bluuebunny/crossref_metadata_2025_split huggingface dataset:
Funktionspolymere‐ein interdisziplinäres forschungsgebiet‐
Authors: Winkler Ekhard , Pielartzik Harald , Schneller Arnold 
Published: April 2003

AbstractFunctional polymers differ from structural polymers in various aspects. The most evident difference is their lack of visibility as they are mostly empolyed in surface applications, e.g. as crystal growth modifiers to inhibit encrustation in detergents, as hair setting agents, or as electro‐conductive films. Additional important differences concerning the motivation for new developments, market aspects, and customer relationships are the subject of this paper.The development of technology and market competence in the field of functional polymers and the special problems of low‐volume, high‐performance chemicals are discussed in detail. The paper deals with examples of recent developments: Polyaramides for membranes, 3,4‐polyethylenedioxythiophene as an electroconductive polymer, polyaspartic acid as a biodegradable polycarboxylate in detergents, highly crosslinked, insoluble vinylpyrrolidone/vinylimidazole copolymers for the removal of heavy metals from wine, and finally an insoluble, crosslinked polyvinylpyrrolidone‐iodine complex for the sterile filtration of liquids. The outlook discusses the research challenges which remain before a full understanding of the structure/property relationships can be attained.
Polymeric prodrugs. Synthesis, release study and antimicrobial properties of polymer‐bound acriflavine
Authors: Patel H. , Raval D. A. , Madamwar D. , Sinha T. J. M. 
Published: April 2003

AbstractA matrix of poly(methyl methacrylate‐co‐maleic anhydride) with surface containing functional anhydride groups of different percentage was prepared by solution polymerization and characterized. Acriflavine was bound on the surface of this matrix by chemical bonding in organic medium. The amount of acriflavine chemically bound to the matrix was spectroscopically characterized and the in vitro release rate of acriflavine in weakly basic medium was established along with the determination of its antimicrobial activity.
Block copolymerization of poly(ethylene glycol) with methyl methacrylate using redox macroinitiators
Authors: Nagarajan Soundappan , Sabdham Kalathur , Srinivasan Vangepuram 
Published: April 2003

AbstractA series of block copolymers of poly(ethylene glycol) (PEG) with methyl methacrylate (MMA) were prepared using a redox system consisting of ceric ion and PEG of various molecular weights in aqueous medium. The block copolymerization experiments were carried out under such conditions in which there was no homopolymerization of MMA by Ce4+ alone. The intermediacy of the PEG macroradical in the redox process was substantiated by ESR spectroscopy and a polymerization proceeding through ‘blocking from’ mechanism was postulated. The formation of the block copolymers was confirmed by chemical test and fractional precipitation as well as by FT‐IR and FT‐NMR (1H and 13C‐(1H)) spectroscopy. The triblock nature of the block copolymers was ascertained through the cleavage of the ether linkage of the PEG segment. Simultaneous TG/DTA studies of the block copolymers revealed multiple stage decomposition patterns and their DSC curves exhibited two glass transition temperatures. GPC investigation of the block copolymers revealed unimodal molecular weight distribution with Mn values showing a smooth increase with ascending molecular weights of PEG. SEM studies indicated a fine dispersion of PEG in the continuous PMMA matrix.
Effect of metal ions on self reinforcement of metal/adhesive interphase by γ‐aminopropyltriethoxysilane
Authors: Gu Xiaohong , Xue Gi 
Published: April 2003

AbstractWhen copper/epoxy joints are pretreated with 1 wt.‐% solution of γ‐aminopropyltriethoxysilane (γ‐APS) in ethanol, the coordination between the copper ions and the amino groups of γ‐APS and 4,4′‐diaminodiphenylmethane could bring about self‐reinforcement of the metal/adhesive interphase when the joints were exposed in 3% aqueous NaCl solutions for 160 d. This is also confirmed with a model experiment by pretreating the aluminium substrates with γ‐APS solution containing moderate amounts of copper salts and subsequent formation of the aluminium/epoxy joints.
Rigid‐chain polyesters grafted with flexible‐chain vinyl polymers
Authors: Braun Dietrich , Wilhelm Volker , Hellmann Götz P. 
Published: April 2003

AbstractThe concept of “molecular reinforcement” has been advanced, in the last decade, as an alternative to conventional fibre reinforcement of thermoplastics: In blends with normal (flexible‐chain) thermoplastics, rigid chains of main‐chain LC polymers (PLC) can act as strengthening fibres on the molecular scale. However, the rigid PLC chains must be well dispersed which is improbable since PLC and normal polymers are usually incompatible. A related concept is “micellar reinforcement”: Graft copolymers made of a rigid‐chain PLC backbone and flexible‐chain grafts can form a microphase morphology of cylinderic micelles where the PLC chains act as reinforcing fibres on a micellar scale. Such rigid‐flexible graft copolymers are discussed in this study. They were pepared from a polyester of terephthaloyl, dihexoxyterephthaloyl and phenylhydroquinone moieties with special comonomer units carrying a double bond onto which styrene was grafted via radical copolymerisation. Grafting occurred with high efficiency, leading to products with the desired morphology of cyclindric micelles.
Synthesis and characterization of polypyrrolepolyurethane cationomer composites
Authors: Buruiană T. , Diaconu I. , Buruiană E. C. , Han X. , Guo F. 
Published: April 2003

AbstractPoly(ether urethane) cationomers based on poly(oxytetramethylene), 4,4′‐bibenzyldiisocyanate, N‐methyldiethanolamine as chain extender, and acrylic acid/poly(acrylic acid) as quaternization agent were synthesized. Pyrrole (15 wt.%%) was polymerized in films of the ionomer containing CuCl2. The films were characterized by dynamic mechanical analysis, thermogravimetry and differential scanning calorimetry. The electric conductivity of the film without polypyrrole is 7.5 · 10−12 Ω−1 cm−1, while incorporation of polypyrrole increases the conductivity to 4.5 · 10−6 Ω−1 cm−1.
Cationic polymerization using allyl sulfonium salt. 3. Allyl sulfonium salt/ascorbate redox couple
Authors: Önen A. , Denizligil S. , Yağci Y. 
Published: April 2003

AbstractThe cationic polymerization of cyclohexene oxide was initiated by reduction of allyl sulfonium salt in the presence of ascorbyl‐6 hexadecanoate and copper (II) benzoate. A redox reaction in which the copper compound serving as an electron carrier for the initiation step was proposed.
Synthesis, characterization and polymerization of waxy monomers
Authors: Moszner Norbert , Fischer Urs Karl , Völkel Thomas , Rheinberger Volker 
Published: April 2003

AbstractWaxy monomers and crosslinkers, respectively, were synthesized from commercially available waxes by esterification with 2‐hydroxyethyl methacrylate, glycerol dimethacrylate, or glycidyl methacrylate or by functionalization with 2‐isocyanatoethyl methacrylate. The resulting opaque methacrylates with melting points between 45 and 80°C were polymerized in bulk and in toluene solution in presence of free radical initiators. The obtained polymers were characterized by a broad molecular weight distribution. Opposite to the bulk polymerization, the double bond conversion in solution polymerization is nearly quantitative. The observed volume shrinkage during polymerization is very low due to the high molecular weight of the monomers. Polymerizates containing crosslinking comonomers exhibit improved mechanical stability.
An investigation of the grafting of cellulose powder with acrylamide under a magnetic field
Authors: Chiriac Aurica P. , Neamtu Iordana , Cazacu Georgeta , Simionescu Cristofor I. , Rozmarin Gheorghe 
Published: April 2003

AbstractCellulose powder obtained from oak furfural lignocellulose by nitration reaction was grafted with acrylamide using a radical initiation. The grafting reactions were carried out and compared both in presence and in absence of a continuous external magnetic field with the intensity extended between 0.15–0.35 T. The effect of monomer and initiator concentration, time and temperature of reaction and magnetic field intensity onto the grafting process were examined. It was observed that the presence of a magnetic field leads to a significant increase of the graft conversion.
Application of molecularly imprinted polymer as a drug retaining matrix
Authors: Sreenivasan K. 
Published: April 2003

AbstractCopolymerization by gamma irradiation of 2‐hydroxyethyl methacrylate with ethylene glycol dimethacrylate in the presence of hydrocortisone as model drug gave a molecular imprinted polymer (MIP). The hydrocortisone was removed from the matrix with chloroform and incorporated again from methanol solution. Release data show that 96% of the incorporated drug is retained after 30 days storage in a methanol/water (3 : 1 v/v) mixture. In comparison with hydrocortisone, only a small quantity of testosterone is absorbed by the matrix.
Surface modification and bonding of poly(p‐phenylene sulfide)
Authors: Piglowski Jacek , Coen Martine Collaud , Schäfer Rüdiger , Kressler Jörg , Mülhaupt Rolf 
Published: April 2003

AbstractIt is demonstrated that both chemical oxidation, e.g. by using acetic acid/hydrogen peroxide or chromosulfuric acid, and plasma treatment of poly(p‐phenylene sulfide) (PPS) surfaces introduce polar groups. The changes of the surface chemistry are detected by FTIR spectroscopy, X‐ray photoelectron spectroscopy, and contact angle measurements. The increased polarity is partially responsible for better adhesion as verified by lap shear measurements using acrylic adhesive. Another important contribution to the improved adhesion originates from increased surface roughness after surface modification as measured by atomic force microscopy. This effect is very pronounced for PPS surfaces treated with chromosulfuric acid.
Polyester composites reinforced with recycled FR‐4 epoxy laminates
Authors: Hong S. G. , Su S. H. 
Published: April 2003

AbstractThe feasibility of using recycled FR‐4 epoxy laminates as reinforcing fillers in manufacturing unsaturated polyester (UP) composites was studied using differential scanning calorimetry (DSC), and flexural tests. UP resins filled with recycled laminates had a higher flexural strength and modulus than the plain UP because of energy dissipation effects from glass fibers and rigid epoxy resins in the laminates. The size and loading of the laminates affected the flexural properties of the molded products. The addition of CaCO3 fillers and Cu decreased the flexural strength but promoted the flexural modulus of the UP. As revealed by DSC measurements the presence of laminates affected the free‐radical reaction of the UP resin and decreased the curing rate. The curing kinetics were also dependent on the size and relative content of the laminates added.
Charakterisierung von vernetzten Polymeren, 9a. Verfolgung der Nachvernetzung von Poly(styrol‐co‐divinylbenzol) zu feinporigen Adsorberpolymeren
Authors: Sommer Christian , Bürger Heidrun , Häusler Karl‐Georg , Popov Georgi 
Published: April 2003

AbstractDie Nachvernetzung von chlormethyliertem Poly(styrol‐co‐divinylbenzol) zu hochvernetzten porösen Adsorberpolymeren wurde über einen weiten Temperatur‐(50–80°C) und Reaktionszeitbereich (bis zu 24,5 h) untersucht. Die vernetzten Materialien wurden durch Stickstoffadsorption/Desorption, Quecksilberporosimetrie, Bestimmung des Chlorgehalts, Quellungsmessungen, Pyrolyse‐Gaschromatographie und Fourier‐Transform‐Infrarotspektroskopie charakterisiert.Die Oberfläche, die Porengrößenverteilung, das Porenvolumen, der Chlorgehalt, ausgewählte Peakverhältnisse in den Pyrogrammen und den FTIR‐Spektrogrammen sind eindeutige Funktionen der Nachvernetzungszeit. Der Nachvernetzungsprozeß kann somit sowohl mit physikalischen als auch mit chemischen Charakterisierungsmethoden verfolgt werden. Darüber hinaus ermöglichen Quellungsmessungen und pyrolysegaschromatographische Untersuchungen Aussagen zur Homogenität und Inhomogenität der chlormethylierten Copolymeren und porösen Adsorberpolymeren.Der Einsatz verschiedener Lösungsmittel bei der Quellung erlaubt die Konstruktion von Quellungsdiagrammen, anhand derer das anomale Quellungsverhalten der Adsorberpolymeren während der Nachvernetzung erklärt werden kann.Im Verlauf der Nachvernetzung werden die Oberfläche und das Porenvolumen stark vergrößert und eindeutige Korrelationen zwischen der Probentextur und den Pyrolyse‐ und FTIR‐Daten gefunden. Die Veränderung der physikalischen Eigenschaften im Verlauf der Vernetzung kann generell auf die chemische Modifikation des Materials zurückgeführt werden.
Die chemische Beständigkeit eines Steinschutzstoffes auf Polyurethanbasis in der künstlichen Bewitterung
Authors: Hagenauer Michael , Gerhard‐Abozari Eva , Höcker Hartwig 
Published: April 2003

AbstractDie Dauerhaftigkeit eines Steinschutzstoffes auf Polyurethanbasis im Sander Schilfsandstein gegenüber chemischen Angriffen wurde nach verschieden langen Bewitterungszeiten in einer Versuchsanlage zur naturnahen Umweltsimulation untersucht. Dabei wurden sowohl die Gelpermeationschromatographie (GPC) als auch oberflächensensible Analysenmethoden (XPS und PAS‐FTIR) zur Untersuchung der Polyurethan‐Mikroschicht im Stein eingesetzt. Nur im Bereich der ersten vier Millimeter Gesteinstiefe konnten bewitterungsbedingte chemische Veränderungen des Polymeren festgestellt werden.
Influence of emulsifier and initiator concentration on the copolymerization of 1,4‐divinylbenzene with comonomers of different solubility in water
Authors: Kaczun J. , Funke W. 
Published: April 2003

AbstractThe influence of the concentration of sodium dodecylsulfate and 2,2′‐azoisobutyronitrile on the crosslinking emulsion copolymerization of 1,4‐divinylbenzene with hydrophobic cyclohexyl methacrylate and with hydrophilic methyl acrylate was studied. The emulsions were prepared by joint and by separate solubilization to study diffusion effects. Monomer conversion was measured and the microgels were characterized by molar mass, particle size diameter and intrinsic viscosity. The monomer conversion was maximal in the transition from a normal to a micellar emulsion. With the hydrophobic comonomer increasingly insoluble coagulates from polymerized monomer droplets were formed on decreasing the emulsifier concentration. Toward higher emulsifier concentration increasingly insoluble agglomerates were formed by reactions between microgels.
Accelerated thermal aging of NBR and other materials under air or oxygen pressures
Authors: Budrugeac Petru 
Published: April 2003

AbstractAccelerated thermal degradation of nitrile‐butadiene rubber, ethylene‐propylene rubber, low density polyethylene and glass reinforced epoxy resin was studied (a) in air, at atmospheric pressure, and various temperatures and (b) in air or oxygen at various pressures (P > 1 atm) and temperatures. On the basis of the experimental results, a kinetic equation of thermal degradation of investigated materials has been derived.
Aspects of poly(p‐phenylene sulfide) degradation and stabilization. Part 1. Influence of polymer end groups on exposure induced coloration
Authors: Deslauriers P. J. , Geibel Jon F. , Das P. K. 
Published: April 2003

AbstractIn this paper we reviewed some of our work on the photo induced coloration of Poly(p‐phenylene sulfide) (PPS) and compared it to recent results obtained from the thermal treatment of resins that varied in molecular weight and ionic content. The results from this study suggest that coloration of amorphous PPS films after UV irradiation is caused by products different from those that cause coloration in semicrystalline PPS after thermoxidation. In addition, we found that polymer end group chemistry and resin molecular weights play important roles in the thermoxidative coloration of PPS, but only nominally influence the photooxidative coloration of the resin. PPS coloration may arise from the accumulation of specific, colored products (e.g., phenyl‐phenyl moieties) and the possible presence of intermolecular aggregates. The mechanism and extent by which these structures occur in UV irradiated or heated PPS are likely dependent upon the polymer morphology of the samples tested.
Oxidation kinetics of poly(4‐methylpentene)
Authors: Guarrotxena N. , Audouin L. , Verdu J. 
Published: April 2003

AbstractThe thermal oxidation (in air between 70 and 150°C) of unstabilised camples of poly(4‐methylpentene) (PMP) were studied by infrared spectrometry and by gravimetry. The behaviour was compared to PP exposed in the same conditions.The thermal oxidation was found to exhibit two well differentiated kinetic regimes both for PP as for PMP. The first regime predominates at temperature higher than 90°C. It is characterized by an activation energy of the pseudo induction period of about 100 kJ mol−1. The induction period of mass gain is about 1,8 time shorter than the induction period of carbonyl gain. These characteristics, and the fact that induction periods are of the same order for both polymers, are consistent with a «close loop mechanistic» scheme with unimolecular POOH decomposition. The advantages of this hypothesis compared to other proposed hypothesis (bimolecular POOH decomposition, heterogeneous oxidation...) are discussed. The main theoretical difficulty is that of explaining why the unimolecular process predominates, whereas POOH are obviously hydrogen bonded, even at very low conversions of the oxidation process. This point remains to be explained.The second kinetic regime predominates at temperature lower than 90°C. It is characterized by a considerably lower activation energy. We have examined many hypothesis to explain the existence of a transition at that temperature (where neither PMP nor PP display a physical transition). A first hypothesis is that unimolecular POOH decomposition is replaced by a bimolecular one, which can explain a decrease of the apparent activation energy of about 50%. The bimolecular initiation creates pairs of radicals (POO·+ PO·). It can be imagined that a part of them desactivate mutually by termination after rearrangement of PO· by β scission. In this case, the transition at 90°C could be also a result of the temperature induced change in molecular mobility. Above 90°C, the radicals would diffuse almost freely out of the cage. In contrast, below 90°C, termination would become competitive with diffusion. A supplementary research is needed to fully elucidate the cause of this transition at 90°C.The eventuality of the existence of spatial heterogeneity of the oxidation process has been discussed. It is well known that oxidation is heterogeneous at the morphological scale, but there is no evidence of heterogeneity at smaller scale, where the chemical kinetic would not be applicable.
Mechanical and morphological properties of stabilized and non‐stabilized HDPE films versus exposure time
Authors: Hoekstra H. D. , Spoormaker J. L. , Breen J. 
Published: April 2003

AbstractNon UV‐stabilized and UV‐stabilized (a UV‐absorber) HDPE films were photo‐oxidized in a Xenotest. The concentration of carbonyl and the UV‐stabilizer, the molecular weight, the crystallinity and the density were studied versus exposure time. Furthermore, the mechanical behaviour was studied at different strain rates by tensile testing.The number of chain scissions was found equal to the number of carbonyl groups. The density of the film increased from 950 to 970 kg/m3 and the crystallinity from 70 to 82%. The increase in density is explained by the increase in crystallinity and by oxygen uptake.The rate at which carbonyl groups are formed, was found to accelerate with exposure time. This acceleration finally resulted in profiles, which could be measured by FT‐IR and verified by computer simulations.After 14 days of exposure the specimen failed in a brittle manner. An activation volume was calculated and found to decrease. It is thought that a change in molecular mobility is responsible for the lower strain at yield values. The change in molecular mobility can also explain the increase in Young's modulus with the strain rate and exposure time. The Takayanagi and the Halpin/Tsai models were used to describe the increase of modulus of elasticity.
Applicability and limitations of current lifetime prediction models for thermoplastics pipes under internal pressure
Authors: Lang R. W. , Stern A. , Doerner G. 
Published: April 2003

AbstractEngineering thermoplastics, in particular polyolefins such as special grades of poly(ethylene), are gaining importance in pipe applications such as gas and water supply systems. To ensure proper performance of such pipes over the required lifetime, polymer physics and mechanics concepts are needed to adequately account for the effects of time, temperature, and environmental conditions as well as the occurrence of pipe defects and imperfections on relevant polymer properties and pipe performance. This article provides a critical overview of the scientific background of current methodologies to describe the long‐term behavior of thermoplastic pressure pipes. In particular, the merits and limitations of two different approaches‐namely, the standard extrapolation method (SEM) described in ISO/TR 9080 and the linear elastic fracture mechanics (LEFM) approach‐are compared. Special attention is given to effects associated with material ageing and degradation.
Controlled degradation in tailor‐made macromolecules elaboration. Controlled chain‐cleavages of polydienes by oxidation and by metathesis
Authors: Reyx Danièle , Campistron Irène 
Published: April 2003

AbstractA chain cleavage reaction allowing the transformation of high molecular weight polymers in well‐defined oligomers can be considered as a step in a synthetic scheme. The control of oligomers with respect to their average molecular weights, their molecular weights distributions and their chain‐end microstructures implies the control of the cleavage reaction with respect to its yield, its regiospecificity and its chemiospecificity. Among several examples of efficient uses of this principle for the preparation of liquid oligomers from unsaturated polymers, attention is focused (I) on controlled oxidative degradation of rubber and (II) on metathetical controlled degradation of 1,4‐polydienes and polyakenamers. (I.a) The mechanism of the phenylhydrazine accelerated oxidation of rubber in the latex phase is described according to accurate structural studies on molecular model molecules. (I.b) The epoxidation of rubber and periodic acid cleavages of epoxides in the latex phase are interpretated referring to the influence of the biphasic medium. The results are in agreement with interfacial blocky epoxidation by the water‐soluble reagent and interfacial arrangement of the epoxidized block to be cleaved. Finally the metathetical degradations resulting from back‐bitting cyclisation and cross metathesis with acyclic alkenes are presented as preparative methods to get (II.a) well‐defined cyclic oligomers and (II.b) telechclic oligomers (i.e. terminally functionalized oligomers).
Introduction to a new class of high performance light stabilizers and the influence of light stabilizers structure on the polymer's life time
Authors: Rytz Gerhard , Hilfiker Rolf , Schmidt Erika , Schmitter André 
Published: April 2003

AbstractThe mode of action of two classes of UV absorbers (2‐(hydroxyphenyl)benzotriazoles and 2‐(2′‐hydroxyphenyl)‐1,3,5‐triazines) is discussed. Theoretical explanations for the superior light stability of the latter are given and confirmed by measured half life times in polycarbonate and solution. A mathematical model for the quantitative prediction of light protection factors is proposed.