摘要:

AbstractNew graft copolymers were synthesized by grafting methyl acrylate onto cutch, a vegetable tanning agent, in acetic acid medium with hydrogen peroxide as the initiator. The graft copolymers were characterized by infrared spectroscopy and thermogravimetric analysis. The dependence of the percentage of grafting, monomer conversion, efficiency of grafting and rate of grafting on the concentrations of initiator, acetic acid, and cutch were investigated. The optimum experimental conditions for grafting were obtained. A probable mechanism of grafting was also proposed.

ISSN:0021-8995    

DOI:10.1002/app.1987.070330701

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe emission of weak visible chemiluminescence (CL) during the cure of a tetraglycidyl 4,4′‐diaminodiphenyl methane (TGDDM)‐based epoxy resin, with three different concentrations of 4,4′‐diaminodiphenylsulfone (DDS) has been studied at 135°C. Spectral analysis indicates that the CL originates from trace oxidation of the TGDDM resin and the emission intensity is sensitive to the viscosity changes during cure. From thermal analysis data, sharp discontinuities in CL intensity are shown to occur at the gel point. The temperature dependence of CL from a cured resin also shows a sharp discontinuity atTg. These results indicate that CL provides a sensitive monitor of both the kinetics of gelation and the network formation in this e

ISSN:0021-8995    

DOI:10.1002/app.1987.070330702

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

年代:1987

数据来源: WILEY

摘要:

AbstractDipole relaxation dielectric loss behavior of a fiberglass‐epoxy composite has been studied following submersion in polar and nonpolar organic solvents as well as in acidic and basic aqueous solutions. Certain adsorbed organic solvents, such as 1,2‐dichloroethane, had little influence on the epoxy relaxation behavior. Other solvents, including chloroform, increased the composite relaxation intensity and shifted the temperature‐frequency region over which the relaxation occurred. Both the amount of solvent uptake and the degree of interaction of solvent molecules with epoxy polar functional groups appear to control the amount of relaxation behavior perturbation. Arrhenius activation energies for relaxation were lowered by solvent uptake from the dry composite value of 18 kcal/M to between 6 and 16 kcal/M, depending on the solvent adsorbed. Submersion in methanol and chloroform sharply increased the direct current conductivity of the composite. Two molar acidic and basic solutions had little influence on composite dipole relaxation behavior other than the well known behavior associated with moisture u

ISSN:0021-8995    

DOI:10.1002/app.1987.070330703

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

年代:1987

数据来源: WILEY

摘要:

AbstractA simple method is described to obtain rheological data on filled polymeric materials in the form of powders. The powder is compacted in a cylindrical chamber by a plunger driven by the cross‐head in an Instron testing machine and the load‐displacement curve is recorded. Further information is obtained by compressing the powder to a fixed load and measuring the load decay with time (stress‐relaxation). The tests are illustrated by application to “monocomponent toner” powders used in dry copying or nonimpact printing processes. It is shown that compaction and stress‐relaxation data are able to differentiate between different toners and facilitate the prediction of their relative performances in terms of pressure fusing. A mechanical spring‐dashpot‐slider model is effective in describing the rheological behavior of these powders and its dependence on the loading of a hard filler (magnetic pigment). The latter affects the “slider” yield stress in the model but has no influence on t

ISSN:0021-8995    

DOI:10.1002/app.1987.070330704

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

年代:1987

数据来源: WILEY

摘要:

AbstractTriphenylchloromethane andp‐toluenesulfonyl chloride were reacted with chopped or powdered cellulose, with and without premercerization, to form trityl–cellulose ethers or tosyl–cellulose esters. Powdered and premercerized cellulose samples were more readily derivatized. Differential scanning calorimetric (DSC) and thermogravimetric (TG) analyses were performed in nitrogen on these derivatives. DSC and TG thermograms were affected by the particular derivative and the degree of substitution. The decomposition temperatures for both derivatives were lower than for the unmodified cellulose. Trityl cleavage may have been detected by DSC as a broad endothermic area showing no weight loss that preceded the major endothermic decomposition peak. Decomposition temperatures were lowered, but not sufficiently to prevent decomposition products from being combustible. No increase in residue was effected. Thermal decomposition of tosyl–cellulose was substantially different from that of the trityl derivative. As the degree of tosyl substitution increased, decomposition occurred at lower temperatures as an increasing exotherm. Tosyl derivatives all produced high residues. These changes in thermal characteristics were indicative of increased flame resistance. Oxygen index (OI) values relate to flame resistance and show that tritylation was detrimental to the cellulose and that tosylation imparted some degree of flame res

ISSN:0021-8995    

DOI:10.1002/app.1987.070330705

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

年代:1987

数据来源: WILEY

摘要:

AbstractA simple, activity‐based solution model is used to develop thermodynamically proper correlation forms for the description of the rate and equilibrium behavior of nonideal polyamidations. The approach is especially useful in systems for which limited equilibrium and kinetic data are available. This model is applied to the nylon 6,6 system. the resulting correlation is valid for water concentrations from 1 to 90 mol% and for temperatures from 200 to 265°C. The equilibrium correlation is a function of the water mole fraction and temperature. At a fixed temperature, there is a maximum in the apparent equilibrium constant at a water concentration of approximately 10 mol%. There is an apparent inversion in the sign of the heat of amidation, as well as a continuous change in the apparent rate of polymerization from second to third order in carboxyl concentration at low water conte

ISSN:0021-8995    

DOI:10.1002/app.1987.070330706

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

年代:1987

数据来源: WILEY

摘要:

AbstractGrafting ofN,N‐dimethylacrylamide (DMAA) onto polytetrafluoroethylene (PTFE) has been carried out by using gamma rays from a60Co source. Degree of grafting was affected by grafting conditions. Especially, solvent for the grafting was found to be a very significant parameter to obtain a higher grafting yield. When ethylacetate or acetone was used as the solvent, grafting yield greater than 5% was obtainable while the graftcopolymerization scarcely occurred in the presence of other kinds of solvent such as ethanol or water.Apparent activation energy of the grafting in ethylacetate was calculated to be 7.90 Kcal/mol, and initial grafting rate of it was proportional to 0.55 power of dose rat

ISSN:0021-8995    

DOI:10.1002/app.1987.070330707

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe hydrodynamic degradation of high molecular weight poly(acrylamide‐co‐Na acrylate) in 1MNaCl in porous media flow was studied as a function of polymer concentration in the dilute and semidilute concentration ranges. Porous media rheometry was used to monitor molecular weight changes due to chain scission. At equivalent superficial velocities of flow through a glass bead pack, polymers at dilute concentrations showed greater loss of molecular weight than polymers at semidilute concentrati

ISSN:0021-8995    

DOI:10.1002/app.1987.070330708

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

年代:1987

数据来源: WILEY

摘要:

AbstractPolymer membranes having cationic charge site, poly(1‐alkyl‐4‐vinylpyridinium iodide‐co‐acrylonitrile) (alkyl: methyl, butyl, or octyl) were prepared in terms of coulombic interaction for separation of water–ethanol mixtures. The incorporation of cationic charge site into the membrane led to improve not only separation factors (selectivity toward water) but also flux number in the separation of aqueous ethanol solution by pervaporation technique. Target values, which were requested to have from the viewpoint of industrial utilization for separation of aqueous ethanol solution were attained as follows: separation factor toward water over 50 and flux value over 500 g m−2h−1, through poly(1‐methyl‐4‐vinylpyridinium iodide‐co‐acrylonitrile) (membrane3) (quarternized fraction of pyridinium moiety, 89.5%; mol fraction of pyridinium moiety, 0.034) and poly(1‐butyl‐4‐vinylpyridinium iodide‐co‐acrylonitrile) (membrane5) (quarternized fraction, 100%; mol fraction of pyridinium moiety, 0.038). It was found that the introduction of cationic charge site into the membrane was one of feasible methods to obtain suitable membranes for water permselective membranes in the s

ISSN:0021-8995    

DOI:10.1002/app.1987.070330709

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe effect of the physical aging of ethylene ionomers was studied for the samples with the acid content of 5.4 mol%, and the degree of neutralization, 0%, 60% Na, 60% Zn, and 90% Zn. The information about the crystal and the cluster part of the physically aged ionomers was obtained by differential scanning calorimetry and by dynamic viscoelastic measurements, respectively. The degree of crystallinity and the dynamic modulus for the ionomers of the degree of neutralization 0%, 60% Na and 60% Zn increased gradually with the aging time; on the other hand, the crystallinity of 90% Zn remained constant and the modulus at 100°C increased to a certain value up to a period of 100 h, but thereafter the crystallinity increased remarkably and the modulus remained. These facts indicate that the crystallization of neutralized ethylene ionomer starts after clustering and the clustering would finish at early stage of the physical aging for intermediately neutralized ethylene ionomer. The physical aging effect of the ethylene ionomers was, thus, found to be important to material design

ISSN:0021-8995    

DOI:10.1002/app.1987.070330710

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

年代:1987

数据来源: WILEY