bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermoelasticity in open systems
Authors: Bleha T. , Valko L.
Published: April 2003

Thermodynamic state equations have been derived making possible to determine the temperature coefficient of unperturbed chain dimensions from thermoelastic measurements of swollen polymer in phase equilibrium with the diluent. Unlike the analysis used previously, the equations derived in the present paper include also the effect of diluent quality on unperturbed chain dimensions.
Effects of aldehyde on stereoregularity of poly(vinyl trifluoroacetate) obtained by radical polymerization
Authors: Matsuzawa Shuji , Yamaura Kazuo , Noguchi Hiroji
Published: April 2003

Vinyl trifluoroacetate was polymerized by free radicals in various aldehydes at temperatures between −40 and 60°C. The syndiotactic and isotactic diad contents of the polymer were determined through the triads obtained by NMR spectra. The differences of activation enthalpies and entropies of isotactic and syndiotactic arrangement were calculated from the temperature dependence of the ratio of isotactic and syndiotactic diads. In the case of the applied aldehydes, a compensation effect exists between the two quantities, the values of which differ from the values of alkanes, vinyl trifluoroacetate, esters and ketones. The syndiotactic diads of a polymer prepared in aldehydes at 60°C vary from 54 to 56% and are higher than those for the other solvents (50–53%), but the temperature dependence is scarcely low. We consider that the interaction between the fluor atoms in the trifluoroacetyl group of vinyl trifluoroacetate and the π‐bond in the aldehyde affect the stereoregularity.
Über die durch das system benzoylperoxid/Rh(I)‐komplex initiierte substanzpolymerisation von methylmethacrylat
Authors: Roda Jan , Hrabák Františk
Published: April 2003

Ein neues Initiierungssystem, das aus einem einkernigen Komplex von einwertigem Rhodium und Diacylperoxid bzw. Hydroperoxid besteht, wurde untersucht. Die Abhängigkeit der Polymerisationsgeschwindigkeit des Methylmethacrylats und des durchschnittlichen Polymerisationsgrades vom Molverhältnis Rhodium‐Komplexverbindung zu Peroxid, von der Temperatur und von der Viskosität des Lösungsmittels wurde bestimmt und die Taktizität der entstandenen Polymeren verfolgt. Der Mechanismus der durch das betrachtete Initiierungssystem ausgelösten Polymerisation von Methylmethacrylat wird diskutiert.
Water‐soluble polymers containing adamantylamino‐and other amino residues
Authors: Holt Paul , Thadani Chandru
Published: April 2003

Water‐soluble polymers have been prepared as potential antiviral agents (a) by the copolymerisation of N‐vinylpyrrolidone and N‐allylaminoadamantane, and (b) by the copolymerisation of N‐vinylpyrrolidone and crotonaldehyde followed by the formation of SCHIFF bases with 1‐aminoadamantane, 2‐aminopyridine, cyclohexylamine, p‐toluidine or tert‐butylamine.
High resolution NMR studies on oligo‐(oxy‐2,2‐dimethylethylenecarbonyl) compounds
Authors: Ogawa Etsuyo , Kondo Shoichi
Published: April 2003

Terminal group effects and solute‐solvent interactions of α‐(3‐hydroxy‐2,2‐dimethylpropionyl)‐ω‐isobutoxyoligo(oxy‐2,2‐dimethylethylenecarbonyl) compounds (Ia—h) and α‐dichloroacetyl‐ω‐isobutoxyoligo(oxy‐2,2‐dimethylethylenecarbonyl) compounds (II a—h) were studied using high resolution NMR technique in four solvents.

The signals of these spectra are assigned by comparing the spectra of these oligomers with the spectra of partially deuterated oligomers. The terminal hydroxyl or dichloroacetoxy group affects the chemical shifts of the methylene groups of the oligomers of type I and II. The terminal hydroxyl shows an influence on the chemical shifts up to the methylene units in the fifth monomeric unit, or up to the protons attached to the 18th carbon atom in these oligomers. It is observed that the chemical shifts of the protons depend on the temperature except for the methylene protons close to the center of the chain.
Polyanion — polycation interactions, 1
Authors: Pal M. K. , Ghosh A. K.
Published: April 2003

The interaction between the basic proteins lysozyme or ribonuclease and polyanions like chondroitin sulphate, DNA or inositol hexasulphate and also ferrocyanide was studied conductometrically and turbidometrically. In the conductometric titrations of the polyanions with basic proteins, breaks in the titration curves were obtained at the stoichiometric amounts. Additional breaks were observed at lower and higher protein concentrations with constant amounts of the polyanions. Thus, two equivalent weights, 840 and 1760, of the basic protein lysozyme were obtained. With DNA, however, only one break was obtained at a concentration higher than the stoichiometric amount, indicating that all the phosphate groups of DNA are not involved in the interaction with the proteins. Turbidometric titrations of lysozyme by the polyanions in water, in a buffer or in aqueous ethanol generally gives one break and the equivalent weight of the protein, calculated from this break, corresponds to the higher value determined conductometrically. Ribonuclease gave higher turbidity than lysozyme under identical conditions of polyanions and pH.

It is concluded that interaction between polyanion and polycation is stoichiometric only under favourable conditions. Salts initially increase the turbidity produced by a polyanion/polycation interaction followed by a progressive decrease; in this respect bivalent cations are more effective than monovalent cations.
Der asynchrone zerfall einiger arylazomalodinitrile. 2. Mitteilung über azo‐initiatoren
Authors: Kerber Robert , Nuyken Oskar , Pasupathy Vinayagar
Published: April 2003

Der thermische Zerfall der unsymmetrischen Arylazomalodinitrile p‐Methoxyphenylazomethylmalonsäuredinitril (I) und 2,6‐Dimethylphenylazomethylmalonsäuredinitril (II) erfolgt nach 1. Ordnung. Geschwindigkeitskonstanten für den Zerfall bei verschiedenen Temperaturen sowie in verschiedenen Lösungsmitteln werden angegeben. Die Temperaturabhängigkeiten der Zerfallsgeschwindigkeit der Azoverbindungen I und II in 1,2‐Dichlorbenzol werden durch folgende Gleichungen beschrieben:

Die Massenspektren der Azoverbindungen I und II sowie die Zersetzungsprodukte von I in 1,2‐Dichlorbenzol beweisen das asynchrone Öffnen der C–N‐Bindungen der C–NN–C‐Gruppe. Auf der Grundlage von isolierten und identifizierten Folgeprodukten wird ein Reaktionsschema aufgestellt.
Momente und verteilungsfunktionen der segmentabstände vom schwerpunkt bei ungestörten polymerketten
Authors: Bruns Wolfgang
Published: April 2003

Für das ungestörte Perlenkettenmodell werden die exakten Momente der Verteilung der Segmente um den Schwerpunkt sowie die zugehörige Wahrscheinlichkeitsdichte abgeleitet. Die für jede Bindungszahl gültigen Ausdrücke werden mit den schon bekannten asymptotischen Formen verglichen und die Unterschiede diskutiert.
Syntheses and condensation polymerizations of N‐(2′,3′‐dihydroxypropyl) derivatives of 5‐halogenouracils, thymine, 6‐methylthiopurine, and adenine 1‐oxide
Authors: Seita Toru , Takahashi Kenji , Kinoshita Masayoshi , Imoto Minoru
Published: April 2003

5‐Chloro‐1‐(2′,3′‐dihydroxypropyl)‐uracil (1a), 9‐(2′,3′‐dihydroxypropyl)adenine‐1‐oxide (7), 9‐ and 3‐(2′,3′‐dihydroxypropyl)‐6‐methylthiopurine (4 and 5) were synthesized. Condensation polymerization of these compounds and other nucleoside analogues with phenoxy‐phosphoryl dichloride or dicarboxylic acids were carried out. All obtained oligomers 9 and 11 are very soluble in water and were found to have rel. mol. masses between 800 and 1300 according to vapor pressure osmometry mesurements.
Kinetik und molekulargewichtsverteilung eines anionischen polymerisationsprozesses mit momentanem start bei simultanem monomerabbruch
Authors: Löhr Gernot
Published: April 2003

Die Kinetik und die Molekulargewichtsverteilung wird für einen anionischen Polymerisationsprozeß mit einem momentanen Startschritt und mit simultanem Monomerabbruch berechnet. Ein derartiger Polymerisationsablauf ist bei der anionischen Polymerisation von Methylmethacrylat in polaren Lösungsmitteln zu erwarten. — Die Molekulargewichtsverteilung geht mit steigendem Monomerabbruch in eine SCHULZ‐FLORY‐Verteilung über.
Über die polymerisation von 2,5‐dioxo‐1,3‐oxathiolan und 2,4‐dioxo‐1,3‐dithiolan
Authors: Kricheldorf Hans R. , Bösinger Klaus
Published: April 2003

Die Polymerisation von 2,5‐Dioxo‐1,3‐oxathiolan (1a) mit verschiedenen tertiären Aminen wird untersucht. Die Wirksamkeit der Katalysatoren hängt ausschließlich von ihrer Basizität ab. Eine CH‐Deprotonierung beim Monomeren wird als Startreaktion, eine anionisch ringöffnende Polymerisation als Wachstumsreaktion diskutiert. Sowohl bei der Polymerisation von 1a als auch von 2,5‐Dioxo‐1,3‐dithiolan (2a) hat der Wassergehalt des Lösungsmittels oder die Anwesenheit anderer Protonendonatoren einen starken negativen Einfluß auf Ausbeute und rel. mol. Masse des resultierenden Polyesters, während elektrophile Reagenzien wie Alkyl‐ oder Säurehalogenide eine geringere Wirkung zeigen. Unter vergleichbaren Bedingungen polymerisiert 2a wesentlich schneller als 1a und liefert auch Polyester mit wesentlich höheren rel. mol. Massen (bis 112000).
Functional monomers and polymers, 15. On the synthesis and reactivity of functional vinyl polymers, containing 2,4‐dioxo‐3H,10H‐benzo[h]pteridine‐10‐yl (10‐isoalloxazinyl) residues
Authors: Kondo Koichi , Fujita Takashi , Takemoto Kiichi
Published: April 2003

As a functional vinyl monomer containing the 10‐isoalloxazinyl (2,4‐dioxo‐3H,10H‐benzo[h]pteridin‐10‐yl) residue, 10‐(2′‐methacryloyloxyethyl)‐3H,10H‐benzo[h]pteridine‐2,4‐dione (2) was prepared by reacting 10‐(2′‐hydroxyethyl)‐3 H,10H‐benzo[h]pteridine‐2,4‐dione (1) with methacryloyl chloride in hexamethyl phosphoric acid triamide solution. Polymerization and copolymerization of the monomer were carried out by 2,2′‐azoisobutyronitrile. Alternatively, vinyl‐type polymers containing the isoalloxazine system (3) were also prepared by a polymer‐analogous reaction. Dehydrogenation reaction of methylmandelate was studied with a copolymer in dimethylformamide solution.
Séparation d'un copolymère greffé de l'homopolymère correspondant par la méthode des gels réversibles, 1. Introduction et principe de la méthode — formation de gels réversibles
Authors: Llauro‐Darricades Marie‐France , Banderet Albert , Riess Gérard
Published: April 2003

Une nouvelle technique, basée sur la formation de gels réversibles, est proposée pour la séparation d'un copolymère greffé de l'homopolymère correspondant aux greffons. La mise au point de la méthode a été faite en vue de son application aux résines ABS.

On montre ainsi que si le tronc porteur des greffons (polybutadiène) a été muni de groupes COOH, une réticulation réversible peut être obtenue par association dipolaire des groupes COOH salifiés (p. ex. par CH3ONa). A partir d'un tel polymère, en solution dans un mélange de solvant apolaire et d'un solvatant (CH3OH) des associats COONa, on provoque la gélification par élimination du solvatant. Cette réticulation par association entre dipoles COONa permet l'insolubilisation presque totale du polymère carboxylé.

Une nouvelle addition de solvatant provoque la dissolution de la phase gel.

Le mélange benzène/CH3OH a été choisi pour effectuer les cycles gélification‐dégélification, le méthanol pouvant être éliminé aisément par distillation azéotropique à température ordinaire.

Les conditions optimales de formation du gel réversible ont pu être définies.

Cette technique de séparation sol‐gel peut être transposée aux copolymères greffés, en vue de leur purification.
Polyamides from trans‐2,5‐dimethylpiperazine and determination of their moisture absorbency
Authors: Iriyama Keiji , Nihongi Tokihiro , Yamaguchi Takashi , Okada Akira
Published: April 2003

The moisture absorbency (m) and the syntheses of polyamides by condensation of trans‐2,5‐dimethylpiperazine and/or hexamethylenediamine with adipic acid and/or benzene‐1,3,5‐tricarboxylic (trimesic) acid were studied. It was found that a high m‐value of 24,2 was obtained in the case of the ratio (2/3 trimesic acid)/adipic acid = 0,1 and a decrease of m with an increasing mole ratio of trans‐2,5‐dimethylpiperazine/hexamethylenediamine.
Novel polycations containing nucleic acid bases, 1. Syntheses and interactions in solution with polynucleotides and with related compounds
Authors: Okubo Tsuneo , Ban Kazuki , Ise Norio
Published: April 2003

Cationic model compounds of polynucleotide, i.e., poly{1‐[2‐(adenin‐9‐yl)ethyl]‐4‐pyridinioethylene chloride} (1), poly{1‐[2‐(thymin‐1‐yl)ethyl]‐4‐pyridinioethylene chloride} (2), and poly{1‐[2‐(theophillin‐7‐yl)ethyl]‐4‐pyridinioethylene chloride} (3), were synthesized by the MENSCHUTKIN reaction of poly(4‐pyridylethylene) with 9‐(2‐chloroethyl)adenine, 1‐(2‐chloroethyl)thymine and 7‐(2‐chloroethyl)theophylline.

The interactions between the model compounds and polynucleotides and between the model compounds themselves were studied by spectroscopy. The apparent hypochromicity was about 20% for the mixture of 1‐Poly A, 15% for that of 1‐DNA and 11% for the 1–3 mixture. The systems 1–2 and 2–3 showed rather small hypochromicities, being 8 and 6%, respectively. The hydrogen bond formation between complimentary bases is not a main factor in the intermolecular interactions in the present cases, but the hydrophobic interactions are suggested to be overwhelming. The UV absorbance of 1–2 or 2–3 mixtures decreased with increasing temperature, confirming the important rǒle of the hydrophobic interactions.
Studies on the polymerization of vinyl compounds in the presence of metal salts, 9. On the initiation mechanism of polymerization of acrylamide by ceric salt
Authors: Narita Hiroshi , Okimoto Tomoyuki , Machida Seishi
Published: April 2003

In order to elucidate the initiation mechanism of the polymerization of acrylamide by ceric salt, the complexation of ceric salt with acrylamide and its methylated derivatives was investigated by IR and NMR spectrometry. The decomposition of the complex was also studied by determining the rate of ceric salt consumption. From the results it was concluded that the oxygen of acrylamide coordinates with the ceric ion to form the complex and that a radical is produced by abstraction of a hydrogen atom from the amide group of the molecule to initiate the polymerization.
Electrostatic effect on electron‐transfer reactions of cobalt(III)‐poly(4‐vinylpyridine) complexes
Authors: Tsuchida Eishun , Karino Yukio , Nishide Hiroyuki , Kurimura Yoshimi
Published: April 2003

Reductions of cis‐[Co(en)2PVPCl]2+ (1) [PVP = poly(4‐vinylpyridine)] by ferrous aquoions and ferrous chelate ions were studied. The rate of reduction by Fe2+ is small compared to that of the monomeric analogue, cis‐chlorobis(ethylenediamine)pyridine cobalt(2+) (cis‐[Co(en)2PyCl]2+) due to the electrostatic repulsion. On the other hand, the reduction by [Fe‐(edta)]2− is accelerated by a factor of 20. With increasing degree of coordination the acceleration factor increases, and with increasing ionic strength the factor decreases. The acceleration was found to be due to the electrostatic attraction of the reductant by the polymer as a polycation. The electrostatic effect is discussed in comparison with the catalysis of polyelectrolytes in ionic reactions.
Mechanical denaturation of high polymers in solutions, 32. effect of flow pattern on shearing stress‐induced crystallization of poly(vinyl alcohol) from its aqueous solution
Authors: Yamaura Kazuo , Karaki Takao , Matsuzawa Shuji
Published: April 2003

The crystallization of poly(vinyl alcohol) (PVA) from an aqueous solution was carried out under a steady‐state flow. The fibrillar crystals occur just under the surface of the solution after a few seconds of stirring and they grow gradually. The fibrillar crystals are produced even from a 0,05% solution. The process of crystallization of PVA under steady‐state flow was classified in seven types. The rate of precipitation increases with decreasing distance between the surface of a cylindrical stirrer and the wall of a test tube or with the diameter of the stirrer.
Size and orientation of cristallites in lightly cross‐linked polyethylene, crystallized from the melt under uniaxial compression
Authors: Kitamaru Ryozo , Hyon Suong Hyu
Published: April 2003

If lightly cross‐linked polyethylene films are crystallized from the melt under uniaxial compression, a very unique alignment of the molecular chains in the crystalline phase of the samples appears. The orientation of crystallites in which the (200) crystal plane is located parallel to the film surface first appears at a relatively low degree of compression, and subsequently the orientation in which the (110) crystal plane is located parallel to the film surface follows at higher degrees of compression.

Despite the fact that the samples were crystallized from the melt rather rapidly, the unitcell density of the crystalline phase was very close to unity and the size of crystallites was very large. The dimensions of crystallites in the direction perpendicular to the film surface were in a range of 170—350 Å but they were as large as more than 1500 Å in the direction parallel to the film surface. Thus it is confirmed in addition by electron microscopic observation that these samples have a new type of lamellar structure in which the molecular alignments are quite different from those for the so‐called lamellar structure for polyethylene crystallized under isotropic conditions.
Formation, properties and structures of bis (o‐hydroxybenzylideneamine)copper(II) chelates of polypeptide ligands
Authors: Dentini Mariella , de Santis Pasquale , Savino Maria , Verdini Antonio
Published: April 2003

Formation, optical properties and structures of bis(o‐hydroxybenzylideneamine)copper(II) chelates of poly(L‐lysine), poly(L‐ornithine), and poly(L‐α,β‐diaminobutyric acid) were investigated.

