bluuebunny/crossref_metadata_2025_split huggingface dataset:
Free radical copolymerization of allyloxyphenylsiloxanes with some vinyl monomers
Authors: Matsukawa Kimihiro , Hirano Hiroshi , Inoue Hiroshi 
Published: April 2003

AbstractTwo p‐allyloxyphenyldisiloxane compounds, 1‐(p‐allyloxyphenyl)‐1,1,3,3,3‐pentamethyldisiloxane (mono‐APDS) and 1,3‐bis(p‐allyloxyphenyl)‐1,1,3,3‐tetramethyldisiloxane (bis‐APDS), were synthesized to study their radical copolymerizations with some vinyl monomers (styrene, methyl methacrylate, N‐phenylmaleimide and maleic anhydride). The reactivities of allyl groups in mono‐APDS and bis‐APDS were found to be almost the same in styrene and methyl methacrylate copolymerization, as evidenced by their composition curves, and increase with the electron‐accepting ability of comonomers. In the case of electron‐poor monomers, such as N‐phenylmaleimide and maleic anhydride, the second allyl group of bis‐APDS readily took part in the crosslinking. Differential scanning calorimetry and thermogravimetry revealed that the increase of APDS contents in those copolymers led to lower glass transition temperature (Tg) and higher thermal degradation temperature.
Degradation and stabilization of PVC in blends
Authors: Braun D. , Böhringer B. , Eidam N. , Fischer M. , Kömmerling S. 
Published: April 2003

AbstractPoly(vinylchloride) (PVC) was mixed with various poly(methacrylate)s, poly(carbonate)s and polymers containing nitrile groups (poly(acrylonitrile), poly(styrene‐co‐acrylonitrile), nitrile rubber, hydrogenated nitrile rubber) and/or C  C double bonds (nitrile rubber, high‐impact poly(styrene)). The thermal stability was measured at 180°C in nitrogen, and the evolved HCl was detected by conductometry.It is shown that the nature of the ester group and the content of nitrile groups and C ‐ C double bonds are the dominating factors for the thermal stability of poly(vinylchloride) in these blends. An influence of the miscibility of PVC with the various blend components on the thermal stability can not be clearly detected.Differential scanning calorimetry (DSC) was used as a powerful method to study the stabilizer distribution of heterogeneous PVC/poly(styrene‐co‐acrylonitrile) and PVC/poly(methylacrylate) blends. It is shown that the stabilizer can be solubilized either in the PVC phase (PVC/poly(methylacrylate)) or in both phases of the blends PVC/poly(styrene‐co‐acrylonitrile)).
The biodegradation of polymers: Recent results
Authors: David C. , De Kesel C. , Lefebvre F. , Weiland M. 
Published: April 2003

AbstractAfter a general introduction including definition of biodegradability, the recent literature is briefly summarized. The results obtained in our laboratory for various polymers in three different composting units are then presented. They demonstrate that there is an urgent need for a quantitative method to characterize polymer biodegradation. For that purpose, a manometric method which allows the measurement of the oxygen consumed by the growing microorganisms has been developed. It has been tested with various inocula of increasing complexity: one Streptomyces sp., a mixture of three Streptomyces (badius, setonii and viridosporus), a compost extract or sewer sludge, growing in the presence of low molecular weight molecules as sole carbon source. Its performances and limitations are discussed. It is then applied to various polymer systems: polyesters and their constituent units, autoxidized polyethylene (APE) and its model compounds, polyvinyl alcohol (PVAl), starch and cellulose. The biodegradability of these polymers is characterized and their potential use as biodegradable materials for packaging, sanitary and agricultural uses is discussed.
Thermo‐mechanical degradation of polymer blends
Authors: La Mantia Francesco Paolo , Valenza Antonino 
Published: April 2003

AbstractPolymer blends can undergo, during processing, degradation phenomena because of the presence of both temperature and mechanical stresses. With respect to pure homogeneous polymers, the degradation of polymer blends shows distinct features because of the possible interaction between the different chemical species. These interaction can give rise to both a faster degradation or to the formation of copolymers which act as stabilizing agents. This latter phenomena is particularly important in the processing of condensation polymers
Reaction of hals in polypropylene during light exposure: Part 1‐iso‐octane as reaction model compound ‐
Authors: Neri C. , Malatesta V. , Costanzi S. , Riva R. 
Published: April 2003

AbstractThe photo and thermal reactivity of nitroxyl radicals derived from di‐, (oligo)meric hindered amine light stabilizers (HALS) on iso‐octane, a model compound for polyprophylene, was studied and compared to that of monomeric 2,2,6,6‐tetramethyl‐ piperi‐dine‐N‐oxyl (TEMPO).The exchange‐interaction among >NO. groups seems to affect only the thermal process.
The bisphenol‐A polycarbonate dual photochemistry
Authors: Rivaton Agnès 
Published: April 2003

AbstractThe photochemical behaviour of Bisphenol‐A polycarbonate (PC) under various types of monochromatic and polychromatic radiations is reported. The PC dual photochemistry observed in the solid state is characterized using both UV and FTIR spectroscopy. At short wavelength, the intrinsic photochemistry, which is associated with the direct photo‐excitation of PC chromophore groups, accounts for the formation of phenylsalicylate, dihydroxybenzophenone, hydroxybiphenyl and hydroxydiphenyl ether groups. The extrinsic photochemistry of PC, related to the excitation of chromophoric defects, is easily observed at long wavelength. This photoinduced oxidation leads to the formation of tertiary hydroperoxides which decompose into alcohols and ketones. The two photochemistries kinetically overlap but their stoichiometry remains independent. PC films can be used therefore to check the relative importance of short and long wavelength radiations emitted by the various sources used in the field of polymer degradation.
Application of chemiluminescence to polymer degradation studies. Thermal oxidation of polyamide 6.
Authors: Matisová‐Rychlá L. , Lánská B. , Rychlý J. 
Published: April 2003

AbstractChemiluminescence (CL) technique was used to study the thermal oxidation of polyamide 6 samples with different ratio of terminal basic and acid groups, which perform a distinct effect on kinetics of the isothermal CL – time runs at 120–140°C. The isothermal experiments are complemented by nonisothermal ramp experiments where the CL intensity is monitored against temperature at a programmed rate of temperature increase.The relation of parameters such as initial CL intensity, integrated value of CL intensity for both isothermal and nonisothermal experiments and rate constants corresponding to CL – time curves was discussed within the results of other oxidation stability tests as absroption of oxygen, thermogravimetry, etc.
Synthesis and properties of polyunsaturated xylitol carbonate methacrylates
Authors: Zaks Irene N. , Penczek Piotr , Rot Alfred S. , Pernikis Ruta 
Published: April 2003

AbstractXylitol carbonate methacrylates were synthesized from 2‐methacryloyloxyethyl chloroformate and xylitol. The composition of the products was investigated by HPLC. Optimum conditions for obtaining the polyfunctional monomer containing 92% penta‐substituted xylitol were determined. Photopolymerization of the monomers was carried out. The polymers show an extremely low birefringence index.
Phase behaviour and bistable effect of a mixture comprising a dye side chain liquid crystalline polymer and a low molecular weight liquid crystal
Authors: Hwang Jenn‐Chiu , Hsiue Ging‐Ho , Jeng Ru Jong 
Published: April 2003

AbstractPhase behaviour and bistable effect of dye side chain liquid crystalline polymer (dye LCP)/low molecular weight liquid crystal (LC) mixtures have been investigated. The smectic dye LCP was observed to be miscible with the nematic LC over wide ranges of concentration and temperature. The electro‐optical effects of the dye LCP/LC mixtures could be classified into the turbid and the transparent states upon a respective application of electric fields at low and high frequencies. Both transparent and turbid states of the mixture could be maintained stable, despite an electric field having been turned off.
Modified styrene‐isoprene‐styrene block copolymer membranes complexed with cobalt‐containing schiff's bases for oxygen permeation
Authors: Hsiue Ging‐Ho , Hsu Wey‐Leun , Yang Jen‐Ming 
Published: April 2003

AbstractThe grafting of 4‐vinylpyridine (VP) and 1‐vinylimidazole (VIm) onto styrene‐isoprene‐styrene (SIS) triblock copolymer by radiation‐induced graft copolymerization was studied. The effect of grafting degree on gas permeability of membranes made of grafted copolymers was investigated. The complex formation of the modified SIS (SIS‐g‐VP or SIS‐g‐VIm) with cobalt‐containing Schiff's bases (CoS) in chloroform solution was studied. Facilitated transport of molecular oxygen in modified SIS membranes containing CoS as fixed carrier of oxygen, and oxygen permeability in modified SIS membranes due to the oxygen binding ability to CoS was observed. Mechanism of oxygen transport across the SIS‐g‐VP‐CoS and SIS‐g‐VIm‐CoS membrane is discussed.
Eigenschaften von binären mischungen aus polyethylenen hoher dichte mit ultrahoher und normaler molmasse
Authors: Grigorova Marietta , Michailov Marin 
Published: April 2003

AbstractUntersucht wurden binäre Mischungen von Polyethylenen hoher Dichte rnit normaler und ultrahochmolekularer Molmasse, die auf zweierlei Weise—in Pulverform oder durch Walzen im Schmelzezustand—homogenisiert und bei Temperaturen zwischen 140 und 220°C gepreßt waren.Es wurde festgestellt, daß die Art der Homogenisierung der Komponenten praktisch keinen Einfluß auf die Eigenschaften bei Preßtemperaturen ≥ 160°C hat. Von besonderem Interesse sind die Eigenschaften der Systeme, in welchen das ultrahochmolekulare Polyethylen die Rolle der Matrixkomponente spielt.
Viscous and elastic behaviour of SEBS triblock copolymer
Authors: Mathew Ivy , George K. E. , Francis D. Joseph 
Published: April 2003

AbstractThe viscous and elastic behaviour of the saturated triblock copolymer polystyrene‐block‐poly(ethylene‐co‐butylene)‐polystyrene (SEBS) was investigated using a capillary viscometer. The viscous behaviour was evaluated from the variation of viscosity with shear and temperature, and the elastic behaviour from the capillary entrance pressure loss, die swell ratio and surface roughness. The melt behaviour was found to result from the two‐phase structure which existed up to a particular shear and/or temperature and thereafter from the single‐phase structure.
Electron beam initiated grafting of methyl methacrylate onto polyethylene: Structure and properties
Authors: Chaki T. K. , Despande R. S. , Majali A. B. , Tikku V. K. , Bhowmick A. K. 
Published: April 2003

AbstractPolyethylene (PE, 100 parts by weight) was mixed with methyl methacrylate (MMA, up to 5 parts by weight) at 120°C and subsequently exposed to electron radiation of different doses (up to 20 Mrad) to prepare PE/MMA graft copolymers. Successful grafting was verified by IR spectroscopy. Gel formation indicated crosslinking. Grafting increased with increasing MMA concentration and increasing irradiation dose. Crystalline melting temperature and percent crystallinity were lower than those of untreated PE. Tensile strength, elongation at break and dielectric constant of grafted samples were measured and discussed.
Transesterification in blends of poly(butylene terephthalate) and bisphenol‐A‐polycarbonate
Authors: Wings N. , Trafara G. 
Published: April 2003

AbstractBy means of differential calorimetric and X‐ray examinations it was shown that poly(butylene terephthalate) (PBT) and bisphenol‐A‐polycarbonate (PC) are only compatible in the melt if they stay in the melt for a short period of time. During mixing in the melt, transesterification begins and block copolymers are formed. A characteristic glass transition temperature is observed for each individual blend. Butylene terephthalate (BT)‐blocks are crystallizable; however, with an increasing share of bisphenol‐A‐carbonate (BPAC) the specific melting enthalpy of the BT‐blocks decreases. Within copolymers with a high BPAC content, the BPAC segments crystallize considerably faster than in pure PC. By means of diffraction measurements with synchrotron radiation, the mechanism of stress‐induced α‐β‐modification change in pure PBT and in block copolymers with high BT‐contents could be explored.
Reactive blending of thermosets: Molecular, morphological and mechanical analysis
Authors: Martuscelli Ezio , Musto Pellegrino , Ragosta Giuseppe , Scarinzi Gennaro 
Published: April 2003

AbstractA number of different approaches were used to enhance the toughness of tri‐ and tetrafunctional epoxies and of unsaturated polyester resins. In the case of epoxies, tough, thermally stable, engineering thermoplastics, namely a bisphenol‐A polycarbonate and a thermoplastic poly(ether imide) (Ultem 1000) were employed as modifiers. For unsaturated polyesters a different approach was adopted: two commercial liquid rubbers were chemically modified to enhance their reactivity towards the matrix functionalities. In particular, a hydroxy‐terminated polybutadiene and an aminoterminated butadiene‐acrylonitrile copolymer were transformed into isocyanate‐terminated and maleimide‐terminated rubbers, respectively. A further system which is described in the present contribution is aimed at mitigating another deficiency of the polyester matrix, namely its rapidly decreasing rigidity at temperatures above room temperature. In this case, a thermosetting bismaleimide was incorporated into the resin as a co‐reactive second component.
Recycling of egyptian bagasse pith wastes in the synthesis of cationic resins
Authors: Metwally M. S. , Metwally N. E. , Samy T. M. 
Published: April 2003

AbstractA series of sulfonated cationic resins have been prepared and characterized from Egyptian bagasse pith wastes (as a source of cheaper and renewable material) with m‐cresol and paraformaldehyde as a crosslinking agent. Reaction conditions for the preparation are presented and properties of the synthesized sulfonated bagasse pith‐m‐cresol‐formaldehyde resins are described and compared with resin not containing bagasse pith. The synthesized resins are stable in water, dilute mineral acids (1 M), organic solvents, and to thermal treatment. The resins having a cation exchange capacity up to 2.91 meq g‐1 of dry resin, are being introduced as new exchangers. The synthesized resins are used in the study of the possible separation of some bivalent cations.
Laser‐induced surface grafting of 2‐hydroxyethyl methacrylate and N‐vinyl‐2‐pyrrolidone onto ethylene‐propylene rubber as biocompatible material
Authors: Mirzadeh H. , Katbab A. A. , Khorasani M. T. , Burford R. P. 
Published: April 2003

AbstractAttempts have been made to provide hydrophilic sites onto the surface of ethylene‐propylene rubber (EPR) by grafting 2‐hydroxyethyl methacrylate (HEMA) and N‐vinylpyrrolidone (NVP) onto the surface of this elastomer using CO2‐pulsed laser as excitation source. The effect of benzophenone (BZP) and azoisobutyronitrile (AIBN) as photosensitizer upon the graft level has been evaluated. CO2‐pulsed laser grafting of HEMA and NVP was found to be dependent upon the wavelength, repetition rate, and fluence of laser. Hydrophilicity of EPR increased upon grafting HEMA and NVP with CO2‐pulsed laser. Surface characterization has been carried out using attenuated total reflectance infrared spectroscopy (ATR‐IR), scanning electron microscopy (SEM) and energy dispersive X‐ray analysis (EDXA). IR‐laser grafting of these monomers is not possible unless the system is irradiated by pulses with the wavelength corresponding to the either maximum absorption of monomer or sensitizer accessible to the laser equipment gain. As the absorption of EPR at these wavelengths is quite low, it is believed that depending upon the wavelength, either photosensitizer and/or monomer molecules are excited through an infrared multiphoton excitation (IRMPE) process above the dissociation energy leading to the decomposition of the excited molecules. Addition of a multifunctional acrylate (MFA) such as 1,1,1‐trimethylolpropane‐trimethacrylate (TMPTA) to the grafting system enhanced the graft yield. Poly(HEMA) grafted onto the surface of EPR by CO2 pulsed laser tends to form a fractal type of morphology. The shape and size of fractals depends upon both laser parameters and HEMA concentration. EDXA analysis showed the presence of ungrafted (hydrophobic areas) as well as hydrophilic sites (fractals) on the surface of modified samples. Finally, the bulk mechanical properties of EPR after being laser‐grafted with HEMA or NVP did not change, as shown by DMTA.
Emulsion polymerization of butyl acrylate, 3. Effect of initiator type and temperature
Authors: Potisk Pavol , Capek Ignác 
Published: April 2003

AbstractThe emulsion polymerizations of butyl acrylate initiated by water‐soluble (ammonium peroxodisulfate, AP) and oil‐soluble (dibenzoyl peroxide, DBP) radical initiators were investigated. Polymerizations were found to be faster with AP. The size of polymer particles formed and the molecular weights decreased with increasing temperature and increased with conversion. The number of particles was constant in the conversion range from ca. 30 to 100%. The overall activation energy (E0) was found to be ca. 50–60 kJ · mol‐1 which is nearly half of that of the bulk polymerization. The activation energy of the AP‐initiated polymerization was found to be independent of conversion while that for the DBP‐initiated polymerization decreased with conversion, and the decrease was more pronounced beyond 60% conversion. This behavior was discussed in terms of the emulsion and bulk polymerizations and variations of the activation energy for termination with viscosity of the reaction media.
Färben in überkritischem CO2: Bestimmung von Einflußgrößen auf das strukturelle Verhalten von Polyethylenterephthalat‐Fasermaterial
Authors: Knittel Dierk , Saus Wolfgang , Hoger Susanne , Schollmeyer Eckhard 
Published: April 2003

AbstractDie Beeinflussung von Merkmalen der Polymerstruktur durch Behandlung mit überkritischem CO2 wird anhand von Polyesterfasermaterial untersucht. Das überkritische System verursacht eine Absenkung der Glastemperatur und bewirkt die Ausbildung netzwerkstabilisierender Kristallite in den fehlgeordneten Bereichen des Fasermaterials, die denen entsprechen, die ohne Gegenwart eines überkritischen Fluids erst bei deutlich höheren Behandlungstemperaturen gebildet werden. Die Bedeutung der Polymerstruktur für Fäbung bzw. Imprägnierung von Fasermaterial in überkritischen Systemen wird diskutiert.
Epoxysiloxane resins by the condensation of 3‐glycidyloxypropyltrimethoxysilane with diphenylsilanediol
Authors: Wipfelder Ernst , Höhn Klaus 
Published: April 2003

AbstractCondensation of 3‐glycidyloxypropyltrimethoxysilane I with diphenylsilanediol II was investigated. Depending on solvent, temperature and catalyst, different products were obtained. Bulk reaction at 120°C using titanium(IV)‐isopropylate as a catalyst provided the transparent resin A. A was characterised by IR, 1H‐ and 13C‐NMR spectroscopy and contained no reactants. GPC and HPLC studies revealed that A consists of trimer and tetramer siloxanes of pertinent diphenylsilane and 3‐glycidyloxypropylmethoxysilane moieties. The proportion of cyclic to linear molecules was evaluated 2:1. Only small amounts of high‐molecular‐weight compounds were observed. The epoxysiloxane product proved to be miscible with various organic solvents and with commercial epoxy resins. Time dependence of viscosity and epoxy content were recorded during ambient storage and monitored by HPLC. Pot‐life was improved by a subsequent thermal procedure.
Synthesis of polypyrrole by electrochemical polymerization using organic anion electrolytes and its application
Authors: An Heishoku , Haga Yutaka , Yuguchi Toshiyuki , Yosomiya Ryutoku 
Published: April 2003

AbstractThe synthesis of polypyrrole from aqueous solutions using various organic anion electrolytes and its electric and mechanical properties and the junction characteristics of sandwich devices were investigated.As electrolytes the following anions were used: p‐toluenesulfonate (p‐TS‐), benzenesulfonate (BS‐), dodecylbenzenesulfonate (DBS‐), naphthalene‐2‐sulfonate (N‐2‐S‐) and sulfosuccinate (SS‐1); their effect on the conductivities of the polypyrroles decreases in the order DBS‐1 > p‐TS‐1 > N‐2‐S‐1 > BS‐ > SS‐. Higher conductivity and mechanical properties were obtained by drawing of films. With indium, polypyrrole forms rectification contacts, whereas ohmic contacts are formed in junction with Au or Pt. From the analysis of the current‐vs.‐voltage and capacitance‐vs.‐voltage characteristics, it is suggested that a Schottky barrier is formed at the interface between polypyrrole and indium.
Kinetics studies on the free radical polymerization of styrene in the presence of asphalts
Authors: Milczarska Teresa , Szafko Jerzy 
Published: April 2003

AbstractA study was made of the free radical polymerization of styrene in bulk at 60°C initiated with 2,2′‐azoisobutyronitrile in the presence of the stable free radical 4‐hydroxy‐2,2,6,6‐tetramethyl‐piperidine‐1‐oxyl (TMHPO) and two types of petroleum asphalts D and F. It was found that petroleum asphalts contain compounds effective as polymerization inhibitors and that they also include substances taking part in initiation processes. The differences between the kinetics behaviour of asphalts in comparison with stable free radicals were the subject of the discussion.
Triazine‐based polymers, 1. Synthesis of poly[(2,4‐dichloro‐6‐ethoxy‐s‐triazine)‐alt‐(bisphenol a)]
Authors: Braun D. , Ziser T. 
Published: April 2003

AbstractPoly[(2,4‐dichloro‐6‐ethoxy‐s‐triazine)‐alt‐(bisphenol A)] (T‐BPA), a polymer with interesting mechanical and thermal properties, was synthesized by phase transfer catalysed interfacial polycondensation. The reaction conditions for the synthesis of T‐BPA were investigated and optimized. The influence of several reaction parameters, such as temperature, reaction time, type and concentration of phase transfer catalyst, concentration of monomers, type of solvent, type of base, salt addition, and molecular weight terminator concentration on the reduced specific viscosity and yield of T‐BPA was investigated. As a result, it is possible to synthesize T‐BPA at reaction conditions being favourable with regard to the costs of energy and equipment.
Preparation and characteristics of amphiphilic membranes by photosensitive poly(vinyl cinnamate)
Authors: Liu Jui‐Hsiang , Chung Yi‐Chan , Lin Ming‐Ter 
Published: April 2003

AbstractA series of hydrophilic‐hydrophobic poly(vinyl cinnamate) (PVCin) membranes was developed. The poly(vinyl cinnamate)s were synthesized from poly(vinyl alcohol) with various amounts of cinnamoyl chloride in the presence of alkali. The amphiphilic membranes, which can be used instead of the traditional two‐layer membranes in the enzyme electrode, were prepared by using photosensitive poly(vinyl cinnamate) and/or poly(vinyl alcohol) with sensitizers. The properties of photocrosslinking, water permeability and oxygen permeability of the amphiphilic membranes were investigated. The combinations of amphiphilic membranes were examined by scanning electron microscopy (SEM).