bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of copolymers modifying PVC on its physical and mechanical properties and its UV‐radiation resistance. VI. Photodegradation and crosslinking of PVC films containing MMA/MA, VC/VAC, MBS or ABS
Authors: Kamińska A. , Kaczmarek H. 
Published: April 2003

AbstractThe degradation and crosslinking induced by 253.7 nm wavelength radiation was investigated in pure PVC films and in films containing 1–10 wt.‐% of modifying copolymers (ABS, MMA/MA, VC/VAC or MBS).It has been found that these copolymers decrease the efficiency of PVC crosslinking. Especially ABS and 3–10 wt.‐% MBS clearly hamper this reaction. The induced changes of the limiting viscosity number (LVN) and solubility observed in samples containing MBS and VC/VAC suggest that these copolymers increase or decrease the efficiency of photodegradative or crosslinking processes, depending on the concentration of the copolymers in the samples.
Contribution à l'etude des propriétés rhéologiques, à l'etat fondu, de matériaux composites à base de fibres de cuir et de polyéthylène basse densité ou de copolymères d'ethylène. I. Etudes en rhéomètre à capillaire
Authors: Ayad D. , Genillon R. , May J. F. 
Published: April 2003

AbstractL'étude des propriétés rhéologiques, à l'état fondu, de matériaux composites à base de fibres de cuir et de polyéthylène basse densité, ou de copolymères d'éthylène, a été effectuée à diverses températures et à différentes vitesses de cisaillement. Le comportement des mélanges, dont la matrice est le polyéthylène basse densité, est différent de celui des mélanges à base de copolymères. Une interprétation de cette différence de comportement, basée sur les intéractions fibre matrice, a été proposée. Un minimum de la viscosité, observé sur les courbes d'écoulement des mélanges à base de polyéthylène basse densité, a été attribué à une séparation de phase du composite.
Crosslinkable copolyisophthalamides
Authors: Serna Felipe J. , De la Campa José G. , de Abajo Javier 
Published: April 2003

AbstractCopolyisophthalamides with nadimide pendent groups have been prepared by polycondensation of 5(5‐norbornene‐2,3‐dicarboximido)isophthaloyl chloride (NCIC) and isophthaloyl chloride with bis(4‐aminophenyl)methane, the ratio between both diacid chlorides being 0/100, 10/90, 15/85, 20/80, 25/75, 50/50, and 100/0. By 1H‐NMR it has been proved that the composition of the copolymers closely coincided with the ratio of monomer's feeds.Properties such as solubility, glass transition temperatures, and thermal resistance have been measured and related to the copolymer's composition. Crosslinking studies have been carried out by DSC, and a comparison of properties of copolymers before and after thermal crosslinking has been made. The effect of crosslinking on the mechanical strength of copolymer films has also been measured.
Chlorination of polypropylene in suspension
Authors: Puszyński Andrzej , Dwornicka Jadwiga 
Published: April 2003

AbstractIt is shown that both, potassium chloride and ammonium molybdate, accelerate the chlorination of isotactic polypropylene up to the content of 15 wt.‐% Cl, while sodium chloride speeds up the process up to 25 wt.‐% Cl. At the same time, no effect of salts on the chlorination of atactic polypropylene was observed. From IR analysis followed that chlorine substitution occurred not only at the ternary carbon atom but occasionally at primary and secondary ones as well.
Solubility of poly(n‐alkylmethacrylate)s in hydrocarbons and in alcohols
Authors: Sander Uwe , Wolf B. A. 
Published: April 2003

AbstractPoly(methylmethacrylate) (PMMA), poly(butylmethacrylate) (PBMA), and poly(decylmethacrylate) (PDMA) are completely miscible with toluene at normal pressure from room temperature up to the boiling point of the solvent. In alkanes (C6 to C10) and 1‐pentanol the solubility increases with the length of the side chain of the polymer: PMMA always exhibits a solubility gap within the above temperature range, PBMA shows upper critical solution temperatures (except n‐hexane, which is a non‐solvent), and PDMA mixes completely with all alkanes under consideration. Alcohols (up to C4) are non‐solvents for PMMA but theta solvents for PBMA and PDMA (except ethanol which is a non‐solvent for the latter). The low temperature demixing of ethanol/PBMA is shifted towards lower temperatures by pressure.
Trocknung als verfahren zur charakterisierung von asymmetrischen ultrafiltrationsmembranen
Authors: Paßlack Jürgen , Staude Eberhard 
Published: April 2003

AbstractStrukturen von und Wasserzustände in Membranen lassen sich auf einfache Weise durch Trocknung erfassen, vorausgesetzt, die Membranen kollabieren nicht. Anhand der Trocknungskurven von Ultrafiltrationsmembranen aus Polyamid, Polysulfon und Polyethersulfon kann sowohl die Asymmetrie nachgewiesen als auch der Anteil an freiem und gebundenem Wasser in der Membran quantititativ bestimmt werden. Vergleichende DSC‐Messungen zeigten eine gute Übereinstimmung der Wasserwerte. Unterschiedliche Trocknungskurven lassen sich eindeutig unterschiedlich hergestellten Membranen zuordnen. Mit steigendem Sulfonierungsgrad nimmt die Hydrophilie von substituierten Polyethersulfonmembranen zu; die jeweiligen Trocknungskurven weisen auf zunehmenden Wassergehalt und auf Änderungen in der Membranstruktur hin.
Anionische lösungspolymerisation von glycolid
Authors: Braun Dietrich , Kohl Paul R. 
Published: April 2003

AbstractDie anionische Lösungspolymerisation von Glycolid zu Polyglycolsäure mit verschiedenen Lösungsmittel‐Initiator‐Systemen wurde untersucht. Das Polymerisationsverhalten in Toluol mit den tertiären Aminen Triethylamin und N,N‐Dimethylbenzylamin als Initiatoren und in Sulfolan (Tetrahydrothiophendioxid) mit N,N‐Dimethylbenzylamin wird in Abhängigkeit von Initiatorkonzentration und Reaktionszeit beschrieben.
Changes in the dynamic properties and in the crystallization of polypropylene by incorporation of surface treated and untreated sepiolite
Authors: Acosta José Luis , Ojeda Maria Carmen , Linares Amelia , Romero Mariano 
Published: April 2003

AbstractIn the present work, the changed properties of isotactic polypropylene caused by adding untreated sepiolite and n‐decylaldehyde treated sepiolite were analyzed by studying the isothermal crystallization processes and the dynamic properties of the resulting composites. Variations in the surface activity of the n‐decylaldehyde treated sepiolite leads to significant changes in the measured properties compared to those observed in the composites containing untreated sepiolite. This allows the assumption that the structure of the interface filler/polymer is modified as a function of filler activity.
Modification of polyacrylonitrile fibers with hydrazine and hydroxylamine in aqueous medium
Authors: Karaivanova S. , Badev A. 
Published: April 2003

AbstractThe interaction between polyacrylonitrile (PAN) fibers and hydrazine and/or hydroxylamine in aqueous medium was investigated. The kinetics of the reaction was studied and a step‐like effect was found, testifying to a diffusion‐controlled stage. The Michaelis‐Menten kinetics was used for the description of the initial stage of the reaction. On the basis of the results and the analytical data the mechanism of the process was discussed. By studying the basic physical and physico‐mechanical indices of the fibers it was found that the chemical modification with these bases and a subsequent processing with aqueous solutions of copper salts takes place with notable changes in structure and properties of the fibers. The results obtained lead to improved methods for the production of fibers with chemical resistance and improved fire resistance.
The reaction of sodium silicate with dichlorotetrakis(dimethylamino cyclotriphosphazene)
Authors: Kajiwara M. , Yamamoto N. 
Published: April 2003

AbstractThe reaction of sodium silicate with dichlorotetrakis(dimethylamino cyclotriphosphazene) was carried out under various experimental conditions. The products were white colored, adhesive materials and were soluble in high polar solvents. It was found that the dichlorotetrakis(dimethylamino cyclotriphosphazene) used reacted with silanol. It did not act as middle but as end group because the molecular weight of the product was not increased compared to that of the product derived from sodium silicate alone.
Calorimetric study of partially crosslinked poly(butylene terephthalate) and poly(ethylene terephthalate)
Authors: Fakirov Stoyko , Avramova Nadka , Schultz Jerold 
Published: April 2003

AbstractAn attempt is made for partial crosslinking (i.e., only in the amorphous regions) of films of poly(ethylene terephthalate) (PETP) and poly(butylene terephthalate) (PBTP) by diffusion of molten dicumyl peroxide. It is demonstrated that because of steric and structural reasons this technique is applicable only to PBTP. A series of crosslinked and non‐crosslinked samples of drawn and undrawn PBTP films annealed at various temperatures were investigated. The average crystallite sizes have been determined by wide angle X‐ray diffraction and the melting temperatures of crosslinked samples have been measured using DSC. Applying the Gibbs‐Thomson equation, the equilibrium melting temperature of PBTP is found to be Tm0 = 250 ± 4°C.
Modifizierung der integralen form der Mayo‐Lewis‐Gleichung zur berechnung der copolymerzusammensetzung bei der semikontinuierlichen polymerisation
Authors: Matějíček Alois , Horký Jaroslav 
Published: April 2003

AbstractEs werden Gleichungen für eine mathematische Simulation der mehrstufigen chargenweisen Copolymerisation zweier Monomerer vorgeschlagen. Mit Hilfe dieser Beziehungen ist es möglich, den Verlauf der Zusammensetzung der Monomerphase und des gerade entstandenen Polymeren sowie die integrale Zusammensetzung des Polymeren in Abhängigkeit vom Monomerumsatz zu berechnen. Die vorgeschlagenen Beziehungen bilden ein System von Differentialgleichungen, deren schrittweise Integration numerisch durchgeführt wird. Der vorgeschlagene Berechnungsvorgang wird an einer semikontinuierlichen Emulsionspolymerisation des Systems Styrol/Acrylnitril demonstriert. Aus den berechneten Abhängigkeiten geht die Bedingung hervor, daß nach Erreichen eines quasistationären Zustandes die Reaktionsgeschwindigkeit der Polymerisation größer sein muß als die Dosierungsgeschwindigkeit des Monomergemisches.
Chlorocarboxylation of polyethylene. I. Preparation and structure of chlorocarboxylated polyethylene
Authors: Joshi Shashikant G. , Natu Arvind A. 
Published: April 2003

AbstractChlorocarboxylated polyethylene (CCPE) is produced by simultaneous reaction of chlorine and maleic anhydride (MA) with polyethylene (PE). Low concentrations of the carboxyl groups in CCPE have been quantitatively estimated by dye interaction method and non‐aqueous titration procedure. IR spectroscopic data are presented for the structural characterization of CCPE. During chlorocarboxylation, maleic anhydride can be anchored to the backbone chlorinated PE (CPE) chain as a chlorinated single monomeric unit without forming any graft copolymer of short branches.
Chemical reactions in the bulk of the epoxy‐functional silane hydrolyzate
Authors: Xue G. , Ishida H. , Koenig J. L. 
Published: April 2003

AbstractChemical reactions in the epoxy‐functional silane hydrolyzate bulk have been studied by Fourier transform infrared spectroscopy (FT‐IR). It was found that the silanol group opened the epoxy ring upon heating, concurrently with the silanol condensation. The kinetics of these reactions were studied, and the relative reaction rates were obtained.
Propriétés viscoélastiques à l'etat fondu de matériaux composites à base de fibres de cuir et de polyéthylène basse densité ou de copolymères d'ethylène. II. Etudes en balance rhéomètre
Authors: Ayad Djamel , Genillon René , May Jean‐François 
Published: April 2003

AbstractL'étude des propriétés viscoélastiques à l'état fondu, de matériaux composites à base de fibres de cuir et de polyéthylène basse densité ou de copolymères d'éthylène, a été réalisée à la balance rhéomètre. Elle confirme les interprétations proposées, basées sur les interactions fibres‐matrice, de l'influence de la charge et de la nature de la matrice. Elle permet également de connaître les variations de la composante élastique qui joue un rôle important en transformation.
End‐groups in poly(methyl methacrylate) and polystyrene prepared by radical polymerization in the presence of derivatives of stilbene
Authors: Bevington John C. , Breuer Stephen W. , Huckerby Thomas N. 
Published: April 2003

AbstractPolymers of methyl methacrylate and styrene have been prepared in the presence of low concentrations of various para‐derivatives of stilbene, using 13C‐benzoyl peroxide as the source of the initiating radicals. Examination of the 13C‐NMR signals due to benzoate end‐groups showed that in each case a high proportion of the initiator fragments was attached to a stilbene unit. The results indicate that each of the stilbenes has very high reactivity towards the benzoyloxy radical, depending upon the nature of the substituent. Radical polymerization involving benzoyl peroxide and a stilbene provides a method for the preparation of polymers with special end‐groups.
Spaltprodukte bei der verarbeitung von phenol‐formaldehyd‐formmassen
Authors: Braun Dietrich , Wolde‐Giorgis Kashai 
Published: April 2003

AbstractBei der Verarbeitung von Phenol‐Formaldehyd‐Harzen mit Asbest und mit Holzmehl als Füllstoff entstehen neben ca. 98% Wasser niedermolekulare phenolische Spaltprodukte, die durch Dünnschichtchromatographie, Gaschromatographie und Hochdruckflüssigchromatographie isoliert und identifiziert werden. Gefunden wurden Phenol, m‐ und o‐Kresol, verschiedene Dimethylphenole sowie 2‐ und 4‐Hydroxybenzylalkohol.
Photo‐induced graft copolymerization. XV. Graft copolymerization of methyl methacrylate onto nylon‐6 using erythrosin as photoinitiator
Authors: Lenka Subasini , Mohanty Indu B. 
Published: April 2003

AbstractThe photo‐induced graft copolymerization of methyl methacrylate onto nylon‐6 was investigated using erythrosin as the photoinitiator. The systems were buffered with phosphate citrate buffer (Na2HPO4/citric acid). The graft copolymerization was carried out within the temperature range of 35–50°C and from the corresponding Arrhenius plot, the energy of activation was evaluated. The effect of monomer, initiator, ascorbic acid, etc. on the graft yield has been investigated. Further, the effect of solvent on the rate of grafting has been investigated and the chain transfer constant (Cs) of the solvent has been evaluated. The kinetic data and other events indicate that the overall polymerization takes place by a radical mechanism. A suitable mechanism has been suggested and rate expressions have been derived.
A study of polystyrene‐polyvinylmethylether blends by excimer fluorescence
Authors: Qian Renyuan , Gu Xiaohong 
Published: April 2003

AbstractStudies of interchain excimer interaction in semi‐dilute and concentrated solutions of polystyrene (PS) in a good solvent have been extended to polystyrene/polyvinylmethylether (PS/PVME) polymer‐polymer compatible blends. The constant fluorescence intensity ratio R ≡ IE/IM for blends with a PS content lower than 5 wt.‐%, which is smaller than the value of PS in a dilute solution implies a mixing of PS and PVME chain segments down to molecular level in the compatible blend. The fluorescence intensity has been found to serve as sensitive criterion for phase separation. The cloud point curve for the used PS/PVME system has been obtained showing an LCST at 113°C at ca. 20 wt.‐% PS. It was shown that the one‐phase PS/PVME system is thermodynamically stable at room temperature presumably over the entire concentration range.
Development of a polyimide resin matrix for composites
Authors: Dolui Swapan K. , Maiti Sukumar 
Published: April 2003

AbstractThe low molecular weight polyimides (PI) end‐capped with bismaleimide or amine terminated monomaleimide of six different compositions were synthesized by reacting benzophenone tetracarboxylic dianhydride, hexamethylene diamine, and maleic anhydride. These low molecular weight reactive imide prepolymers were characterized by infra‐red spectra, 1H‐NMR, elemental analysis, vapour pressure osmometry (VPO) technique, solution viscosity (0.5 g/dl in NMP), density and X‐ray measurements. With these resins carbon cloth reinforced laminates were fabricated by the hot press moulding method. These laminates were evaluated by their flexural strength, interlaminar shear strength, density, void content, and fibre content. Optimization studies in mechanical and thermal behaviour of such composites were also carried out.
Effect of moulding pressure on crystallinity in powder processing of semicrystalline polymers
Authors: Radhakrishnan S. 
Published: April 2003

AbstractThe crystalline content in high pressure compacted polymeric powders has been investigated as a function of moulding pressure. It has been noted that the crystallinity Cp varied with the pressure as [C0 — βPα] where α and β were material dependent constants. There also appears a correlation between α, β, and an empirically defined factor which is related to the glass transition temperature, melting point, and compressive yield strength for all the polymers studied. The results have been discussed in terms of various processes taking place during the high pressure compacting step.
Reaction products of polyacrylonitrile with dicyandiamide — new flocculation agents —
Authors: Gohlke Ulrich , Dietrich Klaus 
Published: April 2003

AbstractA new flocculation agent is prepared by reaction of polyacrylonitrile with dicyandiamide in alkaline solution, followed by acid hydrolysis. The polymer contains guanamine‐, N‐carbimidoyl‐N′‐cyanoguanidine‐, amido‐, hydronaphthiridine‐, and carboxylic‐groups. In consequence of the alkaline and acidic groups present, the polymer shows polyampholytic properties and can be used as a primary flocculation agent. Fields of application are removal of contaminants dispersed in water, like waste, algae, bacteria and also in some cases dissolved substances like dyes, etc. Concepts of the flocculation activity and suggestions of application are discussed.
Studies on the polymerization of methyl methacrylate using ylide as an initiator and degradative transfer agent
Authors: Shukla A. K. , Saini S. , Kumar P. , Nigam S. K. , Srivastava A. K. 
Published: April 2003

AbstractThe polymerization of methyl methacrylate (MMA) initiated by α‐picolinium‐p‐chlorophenacylide in CCl4 at 30, 35, and 40°C for four h was investigated dilatometrically. The orders of reaction with respect to the concentrations of ylide and MMA are 0.22 ± 0.01 and 1.0, respectively. The overall energy of activation and an average value of k/kt are 21.0 kJmol−1 and 0.37 ± 10−2, respectively. The results are explained in terms of radical mode of polymerization with initiator dependent transfer besides bimolecular termination.
Preparation of vinyl chloride‐ethylene copolymers by partial reduction of poly(vinyl chloride)
Authors: Braun Dietrich , Mao Weiyou , Böhringer Bertram , Garbella Rüdiger W. 
Published: April 2003

AbstractReductive dechlorination of poly(vinyl chloride) with tri‐n‐butyltin hydride was used to prepare a series of vinyl chloride‐ethylene copolymers covering the complete range of comonomer composition from poly(vinyl chloride) to polyethylene. Osmotic measurements of the molecular weight showed that polymeranalogous products were obtained by the reduction. IR spectra of the copolymers and UV‐VIS spectra of thermally degraded copolymers were utilized to verify the statistical distribution of comonomer units in the polymer. The copolymers containing more than 73 mol‐% ethylene units show appreciable melting during thermal analysis with differential scanning calorimetry. The relationship between the melting temperature and the composition of the copolymers with a high content of ethylene can be expressed by Flory's equation. The reciprocal glass transition temperatures of vinyl chloride‐ethylene copolymers with high contents of vinyl chloride units change linearly with the weight fraction of vinyl chloride in the copolymers. The influence of the composition and the glass transition temperature on the thermal dehydrochlorination is discussed.
Gloss as an inner morphology characteristic of ABS polymers
Authors: Lednický F. , Pelzbauer Z. 
Published: April 2003

AbstractThe connection between inner morphology and gloss was investigated using a series of model samples of ABS polymers processed in the same way. A relation was derived for the dependence of gloss on particle size, and a rule of mixing was suggested for the eventual gloss of a sample containing a mixture of various rubber particles. The logarithm of gloss decreases linearly with particle size; this dependence was verified also using reported data on coating films.The suitability of the characterization of inner morphology by surface gloss was illustrated using the dependence of impact strength on gloss. The cause of the correlation between the surface properties (gloss) and volume properties (inner morphology, impact strength) is seen in the influence upon the structure of the surface and subsurface layer by the material of the sample's interior.
High‐pressure polymerization of ethylene using methyl isobutyl ketone peroxide as initiator
Authors: Luft Gerhard , Henning Wolfgang , Dorn Max 
Published: April 2003

AbstractAn investigation was carried out into the suitability of methyl isobutyl ketone peroxide (MIKP) as initiator for the high pressure polymerization of ethylene. For this purpose, polymerization tests were carried out in a stirred autoclave at a pressure of 1000 to 2000 bar and a temperature of 195 to 310°C. The initiator concentration of the feed was varied between 6.5 and 42 mol ppm while the residence time was kept at a constant 30 s. Apart from the rate of polymerization, the conversion and the initiator consumption were also determined. The characteristic properties of polyethylene (PE) were determined by measuring the melt flow index, the density and, in some cases, the molecular weight distribution.Conversion levels of 5 to 27% were achieved with rates of polymerization between 1 and 5.5 kg PE l−1 h−1. The initiator consumption at 1700 bar was in the region of 1 to 2 g I kg−1 PE−1 over a temperature range of 220 to 315°C.In view of these results, MIKP can be considered as suitable to initiate ethylene high pressure polymerization at 220 to 310°C, particularly in the tubular reactor.The density of the polyethylene thus prepared is ranging between 0.910 and 0.927 g ml−1. Without the addition of modifiers or cross‐linking agents, the melt flow index varies considerably. The polydispersity of the polymers prepared at a pressure of 1700 to 2000 bar was between 6 and 8 and therefore within the range to be expected for stirred autoclaves. Reducing the pressure to 1000 bar resulted in surprisingly low polydispersity values of 2.4 to 3.7.
Chemical reactions of poly(vinyl pyridine)s with epoxy compounds
Authors: Xue G. , Ishida H. , Koenig J. L. 
Published: April 2003

AbstractChemical reactions of poly(vinyl pyridine)s and epoxy compounds were studied both in homogeneous solution and in solid state by Fourier transform infrared spectroscopy and other techniques. The pyridine side group was found to react with the epoxy group, forming networks which contain pyridone and cyclic amide structures. This reaction was observed also in the interfacial region of poly(vinyl pyridine) and γ‐glycidoxypropyltrimethoxysilane hydrolyzate coatings on poly(ethylene terephthalate) fiber substrates.