摘要:

AbstractAttempts of the conversion of hexamethylene diisocyanate (HDI) into biuret and urea derivatives by treatment with hexamethylene diamine (HDA) at 140°C, 155°C, and 170°C at different molar ratios of the reactants have been described. By means of gel permeation chromatographic analyses, the approximate contents of the mainly formed prepolymers were estimated. Also a scheme of the formation of all obtained oligomers has been proposed. On the basis of the results of physico‐chemical measurements, the influences of temperature and molar ratios of the reagents on the properties of the resulting products have been interpreted. It has been shown, that about 30 prepolymers of molecular weights (MW) up to 1300 having a biuret or a urea structure, are fo

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310101

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractDyeing of wool and wool/polyacrylic fabrics with an acid dye, namely, Kiton Scarlet 4 R, was carried out in absence or presence of different redox systems. The latter were based on sodium, potassium, or ammonium peroxodisulphate or potassium periodate as oxidant and glucose, sodium thiosulphate, potassium pyrosulphite or thiourea as reductant. Regardless of the redox system used, the colour strength was far greater in presence than in absence of the redox system. Except in case of potassium periodate/glucose redox system, increasing the oxidant concentration up to 0.03 mol/l caused significant enhancement in colour strength. The same was observed upon increasing the temperature from 30 to 60°C as well as the time from 10 to 40 minutes. It is postulated that presence of the redox system alters the mode of dye attachment to the substrate. Association of the dye with the substrate, wool in particular, seems to involve covalent bonding beside the usual salt‐linkage. Hence the approach presented is advantageous in producing dyeings with much higher colour strength and dye fixation at relatively low temperatu

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310102

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractDer zeitliche Verlauf der Polykondensation von Phenol mit Formaldehyd zu Resolen wird anhand eines kinetischen Modells mit einem Mikrocomputer simuliert. Durch Variation der Geschwindigkeitskonstanten und des Ausgangsmolverhältnisses von Phenol und Formaldehyd wird der Einfluß unterschiedlicher Reaktionsbedingungen auf wichtige Harzeigenschaften wie Restmonomergehalt, zahlenmittlerer Polymerisationsgrad, Verzweigungs‐ und Methylolierungsgrad untersucht. Die Eigenschaftsmerkmale der Endprodukte werden insbesondere durch das Ausmaß intramolekularer Vernetzungen, d. h., durch den Mikrogelanteil beeinf

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310103

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe alkali pretreatments of cotton linters, bagasse dissolving pulp, and bagasse kraft pulp increased the accessibility of the cellulose hydroxy groups to acetylating molecules. The pretreatment with hot alkali resulted in a higher degree of esterification than with cold alkali.The filterabilities of cellulose acetates obtained from alkali pretreated samples of cotton linters, dissolving pulp, and kraft pulp were better than in case of the untreated samples. Hot refining resulted in better filterability than cold refining, but resulted in stronger degradation and lower thermal stability than cold refining.The presence of hemicelluloses in the untreated pulp lowered the reactivity towards acetylation but favoured the reactivity towards xanthation. In case of cotton linters both reactivities were improved by the alkaline pretreatments. The increase in reactivity resulting from the depolymerization of the cellulose overcame the increase in inaccessibility resulting from drying after the alkaline treatment.The removal of hemicelluloses from the dissolving and kraft pulps by alkaline extraction deteriorated the reactivities towards xanthation, but had a favourable effect on the reactivity towards acetylation.

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310104

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe homopolymerization and graft copolymerization of methyl methacrylate with EPR and EPDM rubber was studied in a variety of solvents using benzoyl peroxide and azobisisobutyronitrile as initiators. Under the conditions of our experiments the yield of homopolymer and of graft copolymer for the solvents used increased in the ordercyclohexane>decaline>toluene>benzeneThe grafting yield depends particularly on the concentration of the rubber solution. The grafting mechanism is discussed in terms of different initiators (AIBN and Bz2O2).

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310105

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe migration of the antioxidant n‐octadecyl‐3‐(3,5‐di‐tert.‐butyl‐4‐hydroxyphenyl)‐propionate from standard polystyrene and selected high‐impact polystyrenes into the test fat HB 307 was investigated by means of radiotracer techniques, especially its dependence on contact time and temperature. Characteristic differences between the migration properties of the additive in standard polystyrene on the one hand and those in the high‐impact types on the other hand were found which obviously are caused by the different physical structures of these plastics. In the high impact types below 70°C the predominant migration process was found to be diffusion from the disperse rubber phase near the contact surface, whereas above this temperature the additive molecules are preferably diffusing through the polystyrene matrix.Simple rules are given by which the procedure for calculating migration values — which we developed earlier for polyolefins — can be used to predict the migration of additives from high

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310106

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA series of cycloalkylhydroquinone terephthalate copolyesters containing varying amounts of 1,6‐hexanediol flexible spacers were prepared by a two‐step reaction procedure and characterized for their liquid crystalline properties. Included in the series were hydroquinone monomers containing norbornyl, cyclohexyl, cycloheptyl, and cyclooctyl substituents. The norbornylhydroquinone series formed nematic melts at 1,6‐hexanediol contents of 30 mol‐% or less, but not at 40 mol‐%. The glass temperatures and melting points were higher than expected in the norbornylhydroquinone series, but analysis of dyad contents by13C‐NMR indicated that the comonomers were randomly

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310107

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractCompatibility of 17 pairs of rubbers has been investigated by means of phase separation, glass transition measurements and electron microscopy. Influence of structural details like side chains, configuration of monomer units and distance between double bonds in the chain on the compatibility of polymers has been elucidated. Experimental data lead to following results:Side chains have the strongest influence on compatibility; poly(isobutene) and poly(pentenamer), e.g., are highly incompatible. With decreasing influence on compatibility follows the configuration of the double bond in the polymer chain. Polymers with equal configuration are more compatible than polymers with different configuration. The structural detail with the weakest influence on compatibility is the distance between double bonds along the polymer chain. Poly(octenamer) and poly(pentenamer), e.g., with 6 and 3 methylene groups between the double bonds are less compatible than poly(butadiene) and poly(pentenamer) with a distance of 2 and 3 methylene groups.Cis‐poly(pentenamer) and natural rubber were found to be highly compatible although electron micrographs show domains with an average diameter of 50

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310108

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe polymerization of 2‐vinylpyridine (2VP) in dimethylformamide (DMF) with azobisisobutyronitrile (AIBN) as initiator was studied with a differential scanning calorimeter. By taking an appropriate amount of AIBN and after correction for its decomposition, the following values could be obtained:Heat of polymerization ΔHp,o= −68 ± 4 kJ/mol; overall Arrhenius activation parameters Ea= 90.0 ± 4 kJ/mol and ln A = 24 ± 1.0 (A = 2.6 × 1010dm3/2/mo

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310109

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe dependence of electrical characteristics of polymer complexes on ambient humidity was studied for complexes of quaternized poly(2‐vinylpyridine) and of quaternized poly(4‐vinylpyridine) with perchlorates (HClO4, LiClO4, KClO4). The electric resistance decreased linearly with the increase in ambient humidity for both types of complexes. The complex containing the perchlorate with the larger ionic radius showed a lower electric resistance. No change was observed in the humidityresistance relationship for more than ten mon

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051310110

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY