摘要:

AbstractBlock copolymers of butadiene and styrene containing 21 and 61 wt.‐% styrene as well as pure polybutadiene have been investigated with respect to the extent of crosslinking produced by the irradiation with60Co γ‐rays. The free radical yield at 77 K,G(R.), has also been measured. Addition of the styrene blocks to the butadiene chains causes a rapid decrease in bothG(X), theG‐value for crosslink formation, and the free radical yield in nearly the same proportion for both, butG(X) is about twice as high as expected if crosslinks arose only from free radical recombination reactions. The effect of the styrene segments in the block copolymers onG(X) is approximately the same as in random copolymers of butadiene and styrene up to 21 wt.‐% styrene comp

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830911

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

Abstract[2‐(Diethylamino)ethyl]dextran hydrochloride (EA) was reacted with a mixture of sodium dextran sulfate (DS) and poly(styrene sulfonate) (NaSS) to form a novel water‐water precipitate, a so‐so polyelectrolyte complex (PEC), comprising three biomedical materials. The mole ratios of (DS + NaSS)/EA in PEC's prepared at higher [H+] were greater than at lower [H+] except for those PEC's prepared in 5% NaOH solution. IR, elemental analyses, solubility measurements, and blood clotting tests for PEC's revealed that the molecular structure of the various PEC's differed according to the [H+], order of mixing in solution, though all PEC's were prepared from the same starting materials. It appears that the degree of dissociation and the conformation of DS, NaSS, and EA change with [H+] and that a different neutralization reaction occured in terms of different order of mixing. Blood clotting tests were performed on PEC tablets. It was found that PEC's suppressed the coagulation of blood compared with

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830912

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThree macrocyclic exchangers are prepared and characterized by grafting on chloromethylated styrene‐divinylbenzene resin, one diazacrown‐ether (7,16‐bis(2‐hydroxyethyl)‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane (1)), one cryptand (21‐(2‐aminoethyl)‐4,7,13,16‐tetraoxa‐1,10,21‐triazabicyclo[8.8.5]tricosane (2b)), and one polymeric cryptand (poly(4,7,13,16‐tetraoxa‐1,10,21,24‐tetraazabicyclo[8.8.8]hexacos‐21,24‐ylene‐2,7‐dihydroxyoctamethylene (3)). Separation of alkali and alkaline‐earth cations is studied by liquid column chromatography with these exchangers in water. The separations occur according to the binding properties of the ligands in solution with an increase of the binding constants in the resin. The resolutions obtained are limited by relatively low capacities of the resins (0,4–0,9 mmol Mn+/g) and mainly by sl

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830913

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe hydrodynamic behaviour of polydisperse branched copolymers of methyl methacrylate with a small amount of ethylene dimethacrylate was investigated in several solvents possessing different “solvent power”. It was found that with increasing degree of branching the viscometric expansion coeficient α 3[η],bof these copolymers decreases compared with the expansion of the linear analogs α 3[η],l(before the gel point α 3[η],b/α 3[η],l≈ 0,5). This phenomenon is demonstrated to be useful in the application of viscometry as a method of estimation or deter

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830914

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe enthalpies of combustion of poly(ethylene oxide), ΔH oc(c)=‐1178,7 ± 1,3 kJ . mol‐1, and of a random copolymer of overall molar composition 0,41 (poly(ethylene oxide)) + 0,59 (poly(oxy‐1,4‐cyclohexylene)), ΔH oc(c)=‐2566,4 ± 1,8 kJ . mol‐1, were measured at 298,15 K by high‐precision bomb calorimetry. The enthalpy of polymerisation of ethylene oxide was derived as ΔH op(l → c) = ‐102,4 ± 1,6 kJ . mol‐1. The enthalpy of copolymerisation of ethylene oxide and 7‐oxabicyclo[2.2.1]heptane was ΔH op(l → c) = ‐63,0 ± 2,1 kJ . mol‐1, compared with ‐68,1 ± 1,6 kJ . mol‐1for producing the two homopolymers in the proportion in which the monomers were present in the copolymer. It is concluded that insertion of an ethylene oxide unit into a poly(oxy‐1,4‐cyclohexylene) chain does

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830915

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe weight fraction and the molecular mass“Relative molecular mass” (systematic IUPAC name) is shortened to “molecular mass” throughout this paper.of polymeric material extracted from a polymer network, the time needed for the dissolution of the network during random degradation, and the molecular mass of the high molecular mass degradation products can be utilised for the determination of previously inaccessible structural details of the network, e.g. the value of the molecular mass of network chains, the chain end correction term, the functionality of the crosslinks, and the inhomogeneity of crosslinking, i.e. the amount, the diameter, and the crosslink concentration of anomalously and highly crosslinked

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830916

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractExperiments on networks crosslinked by peroxides show that the amount of extracted molecules as well as the time needed for a dissolution of a network during random degradation and the molecular mass“Relative molecular mass” (systematic IUPAC name) is shortened to “molecular mass” throughout this paper.of high molecular mass degradation products may be used to determine previously inaccessible structural details, such as molecular mass of the network chains, weight fraction of chains with one free end, functionality of the crosslinks, and inhomogeneity of crosslinking, i.e. the amount, the diameter, and the concentration of crosslinking units of anomalously and strongly crosslinked regions. In crosslinking of polydienes, chain splitting is negligible, but the functionalities of the crosslinks are abnormally high for low peroxide concentrations, because the peroxide radicals may connect more than two chains by polymerization. A relatively high spatial inhomogeneity of the concentration of crosslinking units occurs with polybutadienes, presumably because the radicals of this polymer have especially long life‐times so that they can polymerize sequences of polyfunctional crosslinks via kinetic chains with transfer reactions. In crosslinking of polyisoprene the apparent efficiency of this peroxide is about 1,0 if one takes into account not only the number of crosslinks, but also that of loops, and if one neglects transfer. The efficiency of this peroxide is ≫ 1 in the crosslinking of polybutadiene, because of pronounced transfe

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830917

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractExtraction and random degradation of networks make it possible to determine the molecular mass“Relative molecular mass” (systematic IUPAC name) is shortened to “molecular mass” throughout this paper.of the network chains, the amount of chain ends, the spatial inhomogeneity of crosslinking, the surprisingly high functionality of the crosslinks, and the efficiency and the transfer of crosslinking radicals. These results are compared with the stress‐strain behaviour at low and high extensions, the stress optical coefficient, and the equilibrium swelling degree. A value of the memory term relative to that of crosslinked melts may be deduced from the swelling degree at a given modulus. With this value an “analytical” modulus may be calculated from the analytical results. It corresponds roughly to the Mooney‐Rivlin modulus if one neglects the influence of functionality, but there remain deviations which suggest that another method should be developed for determining the modulus of the covalent network. The modulus measured at low extensions cannot be used to calculate the crosslink density in weakly cross

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830918

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe effect of lateral substituents on the structure of the solutions and on the chain conformations ofN‐substituted andN,N‐disubstituted poly(acrylamide)s is discussed. The water‐soluble polymers show solution properties influenced by the development of strong specific interactions between the chain molecules and the solvent, and by the hydrophobicity of the substituents. In non‐aqueous solvents the interactions between the polar groups of the structural units force the polymer chains to assume unusually large unperturbed dimensions, causing the chain flexibility to depend more on the overall polarity of the molecule than on the bulkiness of the subs

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830919

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractInfrared spectra of monodisperse (DP ≤ 35) and polydisperse (average DP ≤ 45) oligo(ethylene glycol)s are recorded for melts and for solids over a temperature range (+70°C to ‐80°C). Spectra in the hydroxyl stretching region show that the solid monodisperse oligomers with DP ≤ 25 at temperatures well below the melting point have highly ordered lamella end surfaces with hydroxyl groups from adjacent lamellae hydrogen bonded in long chains, whereas the solid polydisperse oligomers of comparable chain length have disordered lamella end surfaces with hydroxyl‐ether as well as hydroxyl‐hydroxyl hyd

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830920

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY