bluuebunny/crossref_metadata_2025 huggingface dataset:
Oberflächenstrukturierung polymerer Fasern durch UV‐Laserbestrahlung. 3. Synergetisches Modell für das Entstehen der Oberflächenstrukturen
Authors: Bahners Thomas , Schollmeyer Eckhard
Published: April 2003

Ein synergetisches Modell wird vorgeschlagen für die Entstehung der Oberflächenstruktur von UV‐laserbestrahlten Polymeren und speziell Synthesefasern. Dabei wird angenommen, daß durch thermische Beiträge zur UV‐Laser‐Polymer‐Wechselwirkung eine sehr dünne, hocherhitzte Schmelzschicht an der Ablationsgrenze entsteht. Das Zusammenwirken von Marangoni‐Konvektion und Schrumpfverhalten aufgrund innerer Spannungen ist dann für das Entstehen der typischen Struktur verantwortlich. Parameter für das Auftreten des Effekts sind hierbei der Absorptionskoeffizient für die jeweilige Wellenlänge, der die Dicke der Schmelzschicht bestimmt, sowie die Existenz des Schrumpfes.
Oxygen transport and surface active properties of silicone containing copolymers of methyl methacrylate II
Authors: Erbil H. Yildirim
Published: April 2003

New organofunctional siloxanes from γ‐methacryloxypropyltrimethoxysilane (MPTMS) were synthesized by transesterification of methoxy groups with linear high alcohols, ether alcohols, and α‐hydroxyacids. The factors affecting the substitution ratios were determined.

These siloxanes were copolymerized with methyl methacrylate (MMA), crosslinked with ethylene glycol dimethacrylate (EGDM) in order to examine the effect of substituted groups to the oxygen permeability coefficient (Pd) and surface free energy properties of the resultant copolymers.

The substitution of the oxygen containing polar groups decreased the oxygen permeability due to the interactions between polar groups decreasing the free volume. However, these groups increased the polar component of surface free energy (γ) and thus total surface free energy (γS). The hydrophilicity of the carbitol and 2‐ethoxyethanol containing siloxane‐MMA copolymers was found to be suitable for biomedical applications.
Chemical reactions of an epoxy‐functional silane in aqueous solution
Authors: Xue Gi
Published: April 2003

Chemical reactions of the functional epoxy group of γ‐glycidoxypropyltrimethoxysilane in aqueous solution have been studied by Fourier transform infrared spectroscopy (FT‐IR). It was found that the epoxy group reacts with the silanol group forming a SiOCC structure, and concurrently reacts with water. The kinetics of these reactions were studied.
A model for predicting elongational viscosity of polymer blends
Authors: Saini D. R. , Shenoy A. V.
Published: April 2003

A model has been proposed to correlate the elongational viscosity of blends with the free volume theory so that the elongational viscosity of a blend at any composition can be determined from the elongational viscosity and the weight fractions of the individual components. The predictions of the model are compared with experimental data in four cases and found to give reasonable good agreement.
Untersuchungen zur thermodynamischen verträglichkeit von polyethylen hoher dichte (HD PE) und polyethylen niederer dichte (LD PE) im schmelzezustand, I. Die bestimmung der löslichkeitsparameter
Authors: Freytag Ulrich , Radusch Hans‐Joachim
Published: April 2003

Für HD PE und LD PE wurden oberhalb der Kristallisationstemperaturen die Löslichkeitsparameter auf der Basis gaschromatographischer Retentionsdaten bestimmt. Als Meßverfahren wurde die Methode der Inversen Gaschromatographie angewendet. Es zeigte sich, daß die Löslichkeitsparameter der untersuchten Polyethylentypen innerhalb der Fehlergrenzen nahezu gleich sind. Aus der Beschreibung der Temperaturabhängigkeit der Löslichkeitsparameter folgt, daß das thermodynamische Verhalten der Polyethylenkomponenten in Mischungen durch ihre unterschiedlichen freien Volumina determiniert ist.
Synthesis and thermal studies of bisitaconimide‐methacrylic acid copolymers
Authors: Rao K. Vijaya Chandra , Nema Suresh K. , Kumar Velayudhan Nair G. , Mathew Suresh
Published: April 2003

A copolymer of 3,3′‐bisitaconimido‐m,m′‐diphenyl sulfone and methacrylic acid was synthesized by free radical polymerization. The copolymer was characterized and the copolymerization parameters were evaluated. The reactivity ratios determined by three different methods were in good agreement and the values suggest an alternating copolymer. The thermal degradation of the bisitaconimide homopolymer and the copolymer were compared and the structural implications on the thermal behaviour are discussed. The activation energies for the different stages of thermal decomposition of both the homopolymer and the copolymer were evaluated from the Coats‐Redfarn plots.
Influence of synthesis conditions of porous copolymers of 1,4‐di(methacryloyloxymethyl)‐naphthalene with divinylbenzene on their structure, 2. Influence of diluent composition
Authors: Gawdzik B. , Matynia T.
Published: April 2003

The influence of diluent composition on the internal structure of porous copolymers of 1,4‐di(methacryloyloxymethyl)naphthalene (1,4‐DMN) and divinylbenzene (DVB) was studied.

A set of copolymers containing 0.5 mole fraction of 1,4‐DMN and 0.5 mole fraction of DVB obtained in the presence of various amounts of toluene in the mixture with n‐decanol was investigated. In order to establish the influence of toluene concentration on the internal structure of 1,4‐DMN and DVB copolymers, surface areas, pore size distributions, and polarities of sorbents were investigated.
Reaction of poly(vinyl alcohol) with n‐butyl isocyanate. Chemical hydrolysis of the resulting polymers
Authors: Arranz F. , Sánchez‐Chaves M. , Martínez R.
Published: April 2003

This study is concerned with some kinetic features of the reaction of n‐butyl isocyanate with poly(vinyl alcohol) without any catalyst and using triethylene diamine as catalyst. The structure of the resulting polymers was determined by means of IR, 1H‐ and 13C‐NMR spectroscopy as well as by chemical analysis. Vinyl alcohol‐vinyl butyl urethane (VAL‐VBU) copolymers were obtained. It has been found a linear dependence of reaction rate on polymer, n‐butyl isocyanate, and triethylene diamine concentrations. Reaction rate constant decreases as reaction time increases. It can be explained by steric hindrance phenomena due to urethane groups incorporated along the polymeric chain. The activation energy was found to be 49.9 kJ/mol. A kinetic study of the homogeneous hydrolysis of VAL‐VBU copolymers has been made as a function of the base concentration, the temperature, and the VBU content. The homogeneous hydrolysis was found to be first order with respect to both hydroxyl ion and VBU contents. The activation energy for the base catalyzed homogeneous hydrolysis was found to be 79.3 kJ/mol. The heterogeneous hydrolysis of VAL‐VBU copolymers in basic medium showed that no hydrolysis takes place under the conditions employed.
Studies on 50/50 natural rubber/styrene butadiene copolymer blend
Authors: Joseph Rani , George K. E. , Francis D. Joseph
Published: April 2003

A carbon black filled 50/50 natural rubber (NR)/styrene‐butadiene rubber (SBR) blend is vulcanized using several conventional curing systems designed by varying the amounts of sulphur and accelerator. The cure characteristics and the properties of the vulcanizates are compared. The quantity and quality of crosslinks in each case are evaluated by chemical probes to correlate them with the vulcanizate properties.
Radiation initiated grafting of styrene and methyl methacrylate onto wool
Authors: Kumar Manmohan , Rao M. H.
Published: April 2003

Radiation initiated grafting of hydrophobic monomers styrene and methyl methacrylate onto wool (dyed and undyed) and dyed carpet has been carried out. The importance of swelling in obtaining appreciable amounts of grafting has been stressed. The rate of grafting with dyed wool and carpet is found to be less than for undyed wool and the results are explained on the basis of protection offered by aromatic moieties of the dye. Efficiency of monomer utilization has been found to be as high as 98% at low concentrations of the monomer since the accompanying (parasitic) homopolymerisation is almost negligible in the presence of scavengers. Reasonable hydrophobicity is achieved in ca. 80% styrene grafted and ca. 150% methyl methacrylate grafted wool.
Synthesis of hydrophilic elastomers by radiation grafting
Authors: Soebianto Yanti S. , Yoshii Fumio , Makuuchi Keizo , Ishigaki Isao
Published: April 2003

Radiation grafting of acrylic acid (AAc) onto ethylene‐propylene rubber (EPR) to obtain hydrophilic elastomers has been investigated. It was found that by addition of alcohol (methanol and 1‐propanol) into water as solvent for grafting the degree of grafting increased and formation of homopolymer was retarded. The grafting by addition of alcohol occurred even in deeper portions of the film compared with no addition of alcohol. Grafting rate differed largely with propylene contents in the EPR. Graft polymerization occurred easily in EPR of lower propylene contents such as 22%. Before introducing AAc in grafting the stability of EPR radicals of lower propylene contents was higher in comparison with other components. Water absorption of EPR increased linearly with increasing grafting yield.
Kernresonanz‐untersuchungen an isophorondiisocyanat/diamin und röntgenstrukturanalyse des cis‐isophorondiamins
Authors: der Heyde W. Auf , Hübel W. , Boese R.
Published: April 2003

1‐Amino‐(3‐aminomethyl)‐3,5,5‐trimethylcyclohexan 1 (IPDA) und 1‐Isocyanato‐(3‐isocyanatomethyl)‐3,5,5‐trimethylcyclohexan 2 (IPDI), die im technischen Hüls‐Produkt jeweils im Isomerengemisch mit 25 und 75% (1a, 1b und 2a, 2b) enthalten sind, wurden durch 1‐H/13‐C‐NMR‐Spektroskopie in ein‐ und zweidimensionaler Technik untersucht und die Konfiguration und Konformation festgelegt. Dabei ergab sich für das zu 75% vorliegende Isomere von IPDA und IPDI eine Sesselkonformation mit cis‐Anordnung des equatorialen NCO bzw. NH2 Substituenten und der equatorialen CH2NH2‐ bzw. CH2NCO‐Gruppe. Die Röntgenstrukturanalyse eines bei tiefer Temperatur gezogenen Einkristalls des flüssigen Hauptisomeren von IPDA bestätigte die NMR‐Befunde (Raumgruppe Pl̄; Zelldimensionen: a = 5,864(2); b = 8,107(3); c = 11,505(5) Å; α = 87,63(3)°; β = 88,85(3)°; γ = 73,34(3)°).
Bismaleimide resins. Effect of aliphatic amines on properties
Authors: Varma I. K. , Gupta S. P. , Varma D. S.
Published: April 2003

Bis(p‐maleimidophenyl) methane (BM) resin was chain extended by nucleophilic addition with aliphatic diamines having 2,4, or 6 methylene groups (EDA, DAB, HMDA) and diethylene triamine (DETA) and triethylene tetramine (TETA). Chain extension of BM with aliphatic amines significantly reduces the curing temperatures. Increasing the methylene content of the aliphatic amines leads to slight reduction in onset temperatures of curing (∼6°C). Heat of polymerization (ΔH) decreases significantly by chain extension with diamines. Further decrease in ΔH is obtained by the addition of triallylcyanurate (TAC) to the chain extended BM. Thermal stability of cured (180 ± 5°C) resin in nitrogen atmosphere was found to be independent of the methylene content of diamines used for chain extension. Mechanical properties of glass fabric reinforced chain extended BM resins were evaluated. Ageing behaviour of these laminates was investigated at 220 ± 10°C for 500 h and changes in mechanical properties were determined.
Zur Morphologie von peroxidisch vernetztem Polyethylen
Authors: Bongardt J. , Michler G. H. , Naumann I. , Schulze G.
Published: April 2003

