril‐Copolymeren mit etwa 40 mol‐% Acrylnitril wurde mit Hilfe der Trübungstitration (TT), der Ausschlußchromatographie (SEC), der TT von SEC‐Fraktionen und der Hochdruck‐Fällungschromatographie (HPPLC) der SEC‐Fraktionen untersucht. Während die TT und die SEC für das unfraktionierte Copolymere zwar breite, aber scheinbar homogene Verteilungen nach der Molmasse und der Zusammensetzung lieferten, offenbarten Kreuzuntersuchungen (TT von SEC‐Fraktionen/HPPLC) das Vorliegen von drei ziemlich unterschiedlichen Komponenten. Dieses Ergebnis wurde zuerst durch die TT der SEC‐Fraktionen mit n‐Hexan als Fällungsmittel gefunden. Nachfolgend wurde es mit der HPPLC unter Verwendung eines Elutionsgradienten mit n‐Hexan und Tetrahydrofuran als Komponenten bestätigt. In einem topographischen Bild wurde die Zusammensetzung der untersuchten

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300103

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractStability constants and thermodynamic parameters (e.g. ΔH0and Δ0) have been determined for intermacromolecular complexes of methacrylic acid‐methacrylamide and acrylic acid‐acrylamide copolymers with poly(vinyl pyrrolidone) (PVP). The presence of nonionic units in the copolymers greatly enhances the stability of the complexes with PVP. The enthalpy and entropy changes of the systems with temperature have been interpreted in terms of various modes of interaction between the compo

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300104

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe aqueous polymerization of acrylamide initiated by potassium permanganate/β‐hydroxybutyric acid has been studied volumetrically at 35 ± 0.01°C in an inert medium. The rate of polymerization shows nearly square root dependence on β‐hydroxybutyric acid at low concentration (3.12 – 12.5 · 10−3mol dm−3). The order with respect to potassium permanganate has been found to be 0.6 indicating thereby a bimolecular mode of termination. The polymerization rate has been varied linearly at low monomer concentrations i.e. from 2.5 –7.0 · 10−2mol dm−3. The dependence of number average degree of polymerization on the initial rate of polymerization and temperature has been determined. The over‐all activation energy has been found to be 51.66 kJ mol−1. A kinetic reaction scheme is proposed on the basi

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300105

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractBy drying at 78°C, the macroporous terpolymer 2,3‐dihydroxypropyl methacrylate‐co‐sodium methacrylate‐co‐ethylene dimethacrylate with a water retention of 3.78 g H2O/g loses porosity which is renewed by reswelling. Drying of this terpolymer at 0–25°C by which water or methyl alcohol is removed does not disturb its porosity. Less swelling copolymers such as 2,3‐dihydroxypropyl methacrylate‐co‐ethylene dimethacrylate with a water retention of 1.71 g H2O/g do not lose its permanent porosity when dried. Inversion gas chromatography has made possible the determination of the glass transition temperature of these macroporous terpolymers (Tg= 45°C) by using heptane and methyl alcohol as retention acids. With respect to this, and using scanning electron microscopy the loss of porosity due to drying was interpreted as sintering of macroporous copolymers whose polymer networks swell to a higher degree

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300106

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractStudies on the electrothermographic and conductivity behaviour of poly(acrylonitrile butadiene styrene) (ABS) films of different thermal pretreatments were carried out. The resistivity in ABS layers stored at 50°C was found to be low (∼ 1015Ω · cm). The charge acceptance and its retention also is poor. The reason for that is the adsorption of water molecules. The layers, when thermally treated at 100°C or more for 5 h, show an enhanced resistivity (∼ 1017Ω · cm at 50°C) and hence an improvement in charge acceptance as well as in charge retention. Environmental and storage conditions as well as thermal treatment during layer preparations have no effect on the temperature dependence of the resistivity be

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300107

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractDie Verwendbarkeit von ataktischem Polypropylen als Pfropfgrundlage für die Pfropfcopolymerisation mit Vinylacetat wird untersucht. Die erhaltenen Pfropfprodukte werden hinsichtlich ihres Quellverhaltens und bezüglich ihrer Glasumwandlungstemperaturen und Pfropfparameter bei unterschiedlichen Pfropfproduktzusammensetzungen charakterisiert.Nach Abmischung der Pfropfprodukte mit Polyvinylchlorid werden einige mechanische Eigenschaften sowohl in Abhängigkeit von der Menge des enthaltenen Pfropfproduktes als auch von der Zusammensetzung der Pfropfcopolymerisate dargestel

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300108

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe conventional pad‐dry‐cure method was used for effecting crosslinking of cotton with N‐methylol finishing agents under different conditions. Factors studied include nature and concentration of finishing agent and softener, type and concentration of catalyst, and curing temperatures. Variation of soiling and soil release characteristics of crosslinked cotton with these factors were investigated. The effect of finishing agent on aqueous soiling followed the order:Carbamate reactant‐fabric>Dimethylolethylene urea‐fabric>Dimethyloldihydroxyethylene urea‐fabric>Untreated fabric>Modified triazinone‐fabric ≥ Modified ethylene urea‐fabric. On the other hand, the effect of these finishing agents was to enhance the susceptibility of the fabric to oily soiling. Nevertheless, nature of the finishing agent governed the magnitude of this enhancement. Aqueous and oily soil release depended also upon the nature of finishing agent, soiling increased and soil release decreased by increasing finishing agent concentration. Type of catalyst exerted a considerable influence on aqueous and oily soil release without significantly affecting the degree of soiling. For aqueous soil release, the following order was found: Al2(SO4)3· 18H2O>MgCl2· 6H2O>urea nitrate>ZnCl2· 6H2O>Zn(NO3)2· 6H2O>urea phosphate>urea oxalate>NH4· H2PO4≥ NH4Cl.A reverse order held good for oily soil release. Both aqueous and oily soil release were impaired by increasing catalyst concentration. Similarly, nature and concentration of the softener had no striking effect on soiling while they did on soil release. Raising the curing temperature from 80 to 140°C caused substantial reduction in case of soil removal of urea salts catalyzed‐crosslinked cotton samples while having the degree of

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300109

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractIn the present investigation an attempt has been made to throw light on the structure of stiff chain amorphous polymers. For this purpose cellulose acetates (CA) having different degrees of substitution (DS) were prepared. The samples were characterised by IR‐spectroscopy, Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). Scanning electron micrographs of the cryogenically fractured surfaces of these polymers showed that along with lamellar structures, nodular structures were also observabl

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051300110

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY