摘要:

AbstractA photochemically active membrane was made by the interfacial copolymerization of 3‐diazo‐4‐oxo‐3,4‐dihydro‐1,6‐naphthalene disulfonylchloride and naphthalene‐1,3,6‐trisulfonylchloride with 1,6‐hexanediamine. The chemical functionality of the membrane surface was modified on irradiation of the surface of the membrane in the presence of various nucleophiles. Surface analysis techniques of attenuated total reflectance‐Fourier transform infrared and scanning electron microscopy have been used to monitor the changes in the chemistry of the thin‐film composite membranes. The surface functionality of the membrane was shown to affect the reverse osmosis flux and separation of various solutes. Results for membranes which have been converted to acid, and ester forms are presented. © 1

ISSN:0021-8995    

DOI:10.1002/app.1993.070480201

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe acrylonitrile (AN) grafted onto polyvinyl alcohol (PVA) can improve the mechanical properties and water resistance of PVA; however, its hydrophilicity is decreased. Prepared PVA‐g‐AN membranes through modification with the NaOH and HCHO aqueous solutions can enhance its hydrophilicity. This modified PVA‐g‐AN membranes were used to separate alcohol/water solution with the pervaporation method. The flux was increased from 0.72 kg/m2h of the original membrane to 2.06 kg/m2h of the modified membrane. Moreover, adding a small quantity of CoSO4to the water‐alcohol mixture can simultaneously increase the separation factor. © 1993 John Wiley

ISSN:0021-8995    

DOI:10.1002/app.1993.070480202

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe kinetics of the high solids content miniemulsion terpolymerization of styrene, 2‐ethyl hexyl acrylate and the methacrylic acid and the final properties of the latexes produced by this method were compared with those resulting from the corresponding conventional emulsion polymerization process. The final latex properties considered were: latex viscosity both prior and after neutralization, mechanical stability, chemical stability, and freeze‐thaw stability. © 1993 John Wiley&Sons,

ISSN:0021-8995    

DOI:10.1002/app.1993.070480203

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

年代:1993

数据来源: WILEY

摘要:

AbstractTwo viscometric methods in the investigation of interpolymer complexes are presented. It has been shown that a presentation of the reduced viscosity ratio (experimental to ideal value) of a mixture of a polyacid with a nonionic polymer at constant total concentration as a function of the polymer mixture composition gives a better insight into the interpolymer association than a presentation of the specific viscosity at constant polyacid concentration as a function of the unit molar ratio. The formation of an expanded structure interpolymer complex is more easily revealed by the former procedure. © 1993 John Wiley&Sons, Inc

ISSN:0021-8995    

DOI:10.1002/app.1993.070480204

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe evaporation of 2‐hydroxy‐4‐methoxybenzophenone (HMB) from polypropylene was studied by an isothermal method at different concentrations of HMB ranging from 0.3 to 1.2 wt %. The evaporation of the additive was correlated according to first‐order kinetics. and rate constants of evaporation were calculated. A linear dependence of the rate constants of volatility on the initial concentration of the additive in the polymer was observed. This result suggests that in the given system, volatility is governed by evaporation from the polymer surface. Volatility of HMB from polypropylene depends on the degree of crystallinity of polypropylene. Samples with different degrees of crystallinity were prepared by quenching of the polymer blends and subsequent annealing at 423K. Isothermal measurements at 383 and 423K yielded higher rate constants for annealed samples than for quenched samples. The rate constant of evaporation at 383K was 20% higher for the annealed sample, whereas at 423K it was 27.5% higher. These results are interpreted on the basis of the concentration changes occurring during annealing. © 1993 John Wiley&S

ISSN:0021-8995    

DOI:10.1002/app.1993.070480205

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of the Lewis acid, iron(III) tris(oxalato)ferrate(III) tetrahydrate (Fe‐[Fe(C2O4)3].4H2O) (A) on the polymerization of butyl methacrylate (BuMA) initiated by a charge‐transfer mechanism has been studied in dimethyl sulfoxide (DMSO) at 60°C. 2,4‐dinitrophenylhydrazine (DNPH) was used as a nitrogen donor compound to initiate the polymerization in the presence of carbon tetrabromide (CBr4). Induction periods are observed for the polymerization initiated by DNPH and CBr4. The rate constant at 60°C for the polymerization of BuMA in the presence of A is 1.70×105L/mols−1. The molecular weight of polymers decreases with the increase of [ A ]. A probable reaction mechanism is proposed to explain the observed results. © 1993 John Wile

ISSN:0021-8995    

DOI:10.1002/app.1993.070480206

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

年代:1993

数据来源: WILEY

摘要:

AbstractSurface fluorination of poly(trimethylsilylpropyne) (PTMSP) membranes by CF4plasma was studied. The surface fluorination of the membranes was carried out in an atmosphere of CF4in a capacitively coupled discharge apparatus with external electrodes. Dramatic increase in selectivity (P o 2/P N 2) was observed. The effect of fluorination conditions such as duration of treatment and discharge power on the permeabilities of the membranes was studied. X‐ray photoelectron spectrometric data of modified PTMSP membranes showed a drastic alternation in the surface layer. TheP o 2andP o 2/P N 2of the membranes were observed to be dependent on the F/C atomic ratio. At F/C>1, theP o 2/P N 2value of the membranes could be more than four

ISSN:0021-8995    

DOI:10.1002/app.1993.070480207

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe kinetics of formation of epoxy resins derived from bisphenol‐A, bisphenol‐S, and epichlorohydrin under stoichiometric conditions was considered. The kinetics of reaction was studied by taking into account the consumption of the added alkali and epoxide value of epoxide oligomers. The obtained results satisfactorily explained that the reactivity of bisphenol‐A with epichlorohydrin is higher than that of bisphenol‐S, the rate of dehydrochlorination of chlorohydrin ether in the presence of alkali and water is much higher than that of the rate of condensation of phenolic hydroxyl group with epichlorohydrin. The apparent reaction order of phenolic groups with epichlorohydrin and terminal epoxide group in the oligomer are all second order. The rate constants and activation energy were determined. The results are discussed. © 1993 John Wiley&S

ISSN:0021-8995    

DOI:10.1002/app.1993.070480208

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

年代:1993

数据来源: WILEY

摘要:

AbstractA theoretical expression for the prediction of the transverse elastic modulus in fiber‐reinforced composites was developed. The concept of interphase between fibers and matrix was used for the development of the model. This model considers that the composite material consists of three phases, that is, the fiber, the matrix, and the interphase. The latter is the part of the polymer matrix lying at the close vicinity of the fiber surface. In the present investigation it was assumed that the interphase is inhomogeneous in nature with continuously varying mechanical properties. Different laws of variation of its elastic modulus and Poisson ratio were taken into account in order to define the overall modulus of the composite. Thermal analysis method was used for the estimation of the thickness of the interphase. The results obtained were compared with the respective values of other models as well as with experimental data. © 1993 John Wiley&Sons, I

ISSN:0021-8995    

DOI:10.1002/app.1993.070480209

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

年代:1993

数据来源: WILEY

摘要:

AbstractA kinetic and thermodynamic study of the thermally or anionically induced cure of aromatic bismaleimide monomers (namely 2,4‐bismaleimidotoluene, 4,4′‐bismaleimidodiphenylmethane and their eutectic mixture) is presented. Calorimetric investigations allowed the determination of heats of polymerization and activation energies for both types of initiations, and the values found are compared with data in the literature. Isothermal cures were also carried out with and without anionic initiator (typically imidazole). SEC measurements were used to monitor the conversion of the monomers as a function of time. The thermally induced polymerization seems to proceed in a rather heterogeneous way, owing to an initiation that is too slow: gelation appears at first only as the formation of microgels, with no immediate increase in the viscosity; macrogelation occurs some time after. On the contrary, the anionically induced polymerization is more homogeneous. A complete study of a particular reacting system revealed no interference between radical and anionic polymerization over a wide range of temperatures, and in this case gelation results in an immediate increase in viscosity. However, the conversion at the gel point is unexpectedly high, which can be interpreted as the result of a very fast initiation as well as of transfer reactions. Glass transition temperatures were also measured as a function of time and curing temperature in order to study the influence of vitrification on the kinetics and to check for the existence of a unique relation betweenTgand conversion. This actually proved to be correct as long as diffusion does not slow down the reaction; in this case Gillham's treatment ofTgversus intwas successfully applied and led to the correct value of the activation energy. All the measurements allowed us to establish the time‐temperature‐transformation cure diagram for a specific reacting system. © 1993 John Wiley

ISSN:0021-8995    

DOI:10.1002/app.1993.070480210

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

年代:1993

数据来源: WILEY