bluuebunny/crossref_metadata_2025_split huggingface dataset:
Einfluß der nukleierung auf struktur und mechanische eigenschaften von spritzgußteilen aus polyhexamethylenadipinamid (PA 66)
Authors: Moos Karl‐Heinz 
Published: April 2003

AbstractDer Einfluß der Variation des Molekulargewichtes und der Verarbeitungstemperaturen beim Spritzgießen sowie der Nukleierung auf Struktur und mechanische Eigenschaften von PA 66 Spritzgußteilen wurde untersucht. Als Folge der Nukleierung traten wesentliche Änderungen von Morphologie, Textur und mechanischen Eigenschaften der Proben auf. Da die nadelförmigen Partikel eines als Keimbildner verwendeten Phthalocyanin‐Farbpigmentes beim Spritzgießen besonders in der Scherzone in Fließrichtung der Schmelze ausgerichtet wurden, traten Bandsphärolithe auf, die zwar die mittlere Kristallitorientierung der Spritzgußteile erhöhten, deren mechanische Eigenschaften aber nicht veränderten. Nach Zugabe eines speziellen Keimbildners für Polyamide hingegen nahm die Reißdehnung um etwa 80% ab und die Streckspannung um etwa 15% zu. Das wird auf die mit Durchmessern von 3−4 μm deutlich kleineren Sphärolithe in diesen gegenüber denjenigen in den übrigen Proben (ØSp ≡ 30 μm) zurückgeführt.Die Ergebnisse weisen auch darauf hin, daß die DSC‐Methode—Messung der Verschiebung der Temperatur der maximalen Kristallisationsgeschwindigkeit einer nukleierten gegenüber der einer nicht nukleierten Probe bei linearer Abkühlung aus der Schmelze — bei schnell kristallisierenden Polymeren zur Beurteilung der nukleierenden Wirkung von Fremdsubstanzen ungeeignet ist.
Untersuchung der ursachen für das auftreten mehrerer schmelzpeaks in den DSC‐thermogrammen von hochverstreckten und getemperten folien aus isotaktischem polypropylen
Authors: Lenz Jürgen , Wrentschur Erich , Geymayer Wolfgang 
Published: April 2003

AbstractIsotaktische Polypropylen‐Folien wurden hoch verstreckt und unter Streckspannung bei Temperaturen bis maximal 206°C während 20 s getempert. Das Schmelzverhalten dieser Folien wurde mittels DSC verfolgt. Es wurden zwei Schmelzpeaks registriert, die bei ca. 165°C und 174°C auftreten. Die Schmelzenthalpie des erstgenannten Peaks überwiegt, wenn die Folientemperatur beim Tempern auf über 190°C angehoben wird. Seine Lage ist unabhängig vom Streckverhältnis. Dieser Schmelzpeak konnte einer kristallinen Phase mit einer Langperiode von 140 bis 160 Å bei nichtorientierten, zwischenkristallinen Bereichen zugeordnet werden. Der 2. Schmelzpeak entsteht beim Verstrecken. Seine Temperatur steigt mit zunehmendem Streckverhältnis an. Er wurde auf eine kristalline Phase mit einer Langperiode von über 200 Å bei einer mittleren amorphen Orientierungsfunktion der zwischenkristallinen Regionen von 0,4–0,5 zurückgeführt. Bei dieser Fraktion handelt es sich offenbar um die parakristallinen Bausteine der Mikrofibrillen, welche sich bei Folientemperaturen von über 190°C zum größeren Teil in kleinere Lamellen‐bildende Parakristalle umwandeln. Der übergang der Fibrillen‐ in eine Lamellentextur wurde elektronenmikroskopisch sichtbar gemacht.
Photopolymerization of methyl methacrylate with the triethylamine‐bromine charge transfer complex as photoinitiator
Authors: Mishra Munmaya K. , Sar Bidulata , Gaylord Norman G. 
Published: April 2003