Das Vernetzen von LDPE mittels Peroxiden hat neben einer Abnahme der Kristallinität eine Veränderung der übermolekularen Struktur zur Folge. Mit steigender Vernetzung nimmt der Durchmesser der Sphärolithe bzw. der garbenförmigen überstrukturen ab. Dieses Ergebnis ist auf eine rückläfige Kristallwachstumsgeschwindigkeit zurückzuführen, bedingt durch eine fallende Kristallisationstemperature und einen Anstieg der Schmelzviskosität infolge zunehmender Vernetzungsdichte. Durch die Vernetzung entstehen zusätzliche konstitutionelle Störungen in der PE‐Kettenstruktur, wodurch die Abmessungen der Lamellenkristalle und die Größe der Mosaikblöcke beeinflußt werden.
Photoconductive properties of cadmium sulfide encapsulated in polymers
Authors: Haga Yutaka , Nakajima Masahisa , Yosomiya Ryutoku
Published: April 2003

Cadmium sulfide (CdS) was encapsulated in poly(methylmethacrylate), poly(styrene) or poly(vinylcarbazole) by the encapsulating polymerization process, and its photoconductivity was investigated. As result, it was observed a remarkable light‐sensitive effect. The light sensitive effect of CdS encapsulated in poly(methylmethacrylate) (C‐MMA‐CdS) is particularly marked and depends largely on the encapsulation rate. The photosensitive mechanisms of encapsulated cadmium sulfide (C‐CdS), CdS material, and CdS/polymer dispersion composites were discussed and compared. Furthermore, the temperature dependence of the dark current and the initial rising rate of the sensitizing photocurrent were studied.
Spectroscopic study of gangue of coal and its application as filler in PVC compounds
Authors: Xue Gi , Fu Qiang , Ding Jianfu , Jiang Shagen , Liu Shiying , Xi Yuinxia
Published: April 2003

Fillers for PVC compounds have been made from coal gangue. FT‐IR studies show that it contains aromatic components with phenolic groups. Application of gangue as a filler in rigid PVC compounds gives rise to materials of good mechanical properties, high heating and chemical resistance, and lower cost.
Styrene‐divinylbenzene copolymers, V. Inhomogeneity in the structure and the average degree of swelling
Authors: Okay Oǧuz
Published: April 2003

The compositional inhomogeneity and the average degree of swelling of heterogeneous styrene‐divinylbenzene (S‐DVB) copolymers were investigated using two morphological features of porous copolymers. At a fixed volume fraction of a nonsolvating diluent, the extent of inhomogeneous crosslinking increases with increasing DVB concentration. In addition, the crosslinking density of less crosslinked regions of the network decreases as the DVB concentration increases. The experimental results can be explained by the microgel‐model of the network formation. The average degree of volume swelling can be predicted from the composition of the starting monomer mixture and from the porosity of the final copolymer dried from water. Depending on these parameters, the changes in the value of v2, the volume fraction of copolymer in the swollen gel, and the conditions for the pore stability are discussed.
Eine rheo‐optische Apparatur für die Durchführung homogener, einfacher Dehnungen an Polymerschmelzen mit simultaner Aufzeichnung der Deformation, der mechanischen Spannung und der Doppelbrechung
Authors: Dinkel Alfred , Hoppler Hans Ulrich , Tomka Ivan , Vancso Gyula
Published: April 2003

Es wird über eine rheo‐optische Apparatur zur Verstreckung von Polymerschmelzen mit rotierenden Klemmen berichtet, die mit einer Doppelbrechungs‐Meßeinrichtung ausgerüstet ist. Mit dieser Einrichtung können einfache Dehnungen an Polymerschmelzen bis zu hohen Verstreckgraden unter homogenen Bedingungen durchgeführt werden. Während des Deformationsvorganges können die Spannung, die Doppelbrechung und die Probendicke mit einer Meßrate von 20 Hz, sowie die Probenbreite mit ca. 3 Hz erfaßt werden.

Wir haben Messungen an Polyisobutylen bei Raumtemperatur mit verschiedenen Dehngeschwindigkeiten (0,01 s−1 < \documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon$\end{document} < 1 s−1) bis zu einem Verstreckgrad von λ ≈ 200 durchgeführt. Dabei wurden Spannungen bis zu 2 · 106 Pa erhalten. Das spannungsoptische Gesetz war bei homogener Versuchsführung stets erfüllt. Es wird gezeigt, daß ohne Kontrolle der Dehngeschwindigkeit und insbesondere bei inhomogener Dehung nicht nur Abweichungen vom spannungsoptischen Gesetz, sondern auch große Fehler bei der Spannungs‐ bzw. Viskositätsberechnung auftreten. Deshalb wurde großer Wert auf die Prüfung der Homogenität der Dehnung gelegt.
Blends of polychloroprene and polyvinylchloride
Authors: George K. E. , Joseph Rani , Francis D. Joseph
Published: April 2003

Blends of polychloroprene rubber and plasticized polyvinylchloride have been prepared in various compositions and their properties evaluated. The properties of the blends show that they can be used to replace polychloroprene in many applications.
About the influence of filler particle size on toughness of filled polypropylene
Authors: Švehlová Vítězslava , Polouček Eduard
Published: April 2003

The content of the largest filler particles and their agglomerates has been evaluated in polypropylene‐calcium carbonate composite. A strong decrease of tensile impact strength was noted with the increasing value of Av, i.e. the ratio of area belonging to inclusions greater than about 10 μm to the overall area. A similar dependence was observed for three different types of polypropylene matrix and different ways of composite preparation.
Correlation between the porous structure of polystyrene and its discolouring ability
Authors: Simitzis Johannis
Published: April 2003

Porous polystyrene was prepared according to the following methods by variation of the production parameters: (A) Method based on the suspension polymerization using a nonsolvent of the polymer. (B) Method based on the dissolution of polystyrene in a solvent and then precipitation using a nonsolvent of the polymer. The molecular weight of the polymer, its structure using Hg‐porosimetry, and the microscopic pattern of the polymer grains were determined. The ability of the produced polystyrene to discolour aqueous solutions of different dyes (mainly methylene blue) was also examined.