Experimental evidence was obtained for a definite structure of these polycomplexes in alcoholic/aqueous solution. Structural features showed that asymmetric polypeptide matrices bind metal chelates stereospecifically. On the basis of these results stereoselective reactions on bis(o‐hydroxybenzylideneamine)copper(II) polycomplexes are expected.
Icosahedral carboranes, 20. Polymerization and crosslinking mechanism of poly(m‐carboranylene‐siloxane)s
Authors: Dietrich Heinz. J. , Alexander R. P. , Heying Theodore L. , Kwasnik Herbert , Obenland Clayton O. , Schroeder Hansjürgen A.
Published: April 2003

The FeCl3 catalyzed bulk polymerization of a 1,7‐bis(methoxysilyl)‐1,7‐dicarba‐closo‐dodecaborane (12) (m‐carborane) (2) and a dichlorosilane resulting in a poly(m‐carboranylene‐siloxane) raw gum (1b, DEXSIL 200®) was found to occur in three distinct parts: First, the low temperature polymerization stage which includes end group exchange and the subsequent formation of poly(oxydimethylsilanediyl)s, second, the high temperature polymerization stage in which equilibration between the carboborane containing monomers and the polysiloxane occurs to produce polymeric material approximating 1b in composition, and third, the foaming stage in which the polymer chains are crosslinked to provide insoluble raw gum.
Studies on intramolecular association of salt groups in polymers following their binding with a metachromatic dye
Authors: Guhaniyogi Suhas C. , Mandal Broja M.
Published: April 2003

Intramolecular association in dilute solution between carboxylate groups present at the ends of a polymer molecule was studied with reference to the effect of solvent and chain length of the polymers. The interaction was followed from the spectral change of a cationic metachromatic dye, pinacyanol (1), bound to the carboxylic groups of α,ω‐poly(butadiene dicarboxylic acid)s and α,ω‐poly(styrene dicarboxylic acid)s. It was found, as expected, that the extent of association decreases with the increase in polymer chain length and the increase in solvent polarity. Evidence was presented for the fact that in case of short chain polymeric dicarboxylic acids in benzene bis‐dye salt formation occurs to a considerable extent, even if less than 50% of the carboxylic groups are converted to the dye salt.
The effect of chain length on the solid‐state polymerization of N‐alkylmaleimides
Authors: O'Donnell James H. , Sothman Robert D.
Published: April 2003

N‐alkylmaleimides from the N‐methyl to the N‐octadecyl derivative were polymerized in the solid state by γ‐radiation. Polymerization during irradiation generally showed sigmoidal conversion curves with high rates and complete conversion 10°C below the melting point. Post‐irradiation rates were lower and showed the typical approach to a “limiting” conversion. The polymerization rates increased with temperature and radiation dose and with the length of the alkyl chain. N‐methylmaleimide had a high rate of in‐source polymerization which was attributed to the volatility of the monomer.
Cristallisation de poly(oxyéthylène)s segmentés
Authors: Galin Jean‐Claude , Spegt Pierre , Suzuki Sunichi , Skoulios Antoine
Published: April 2003

On a étudié par analyse enthalpique différentielle, dilatométrie et diffraction des rayons X aux petits angles deux séries homologues de poly(oxyéthylène)s segmentés, comportant de 1 à 4 segments et obtenus par condensation de deux α,ω‐dihydroxy poly(oxyéthylène)s de masse moléculaire 2750 et 10600 respectivement sur du diisocyanate‐2,4 de toluène.

On a montré que la structure de ces polymères est lamellaire, comme pour les poly(oxyéthylène)s ordinaires. Que le taux de cristallinité et la température de fusion diminuent sensiblement à mesure que le degré de condensation augmente. Que l'épaisseur des lamelles des polymères bisegmentés varie beaucoup, et de manière discontinue, avec la température de Cristallisation, comme pour les poly(oxyéthylène)s faiblement polydispersés, ordinaires. Et qu'en revanche cette épaisseur varie peu, ou pas du tout, avec la température de Cristallisation pour les polymères tri‐ et tétrasegmentés.

On a conclu que ce comportement est dǔ au blocage structural exercé par les fonctions diuréthane lors du processus de recuit. Exclues des domaines cristallins, ces fonctions jouent le měme rǒle que les extrémités des chaǐnes des poly(oxyéthylène)s ordinaries.
Persistent problems and recent progress in the field of cationic polymerization
Authors: Sigwalt Pierre
Published: April 2003

Some of the most important unsolved problems of cationic polymerizations are reviewed together with the most significant progress made recently.

In the field of initiation reactions, there are more and more data showing that initiation of ethylenic monomers by Friedel Crafts catalysts does not always necessitate a coinitiator. The different hypotheses already put forward to explain these “direct initiations” are discussed and a new mechanism is proposed. The mechanisms of termination and transfer reactions are also examined.

Concerning the mechanisms of propagation reactions, the difficulties in determining the concentration of active centers are outlined. Some progress was made by using stable carbocations as initiators, but some discrepancies between the results are discussed (existence of apparently negative activation energies). The different types of active species in equilibrium are examined, together with the nature of the non dissociated species. The differences between the propagation rate constants over free ions, measured in systems initiated by high energy radiations or more classical cationic initiators, are also discussed.
Electric field effects and electroinitiation in cationic polymerizations
Authors: Giusti Paolo
Published: April 2003

The results obtained by various authors in the study of cationic polymerizations carried out in the presence of an electric field of high strength, that we propose to call “electro‐influenced polymerizations”, are shortly reviewed.

The most relevant results obtained in the author's laboratories, for the “electroinfluenced” cationic polymerization of anethole, isobutyl vinyl ether and cyclohexyl vinyl ether with constant or periodically reversed field polarity are illustrated.

The analogies between these results and those obtained from studies on electroinitiated cationic polymerizations of various vinyl monomers with tetraalkylammonium perchlorates, tetraalkylammonium iodides or tetraalkylammonium triiodides are emphasized.

On the basis of these analogies, we interpret the increase of the polymerization rate which is observed in some cases when a d.c. field is applied to a cationically polymerizing system as being due to electrodic processes, namely the anodic generation of new active centres through electrolysis of the counterions. This new interpretation can be formalized in a mathematical model which fits most of the experimental results so far obtained for electro‐influenced cationic polymerizations initiated by iodine.
Organometallic polymers, 28 Condensation polymerization of cobalticinium salts
Authors: Pittman C. U. , Ayers O. E. , Suryanarayanan B. , McManus S. P. , Sheats J. E.
Published: April 2003

Ionic polyesters of fairly low molecular weights were prepared by melt phase polytransesterification of 1,1′‐bis(carbethoxy)cobalticinium hexafluorophosphate (1a) and diols such as 1,10‐decanediol and 1,4‐bis(hydroxymethyl)benzene. Attempts to prepare polyamides by melt condensation from alkylene diammonium salts of 1,1′‐bis(carboxy)cobalticinium hexafluorophosphate 5a–d resulted in extensive decomposition, and pure polyamides could not be obtained. The polyesters were characterized by analyses, IR spectroscopy, gel permeation chromatography, and differential scanning calorimetry.
Chain transfer reaction of azoisobutyronitrile during polymerization of methyl methacrylate at 60°C
Authors: Ayrey Geoffrey , Haynes Alan C.
Published: April 2003

The kinetics of methyl methacrylate polymerization initiated by 14C labelled 2,2′‐azoisobutyronitrile at 60°C was re‐examined and the chain transfer constant of the initiator, CI, calculated to be approximately 2.10−2.
Hemicelluloses fractionation
Authors: Uglea C. V.
Published: April 2003

The solution properties of the hemicelluloses obtained from Phragmites communis and Arundo donax were investigated. The presented experimental data led to the conclusion that the molecular weight distribution of hemicelluloses depends on the studied product. The parallel existence of the chemical inhomogeneity and the molecular weight distribution determine the bimodal aspect of differential distribution curves obtained by fractionation.
Enzymes immobilisées, 6. Préparation d'invertase et de glucose oxydase immobilisées sur les vanacryls
Authors: Brown Erich , Joyeau Roger
Published: April 2003

De nouveaux polyaldéhydes, le vanacryl et les convanacryls (polyméthacrylate de vanilline et copolymères d'alcool allylique et de méthacrylate de vanilline, respectivement) ont été utilisés comme supports pour immobiliser l'invertase et la glucose oxydase. Les paramètres de la réaction d'immobilisation et les propriétés de l'enzyme immobilisée (activité en fonction du pH, km apparent, stabilité au cours du temps, utilisation intermittente et utilisation en continu sur colonne) ont été étudiées.
High 1,4‐cis‐polybutadiene by uranium catalysts, 2. Bulk and solution crystallization of polymers
Authors: De Chirico Aurelio , Lanzani Primo C. , Raggi Ernestina , Bruzzone Mario
Published: April 2003

Bulk isothermal crystallization kinetics of some highly tactic 1,4‐cis‐polybutadienes obtained with a new catalyst based on uranium derivatives were dilatometrically measured over a crystallization temperature (Tc) range from −30 to 0°C.

The corresponding experimental melting temperatures (T) of uranium polybutadiene range from 3 to 12,5°C. A relationship between the isothermal bulk half‐crystallization time (t1/2) at −10°C and the molecular weight (MW) has been obtained.

High MW fractions crystallize faster than low MW fractions as previously reported for 1,4‐cis‐polyisoprene. Uranium polybutadiene has been fractionated by crystallization. by cooling and stirring a dilute toluene solution. Under the same experimental conditions + rubber does not crystallize.
Decomposition, initiation, and chain transfer mechanism of dibenzoyldisulfane
Authors: Kondo Shuji , Tsuda Kazuichi
Published: April 2003

In order to understand the decomposition, initiation, and chain transfer mechanism of dibenzoyldisulfane (2), it was thermally and photochemically decomposed in cyclohexene Mechanistic proposals are made based on the primary reaction products. A comparison of the decomposition of 2 with that of benzoyl peroxide was also made, and it was found that the reaction mechanisms are different.
Untersuchungen zur friesschen verschiebung an hydroxybenzylphenol‐derivaten
Authors: Evers Heinz , Niemann Wilhelm , Böhmer Volker , Kämmerer Hermann
Published: April 2003

An den Acetaten 2a–c, 3b, 4b und 4d von sechs Hydroxybenzylphenol‐Derivaten wurde die Friessche Verschiebung mit AlCl3 als Katalysator in Nitrobenzol bei Temperaturen zwischen 40 und 70°C durchgeführt. Neben den zu erwartenden Hauptprodukten der Friesschen Verschiebung konnte durch Säulenchromatographie eine Reihe von Zwischen‐ und Nebenprodukten isoliert werden. Daraus ging hervor, daß wahrscheinlich eine teilweise Verseifung der Acetate als Nebenreaktion stattfindet. Eine Wanderung der Acetylgruppe an den benachbarten Phenolbaustein des gleichen Moleküls konnte nicht beobachtet werden. Sämtliche Verbindungen, einschließlich der Ausgangsprodukte, wurden durch ihre IR‐ und 1H‐NMR‐Spektren charakterisiert.
Untersuchungen von polymeren im massenspektrometer, 4. Abbaureaktionen von polybenzylen
Authors: Lenz Robert W. , Lüderwald Ingo , Montaudo Giorgio , Przybylski Michael , Ringsdorf Helmut
Published: April 2003

Die Abbaureaktionen von unsubstituierten Poly(1,4‐phenylenmethylen)en (A) (Polybenzylen), Poly[(2,5‐dimethyl‐1,4‐phenylen)methylen] [Poly(2,5‐dimethylbenzyl)] (B), Poly[(2,3,5,6‐tetramethyl‐1,4‐phenylen)methylen] [Poly(2,3,5,6‐tetramethylbenzyl)] (C) und Poly(1,4‐phenylenäthyliden) [Poly(α‐methylbenzyl)] (D) wurden durch direkte Pyrolyse im Massenspektrometer untersucht. Die Massenpyrogramme von unter verschiedenen Reaktionsbedingungen dargestellten Polybenzylen wurden verglichen, mit dem Ziel, direkt Informationen über Strukturunterschiede wie Kettenverzweigung und unterschiedliche Verknüpfung der Benzyleinheiten zu erhalten; hierbei konnten in einem Falle auf höhere Kettenverzweigung deutende Bruchstücke nachgewiesen werden.

Der thermische Abbau der unsubstituierten Polybenzyle und des Poly(2,5‐dimethylben‐zy1)s verläuft uberwiegend unter Disproportionierung und Übertragung von Wasserstoff der Methylengruppen. Es werden bei diesen Polymeren monomere und oligomere Pyroly‐sebruchstücke mit gesättigten (Phenyl‐, Alkyl‐) und ungesättigten (Chinonmethid‐) Endgruppen gefunden, während beim Poly(α‐methylbenzyl) auch Bruchstiicke mit Vinyl‐End‐gruppen auftreten.

Das Abbauverhalten des Poly(2,3,5,6‐tetramethylbenzyl)s unterscheidet sich aufgrund der sterischen Spannung durch die Kernsubstituenten erheblich von den anderen Polybenzylen; neben geringerer thermischer Stabilität werden Hinweise auf einen unterschiedlichen Abbaumechanismus gefunden.