AbstractThe triethylamine‐bromine (TEA‐Br2) charge transfer complex was employed as photoinitiator in the photopolymerization of methyl methacrylate under light of 440 nm. The initial rate of conversion was 0.418%/min with an induction period of 56 min. The initiator and monomer exponents were 0.5 and 1.0, respectively. The polymerization was inhibited in the presence of hydroquinone but oxygen had a very little inhibitory effect. The value of k/kt was 5.13 · 10−2 l/mol · s and the activation energy was 19.18 kJ/mol. The rate constant for the decomposition of the charge transfer complex (kε) was 4.61 · 10−6 1/s. Kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism.
Beiträge zur galvanisierung von polymeren, 7. Metallisierung von epoxidharzen mit hilfe von haftvermittlern
Authors: Springer Jürgen , Förster Frank , Sezi Recai , Sirinyan Kirkor 
Published: April 2003

AbstractEpoxidharze lassen sich mit einer haftfesten Metallschicht überziehen, wenn sie zuvor mit einem metallisierbaren Haftvermittler beschichtet worden sind. Ein solcher Haftvermittler besteht z.B. aus einem partiell epoxidierten Styrol‐Butadien‐Styrol‐Triblockcopolymeren, einem Epoxidharzvorprodukt und einem Aminhärter.Das Mischungsverhältnis dieser Komponenten sowie die Art des Amins beeinflussen die Abzugsfestigkeit der galvanisch aufgebrachten Metallschicht. Der höchste Wert wurde bei der Verwendung eines niedermolekularen Amins mit ca. 45 N/25 mm erreicht, während beim Einsatz von höhermolekularen Aminen nur Werte bis ca. 10 N/25 mm erzielt werden konnten.
A comparative study of the kinetic theories of the glass transition phenomenon in high polymers
Authors: Vijayakumar Chinnasamy Thangavel , Kothandaraman Harimurthi 
Published: April 2003

AbstractThe effect of thermal history on the glass transition temperature (Tg) of poly(vinyl chloride) was studied. The parameters like the hole energy (Eh), the activation energy for the disappearance of holes (Ej), the activation enthalpy for the structural relaxation (Δh1* and Δh2*) and the activation energy for the glass transition process (E) were calculated. The increase of Eh value with the increase in Tg value shows that there exists a holesize distribution. The Ej (26.9 ± 0.5 kcal/mol) value calculated according to Wunderlich's treatment, the Δh1* (27.8 ± 0.6 kcal/mol) value obtained by Moynihan's procedure and the E (35.3 kcal/mol) value from Barton‐Critchley's method agree well with one another in the poly(vinyl chloride) system. The Δh2* quantity, obtained through Moynihan's formulations, increase as the rate of heating was increased, a result similar to the variation of Eh value with the rate of heating.
Thermal properties of nylon 6 fibres grafted with acrylic monomers
Authors: Mukherjee A. K. , Goel H. R. 
Published: April 2003

AbstractThermal Properties of methyl methacrylate (MMA), ethyl methacrylate (EMA) and n‐butyl methacrylate (n‐BMA) grafted onto nylon 6 fibre with various graft levels were investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) and the results compared with that of parent nylon 6 fibre. It was found that the initial decomposition temperatures (IDT) of the grafted samples were lower than that of the parent nylon 6 fibre. On the other hand with all the three monomers, there was an increase in overall thermal stability followed by subsequent decrease with increase in the graft level. Among the grafted samples both the IDT and IPDT (initial procedural decomposition temperature) followed the order MMA‐g nylon > EMA‐g nylon < n‐BMA‐g nylonDifferential thermal analysis shows a depression in glass transition temperature (Tg) as well as in melting temperature (Tm). In the case of the MMA and EMA grafted samples, the depression is small over a wide range of graft level. In the case of the n‐BMA grafted samples, the depression is higher. A wide melting range was obtained in the grafted samples. Flammability studies also showed that with an increase in the graft level as well as an increase in the alkyl chain the ease of flammability increased as expressed by limiting oxygen index (LOI) values. The possible reasons for the phenomena occurred have been discussed.
A calorimetric investigation of suspension and emulsion polymerization of vinyl chloride
Authors: Nilsson Holger , Silvegren Christer , Törnell Bertil 
Published: April 2003

