摘要:

AbstractThe dependence of molecular weight of poly(diallyldimethylammonium chloride) on conversion was studied and a model is proposed for the calculation of the conversion dependence of molecular weight under consideration of gel effect and chain transfer reactions to monomer and polymer. The influence of tetramethylammonium chloride concentration on the ionic conductivity of the solid polymer was studied. A maximum specific ionic conductivity of 2.2 · 10−4S cm−1was meas

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650101

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractKinetics of the esterification of pentaerythritol by long‐chain carboxylic acids (C7– C18) has been followed by potentiometric titrimetry. A simplified approach for the estimation of the rate constant values and the rate constants of the consecutive processes was developed according to the previous established kinetic law for similar systems.A computer simulation of the component concentrations variation has been carried out in order to prove the selected kinetic mo

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650102

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractUnidirectional composite materials of novolac resin with carbon fibers were fabricated according to the prepreg method. Novolac resin was prepared by polymerization of phenol with formaldehyde (mole ratio 1 : 0.82) in the presence of oxalic acid as catalyst (1.5 wt.‐% to phenol). The curing of novolac resin was performed with hexamethylenetetramine (hexa), while the appropriate proportion was determined by using the IR‐spectroscopy.Specimens of novolac/hexa (weight ratio 14:1) reinforced with carbon fibers commercially available were fabricated under different conditions (e.g. different thermal programs and different proportions of novolac/carbon fibers). The mechanical properties of the fabricated specimens (like flexural strength, tensile strength, etc.) were determined and their structure was examined by scanning electron microscopy.By increasing the volume proportion of carbon fibers, not only all mechanical properties of the composite material were increased, but also their degree of utilization was increased and also the production conditions had greater influence. Concerning the specimens produced by the same proportion of carbon fibers (e.g. 15 vol.‐%) their mechanical properties were improved by increasing the curing of novolac. The degree of curing of novolac during the initial phase (gel time) and during the ultimate phase (post‐curing) can be followed with the aid of IR‐spectra of the cured resin, while the degree of curing for the intermediate phase can be obtained only indirectly from the values of the mechanical properties of the corresponding specimens.From the correlation between the production parameters and the mechanical properties of the samples the optimal conditions for processing of the thermopress for the manufacture of carbon fiber reinforced novolac were concluded (1. phase: T1= 125–145°C, t1= 20 min – 1 h, without pressure; 2. phase: T2= 180–195°C, t2= 40 min

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650103

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractIn der vorliegenden Arbeit werden die Eigenschaften des früher1,2entwickelten Modells untersucht und diskutiert. Die Variation der Modellparameter zeigt einen großen Einfluß der Aggregationsprozesse auf die Subkornmorphologie. Bei niedrigen Monomerumsätzen ist das Zeitintervall zwischen zwei aufeinanderfolgenden Aggregationsschritten sehr klein, so daß für das Teilchenwachstum die Geschwindigkeit der Aggregation der Unterstrukturen entscheidend ist. Im Bereich zwischen 5% und 20% Monomerumsatz sinkt die Aggregationsgeschwindigkeit sehr stark, so daß für das Teilchenwachstum zunehmend die Polymerisationsreaktion an Bedeutung gewinnt. Aggregative Stabilität wird nach dem Modell für einen Teilchengrößenbereich erhalten, der sich in Übereinstimmung mit experimentellen Daten aus der Fachliteratur befindet. Die berechneten Teilchengrößen entsprechen ebenfalls den in der Literatur publizierten experimentellen Werten, so daß das Modell eine gute Grundlage für die Beschreibung einiger morphologisch bestimmter Polymereige

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650104

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractRespropiophenone‐formaldehyde copolymers (RPP‐F) were synthezised by the condensation of 2,4‐dihydroxypropiophenone (respropiophenone (RPP)) and formaldehyde (F) in the presence of NaOH or H2SO4as catalyst with varied molar ratios of reacting monomers. The copolymers were characterized by elemental analysis, IR spectra, viscosity, and TGA studies. Their M̄nwas determined by nonaqueous conductometric titrations and vapour pressure osmometry (VPO). Chelation ion‐exchange properties have also been studied employing the batch equilibration method. Polychelates of Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(II), and UO2(II) with RPP‐F‐AI copolymer were prepared. The analytical data agree with 1 : 2 metal‐ligand stoichiometry. Elemental analysis, magnetic, spectral, and thermal properties of polychelates have been studied and probable structures are assigned to the polychelates. All the polychelates are amorphous powders, insoluble in common or

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650105

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractIn this study we are interested in the effect of concentration and temperature on the electrical resistivity of butyl rubber (IIR) loaded with two types of carbon black, (namely, high abrasion furnace black (HAF), and fast extrusion furnace black (FEF)). It was found that the conductivity at low carbon black concentrations is mainly achieved by thermal activation of carriers. Tunneling mechanism at low termperature followed by thermal activation at relatively high temperature is found to be predominant for moderate concentrations for both carbon blacks. The metal‐like behaviour which was observed in highly loaded compounds was attributed to both, the thermal expansion of the tunneling paths between carbon‐carbon agglomerates and the breakdown of carbon agglomerates with temperat

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650106

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThis study deals with the synthesis of halogenated derivatives of phenyl glycidyl ether and with possibilities of their use as flame retardants and reactive diluents of epoxy resin.The best reaction conditions optimized by Nelder‐Mead simplex method were found. The products of very high quality were prepared. They were mixed with a lowmolecular epoxy resin and cured by diamino diphenyl methane.The viscosity of the resin mixtures and limiting oxygen index of cured systems were determined. It was found that a higher content of halogen, both chlorine and bromine, causes increasing viscosity and reduced flammability of the epoxide

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650107

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractBy measuring Tg, Tmand Tc(cloud point) phase diagrams for the four miscible blends of chlorinated isotactic polypropylenes (chlorine content 39.2 (CPP‐40) and 49.8 wt.‐% (CP‐50)) with Poly(ethylene‐co‐vinyl acetate)s (vinyl acetate contents 40 (EVA‐40) and 45 wt.‐% (EVA‐45)) were investigated. The blend of CPP‐50 with EVA‐40 was the most compatible of t

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650108

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe synthesis and the characterization of the PE‐PS‐DVB interpolymer cationexchange membranes in the electrolysis of borax solutions to produce boric acid and sodium hydroxide simultaneously was carried out. The characterization of the teflon based “Nafion 324” and polystyrene‐DVB based “Permaplex C‐20” membranes was also performed in the same system for comparison.The DVB contents were varied between 3 – 12% (by wt. in total monomers) and the increase of the cross‐links resulted in the decrease of the water contents and ionexchange capacities of the membranes. The PE present in the membrane acted as a barrier for electroosmotic water transport. The membranes with high DVB contents showed better electrolysis performance due to their low water contents and low electroosmotic water transport properties. The use of the interpolymer membrane containing 11.6% DVB resulted in high current efficiency and high sodium cation dynamic transport number and worked satisfactorily at the process conditions of

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650109

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractInclusion polymerization of cyclic diene monomers, such as cyclopentadiene, 1,3‐cyclohexadiene, 1,3‐cycloheptadiene, 1,5‐cyclooctadiene, and 2,5‐norbornadiene, was studied, using deoxycholic acid (DCA) as the canal component.The formation of monomer‐DCA adducts was observed, however, the polymerization occurred only in the case of cyclopentadiene, 1,3‐cyclohexadiene, or 1,3‐cycloheptadiene. The polymers obtained consisted preferably of 1,4‐units and almost 100% of 1,4‐units in the case of 1,3‐cyclohexadiene. ESR measurements revealed that inclusion polymerization of cyclopentadiene or 1,3‐cyclohexadiene in DCA canals proceeds by a f

ISSN:0003-3146    

DOI:10.1002/apmc.1989.051650110

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY