摘要:

AbstractA variety of crosslinked resin copolymers have been synthesized by condensingo‐hydroxy acetophenone with formaldehyde and chloro‐substituted benzoic acids and anilines in the presence of acidic and basic catalysts. The physico–chemical properties of the resins are reported. The thermogravimetric analysis method was used to study the thermal behaviour of the resins; the evolution of kinetic parameters and degradation mechanism was also investigated. Resins from chlorobenzoic acids showed clear two‐step degradation neglecting moisture loss, whereas those from chloro anilines gave a somewhat continuous sigmoid. The effect of reaction conditions like monomer, molar ratio, and catalyst is also reported. © 1993 John Wiley&S

ISSN:0021-8995    

DOI:10.1002/app.1993.070500301

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

年代:1993

数据来源: WILEY

摘要:

AbstractA stepwise scheme, reported recently for the calculation of molecular weight distributions in AB monomolecular condensation polymers under the condition of unequal reactivity, has been applied to the more common AA, BB bimolecular condensation polymers. In the scheme a condensation polymerization is arbitrarily subdivided into a number of steps. The polymer obtained in one step is treated as the monomer for the next step. In each of the steps, Flory's distribution for condensation polymer under equal reactivity is used as the molecular weight distribution for that step. Reactivity variances are incorporated into the calculation through the application of weighing factors on the concentrations of the reacting molecules in each of the steps. In the bimolecular case, three types of monomers, AA, BB, and AB, must be considered for the intermediate polymerization steps. The required distribution of this trimolecular condensation under equal reactivity conditions is not available and has to be derived. As expected, the application of the scheme to bimolecular condensation is more complex but numerical calculations using the scheme should still be manageable on a desktop computer with suitable memory capacity. © 1993 John Wiley&Sons, Inc

ISSN:0021-8995    

DOI:10.1002/app.1993.070500302

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

年代:1993

数据来源: WILEY

摘要:

AbstractAs part of a program to synthesize water‐soluble polymeric carriers suitable for drug binding, the polyaddition reaction of methylenebisacrylamide with comonomers containing two pri‐mary amino groups is investigated. The copolymerization of the bisacrylamide with equi‐molar quantities of primary diamines under properly controlled experimental conditions is found to proceed in a linear propagation, giving rise to the formation of polyamides comprising two or more secondary amino groups in the recurring unit. Selected diamine monomers include ethylenediamine, diethylenetriamine, triethylenetetramine, 1,2‐bis (3‐aminopropylamino) ethane, and three 0,0´‐bis‐(2‐aminopropyl) derivatives of poly(ethylene glycol) of different chain length, the last three monomers being chosen because of their outstanding hydrosolubilizing properties. Use of two different diamines in the proper stoi‐chiometry leads to corresponding copolymers. The reactions are conducted in aqueous phase over periods of 1–3 days at 65°C, and the polymeric products, possessing the linear polyamidoamine structures1and2, are fractionated by dialysis in membrane tubing with 12000–14000 molecular‐mass cutoff and are isolated by freeze‐drying as solid or resinous materials possessing complete solubility in water. Inherent viscosities are in the range of 8– 40mLg‐1. Microanalytical and spectroscopic data confirm the proposed structures. The suitability of the intrachain secondary amine functions for side chain attachment and drug coupling is demonstrated in model reactions involvingN‐substitu

ISSN:0021-8995    

DOI:10.1002/app.1993.070500303

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

年代:1993

数据来源: WILEY

摘要:

AbstractNew polymerizable urethane functional monomers containing hindered amine (III, III′) and their copolymers with styrene (S) and methyl methacrylate (MMA) are characterized and tested as hindered amine light stabilizers (HALS). Experimental results indicated that the monomers possess high photostabilizing effectiveness comparable to that of Tinuvin 770 and Tinuvin 765. Their copolymers with S and MMA showed lower photostabilizing effectiveness mainly due to the low hindered amine content in the copolymers. The copolymers, however, showed very high resistance to liquid extraction. UV and ESR analyses indicate that the photostabilizing mechanism of these HALS is through the scavenging action of nitroxyl radicals formed from degradation of the substrate polymer. © 1993 John Wiley&Sons, I

ISSN:0021-8995    

DOI:10.1002/app.1993.070500304

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe optical and electrical properties of BF−4deposed polypyrrole (PPY) have been studied in detail. The effect of annealing on the optical and electrical properties of BF−4doped PPY is reported. Interestingly, these properties are modified with annealing and it is observed that PPY is similar to other inorganic amorphous semiconductors. It is also seen that the electrical and optical properties of BF−4doped PPY are stabilized after 70 h of annealing at 70°C. © 1993 John Wiley&So

ISSN:0021-8995    

DOI:10.1002/app.1993.070500305

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

年代:1993

数据来源: WILEY

摘要:

AbstractPolyamic acids were synthesized from benzophenonetetracarboxylic dianhydride and di‐amines, viz., 4,4′ ‐diaminodiphenymmethane and 4,4′ ‐diaminodiphenyl ether. The course of imidization of the polyamic acids both by thermal and microwave treatments was tracked by infrared spectroscopy. The mechanical properties, namely the tensile strength and toughness of the films of polyimides with varying degree of imidization obtained by the two treatments were compared. The effect of degree of imidization of polyimide coatings on adhesion to copper substrate was also studied. Nearly 100% imidization was achieved by the thermal process, whereas the maximum imidization that could be achieved by the microwave process was about 50%. In thermal imidization, the adhesion values of the coatings slowly increased, attaining a maximum value at 80% imidization, after which there was a decrease in adhesion. © 1993 John Wiley

ISSN:0021-8995    

DOI:10.1002/app.1993.070500306

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

年代:1993

数据来源: WILEY

摘要:

AbstractA gas‐phase reactor system was developed to polymerize ethylene using the MgCl2/ethyl benzoate (EB)/TiCl4+ triethylaluminum (TEA) catalyst. The reproducibility of the reactor was tested and found to be adequate for kinetic study. The effects of TEA and temperature were studied with the multisite model that assumes a multiplicity of active sites. It was found that the productivity increased with Al/Ti molar ratio while initial activity leveled off. The deactivation rate, after an initial increase, Al/Ti molar that assumes a multiplicity of active sites. It was found that the productivity increase, decreased with Al/Ti. This corresponded with a transition in deactivation order: below Al/Ti = 70, first‐order deactivation was predominant; above Al/Ti = 70, second‐order deactivation was predominant. The second‐order deactivation reactions were made less disperse at higher Al/Ti. Molecular weight of the polyethylene was very high (>1,000,000) indicating negligible transfer reactions. For Al/Ti>130 a monomer sorption limitation for polymerization was found. The effect of temperature was also studied with a maximum in productivity at 55°C for Al/Ti = 98.0 and no maximum when Al/Ti = 53.0. Apparent activation energies (Ea) for activity were found to be 19.5 ±3.3 kJ/mol at Al/Ti = 98.0 and 9.3±1.1 kJ/mol at Al/Ti = 53.0. for deactivation Eawas found to be 36.6±5.0 kJ/mol at Al/Ti = 98.0 and–15.5± 4.4 kJ/ mol at Al/Ti = 53.0. Temperature increased the dispersity of second‐order deactivation reactions. © 1993 Joh

ISSN:0021-8995    

DOI:10.1002/app.1993.070500307

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

年代:1993

数据来源: WILEY

摘要:

AbstractElectrokinetic properties of normal polyester flat filament, texturized polyester and cationic dyeable polyester were studied when solutions of different pH and cationic dye concentrations were run through them. The textured polyester exhibited maximum negative zeta potential whereas cationic dyeable polyester showed minimum. The negative zeta potential was found to be maximum near neutral pH. The effect of heat‐setting at extreme conditions (220°C, 90 s) on electrokinetic properties was also studied. Such heat‐setting was found to lower negative zeta potential, attributed to a decrease in surface area. Cationic dyeable, “easy” dyeable, and normal flat filament type polyester were also investigated. Results with respect to negative zeta potential, surface charge density, and surface conductivity, are discussed. © 1993 John Wiley&

ISSN:0021-8995    

DOI:10.1002/app.1993.070500308

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe gamma‐induced changes in the structure of Poly(Acrylamide) (PAAm) treated with metal chlorides were investigated by following the corresponding variations in their ultra‐violet spectra. Careful examination of UV spectra revealed that irradiation of the specimens results in the appearance of an absorption peak at 275 nm whose intensity depends on the applied dose and the nature of the metal ions. This band is ascribed to the formation of the carbonyl group. The results indicate that the dependence of the intensities of the band at 275 nm on the nature of the metal used provides strong evidence for the formation of metal polymer complexes. It was found that the pretreatment of PAAm with the appropriate concentration of ZnCl2, CoCl2, or NiCl2reduces the effects of heating and the oxidation effects of γ‐irradiation. These results show that these metal ions can be used as stabilizers against thermal degradation of PAAm in the temperature range up to 160°C. © 1993 John Wiley&S

ISSN:0021-8995    

DOI:10.1002/app.1993.070500309

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

年代:1993

数据来源: WILEY

摘要:

AbstractButyl acrylate, styrene,N,N‐dimethylaminoethylmethacrylate, andN‐(n‐butoxymethyl) acrylamide were copolymerized to prepare a cationic acrylic copolymer (I) containing butoxymethylamide groups. This copolymer can be mixed with an epoxy‐amine adduct (II), acetic acid, and deionized (D.I.) water to form a coemulsion containing two cationic resins. The electrophoretic codeposition of the coemulsion and physical and chemical properties of the deposited film were investigated. The resin composition of film deposited from coemulsion was determined by Fourier transform Infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic codeposition behavior. The applicability of this two‐component coemulsion in primer‐surfacer (pricer) electrodeposition paint was also discussed. The results indicate that at any coemulsion resin composition the resin composition of electrodeposited film is almost equal to the coemulsion resin composition. The throwing power of emulsion increases with increasing applied voltage, as expected. However, the throwing power of coemulsion is almost equal to that of theIIemulsion but greater than that of theIemulsion. Furthermore, all cured films derived from mixtures ofI/IIshow excellent adhesive strength, good hardness, and high levels of salt spray resistance. © 1993 John Wil

ISSN:0021-8995    

DOI:10.1002/app.1993.070500310

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

年代:1993

数据来源: WILEY