AbstractAn isothermal calorimeter for studying radical polymerization in heterogeneous systems is presented. The calorimeter was used for investigation of suspension and emulsion polymerization of vinyl chloride at 50°C. The results from the suspension polymerization experiments showed that the termination rate constant in the PVC phase was diffusion controlled and very sensitive to the vinyl chloride activity. During suspension polymerization the pressure started to drop at a much lower conversion than in emulsion polymerization. Mass balance calculations showed that this was due to entrapment of a large amount of liquid vinyl chloride in the fine capillary system of the suspension particles. The results from emulsion polymerization experiments in which the particle number spanned the range from 0.094.1018 to 1.7.1018 dm−3, were analyzed according to the kinetic model developed by Ugelstad et al. Using the concentration‐dependent termination rate constant obtained from the suspension experiments and assuming proportionality between the radical adsorption and desorption rate constants, this model gave a very good fit of the experimental rate over the entire interval II and most of interval III. The results strongly indicated that termination in the aqueous phase was of measurable importance during interval II and became the dominating termination in interval III.
Polymerization of lactams, 49. Hydrolytic polymerization of 6‐caprolactam in the presence of its cyclic dimer
Authors: Krajník Václav , Kondelíková Jaroslava , Králíček Jaroslav , Mössinger Ivan 
Published: April 2003

AbstractThe hydrolytic polymerization of 6‐caprolactam has been studied at 260–280°C in the presence of 5, 10 and 15 mol‐% of cyclic dimer of 6‐caprolactam and 2 mol‐% of 6‐aminocaproic acid as an initiator. The content of monomer and cyclic oligomers, including pentamer, was determined by HPLC. It has been proved that the rate of polymerization decreases with increasing content of cyclic dimer in the initial mixture and the time required to attain the equilibrium content of polymer increases as much as by an order of magnitude. The cyclic dimer is incorporated into the polymer above all in the final reaction stage.
Poly(vinyl alcohol) modification with n‐alkyl chloroformates
Authors: Arranz F. , Sánchez‐Chaves M. , Molinero A. 
Published: April 2003

AbstractThis work deals with the modification reaction of poly(vinyl alcohol) with n‐alkyl chloroformates using pyridine as catalyst. The structure of the modified polymers was determined by means of IR, 1H and 13C‐NMR spectroscopy as well as by chemical analysis. Vinyl alcohol‐vinyl n‐alkyl carbonate copolymers were obtained. The presence of cyclic carbonates has not been observed. It has been found a linear dependence of reaction rate on polymer, n‐alkyl chloroformates, and pyridine concentrations, respectively. The activation energy found was of 15.4 kcal/mol. The water absorbed in the copolymers made it reasonable to conclude that the hydrophilic character of the copolymers decreased progressively when either the carbonate groups content or the side chain length increased. Water insoluble alcohol‐vinyl n‐alkyl carbonate copolymers were hydrolyzed in an alkaline medium. They were found to recover their solubility in water after a certain hydrolysis extent was reached.
Solubility parameters of poly(di‐n‐alkyl cyclohexyl‐) and poly(di‐n‐alkyl phenyl itaconates)
Authors: Veličković J. , Petrović‐Djakov D. , Filipović J. 
Published: April 2003

AbstractSolubility parameters of poly(dicyclohexyl‐), poly(diphenyl itaconate) and of the first three members of the poly(dialkyl cyclohexyl‐) and poly(dialkyl phenylitaconate) homologous series were determined from limiting viscosity numbers in various solvents and solvent mixtures, differing in structure, polarity and composition. The values obtained are within limits of 19.0 and 16.7 (J1/2. cm‐3/2). Phenyl groups in the substituents lead to slightly higher values than cyclohexyl rings and the introduction of alkyl groups in both series results in a progressive decrease of the solubility parameter. The experimental values are slightly lower than those obtained by calculation from molar attraction constants.
Organic solvent treatment of isotactic polypropylene films, 1. Effects of organic solvent treatment on proton spin‐lattice and spin‐spin relaxation times
Authors: Tanaka Hiroshi , Yoshida Yoshio 
Published: April 2003

AbstractAn isotactic polypropylene film was treated with cyclohexane, toluene, 1‐chloronaphthalene, and glycerin. The morphological changes were characterized by measurements of weight loss, density, molecular weight, and spin‐lattice and spin‐spin relaxation times. There is a relatively narrow temperature range at which a sharp increase in weight loss occurs corresponding to the kind of the solvent. The change in density occurs almost linearly with treatment time for all solvents. Molecular weight also increases as the weight loss is increased. There is a considerable increase in T1 with increasing treatment temperature. T2 of the amorphous region, T2a, also increases as the treatment temperature is increased, but some decrease in T2a is found in the samples treated with toluene and cyclohexane at higher temperatures. The fraction of the rigid region, Fc, increases and that of the mobile one, Fa, decreases with proceeding solvent extraction. The value of Fc is considerably different from the crystallinity calculated from the density in the early stage of the treatment followed by the gradual approach to the value calculated from the density, although some different behaviour was found with the samples treated with cyclohexane.
Anionic polymerization using rotating disk reactor (I)
Authors: Yamaguchi Tadashi , Nozawa Masayuki , Egashira Akihiko , Kumagai Hiroshi , Imai Hideki 
Published: April 2003

AbstractAnionic polymerization of styrene with sodium naphthalene was carried out using the rotating disk reactor. The mode of disintegration of the polymerization mixture changed from dropwise to filamentwise and finally to filmwise within a few minutes of reaction at low speed revolution and a large amount of flow. Under the condition of high speed revolution and a small amount of flow, only dropwise disintegration was observed and a beadlike polymer was obtained having a unimodal molecular weight distribution. The polymer was found to have a bimodal distribution when the polymerization was terminated on the rotating disk. These results are explained by assuming that a highly viscous layer was formed near the disk surface.
Attempts to prepare regularly sequenced polyamides containing oxyethylene and iminoethylene units
Authors: Kern Werner , Kämmerer Hermann , Böhmer Volker , Bhagwat Madhusudan M. 
Published: April 2003

AbstractWater soluble polyamides with iminoethylene and oxyethylene units in the main chain were obtained by condensation polymerization of diethylenetriamine and triethylenetetramine with suitable dimethylesters containing two or three oxyethylene units. The molecular weights were in the range of M̄n = 5000–7000. By potentiometric and conductometric titration only 80–85% of the expected amount of basic groups was found which was probably caused by branching.
Study of the reactions of phenol, 2,5‐ and 3,5‐dimethylphenol with acrolein
Authors: Šebenik Anton , Osredkar Uči 
Published: April 2003

AbstractThe reactions of phenol, 2,5‐ and 3,5‐dimethylphenol with acrolein in neutral medium were studied by means of 13C NMR. The addition of the double bond of acrolein seems to be the dominant reaction, although from the spectra small amounts of cyclic compounds and polymeric acrolein were detected. This indicates side reactions of the double bonds and of the carbonyl groups. Acrolein reacts with phenols mainly at the para position. The ratio of CH2‐signals bonded at the ortho and para positions was found to be 1:6 for 2,5‐dimethylphenol and 1:1.4 for 3,5‐dimethylphenol.
Primary processes of the thermal degradation of HET acid containing unsaturated polyester cured with styrene
Authors: Vijayakumar Chinnasamy Thangavel , Fink Johannes Karl , Lederer Klaus 
Published: April 2003

AbstractThe primary processes of thermal degradation of 1,4,5,6,7,7‐hexachloro‐5‐norbornene‐2,3‐dicarboxylic (HET) group containing unsturated polyesters cured with styrene were investigated. DTA traces in nitrogen atmosphere showed a much more pronounced endothermic reaction as the chlorine content in the unsaturated polyester resin decreased. This could be associated to the unzipping of the polystyrene units which is interfered by hexachlorocyclopentadiene ejected during degradation. Actually the styrene formation is prevented in a certain range of temperature due to the interaction with hexachlorocyclopentadiene. This was proved by on‐line mass spectroscopic analysis of the degrading polymer.
Poly(vinylalcohol) as polymeric support for metal chelating phosphoric acid and derivatives
Authors: Bayer Ernst , Grathwohl Paul‐Anton , Geckeler Kurt 
Published: April 2003

AbstractSynthesis and application of several polymeric agents based on poly(vinylalcohol) with phosphorus containing functional groups were investigated. Monomer and polymer syntheses of phosphoric acid and derivaties with poly(vinylalcohol) are described. Multifunctional derivaties of the hydrophilic polymer were obtained by polymer‐analogous reactions with mono and diethyl esters of phosphoric acid. Studies on chelating properties of the polychelatogenes at different pH values for nickel were carried out by means of membrane filtration. Metal determination in filtrate and retentate yielded typical chelating curves. Differences of the polymer supports and influences of the functional groups are discussed.
Pestizide Polymere, 1. Herstellung und Untersuchung endosulfanhaltiger LDPE‐ und EVA‐Folien
Authors: Bahadir Müfit , Pfister Gerd , Herrmann Rainer , Moza Prannath , Korte Friedhelm 
Published: April 2003

AbstractMischungen aus Endosulfan mit LDPE‐ bzw. EVA‐Granulaten wurden unter unterschiedlichen Bedingungen zu Flachfolien extrudiert und diese untersucht. Es konnte gezeigt werden, daß bei Extrusionstemperaturen bis 190°C keine Veränderung des Endosulfans erfolgt. Additive wie Benzophenonderivate und Ölsäureamid hatten ebenfalls keinen Einfluß auf das Extrusionsverhalten des Endosulfans. Bedingt durch die unterschiedlichen Löslichkeiten der Isomeren des Endosulfans betrugen die Sättigungskonzentrationen in der LDPE‐Folie für α‐Endosulfan ca. 0,8% und für β‐Endosulfan ca. 0,2%. Bei EVA‐Folien mit ≥ 10% VAC‐Anteil konnten ≥8% (α + β) Endosulfan homogen gelöst werden.
Immobilisierung von Corynebakterium simplex durch Photovernetzung von vinyliertem Polyvinylalkohol zur mikrobiologischen Steroidumwandlung
Authors: Manecke Georg , Beier Wilfried 
Published: April 2003

AbstractDie Steroidumwandlung von Hydrocortison zu Prednisolon wurde mit immobilisierten Corynebakterium simplex‐Zellen (A.T.C.C. 6946) untersucht. In partiell mit Acrylsäure verestertem Polyvinylalkohol wurden die Zellen durch Bestrahlung des Polymeren mit sichtbarem bzw. UV‐Licht in Gegenwart von Riboflavin‐5′‐monophosphat durch Photovernetzung immobilisiert. Die Steroid‐Δ1‐Dehydrogenase‐Aktivität der immobilisierten Zellen ließ sich durch Enzyminduktion erhöhen.Die Abhängigkeit der Steroid‐Δ1‐Dehydrogenase‐Aktivität von der Zell‐, Substratund Cofaktorkonzentrtion, der Reaktionstemperatur und der Lösungsmittelkonzentration wurde untersucht. Die Halbwertzeit der Immobilisate wurde mit und ohne Nährmedium bestimmt. Die Aktivität der Corynebakterium simplex‐Immobilisate betrug 169 μmol/gImm h mit einer relativen Aktivität von 246%.
Quantitative determination of antioxidants and ultraviolet stabilizers in polymers by high performance liquid chromatography
Authors: Francis Vadakkoott C. , Sharma Yoginder N. , Bhardwaj Ishwar S. 
Published: April 2003

AbstractThe quantitative determination of antioxidants and ultraviolet (UV) stabilizers in a polymer matrix has been standardized using HPLC. The additives were extracted out of the matrix using low boiling solvents in order to minimize the degradation of additives at elevated temperatures. Carbon tetrachloride and tetrahydrofuran have been found to be most suitable solvents for low density polyethylene and polypropylene respectively. The method has been found to be highly reproducible and the standard deviation is very low. This method does not suffer from the problems like overlapping frequencies as observed in spectroscopic methods.
High‐temperature oxidation of polymers
Authors: Shlyapnikov Yu. A. , Serenkova I. A. 
Published: April 2003

AbstractAbove the certain temperature which depends on the composition of the polymer and usually exceeds 200°C the mechanism and regularities of polymer oxidation markedly change: the main reaction of peroxide radicals RO becomes decomposition with formation of low‐molecular radicals, activation energy decreases and the rate of oxygen consumption becomes directly proportional to the oxygen pressure.
Einfluß der mechanischen spannung und der temperatur auf die photooxidation von polyethylen
Authors: Peewa L. , Ewtimowa S. 
Published: April 2003

AbstractThe tensile stress and temperature effects on the Polyethylene photooxidation kinetics have been investigated. Subjects are light stabilized and not stabilized high density Polyethylene films. The tensile stress used were 10% and 20% of the breaking stress. Temperatures of 50°C, 30°C, 5°C were realized in a chamber for an artificial climate with an irradiation source mercury ark lamp type 𝔫PK‐2. The duration of exposure was up to 1500h. The oxidation degree has been appreciated by the carbonyl index determined by means of a IR spectrophotometer.It was established that the photooxidation process rate depends on the temperature as well as on the mechanical stress. At the tensile stress used it was found a decrease of the oxidation rate in comparison with the unloaded samples. The mechanical stress influence was stronger when testing unstabilized Polyethylene.
Influencing parameters in the accelerated weathering of pigmented plastics and paints – new findings and possible progress
Authors: Kämpf G. , Papenroth W. 
Published: April 2003

AbstractA report is given of recent studies into the influence of spectral energy distribution, irradiation intensity, moisture, oxygen pressure and specimen temperature on the results obtained during the accelerated weathering of unpigmented and pigmented polymers. In particular, a “radiation‐related spectral energy absorption” is defined and its possibilities for providing information on the sequence of the degradation processes that take place during weathering is discussed; in this respect it is possible to differentiate between the degradation of the polymer matrix by UV‐degradation, degradation by photocatalytic oxidation of the polymer when photoactive pigments are used and the protective action of high‐grade inorganic pigments. Finally, the possibilities for improving the process and equipment used in accelerated weathering are discussed.
Alterung von copolymeren, die ketogruppen enthalten
Authors: Nenkov G. , Bogdanzaliev T. , Stoyanov A. , Kabaivanov W. 
Published: April 2003

AbstractPolymers of polystyrene and polyoelefine, containing covalently linked keto groups, are obtained. Polystyrene polymers are prepared by polymerization of styrene and unsatured ketones in the presence of polybutadiene while polyolefines are obtained by grafting unsatured ketones to the polymer. Films of copolymers, thus prepared, undergo photochemical degradation when exposed to natural and artificial light. The rate of degradation is considerably higher, as compared to the analogical polymers without keto groups, and it depends on the type and concentration of the ketone used. The reaction of degradation is propably mainly Norish II‐type which has the effect of decreasing the molecular weight of copolymers. That assumption is confirmed by the observed alteration in carbonyl and hydroxyl range ‐ 1720 cm−1 and 3450 cm−1 respectively in the polymer chains when they are irradiated.
Über die wirkung der breite des spektralbereichs auf die alterung von kunststoffen
Authors: Nyitrai Zs. , Lovas I. , Ocskay Gy. , Wein T. 
Published: April 2003

AbstractThe effect of the short wavelength range of the UV spectrum and the influence of elevated temperatures to the degradation of the plastics were measured in three different artificial weathering devices.