From the correlation between porous structure and discolouring ability in comparison with corresponding discolouring examination of other adsorptive agents (activated carbon) the importance of the following parameters was found out and evaluated: (a) total value of pore volume or pore volume distribution, (b) intermediate part of pore distribution 10000 – 100 Å for the adsorption of the given dyes, (c) shape of pores, which are different in method A and B (the comparison of produced polystyrene by different production parameters should be done only by independent methods and not between A and B method). It also resulted that it is necessary to introduce appropriate groups into the molecules of the porous polystyrene in order to increase the adsorption rate of an ionic or a polar substance. In conclusion, by appropriate choice of the production parameters of porous polystyrene a product with the desired characteristics of porosity could be produced.
Cashewnut shell liquid: Characterization and studies of PVC degradation in solution
Authors: Varma I. K. , Dhara S. K. , Varma M. , Biddapa T. S.
Published: April 2003

Cashewnut shell liquid (CNSL), which is basically a mixture of several alkyl substituted phenols was characterized using 1H and 13C‐NMR, FT‐IR, and mass spectroscopic techniques. The major constituent was found to be cardanol having one, two, or three double bonds in the alkyl side chain. Presence of one hydroxy group was confirmed by acetylation and 1H‐NMR studies. Distillation of CNSL under atmospheric conditions resulted in partial oxidation of the side chain. Such an oxidation was confirmed by elemental analysis and FT‐IR studies. Thermal degradation of poly(vinyl chloride) (PVC) in CNSL was studied in nitrogen atmosphere in the temperature range of 180–220°C. Rate of dehydrochlorination of PVC was found to be lower in CNSL in comparison to the degradation in ethyl benzoate. An induction period ranging from 23 min to 55 min was observed in CNSL and was found to depend on the concentration of PVC in solution and temperature of dehydrochlorination. Activation energy for dehydrochlorination of PVC in CNSL was found to be 43 ± kcal/mol. Compatibility studies of PVC in CNSL were done using differential scanning calorimetry (DSC). Good plasticization was observed by blending PVC up to 10% of CNSL. Overall thermal stability of PVC was not altered by the presence of CNSL in these low concentrations.
Graft copolymerization of starch with alkylene methacrylates
Authors: Sandle N. K. , Singh Om Pal , Varma Indra K.
Published: April 2003

Graft‐copolymerization of 2‐hydroxyethyl methacrylate (HEMA) and ethylene dimethacrylate (EDMA) onto starch using cerium (IV) as an initiator was investigated. The rate of graft copolymerization had a first order dependence on monomer concentration suggesting that grafting followed the typical free radical polymerization kinetics. In the infrared spectra of graft copolymers a very sharp and strong band at 1730 cm−1, which is characteristic for the vCO stretching of esters, was present. The grafting of HEMA or EDMA onto starch reduced the density of starch. Thermal behaviour of graft copolymers having different % graft‐on was investigated by thermogravimetric analysis. An increase in % graft‐on of EDMA from 19.7 to 95.7% resulted in an increase in thermal stability. However, at high % graft‐on (i.e. 163.4%) a reduction in thermal stability was observed.
Einfluß von Weichmachern auf die Löschung der Lumineszenz von Pyronin B in Polymerfilmen
Authors: Müller Franz Werner , Schiller Kurt , Marx Jörg , Klein Norbert
Published: April 2003

Den polymeren, transparente Schichten ergebenden Bindemitteln Cellulosediacetat und Polyvinylalkohol wurden verschiedene Weichmacher zugesetzt, um spezifische konzentrationsabhängige Wechselwirkungen zwischen Polymerem und Weichmacher zu analysieren. Als Untersuchungsmethode dient dabei die Verfolgung der Löschung der verzögerten Fluoreszenz der Sonde Pyronin B in diesen Polymerfilmen. Es wird gezeigt, daß kleine Weichmacherkonzentrationen die Matrix verfestigen und damit beispielsweise die Sauerstoffpermeabilität einschränken. Dieser Effekt ist besonders in Cellulosediacetat ausgeprägt, für einige Weichmacher bis in den Bereich von 30%.
Polymere Dispergiermittel I. Molmasse und Dispergierwirkung der Melamin‐ und Naphthalin‐Sulfonsäure‐Formaldehyd‐Polykondensate
Authors: Pieh Stefan
Published: April 2003

Der Einfluß des mittleren Molekulargewichts (Viskositätsmittel) von Naphthalinsulfonsäure‐ und Melaminsulfonsäure‐Formaldehyd‐Polykondensaten auf ihre Eigenschaften als Dispergiermittel wurde an wässrigen Portlandzement‐ und Anhydritsuspensionen untersucht. Die rotationsviskosimetrische Erfassung der Dispergierwirkung führte zur Definition eines allgemein anwendbaren Dispergierindex. Es zeigte sich, daß die untersuchten Polykondensate nur in einem verhältnismäßig schmalen Molekulargewichtsbereich, und zwar von Grenzviskositätszahl [η] = 0,02 dl/g bis [η] = 0,10 dl/g eine gute Dispergier‐ und Plastifizierwirkung zeigen und oberhalb dieses MV‐Bereichs zur Erhöhung der Viskosität, also Versteifung der Zement‐ und Anhydritsuspensionen führen. Basierend auf Adsorptionsuntersuchungen zur Bestimmung der adsorbierten Polymermenge und der DLVO‐Theorie wird versucht, in der mit steigender Molekülgröße auftretenden Überlappung der Polymerhüllen eine Erklärung für diesen Zusammehang zu finden.
Glasübergänge in Poly(vinylchlorid)/Poly(methacrylat)‐Systemen
Authors: Pigłowski Jacek
Published: April 2003

Poly(methylmethacrylat) (PMMA), Poly‐n‐(butylmethacrylat) (PnBMA) sowie Poly(methylmethacrylat‐ran‐n‐butylmethacrylat) sind mischbar mit Poly(vinylchlorid) (PVC). Die Dreikomponentenmischungen liegen jedoch in zweiphasigen Systemen vor. Jede dieser Phasen besteht aus PVC und entsprechenden Methacrylatpolymeren. Die Abhängigkeit der Glastemperatur von der Mischungszusammensetzung für PVC/PnBMA läßt sich durch Einführen eines zusätzlichen Terms in der Gordon‐Taylor‐Gleichung beschreiben.
Polymerization of n‐butyl vinylether initiated by polymeric peroxycarbamates and active polystyrenes
Authors: Yagci Yusuf , Acar Metin , Hizal Gurkan , Yildirim Huseyin , Baysal Bahattin
Published: April 2003

The free radical promoted cationic polymerization of n‐butyl vinylether (BVE) was achieved by thermal decomposition of polymeric peroxycarbamates (PPC) or active polystyrene (APS), having fragments of PPC in the presence of diphenyliodonium hexafluorophosphate (Ph2I+ PF) or silver tetrafluoroborate (AgBF4). Polymerizations were accompanied by phase separation. Formation of block copolymers, mainly in the solid phase, was evidenced by NMR spectroscopy. Polymer samples obtained by this procedure contained only a very small fraction of block copolymer structure due to the phase separation and very effective chain transfer reactions predominating the cationic polymerization of BVE.
Studies on the thermal degradation of aromatic polyamides by pyrolysis‐field ionization mass spectrometry and pyrolysis‐gas chromatography
Authors: Schulten H.‐R. , Plage B. , Ohtani H. , Tsuge S.
Published: April 2003

The thermal degradation of aromatic polyamides such as poly&(1,4‐phenyleneterephthalamide) (Kevlar) and poly&(1, 3‐phenylene‐isophthalamide) (Nomex) was studied by pyrolysis‐field ionization mass spectrometry (Py‐FIMS) and pyrolysis‐gas chromatography (Py‐GC). In Py‐FIMS, the thermal degradation products were recorded which were formed in the ion source of a double focusing mass spectrometer. Usually a temperature range from 50 to 750°C and a heating rate of 1.2°C/s were employed. Various common and characteristic products for the two samples, respectively the corresponding para‐ or meta‐isomers, were observed up to m/z 500 with significant differences in intensity. The main products observed were produced by both radical homolytic and hydrolytic decompositions.

On the other hand, in flash Py‐GC the instantaneous thermal degradation products at 720°C were gas‐chromatographically separated by a fused‐silica capillary column and detected both by a flame ionization detector and a mass spectrometer with electron ionization (EI). Although many of the degradation products were identical with those observed by Py‐FIMS, the former almost entirely consisted of the fragments formed through radical homolytic degradation. In general, the differences between the samples with Py‐GC were much less than those observed in Py‐FIMS.
Effect of some free and chelated iron ions on the aqueous polymerization of methyl methacrylate
Authors: Abd El‐Ghaffar M. A. , Abd El‐Hakim A. A. , Badran A. S. , Moustafa A. B.
Published: April 2003

The aqueous polymerization of methyl methacrylate was carried out in absence and in presence of some inorganic iron salts and complexes using sodium bisulphite as a producer of initiator radicals. Polymerization in absence of iron salts or complexes resulted in the highest average molecular weights formation and the least reaction rates, while using salts in which the iron is ionizable lowered both the apparent energy of activation (Ea) of the system and the obtained average molecular weights and increased the initial rates. On the contrary, when the iron is chelated, as in case of potassium ferrocyanide and potassium ferricyanide, a retardation or complete inhibition of the polymerization reaction took place, respectively.
Thermal stability of some acetylenic poly‐ and copolymers obtained by electrochemical polymerization
Authors: Simionescu C. I. , Bulacovschi V. , Grovu‐Ivǎnoiu Maria
Published: April 2003

The thermal stability of some polymers with conjugated double bonds has been studied under dynamical conditions of heating. It was found that nature of the substituents plays an important role in the thermal behaviour of the polymers.
Effect of the anhydride structure and the epoxy fortifier on the reactivity in curing of epoxy resins
Authors: Patel Ravji D. , Patel Ranjan G. , Patel Vithal S.
Published: April 2003

The curing reactions of the epoxy resin triglycidyl‐p‐aminophenol with acid anhydrides using tertiary amine as catalyst were studied kinetically by differential scanning calorimetry. The dynamic scans in the temperature range 30–300°C were analyzed to estimate the activation energy and the order of the reaction for the curing process using some empirical relations. The curing process was found to follow a simple Arrhenius type kinetics having activation energies in the range 75 – 142 kJ/mol and the order of the reaction is about 1. The effect of the variation in acid anhydride structure and of the incorporation of the epoxy fortifier on the cure characteristics is investigated.
A modification of diglycidylether of Bisphenol A with diimide‐diacids
Authors: Serra Angels , Cádiz Virginia , Mantecón Ana
Published: April 2003

A conventional epoxy resin derived from Bisphenol A has been modified with aromatic diacids containing a preformed imide ring in order to achieve an improvement in their thermal properties. These new resins were characterized by IR and 13C‐NMR spectroscopy, and it was possible to verify two types of oxirane ring openings by diimide‐diacid.
Interactions of polymer backbones and complexation of polychelatogens with methylthiourea ligands in aqueous solution
Authors: Geckeler K. E. , Shkinev V. M. , Spivakov B. Y.
Published: April 2003

The interactions of the polymeric backbone and complex formation with a series of metals were investigated for poly(ethyleneimine), poly(vinylpyrrolidinone), and poly‐(acrylamide) as basis polymers with methylthiourea as ligand. Retention studies by application of membrane filtration of aqueous solutions were used for the evaluation of interaction between the metal ions and macromolecules as function of pH. It was shown for the Na, Co, Ni, Cu, Zn, Cd, Hg, Fe ions that the interaction depends both on the type of polymer backbone and the pH.

Whereas for poly(ethyleneimine)‐based copolymers the retention data were influenced only slightly by pH, the two other copolymers investigated showed a strong pH dependency for the individual metals. A dominating effect of the functional ligand comonomer in terms of the interaction over the basis monomer was observed for the majority of metal ions investigated.
Preparation and properties of selectively p‐chlorinated polystyrene
Authors: Kiji Jitsuo , Konishi Hisatoshi , Okano Tamon , Takada Hiroyuki
Published: April 2003

Polystyrene has been chlorinated in the liquid phase by SbCl3 catalyst combined with 10‐trifluoroacetylphenothiazine to afford a polymer, which is represented by the formula . The aromatic substitution reaction (x > 1) occurs predominantly at the p‐position, the ratio of p‐ to o‐chlorination being 10‐12. The intrinsic viscosity of the toluene solution at 30°C decreases with content of chlorine, x. The refractive index, nD, increases with x. The nD value of a 25.05% chlorine‐containing polymer (x ≃ 1) is 1.6041.
Studies on chemical resistance of polyesters
Authors: Bansal Raj K. , Malik G. S. , Singh Parkash , Dabholkar D. A.
Published: April 2003

Chlorendic anhydride based polyester (I,) tetrachlorophthalic anhydride based polyester (II), dibromoneopentyl glycol based polyester (III,) general purpose polyester (IV,) blend of dibromoneopentyl glycol based polyester with general purpose polyester (V,) chlorendic anhydride and dibromoneopentyl glycol based polyester (VI), and a blend of chlorendic anhydride based polyester and dibromoneopentyl glycol based polyester (VII) were prepared and their chemical resistance and moisture absorption studied in various reagents, acid, alkali, and water, at 25 and 65°C. It is found that the polyester (III) is the least affected in the presence of the acids. In 20% NaOH, there was a decrease in weight for all polyesters at both the temperatures compared to the control except the polyester (VII). Increase in weight of all the polyesters was observed during the absorption of moisture both at 25 and 65°C. The increase was higher at higher temperature. Polyester (III) thus shows the least absorption of moisture.
Synthesis and characterization of some polyurethanes
Authors: Patel Prashant , Patel Mayur , Suthar Bhikhu P.
Published: April 2003

Polymers containing urethane units were synthesized by solution polymerization of bisphenols A, C, and F with diisocyanates viz. toluene‐2,4‐diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate, respectively. Thus obtained polymers were pale yellow amorphous powders. These polymers were characterized by infrared spectral studies and nitrogen content. The number‐average molecular weights (M̄n) were estimated from conductometric titration and limiting viscosity number [η] in dimethyl formamide. From thermogravimetric analyses, the thermal behaviour was studied. Kinetic parameters for their degradation were computed.
Synthesis of asymmetric diglycidyl ester compounds. Reaction with aromatic diamines
Authors: Mantecón Ana , Cádiz Virginia , Serra Angels , Martínez Pedro Alberto
Published: April 2003

New diglycidyl esters coming from the corresponding diacids and epichlorohydrin were synthetized using a quaternary ammonium salt as a catalyst. The new asymmetric compounds were characterized by spectroscopic methods and employed as starting monomers in a crosslinking process. The course of the reactions was followed by IR spectroscopy. Some intermediate species were identified in the onset of the reactions by recording 13C‐NMR spectra until the products became insoluble in the usual deuterated solvents. The thermal behaviour of these cured epoxy resins was also studied.
Modification of cyclohexanone‐formaldehyde‐resin
Authors: Akar Ahmet , Öztürk Turan
Published: April 2003

The reactions of cyclohexanone‐formaldehyde‐resin via its hydroxy and carbonyl functional groups with a number of different reagents such as acetic anhydride, benzoyl chloride, hydroxylamine, semicarbazide, and phenyl hydrazine were studied. Melting points, IR spectrums, and solubilities in various solvents of the products were determined.
PAN‐Grafted guaran. II. Short‐chain grafting
Authors: Naidoo Sugantheran , Joffe Ray , Neuse Eberhard W.
Published: April 2003

The room‐temperature grafting of polyacrylonitrile (PAN) onto guaran (guar gum) in 2.5 × 10−3 M aqueous sols or aqueous‐methanolic suspensions, initiated by (NH4)4 Ce(NO3)6 in 1M HNO3, leads to PAN‐branched polysaccharides with graft contents of 11 – 53%. Main chain degradation by treatment with boiling aqueous HCl results in detachment of the PAN side chains, for which number‐average molecular masses of ca. 15000 – 48000 are determined viscometrically with the aid of the known Mark‐Houwink relationship (K = 3.92 × 10−4, a = 0.75). Grafting frequencies are in the range of 0.004 – 0.012, equivalent to an average of 80 – 250 non‐grafted repeat units for every singly grafted unit in the guaran main chain. The graft copolymers are of interest as precursors of carboxyl‐functionalized, water‐soluble polysaccharides to serve as polymeric micronutrient and drug carriers of future studies.
Synthesis and applications of reactive carbohydrates. III. Preparation and methylolation of polyacrylamide‐carboxymethyl cellulose graft copolymers
Authors: El‐Sisi Fatma , Hafiz Sayed Abdel‐Samea Abdel , Hebeish Ali
Published: April 2003

Carboxymethyl cellulose (CMC) was treated with HCl at 80°C for different time periods (15 – 60 min). The hydrolyzed CMC samples as well as the original sample were graft copolymerized with acrylamide using K2S2O8 as initiator. It was disclosed that the increasing duration of acid hydrolysis is accompanied by a progressive increment in the copper number of CMC, meanwhile its carboxyl content decreases. Acid hydrolysis enhances significantly the susceptibility of the CMC toward grafting. The latter reduces the copper number of the hydrolyzed CMC samples most probably via conversion of the aldehydic to carboxylic groups under the action of K2S2O8 during grafting. Grafting also reduces the carboxyl content of the original CMC sample while increasing those of the hydrolyzed CMC samples. Methylolation of the polyacrylamide‐CMC graft copolymers results in reactive finishes. When the latter were applied to cotton fabric according to the conventional pad‐dry‐cure method followed by a thorough washing, the fabric retained ca. 86% of the finish derived from the copolymer of CMC and 92% of finishes derived from the copolymers of hydrolyzed CMC.
Free radical grafting of some hydrophilic monomers onto unsaturated segmented polyurethanes — a kinetic study
Authors: Egboh Sunday H. O.
Published: April 2003

Grafting of unsaturated segmented polyurethanes with some hydrophilic monomers such as N‐vinyl pyrrolidone, 2‐hydroxyethylmethacrylate and acrylamide in N,N‐dimethylformamide have been studied using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. Graft copolymers were isolated from homopolymers by selected solvent extraction using a Soxhlet apparatus. A kinetic study of graft copolymerization reactions showed that the reactions follow the conventional kinetic behaviour of free radical polymerization. The dependencies of the grafting rate on initiator and N‐vinyl pyrrolidone concentrations were of 0.5 and 1.00 order, respectively. However, for the 2‐hydroxyethylmethacrylate, the dependencies of the grafting rate on initiator and monomer concentrations were found to be of 0.5 and 2.00 order, respectively. The overall activation energy for the graft copolymerization of the 2‐hydroxyethylmethacrylate and N‐vinyl pyrrolidone were 21.81 kJ/mol and 16.28 kJ/mol, respectively.
Styrene‐N‐Vinylcarbazol copolymers with enhanced thermal stability
Authors: Schopov Ivan , Bratschkov Christo
Published: April 2003

Styrene copolymers with low (up to 5 wt.‐%) N‐vinylcarbazol content were prepared. The copolymers showed enhanced thermal stability in comparison with the pure polystyrene. This is explained by a charge transfer complex formation between the carbazol rings as donor and the radicals, formed during the degradation, as acceptors.
Dielectric behaviour of shellac‐incorporated natural rubber gum stocks
Authors: Goswami D. N. , Singh Radha , Khanna B. B.
Published: April 2003

The dielectric properties of shellac‐incorporated natural rubber gum stocks were studied in the frequency range 100 Hz to 100 kHz and at different periods of curing. Incorporation of shellac in the gum stock resulted in decrease of the dielectric loss values of natural rubber.
Mechanochemically initiated copolymerizations, 10. Kinetic data on the copolymerization of the acrylonitrile/vinyl acetate/α‐methyl styrene ternary system by vibratory milling
Authors: Oprea Cleopatra Vasiliu , Popa Marcel , Dumitriu Severian
Published: April 2003

The kinetics of mechanochemical copolymerization of the ternary system based on acrylonitrile, vinyl acetate, and α‐methyl styrene, by vibratory milling activation was studied. A general relation for expressing the reaction rate is proposed as follows:

Kinetics has been followed by measuring the amount of unreacted monomer by gas chromatography. Partial reaction orders – related to each comonomer, had almost unitary values, being determined from the conversion‐time curves for 7 ternary systems with different comonomer ratios. The values of the reaction rate constant – taken for three temperatures – permitted the computation of the activation energy (18.82 kJ mol‐1), such a low value showing that the contribution of the thermal energy in this type of synthesis is unsignificant.
Neue synthetische träger zur fixierung von enzymen
Authors: Burg Karlheinz , Mauz Otto , Noetzel Siegfried , Sauber Klaus
Published: April 2003

Es wird die Synthese von perlförmigen makroporösen Tägern für Enzyme durch Suspensionspolymerisation von Vinylacetat und N,N'‐Divinylethylenharnstoff in Wasser, durch partielle Verseifung der Acetat‐ zu Hydroxygruppen und durch anschließende Umsetzung mit Epichlorhydrin beschrieben. Reaktive Gruppen der Träger sind Epoxide. Die Hydrophilie der Träger ist durch Vinylalkohol‐ und Harnstoffgruppen gegeben.

Die physikalischen Eigenschaften der Träger im nicht gequollenen Zustand wurden mit Hilfe der Elektronenmikroskopie, der Quecksilber‐Porosimetrie und von BET‐Messungen untersucht.

Eine Reihe von Enzymen (Trypsin, Chymotrypsin, Urease und Penicillinacylase) wurde auf verschiedenen Trägern (Anzahl der Epoxidgruppen, Teilchengröße der Träger) fixiert. In Abhängigkeit vom Epoxidgruppengehalt, vom Enzymangebot und vom pH‐Wert der Substratlösung weisen die Enzyme deutliche Unterschiede bezüglich spezifischer Aktivität und Bindungsausbeute auf.

Im Falle der trägergebundenen Penicillinacylase war eine 65‐fache Wiederverwendung ohne Aktivitätsverlust möglich. Die Trägermaterialien überstehen eine Dampfsterilisation ohne Eigenschaftsveränderung.
Kohlenstoffasern auf der basis von mit wasserstoff‐peroxid voroxidierten PAN (S.A.F)‐fasern
Authors: Popovska Nadeshda
Published: April 2003

Untersucht wurde die Voroxidation einer speziellen hochfesten PAN(S.A.F)‐Faser (93% Acrylnitril, 6% Methylacrylat, 1% Itaconsäure) mit Wasserstoffperoxid in alkalischen Lösungen (2 – 10 Gew.‐% NaOH) als erste Stufe der Herstellung von Kohlenstoffasern. Die kombinierten Ergebnisse aus IR‐ und DTA‐Untersuchungen zeigen, daß die Voroxidation in schwachalkalischen Lösungen (2 – 5 Gew.‐% NaOH) die Geschwindigkeit der Cyclisierungs‐ und Oxidationsprozesse bei anschließender Stabilisierungsstufe erhöht. Eine hohe Konzentration an Reaktionszentren und ein hoher Gelanteil (oberhalb 90%) einer in 8 bzw. 10 proz. NaOH voroxidierten PAN‐Faser verzögern die anschließenden Stabilisierungsreaktionen. Die Cyclisierung der nicht voroxidierten und der voroxidierten PAN‐Fasern verläuft nach einem ionischen Mechanismus. Die Kohlenstoffasern aus mit Wasserstoffperoxid in schwach alkalischen Lösungen voroxidierten PAN(S.A.F)‐Fasern weisen erhöhte Zugfestigketis‐und E‐Modul‐Werte auf bei Glühtemperaturen bis 1350°C. Weitere Steigerung der Glühtemperatur verschlechtert die mechanischen Eigenschaften der gewonnenen Kohlenstoffasern. Eine deutliche Korrelation zwischen E‐Modul und magnetischer Suszeptibilität bzw. Anisotropieverhältnis wurde festgestellt.
Stability of plastics ‐ characteristic property or environmental problem?
Authors: Hubeny Helmut
Published: April 2003

Plastics in general exhibit a high stability. For decades, technical and scientific research has endeavoured to improve polymers in such areas as ageing, light fastness, climatic stability, resistance to rotting, chemical stability, and resistance to stress crazing and cracking,

Today, many of the demands put forth in the interest of disposal, reusability of products, as well as the questionable nature of certain additives and their concentration found in waste, seem to countermand this development. This paper discusses the problems and contradictions of some successful long‐range applications (tubings, sheets, building materials), of some short‐range uses (packaging), as well as of certain select materials systems.

A state‐of‐the‐art solution to the problem is being offered in view of the dual function of plastics as work‐materials and as transducers of energy as, for instance, in closed circuitry.
Accelerated and natural ageing of PVC foils
Authors: Genova Fenka , Gancheva Tamara , Marinova Atanasija
Published: April 2003

The photooxidation stability of PVC foils with various thicknesses (0,4; 0,2; 0,3 and 0,14 mm) intended for agricultural use is investigated during accelerated and natural ageing.

The surface state variations are investigated by surface crazing, total colour variation and chemical composition of the surface layer (IR‐spectra of MIR‐IR‐spectroscopy).

The foil volume variations are investigated by means of differential IR‐spectra, light transmission decrease and the specific elongation. An analogy in the PVC foils properties of 0,4 mm thickness both for accelerated and natural ageing is observed. It is established that during the 12 months induction period of time foils change negligibly their properties. The original properties of foils with thickness of 0,14 mm weathering for 15 months have changed less. For a period of 12 months the changes are considerable: the specific elongation decreased more than 50%, the plasticizers' concentration decreased by 8% and the light transmission — by 40% compared to the original values. The msuface roughness increased up to 5—7μm and the total colour rariation Δ E*ab achieved 25–40 relative units.

During the artificial ageing in Xenotest‐1200 it is found out that the foil thickness induces the photooxidation processes.
On the weathering of modified PVC based compounds during the polymerization process
Authors: Gancheva Tamara , Genova Penka , Marinova Atanasija
Published: April 2003

The variations of molecular spectra, colours and characteristic viscosity of modified and unmodified PVC compounds during the polymerization process in various periods of time of natural ageing have been investigated.

The PVC types modified during synthesis by 0,25 % vol. plasticizers or plasticizers' mixture are characterized by 10 – 12°C lower glass transition temperature, higher thermal stability, long‐term behaviour and better physical and mechanical properties. The Charpy‐impact resistance is increased by 50 to 85%. The rate of the relative UV‐sorption variation during outdoor exposure was lower for compounds based on the modified PVC types.

The polyene parts amount of chain length n = 13, evaluated by means of Raman spectra, was increased during the first and second month, both on non‐irradiated and irradiated surface. The total colour variation ΔEab of the new PVC grades in a 10‐month poriod of weathering was of 10‐30% less compared to the unmodified PVC grades.

By means of IR‐spectroacopy the variations of the hydroxyl‐ and carbonyl groups were .valuated and the diffemncee in the oxidation kinetica were establiehed.
Beiträe zur künstlichen bewitterung von PVC
Authors: Imhof Jörg , Haberleitner Robert
Published: April 2003

Die künstliche Bewitterung von PVC‐Proben liefert nicht unter allen Bedingungen gleichartige Ergebnisse, wie im Freien. Gut bewährt haben sich die Xenotest‐Prüfungen bei weißen Fensterprofilmustern, sowie bei grau eingestellten Dachfolien. Die Bewitterung im QUV‐Gerät, unabhsngig von der Bestückunq, gibt eine wesentlich schnellere Veränderung als im Freien, wobei manche Effekte die im Freien auf‐treten, im QUV durch den Zeitraffereffekt nicht erkennbar werden.
Measurement of thermooxidative stability of polyolefins by isothermal differential thermal analysis
Authors: Kramer E. , Koppelmann J. , Dobrowsky J.
Published: April 2003

Isothermal differential thermal analysis (DTA) is a well known method of testing thermooxidative stabilities of polyolefins. Oxidation induction times, measured up to 7000 hours and over a temperature range from 260°C to 130°C has been used to study the stability of polybutene‐1 in the melt state.

The Arrhenius plots of DTA results show that straight line extrapolation from high to low temperatures is not possible. Thermoanalytically measured oxidation induction times and mechanical failure in oven ageing experiments agree well for polybutene‐1. Measurements of molecular weight and of mechanical properties of polybutene‐1 during the induction period of oven ageing experiments revealed that molecular weight and tensile properties are not sensitive indicators for the beginning of ageing. The state of deterioration can be estimated easier by measurement of residual lifetime in the isothermal DTA experiment. At high ageing temperatures the residual lifetime decreased linearly during the induction period, at ageing temperatures below 160°C the decrease of residual lifetime was found degressive.

Finally the extraction of stabilizer by not water could be measured by isothermal DTA.
Transformation products of antioxidants: The role in stabilization mechanisms
Authors: Pospíšil Jan
Published: April 2003

Antioxidants acting in polymers by chain‐breaking and hydroperoxide decomposing mechanisms are chemically transformed during the stabilization process as a consequence of trapping radicals R•, RO• or RO and/or reactivity with hydroperoxides. New chemical compounds with typical structures characteristic of the starting stabilizer are formed stepwise in the polymer mass. Most of these transformation products participate actively in consecutive steps of polymer degradation. Finally observed phenomena depend on the concentration of individual transformation products. Generally, autocooperative effects with starting stabilizers take place. Important data regarding properties of transformation products have been summarized.