摘要:

AbstractGraft copolymerization of ethyl acrylate onto starch initiated by ceric ion in an aqueous medium was studied at 29°C. It was found that the grafting frequencies and molecular weights of grafted poly(ethyl acrylate) changed from 2 graft polymer molecules per 104anhydroglucose units (AGU) and 3.03 · 105to 34 and 6.80 · 105, respectively, when the starch content was varied from 1.0 wt.‐% to 0.2 wt.‐%. The influence of dilution of ceric ion on the extent and rate of graft polymerization of ethyl acrylate onto starch was also ex

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840101

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effect of reactive diluents such as bis(4‐allyl 2‐methoxyphenyl) adipate (AEg), bis(4‐allyl 2‐methoxyphenyl) terephthalate (TEg), and bis(o‐allyl phenyl) sebacate (APS) on curing characteristics and thermal behaviour of bis(4‐maleimidophenyl) methane (BM) chain‐extended with 4,4′‐diaminodiphenyl methane (DADPM) is described. Samples containing 5, 10, 15, 20, 25, 35, and 45 wt.‐% of these reactive diluents and bismaleimide resin were prepared. Addition of APS, AEg, and TEg affected the curing exotherm of bismaleimides. The thermal stability of bismaleimide decreased on addition of APS or AEg, but in presence of TEg an improvement in char yield at 800°C was observed. Glass fibre reinforced laminates fabricated from bismaleimide resin containing 10% APS exhibited interlaminar shear strength of 20.8 N/mm2and flexural s

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840102

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractFor the study of the effect of ceric ammonium nitrate (CAN) initial concentration on the graft copolymerization of 4‐vinylpyridine (4‐VP) onto cotton three series of experiments were carried out. In the first one the CAN concentration was varied from 0.5 to 100 mmol/l and so, parallely, the total nitrate ion concentration. In the other two series the CAN initial concentration was varied, but keeping the total nitrate ion concentration constant at 1.09 and 1.59 M, respectively, by sodium nitrate addition. Increasing the ceric salt concentration the graft yield and total conversion reached a maximum. When the nitrate ion concentration was kept constant the maximum graft yield value was achieved at CAN concentrations lower than when it was varied. However, for all the three series of experiments the maximum graft yield value was nearly the same. The ceric ion consumption increased with increasing initiator concentration. The higher the total nitrate ion concentration, the higher was the ceric ion consumpt

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840103

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractFor the purposes of new membrane material development for pervaporation separation based on crosslinked polyvinyl alcohol (PVA), IR spectroscopy and DSC were used to characterize the crosslinking reaction and the imidization of the (PVA)‐amic acid system. The IR spectra and the thermal analysis were performed on specimens that had been reacted for several different times at 150°C. The crosslinking reaction between the hydroxy groups of PVA and the carboxylic groups of amic acid was faster than the imidization of the amic acid. The best reaction times were about 30 min for the crosslinking reaction and 90 min for the imidization. The effects of the reaction time and the amic acid content on the thermal and mechanical properties have also been investigat

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840104

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractComposites based on resin of furfuryl alcohol‐formaldehyde or poly(furfuryl alcohol) and olive stones (pressed and extracted as received from industrial production) were cured as small cylinders and then pyrolyzed. The pyrolysis was studied by thermogravimetric analysis up to ∼︁ 1000°C and by FTIR‐spectroscopy for the initial composites and their pyrolysis residues up to 500°C. The specific surface areas of the carbonaceous residues and their discoloring ability for dyes of methylene blue and alizarin yellow were determined. The results are interpreted and discussed under the aspects of the pyrolysis process and the new carbonaceous materials produced. The usage of olive stones in mixture with resins based on furfuryl alcohol is more advantageous (e. g. leading to higher adsorption of the dyes) than the usage of the re

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840105

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractAmbient dielectric measurements as functions of frequency in X‐band microwave region have been made on solid samples of polystyrene. Effects of temperature (−120 to +160°C) at three different frequencies have also been studied. The measurement technique applied based on short‐circuited waveguide method of Roberts and von Hippel modified by Dakin and Works for low loss and medium loss samples. Two different types of relaxations are identified originating from main chain motion, wagging, and rotational motions of pendent phenyl group. Intrinsic activation energy for polystyrene molecule, dipole moment per repeat unit, and the average apparent energy of a polystyrene molecule associated with its induced transient dipoles have also been calculated and the data so obtained are explained and compared with standard lite

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840106

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractSous l'action d'un traitement thermique, la réticulation d'un adhésif en film s'accompagne d'une variation des propriétés rhéologiques et électriques de la résine. L'intérêt des mesures non destructives d'impédance électrique est de permettre de suivre en continu la réticulation, de déterminer en particulier le début et la fin du mouillage, le point de gélification et la fin de la réticulation du film d'adhésif (FM 96) utilisé en vue d'élaborer un joint collé métal/métal (acier inoxydable 22 CN 18‐10). L'influence de la température et de la durée de réticulation est également mise en évidence. Aprés un second balayage en température, les diagrammes d'impédance sont caractéristiques de l'existence d'un reéiculat polyphasé. Ces résultats sont confirmés

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840107

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe polyurethane(PU)‐crosslinked diglycidyl ether of bisphenol A (DGEBA) was prepared from the reaction of the pendent secondary hydroxy group in DGEBA with the isocyanate‐terminated group present in the PU prepolymer. Though the PU acted as a crosslinking agent for the DGEBA, the morphology and dynamic mechanical behaviour of these PU‐crosslinked DGEBA could be different among themselves depending on the type and molecular weight of polyols employed in the PU. There was no significant shift in the loss modulus (E″) peaks of the DGEBA crosslinked with the polyester‐type and polyether‐type polyurethanes, but the intensity of the E″ peaks increased as the polyester‐type PU employed. The morphology of this polyester‐type PU‐crosslinked DGEBA exhibited a homogeneous one‐phase system, while the DGEBA crosslinked with the polyether‐type PU showed a two‐phase morphology with the PU particles

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840108

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractMulticomponent interpolymer complexes have been prepared by interacting a phenolic copolymer of known composition with several non‐ionic homopolymers, e.g., PVP, PEO, PVA and polyelectrolytes, such as PAA and PEI. The formation of these complexes has been studied by several techniques, such as viscometry, potentiometry, conductometry, and IR spectra. A scheme has been presented to explain the mode of interaction of the various component polymer

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840109

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractEquations for the molecular weight distribution and the average molecular weights of a living anionic polymerization with very rapid or slow initiation are presented for a series of stirred tank reactors. It is shown that polydispersity of the polymer in the last vessel of a cascade takes for nearly complete conversion of monomer then a minimum, when the reaction is performed isokinetically with concern to monomer conversion, i.e. when monomer conversion in each vessel of a cascade of n tanks is 1/n. Now, polydispersity of the polymer in the mth vessel of the cascade (1 ≤ m ≤ n) is Dm= 1 + 1/m. Values of all systems variables needed for isokinetic control of the polymerization may be precalculated from kinetic models. For vessels of equal size and with equal residence times reaction temperature is suggested as control variable increasing stepwise from vessel to vessel. The proposed procedure was checked for the systems styrene/n‐butyllithium/toluene, styrene/s‐butyllithium/benzene, and isoprene/s‐butyllithium/n‐heptane. A satisfying agreement between calculated and measured values of the objectives monomers conversion, number average molecular weight, and polydispersity was found. It is proposed to use the described procedure for the preparation of ABA block copolymers with negligible tapering between the blocks by living anionic polymerization in a series of stirred ta

ISSN:0003-3146    

DOI:10.1002/apmc.1991.051840110

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY