摘要:

AbstractImmitted spruce wood meal (ISWM) was modified with 3‐chlor‐2‐hydroxypropyltrimethyl‐ammoniuchloride (CHMAC) or 1,3‐bis(3‐chlor‐2‐hydroxypropyl)imidazoliumhydrogensulphate (BCHIHS) in alkaline medium. The obtained material was gradually extracted with water and 5% NaOH. The yields of water‐soluble hemicelluloses modified with quarternary ammonium groups were lower in comparison to healthy spruce material obtained under the same conditions but even more material could be obtained from ISWM‐holocellulose. The quantity of alkali‐soluble polysaccharides from ISWM was the same as obtained from undamaged spruce. The residues after alkali extractions are suitable ion exchangers with low solubility in dilute alkali solutions. The yields of extracts from material modified with BCHIHS were lower than yields of extracts from material modified with CHMAC because ISWM was crosslinked when alkylated with b

ISSN:0021-8995    

DOI:10.1002/app.1987.070340601

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractRelease of desmetryn into the gas phase from films of ethylene‐vinyl acetate copolymer, in which the herbicide was incorporated for special agricultural applications, was investigated for comparison with release into water and under outdoor conditions. It could be shown that the rate of release of the active chemical into the gas phase was negligible compared with that into water and only slightly dependent on temperature in the range 0–7

ISSN:0021-8995    

DOI:10.1002/app.1987.070340602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractPolydivinylbenzene‐4‐vinyl‐N‐methylpyridinium iodide (MeVP+‐DVBI−) membranes are obtained by solvent evaporation from dispersions of copolymer powder in polysulfone dichloroethane solutions. The membranes' macroporosity increases from 2.5 to 46.4% and the pore size distribution concentrates in the 103–105Å range upon varying the concentration of polypyridinium polymer from 0 to 67% w/w. Similarly, the specific conductivity increases from 10−11to 10−4ohm−1cm−1and the mechanical strength decreases from 500 to 8.8 kg/cm2. The ion selectivity is maximum at 40–50% MeVP+‐DVBI−and lower above or below this concentration range. The properties are discussed in relation to the membrane chem

ISSN:0021-8995    

DOI:10.1002/app.1987.070340603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractA model for the prediction of the elastic response of reinforced materials over wide ranges of concentration is presented. The method is based on the mathematical analogy between the motion of particles suspended in viscous media and the elastic deformation of solids. The system is locally described by linearized forms of the elastic moduli. The validity of these relations is then extended to all concetrations under the assumption that any new portion of filler “sees” the existing structure as a noniteracting homogeneous matrix. The method predicts the behavior of reinforced materials with solid spherical inclusions and foams over wide ranges of concentration. The model, free from adjustable parameters, shows excellent agreement with existing experimental data. The extension of the method to other inclusion geometries is straightforw

ISSN:0021-8995    

DOI:10.1002/app.1987.070340604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractElectro‐copolymerization of methyl acrylate, acrylic acid, methacrylic acid, acrylamide, and methyl methacrylate with acrylonitrile onto graphite fibers has been successfully done in our laboratory. The coatings are relatively uniform and their properties, especially their modulus, can be systematically varied by controlling the monomer ratio in the eletrolyte solution. This technique is being used to introduce a ductile interlayer of contrlled composition and thickness between the composite fibers and matrix. Copolymers of methyl acrylate and acrylonitrile formed by this technique are random copolymers, withTg′s varying from 10 to 90°C. These copolymers have fairly high molecular weight, in the range of 100,000 g/mol. Monomer reactivity ratios were determined, based upon free radical polymerization kinetics, from cyclic voltammetry. An indirect initiation mechanism is suggested. Bonding between interlayer and matrix can be improved by introducing vinyl monomers with proper functional groups, capable of reacting with the epoxy resin, at the last stage of the electropolymerization pro

ISSN:0021-8995    

DOI:10.1002/app.1987.070340605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractButyl acrylate was graft polymerized onto silica gel, which had been doubly modified with γ‐aminopropyltriethoxysilane and 4,4′‐azobis(4‐cyanovaleric acid). 2‐(Methoxycarbonnyl)ethyltrichlorosilane was treated on another silica gel. The ester groups on both silica gel surfaces were transformed to azide to immobilize lipase. The activities of the immobilized lipase for interesterfication of triacylglycerol in isopropyl ether were examined and compare with that of adsorbed lipase on silica gel, and the polyacrylate‐graft silica gel was found to be an effectual support for the enzymatic interesterification. An apparent shift of the reaction equilibrium by removing water as an azeotrope of isopropyl ether is al

ISSN:0021-8995    

DOI:10.1002/app.1987.070340606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractA number of resin copolymers have been prepared by condensation of substituted aromatic compounds with formaldehyde in the presence of different acid catalysts. The resin copolymers were characterized by IR, thermal, X‐ray diffraction, and by their reactivity ratios. The resins were found to possess high thermal stability. Activation energies of resin degradation were computed using the Freeman–Anderson method. The antifungal activities of several previously synthesized resins were stud

ISSN:0021-8995    

DOI:10.1002/app.1987.070340607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe dynamic mechanical properties, transition behavior, and morphology of polycarbonate (PC)‐polyurethane (PU) semi‐interpenetrating polymer networks (semi‐IPNs) and linear blends were studied by means of Rheovibron, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). Two glass transition temperatures corresponding to polycarbonate and polyurethane were observed and microphase separation was further evident with TEM. In PC/PU semi‐IPNs, two glass transition temperatures were shifted inwardly indicating that the interpenetrating network of polyurethane increases the mutual miscibility of PC and PU. The average phase domain was 500Å in semi‐IPNs and the phase domains were in the range 1000–6000 Å in linear blends of the corresponding polymers. The compatibilities of PC and PU were greatly influenced by the molecular weight of polyols in PU prepolymer and the ratio of NCO/OH; lower molecular weight polyols and higher NCO/OH ratio resulted in better compatibility, and finer phase domains in PC and PU linear blends

ISSN:0021-8995    

DOI:10.1002/app.1987.070340608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractHighly viscous systems made up of 70 wt% epoxy resin dissolved in 30 wt% monomer mixtures of acrylic acid and styrene were irradiated with 1.5 MeV electrons to initiate graft copolymerization. The temperature measurement of the systems reveals that the polymerization reaction takes place both during and after the electron‐beam exposure of about 5‐sec duration. The reaction lasts about 50 sec for a low beam current of 0.6 mA, while for a high beam current of 6.0 mA it lasts merely about 20 sec. The gel permeation chromatography (GPC) measurement of obtained products demonstrates that the molecular weight distribution of ungrafted copolymer of acrylic acid and styrene becomes strikingly broader as the beam current is lowered. The GPC data suggest that the fraction of epoxy resin having a grafted branch increases with an increase in the beam current. All of these results are interpreted in terms of the mobility and the concentration of reactive species such as polymer radicals and low molecular weight free radic

ISSN:0021-8995    

DOI:10.1002/app.1987.070340609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractHighly viscous systems made up of 70 wt% epoxy resin dissolved in 30% monomer mixture of styrene and acrylic monomers were irradiated with 1.5 MeV electrons to initiate graft copolymerization. The obtained product of graft copolymer mixture was fed into a mixed solvent ofn‐butanol and cyclohexanone, and was heated 2 h at 70°C to form a predispersion. Then aqueous solution of 2‐dimethylaminoethanol or ethanol was added to the predispersion, thus giving a stable dispersion in water or in ethanol. The particle diameter of the aqueous and ethanol dispersions is practically the same, thus suggesting that polymer particles are virtually generated during the predispersing procedure, and at this step the size of the particles is actually determined. The particle diameter increases inversely proportional to the polymer concentration in the predispersion. Furthermore, the particle diameter shows a tendency to decrease with an increase in the hydrophilicity of monomers used in the graft copolymerization. The stopped‐flow measurement, on the other hand, reveals a characteristic pH dependence of the dispersion stability to the addition of NaCl. This result is interpreted based on a particle model consisting of a particle core of epoxy resin and its surrounding layer of acrylic cop

ISSN:0021-8995    

DOI:10.1002/app.1987.070340610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY