摘要:

AbstractThe complexation of amino functions supported on poly(acrylamides) with 2–20 mol‐% of N‐(acrylamidomethyl)acrylamide (NNMBA) crosslinks towards Co(II), Ni(II), Cu(II), Zn(II), and Hg(II) ions was investigated. The metal ion uptake was found to be dependent on the extent of the NNMBA crosslinking. The observed trend in complexation is Hg(II) ≫ Cu(II)>Zn(II)>Ni(II)>Co(II). The kinetics of complexation was found to be of first order. The derived metal complexes were characterised by IR and EPR. The complexed resins can be recycled several times without capacity loss. The metal‐desorbed resins showed specificity to the metal ion which was initially present. The extent of swelling of the complexed resins is lower than that of the uncomplexed resins and it varies with the extent of cro

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080101

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe electrical conduction of polycarbonate (PC) doped with different transition metals was studied in the temperature range of 293–493 K. The conductivity of PC doped with FeCl3is 7 orders higher in comparison with the other samples. The effective potential barrier (Φ) for pure PC was calculated (0.2 eV). Also, the dielectric constant at different temperatures was studi

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080102

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe efficiency of light stabilizers is investigated by electric methods in the initial stage of photooxidative ageing of low density polyethylene (LDPE). Three types of UV light stabilizers are tried to improve the UV stability of LDPE: a phosphite type (3,9‐bis‐[(2,4‐di‐tert‐butyl)phenoxy]‐2,4,8,10‐tetraoxa‐3,9‐diphosphaspiro[5.5]undecane) a benzophenone type [2‐hydroxy‐4‐octyloxy‐benzophenone] and a stabilizer based on chelate salt [2,2′‐thiobis(4‐tert‐octyl phenolato) (n‐butylamine) nickel (II)]. LDPE is very susceptible to ultraviolet light. UV light stabilizers improve the stability of low density polyethylene for electrical applications, especially the

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080103

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractResponsive poly(vinyl alcohol) PVA hydrogels obtained by electron irradiation after heating of a water‐swollen film show higher elasticity and tougher properties even after boiling in water, although some swelling did occur. The volume of the hydrogel after boiling was very sensitive to solvent (acetone) and temperature. The crosslinked hydrogels show higher tensile strength after rapid contraction by immersion in acetone. The crosslinked PVA was boiled and cooled to induce contraction and swelling cycles. The swelling ratio of hydrogel decreased remarkably at temperatures higher than 40

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080104

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe thermal aging of extruded samples of electron beam‐crosslinked linear polyethylene has been studied in the 110–170°C temperature range. Short and long term changes of mechanical (tensile) properties were observed, and the corresponding mechanisms are discussed on the basis of complementary sol‐gel and gravimetric measurements on whole samples, and density, FTIR and tensile testing on microtome sections.Two mechanisms are involved in short term changes: a post‐crosslinking and a change of the crystalline morphology (for samples exposed above the melting point). The latter effect is especially important in the case under study where the polymer was crosslinked in the solid state and leads to a noticeable decrease (∼5 MPa) of the yield stress.The long term changes take place after the end of the induction period of oxidation. They can be interpreted in terms of ductile‐brittle transition induced by structural changes occurring on the macromolecular level (chain scission) as well as macroscopically (core‐shell structure resulting of the diffusion control of oxidation kinetics). It appears that noticeable changes of ultimate elongation occur just before the end of the induction period as detected by IR

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080105

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

Abstract2,2′,6,6′‐Tetrabromobisphenol‐A (TBBPA), a sterically hindered bisphenol, is known to give only low‐molecular‐weight polymers using the interfacial phosgenation process. The low reactivity is attributed to the bulkiness and electron‐withdrawing character of bromine substituents at the ortho positions. From the formation of carbamate products in model compound (2,4,6‐tribromophenyl chloroformate, TBPC) reactions with trialkylamines, the trialkylamine catalyst was found to act as a terminator by the degradation of the chloroformate‐trialkylamine complex. The generation of carbamate occurs through the decomposition of the acyl ammonium salt proceeding via nucleophilic displacement by Cl−at the carbon attached to the positive nitrogen center. The relative catalytic abilities of trialkylamines and pyridine derivatives were determined in the homogeneous (dichloromethane) and interfacial (dichloromethane/water) systems. From the results of model reactions with TBPC and sodium tribromophenolate, 4‐dimethylaminopyridine (DMAP) was found to

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080106

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractSchottky diodes of aluminium/poly(3‐octylthiophene)(P30T)/indium‐tin oxide with large active area are prepared by using the proposed new casting technique. Their rectifying behavior and junction characteristics are dependent on whether the P30T is doped and on the storage time, but independent of the thickness of the P30T layer. The present technique can also be applied in a fabrication of electronic devices with other soluble conjugated polym

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080107

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effects of temperature and ionic strength of a solution of C. I. Basic Red 18 on the cooperative interaction with carboxymethylcellulose were investigated by the dynamic dialysis method and the binding parameters were determined. The molecular model of the cooperative binding is presented.

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080108

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractTwo series of copoly(1,4‐arylene‐1,2,4‐oxadiazole)s (co‐PAOs) having n‐butyloxymethyl and n‐octyloxymethyl side branch were prepared by solution cyclodehydration of the corresponding precursor copoly(1,4‐arylene terephthaloyl amide oxime)s (co‐PAAs) obtained by solution polycondensation of mixtures of 2,5‐bis(n‐alkyloxymethyl)‐1,4‐benzenediamide oximes (DIS‐TADO) and terephthaldiamide oxime (TADO) with terephthaloyl chloride. Thermal properties of the copolymers were investigated and discussed in connection with the length and the content of side branches. All the c

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080109

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractBoth the effect of the diamine chain extender on solution properties and the effect of added LiCl destroying the urea hydrogen bonds of the PUU's (polyurethane ureas) in DMF have been investigated. PUU solutions with an even number of CH2units in the chain extender have higher viscosities than the corresponding solutions with an odd number of CH2units. While the viscosity of solutions with odd‐numbered methylene groups is independent of time, the even‐numbered ones show a drastic increase in dependence on time and gelation may even occur. Due to diminished associates, time‐independent solution systems of low viscosity have also been obtained by adding a small amount of LiCl to solutions with even‐numbered methylene groups.In films cast from the solutions the effect of LiCl has been proved in the soli

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052080110

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY