bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyurethane‐elastomer‐actuator
Authors: Hirai Toshihiro , Sadatoh Hiroki , Ueda Tsutomu , Kasazaki Toshiaki , Kurita Yasushi , Hirai Mitsuhiro , Hayashi Sadao 
Published: April 2003

AbstractPolyurethane elastomers were investigated as electrically active materials for actuators. Components in hard segment and soft segment in the elastomers were varied. The elastomers with excellent electrostrictive properties were limited to those which had soft segments of polyesters and polylactones. It turned out, that the elastomers, whose soft segments are polyethers are electrically inert under the experimental conditions. The chemical structure of the hard segment seems not to influence to the electrostrictive property. The charging and discharging process was investigated. The charging process was found to proceed simultaneously with the contracting process caused by the electric field, suggesting that the orientation of the soft segment in the elastomer plays critical rolls in the electrostrictive action. In the elastomer, which has a soft polyether segment and was inactive to the electric field, could be actuated very efficiently when the elastomer was swollen with dimethyl sulfoxide. We conclude that the polyurethane elastomer, whose soft segment has chemical bonds with a relatively large dipole moment, can be actuated by the electric field application, and that even the elastomer, whose soft segment is inactive, could be actuated in the presence of a solvent with a large dipole moment. Thus, the concept found with the gel, could be applied to an elastomer, the soft segment of which plays partly the roll of the solvent in the gel.
Chemical reactions on polysaccharides, 5. Reaction of mesyl chloride with pullulan
Authors: Mocanu Georgeta , Constantin Marieta , Carpov Adrian 
Published: April 2003

AbstractThe reaction of mesyl chloride with crosslinked pullulan microparticles was investigated, in particular the influence of the reaction conditions on the ratio between the two possible products chlorodeoxy or O‐mesyl pullulan. It was found that in N,N‐dimethylformamide the preponderent reaction product is chlorodeoxy pullulan, while in pyridine at low temperatures the main product is the mesyl ester of pullulan. In N,N‐dimethylacetamide, the substituent groups are both chlorodeoxy and mesyl ones, in about 2:1 ratio. By the introduction of either chlorodeoxy or mesyl groups, the pullulan‐crosslinked microparticles become hydrophobic.
Friedel‐crafts polyketones: Synthesis, characterization and antimicrobial properties
Authors: Patel R. K. , Patel R. T. , Patel R. M. , Sinha T. J. M. 
Published: April 2003

AbstractA series of seven polyketones was prepared by Friedel‐Crafts reaction using 2‐chloroanisole, choroacetyl chloride, 1,2‐dichloroethane and dichloromethane with anhydrous aluminium chloride as catalyst and carbon disulfide as a solvent under different experimental conditions. The polyketones thus obtained were characterized by determination of the chlorine content (Carius method), IR spectroscopy, vapour‐pressure osmometry, thermogravimetry and differential scanning calorimetry. All these polyketones were tested for their antimicrobial properties against selected microorganisms. The results indicate that some of these resins show fair to good antimicrobial properties towards tested microorganisms and may be used as commercial biocides.
Structural analysis of poly(4‐hydroxybutyl acrylate)‐grafted silk fibres
Authors: Tsukada Masuhiro , Freddi Giuliano , Shiozaki Hideki , Kasai Nobutami , Kobayashi Masao 
Published: April 2003

AbstractPoly(4‐hydroxybutyl acrylate) poly(4‐HBA) was graft‐copolymerized onto silk fibres (bombyx mori) in aqueous medium with ammonium persulfate as initiator. The weight gain increased with increasing concentration of monomer in the grafting system. The grafting efficiency ranged from 45 to 65%. Equilibrium moisture regain decreased sharply beyond 10% weight gain. The tensile properties of the silk fibres did not change significantly as a function of the increasing weight gain. Birefringence and isotropic refractive index decreased until 35% weight gain and then remained unchanged. The X‐ray diffraction patterns showed that the crystalline structure was not affected by grafting. Differential scanning calorimetry (DSC), thermomechanical (TMA), and thermogravimetric (TG) measurements showed that poly(4‐HBA)‐grafted silk fibres underwent only slight changes in the thermal behaviour. The dynamic mechanical measurements (DMA) exhibited a downward shift of both the storage (E′) and loss modulus peak (E″) with increasing weight gain. Scanning electron microscopy (SEM) observations showed the presence of some deposits adhering to the surface of silk fibres grafted at high monomer/silk ratio (>50%).
Partial hydrolysis of cellulose acetate in toluene/acetic acid/water system
Authors: Olaru Niculae , Olaru Liliana , Andriescu Adrian , Tudorachi Niţǎ 
Published: April 2003

AbstractThe partial hydrolysis of cellulose acetate was studied in homogeneous toluene/acetic acid/water media of different compositions using sulfuric acid as a catalyst. The presence of toluene considerably increases the hydrolysis rate. Products with a degree of substitution (DS) of about 1.70, useful for further derivatization, were obtained at 60°C with 15–34 wt.‐% toluene in the reaction medium and without addition of water during the process in shorter times than in the conventional procedure free of toluene. The kinetic behaviour of toluene‐containing systems is dependent on the composition of the reaction medium, as well as on the temperature. The reaction systems with 15 wt.‐% and 20 wt.‐% toluene, respectively, were found to obey a linear relationship of ‐ln(DS/DS0) versus time. The behaviour of the studied reaction systems is tentatively explained by an enrichment of the solvation shell in water and sulfuric acid, since the acidity function of the sulfuric acid was not influenced by the presence of toluene. The hydrolysed products obtained by the described procedure are soluble in some common organic solvents used for derivatization, such as dimethylformamide, acetic acid and dimethyl sulfoxide.
Characterization and application of poly(vinyl alcohol)/starch composite as a sizing agent
Authors: Hashem Mohamed M. , Kesting Wolfgang , Hebeish Ali A. , Abou‐Zeid Nabil Y. , Schollmeyer Eckhard 
Published: April 2003

AbstractA macromolecular sizing agent based on the copolymerization of poly(vinyl alcohol) (PVA) with hydrolysed starch was prepared using the chemically reactive bifunctional compound N‐methylolacrylamide. Detailed characteristics of the resultant PVA/N‐methylolcarbamoylethylated starch copolymer were studied where emphasis has been placed on solubility, rheological properties, molecular weight distribution, adhesive power and stability. Elucidation of the nature of the macromolecular segments of both N‐methylolcarbamoylethylated PVA as well as PVA/N‐methylolcarbamoylethylated starch copolymer fulfilled the prerequisite to tailor PVA/starch copolymer which is appropriate for application as a water‐soluble recyclable sizing agent by ultrafiltration.
Properties of mixed aqueous solutions of perfluorooctanoate with poly(N‐vinylpyrrolidone)
Authors: Iijima Toshiro , Sugiyama Chisato 
Published: April 2003

AbstractAqueous mixtures of ammonium perfluorooctanoate (C8FN) and poly(N‐vinylpyrrolidone) (PVP) were characterized by measuring the surface tension, conductivity and solubilization. Sodium perfluorooctanoate was also used for comparison. The critical micelle concentration (c. m. c.) of C8FN was found to be 30 mmol L‐1. The dependence of the surface tension on the surfactant concentration could be successfully described by the surface condensation based on the Langmuir‐type adsorption. The cross‐sectional molecular area of the C8FN oriented perpendicular on the surface is estimated at 19.8Å2. The addition of PVP increases the molecular area, suggesting an interaction between C8FN and PVP on the surface. The solubilization of p‐aminoazobenzene (PAAB) in these systems shows a synergetic effect in the low‐concentration range of C8FN and PVP. Changes in the absorption spectra of PAAB indicated the interaction between C8FN and PVP.
Beeinflussung der Fließeigenschaften von Polyamid 6 durch submikrone Additive
Authors: Koine Axel , Mennig Günter , Schütz Angelo , Haufe Andreas 
Published: April 2003

AbstractDer Einfluß submikroner mineralischer Additive auf die rheologischen Eigenschaften von Polyamid 6 (PA 6) wurde untersucht. Üblicherweise steigt bei niedriger Schergeschwindigkeit die Viskosität nach der Einarbeitung zunehmender Mengen kommerzieller Füllstoffe (Mikronbereich der Korngrößen) stetig an, weil die Reibung in den Gleitschichten zunimmt.Nach intensiver Dispergierung submikroner Additive in Ethylenglykol unter Zusatz von Polyethylenimin als kationaktivem Dispergierhilfsmittel wurde eine agglomeratfreie Dispergierung aller untersuchten Additive erreicht. Unter Standardbedingungen wurden die glykolischen Suspensionen mit Hilfe eines Doppelschneckenextruders in die PA 6‐Matrix eingearbeitet, dabei mittels einer Entgasungsstufe sofort der Glykolüberschuß entfernt. Die erwarteten Effekte verbesserten intramolekularen Gleitens zeigten sich in unterschiedlicher Höhe bei TiO2, Al2O3, SiO2, Kaolin und Talkum. CaCO3 dagegen schränkte auch im Submikronbereich das intramolekulare Gleiten schon in Konzentrationen unter 1 Gew.‐% deutlich ein. Bei der Einarbeitung pulverförmiger Additive mittels eines Doppelschneckenextruders direkt in die PA 6‐Matrix wurden analoge Effekte nicht erreicht.
Emulsion polymerization in the presence of colloidal silica particles. Application to the reinforcement of poly(ethyl acrylate) films
Authors: Bourgeat‐Lami E. , Espiard P. , Guyot A. , Gauthier C. , David L. , Vigier G. 
Published: April 2003

AbstractEmulsion polymerization of ethyl acrylate was carried out in the presence of different kinds of functionalized and non‐functionalized silica particles. 3‐(Trimethoxysilyl)propyl methacrylate, 2‐hydroxyethyl methacrylate and 3‐(triethoxysilyl)‐propanethiol functionalization agents were examined. It is demonstrated that use of the first two coupling agents results latexes able to give films which display remarkable mechanical properties similar to those of vulcanized elastomers reinforced with solid particles. A qualitative model is then set up to give account for these properties. It is proposed that a part of the polymer is covalently bound to silica as tight loops, giving rise to a set of strong entanglements with the non‐grafted polymer during film formation. This model is supported by stress‐strain measurements. Some validation experiments are described using the third grafting agent of the series.
New results of the self‐initiation mechanism of SH/En addition polymerization
Authors: Kühne Gudrun , Diesen Jarle Sidney , Klemm Elisabeth 
Published: April 2003

AbstractNo radicals are formed in bis(mercaptopropionate)‐diene‐mixtures, as shown by means of ESR spectroscopic investigation. Radicals are produced spontaneously only in the presence of triethylene glycol dithiol. The hydrogen‐bonded structure of the dithiopropionates is obviously responsible for the inhibition of the charge transfer interaction with the diene compounds and prevents subsequent radical formation. The 13C NMR spectra confirm the anti‐Markownikow structure of the polymers formed with diallyl succinate and diallyl terephthalate.
Evaluation of terpolymers of 2‐hydroxyethyl methacrylate, dodecyl methacrylate and ethylene glycol dimethacrylate as matrices for hydrophobic interaction chromatography
Authors: Bryjak Marek , Trochimczuk Andrzej , Bryjak Jolanta 
Published: April 2003

AbstractPolymer matrices were prepared by suspension polymerization of 2‐hydroxyethyl methacrylate, dodecyl methacrylate and ethylene glycol dimethacrylate. It was shown that porosity decreased with the addition of monomers with hydrophobic side chains. Trypsin, bovine serum albumin and lipase served as standard proteins in sorbent hydrophobicity evaluation. Isocratic chromatography at various ionic strengths revealed different elution behaviours. Some sorbents exhibited an ion‐exchange mode in the whole range of ionic strength variation. Some others showed a hydrophobic interaction character when the salt concentration exceeded a critical value. It is suggested to take this critical salt concentration as a relative measure of hydrophobicity for particular protein‐matrix‐salt systems. It was shown that the matrix containing 90 μmol/g of dodecyl methacrylate was enough hydrophobic to differentiate proteins and thus could be used effectively for hydrophobic interaction chromatography of proteins.
Fluorinated poly(1,3,4‐oxadiazole‐imide‐amide)s
Authors: Hamciuc Corneliu , Hamciuc Elena , Bruma Maria 
Published: April 2003

AbstractA series of new fluorinated poly(1,3,4‐oxadiazole‐imide‐amide)s containing various ratios of amide/oxadiazole groups in the repeating unit have been prepared by cyclodehydration of the corresponding poly(hydrazide‐imide‐amide)s resulting from the reaction of diacid dichlorides incorporating both hexafluoroisopropylidene bridges and imide rings with p‐aminobenzhydrazide or with mixtures of certain aromatic diamines and p‐aminobenzhydrazide or terephthalic dihydrazide. The new polymers are soluble in polar amidic solvents and can be processed into flexible films by casting from solution. Their glass transition temperatures are in the range 254–325°C and they are thermally stable up to 415–450°C.
Macromonomers based on low‐molecular‐weight polyisobutenes
Authors: Maenz Karsten , Stadermann Dietmar 
Published: April 2003

AbstractRadically polymerizable macromonomers were synthesized by alkylation, epoxidation and SH‐en addition of low‐molecular‐weight polyisobutenes followed by esterification with methacrylic acid derivatives. Highly functionalized products (≥ 95%) can be obtained from polyisobutenes with double bond content ≪ 1 by separation of non‐functionalized polymer by column chromatography.
Tensile and transformational behavior of poly(ether sulfone)/polycarbonate blends
Authors: An Lijia , Wang Zhigang , Yu Donghong , Jing Jiaokai , Jiang Zhenhua , Ma Rongtang , Kou Xichun 
Published: April 2003

AbstractBlends of a poly(ether sulfone) (PES) and a polycarbonate (PC) were prepared by melt‐mixing and were studied by tensile tests, differential scanning calorimetry, dynamic mechanical analysis, density measurements and transmission electron microscopy (TEM). The blends were found to be two‐phase systems and an interfacial layer was presumed to be formed between two phases, which was verified by TEM. A synergism of elongation at break and tensile modulus was shown in PES/PC blends. The effects of the crosshead speed on the mechanical properties were discussed for blends with different PES/PC weight ratios.
Functionalization of isotactic poly(propylene) with maleic anhydride in the solid phase
Authors: Lazár Milan , Hrc̆ková L̆udmila , Fiedlerová Agnesa , Borsig Eberhard , Rätzsch Manfred , Hesse Achim 
Published: April 2003

AbstractThe influence of temperature and type of initiator on the grafting efficiency of maleic anhydride onto isotactic poly(propylene) powder under solid‐state reaction conditions was investigated. The level of bonded maleic anhydride was found to be about 20% higher using aliphatic peroxide, such as lauroyl peroxide, in contrast to dibenzoyl peroxide, dicumyl peroxide, 2,5‐dimethyl‐2,5‐di‐tert‐butylperoxyhexane or tert‐butyl perbenzoate as initiator.The higher grafting efficiency of maleic anhydride onto polyethylene when compared with poly(propylene) is accounted for by a higher kinetic length of the addition‐transfer chain reactions.
Epoxidation of cis‐cyclooctene with molecular oxygen catalyzed by magnesium oxide supported polytitazane cobalt (III) complexes
Authors: Ma Zhao‐Hui , Wang Tie‐Jun , Yan Yuan‐Yong , Huang Mei‐Yu , Jiang Ying‐Yan 
Published: April 2003

AbstractMagnesium oxide supported polytitazane cobalt (III) complex is demonstrated as an effective catalyst for the epoxidation of cis‐cyclooctene with molecular oxygen at atmospheric pressure in the presence of isobutyraldehyde as the sacrificial reductant. XPS data show that the high‐valent cobalt (III) is stabilized by the multidentate nitrogen ligand of polytitazane. The conversion of cis‐cyclooctene is as high as 95.2% with 100% selectivity to the cis‐cyclooctene oxide at 25°C within 5 h. The catalyst can be used at least nine times without loss of its activity.
Effects of morphological changes on the oxygen transport properties of poly[(ethylene terephthalate)‐co‐(1,4‐cyclohexylene dimethylene terephthalate)]
Authors: Testa Giovanni , Seves Alberto , Vicini Loredana , Pedrelli Turno , Marcandalli Bruno 
Published: April 2003

AbstractTo improve the physical picture of the polymeric glassy state, the influence of morphological changes achieved by different thermal treatments of an amorphous glassy poly(alkylene terephthalate) film on the oxygen transport properties has been studied. Annealing treatments were performed on films in constraint imposed giving samples of different crystallinity contents and morphology.The dependence of the oxygen permeability and diffusion as the free volume from crystallinity content was investigated at sub‐Tg temperatures within the range of 303–348 K.The investigations reveal that on crystallized samples, permeability and solubility coefficients decrease at higher crystallization temperature, while annealed samples showed an opposite trend despite higher crystallinities. Further, annealed films showed higher free volume content.The trend of results suggests that different parameters are likely to play a significant role in determining apparent permeability coefficients. The presence of microvoids in annealed samples may be supposed.
Cellulose‐based polymer blend filaments spun from N‐methylmorpholine‐N‐oxide
Authors: Morgenstern Bernd , Leillinger Olaf , Maron Reinhard 
Published: April 2003

AbstractThe influence of a small addition (<15 wt.‐%) of an aromatic polyamide [poly(2,6‐dichloro‐1,4‐phenylene terephthalamide) (P26C1PTA)] as additive on the textile‐physical properties of cellulose filaments was investigated. The blend filaments were spun from homogeneous blend solutions prepared in the common solvent N‐methylmorpholine‐N‐oxide. Most of the estimated properties of blend filaments containing not more than 10 wt.‐% of P26C1PTA do not differ significantly from those of pure cellulose filaments. However, the wet abrasion resistance attains a maximum at a P26C1PTA content of 10 wt.‐%. At higher P26C1PTA content the fibrillation tendency of the blend filaments is increased. Coincidentally, a decrease of tenacity and wet abrasion resistance was obtained.
Synthesis and properties of powdery hydrogels based on acrylamide, methacrylamide, and their N‐substituted derivatives
Authors: Lopour Petr , Ševčík Stanislav , Labský Jiří , Lednický František 
Published: April 2003

AbstractLightly crosslinked hydrogels based on acrylamide, N‐(1,1‐dimethyl‐3‐oxobutyl)‐acrylamide, N,N‐dimethylacrylamide, methacrylamide, N‐(2‐hydroxypropyl)methacrylamide and N‐[tris(hydroxymethyl)methyl]methacrylamide were synthesized in form of fine powders, consisting of aggregates of very small (∼10−1 μm) particles. The powdery hydrogels were obtained by precipitation polymerization in acetone and diethyl ether, using N,N′‐methylenebisacrylamide and ethylene dimethacrylate as crosslinking agents. Dependences of water‐swellability, particle size, aggregation, specific surface and content of the uncrosslinked water‐soluble polymers and low‐molecular‐weight substances in the hydrogels on the conditions of their synthesis were studied. Suitability of particular powdery hydrogels synthesized for the preparation of silicone rubber‐hydrogel composites is discussed.
Phase diagram and crystallization of polycarbonate/poly‐ϵ‐caprolactone blends
Authors: Hatzius Knut , Li Yong , Werner Martin , Jungnickel Bernd‐J. 
Published: April 2003

AbstractIt is reported on the equilibrium melting point depression of polycarbonate from bisphenol A (PC) in its blend with poly‐ϵ‐caprolactone (PCL). To this end, a model which explains the bended course of the measured Hoffman‐Weeks plots is developed which takes into account the composition changes at the crystal growth front upon progressive crystallization. The occasional melting point depression of the PCL component is discussed. The calculated Flory‐Huggins parameter of χ12 ≈︁ −0.09 indicates only weak enthalpic interactions. The remarkable drop in the glass transition temperature of PC with blending allows PC degrees of crystallinity up to 25% upon crystallization from the melt.
PVC‐ein werkstoff im wandel
Authors: Engelmann Manfred 
Published: April 2003

AbstractThe consumption of PVC amounts to 5.3 Mio t in Western Europe with an annual increase of about 2%. The most important field of application is building and construction.The main targets relating to the production process are less energy consumption, the reduction of emissions to air and water and the increase of the productivity of the plants.In the field of processing a dramatic increase of the output of extrusion or calandering devices has been realized ‐ connected with an improvement of quality and economy.
Polycarbonat‐ein vielseitiger werkstoff mit zukunft
Authors: Zaby G. , Fengler G. , Genz J. 
Published: April 2003

AbstractThe market development of bisphenol‐A‐polycarbonate has shown higher growth than any other engineering thermoplastic. The reasons can be found in the permanent improvement of the cost/performance‐relationship and in the technical use of the variability of the basic structure. Incorporation of specific monomer units leads to tailor‐made properties for a wide range of applications, as for example medical devices, electronic parts and glazing.This process has not yet slowed down, rather it is accelerated by new results from research and development. The improvement of flaw behavior and pit replication for new grades of materials for the next generation of compact discs, new grades that can be sterilized by γ‐radiation without degradation and the microstructuring by low‐energy laser systems are examples for the ongoing expansion of polycarbonate applications. Surface modification by hardcoatings with nanosized particles will allow to enter the fast growing market of glazing.
Polyethylen, polypropylen: Neue perspektiven für standardpolymere
Authors: Böhm L. L. , Enderle H.‐F. , Fleissner M. , Kloos F. 
Published: April 2003

AbstractPolyolefins like polyethylene (PE), polypropylene (PP) and their copolymers inclusive elastomers (EPM, EPDM) are materials with wide ranges of properties and excellent environmental compatibility. Therefore use and production of these products increase steadily. By the development of new catalysts and advanced technologies tailor‐made products with new combinations of properties are available which open superior applications. To these products belong materials with Schúlz,Flory‐ or bimodal molecular mass distributions, new types of linear low density products with homogeneous comonomer distribution, multiphase polypropylene blends and long glass fibre reinforced polypropylene materials. With metallocenes new types of polyolefins can be synthesized like syndiotactic polypropylene and other polyolefins.