Die elektronenstoßinduzierte Fragmentierung der ionisierten Pyrolysebruchstucke verläuft überwiegend unter “α‐Benzyl‐”, “β‐Benzyl”‐, “Alkylspaltung” und ortho‐ Umlagerung.
Photolysis of poly(methyl acrylate) in solution
Authors: Grassie Norman , Davis Thomas I.
Published: April 2003

Solutions of poly(methyl acrylate) in methyl acetate, chloroform, methylene dichloride and benzene have been irradiated by 2 537 Å radiation and changes in number average molecular weight measured. The effect of time of irradiation, solvent, polymer concentration and the presence of radical initiator have been investigated and it is concluded that the scission results from random absorption of radiation directly by the polymer without direct participation by the solvent which acts only as an optical filter.
Untersuchungen zum oxidativen Abbau nativer Cellulose, 2. Einfluß der Alkalibehandlung auf die Viskositäts‐Molekulargewichts‐Beziehungen
Authors: Palma A. , Schulz G. V.
Published: April 2003

Um die Kinetik des oxidativen Abbaus nativer Cellulose viskosimetrisch verfolgen zu können, müssen neue [η]‐M‐Eichbeziehungen aufgestellt werden, da die Behandlung der Cellulose mit konzentriertem Alkali den Staudingerindex [η] erniedrigt, ohne das Molekulargewicht M zu verändern. Es wurden zwei Reihen oxidativ abgebauter, verschieden lange mit Alkali vorbehandelter Cellulosen hergestellt und an diesen die Konstanten der Kuhn‐Mark‐Houwink‐Gleichung für die Cellulosenitrate in Aceton und die Cellulosen in Cuoxam (Cu(NH3)4(OH)2) durch Vergleich mit Lichtstreuungsmessungen bestimmt.
Modélisation de l'homopolymérisation radicalaire à l'aide de la théorie des chaînes de Markov
Authors: Pflugfelder Bernard , Manzato Franck
Published: April 2003

A l'aide des concepts de la théorie des chaînes de Markov il a été possible de construire un modèle d'homopolymérisation. Ce modèle dépend de six paramètres et décrit une homopolymérisation en masse en y incluant les mécanismes de terminaison des chaînes (couplage et disproportion) ainsi que le transfert sur monomère.

Cette modélisation, suivant les valeurs des paramètres, est capable de représenter des polymérisations pouvant avoir des indices de polydispersité supérieurs à deux, et saffranchit ainsi des contraintes habituelles.
The application of the molecular probes gas‐chromatographic technique to the study of polypropylene transitions
Authors: Galassi Silvana , Audisio Guido
Published: April 2003

By means of molecular probes gas‐chromatographic technique we have investigated the first and second order transitions of three stereoisomeric polypropylenes: isotactic, syndiotactic, atactic. The choice of the molecular probe for the detection of the first order transition is not particularly difficult. For the 2nd order transition one must choose a molecular probe which, at the transition temperature range, has a appropriate solvent action on the polymer, used as stationary phase: thus, at low temperatures and for hydrocarbon polymers, a suitable molecular probe is a solvent for the polymer and, at high temperatures, a molecular probe is one with limited solvent action and with no specific interactions with the polymer.
Ring‐Opening polymerization of cycloolefins with catalysts derived from ruthenium and iridium
Authors: Porri Lido , Rossi Renzo , Diversi Pietro , Lucherini Antonio
Published: April 2003

An investigation was carried out on the polymerization of norbornene, cyclopentene and cyclooctene by the following iridium and ruthenium compounds: chlorobis(cyclooctene)iridium (1), carbonylchlorobis(cyclooctene)iridium (2), trifluoroacetatobis(cyclooctene)iridium (3), chloroiridic(IV) acid (4), dichloro(2,7‐dimethylocta‐2,6‐diene‐1,8‐diyl)‐ruthenium (5a), and bis(trifluoroacetato)‐(2,7‐dimethylocta‐2,6‐diene‐1,8‐diyl)ruthenium (5b). All the above catalysts were found to be very active for the polymerization of norbornene via ring‐opening. Iridium catalysts were practically inactive for the polymerization of cyclopentene and cyclooctene, but gave copolymers of norbornene with cyclopentene and cyclooctene via ring‐opening. The ruthenium catalysts displayed no activity for the polymerization of cyclopentene and cyclooctene, but it was found that after treatment with H2 they became active for the polymerization of cyclopentene. The results obtained from the reaction of norbornene and aliphatic olefins suggest that the above catalysts act by metathesis. The particular features of these catalysts were examined.
Synthesis and viscosity behavior of poly(γ‐p‐biphenylmethyl‐L‐glutamate) in benzene/dichloroacetic acid mixtures, a comparison with poly(γ‐benzyl‐L‐glutamate)
Authors: Feijen Jan , Sederel Wim L. , de Groot Klaas , de Visser Anthonie C. , Bantjes Adriaan
Published: April 2003

The synthesis of poly(γ‐p‐biphenylmethyl‐L‐glutamate), PBPLG, (poly{L‐imino‐1‐[2‐(4‐biphenylylmethoxycarbonyl)ethyl]‐2‐oxoethylene}), (1d) is described. The viscosity behavior of this polymer in benzene/dichloroacetic acid mixtures (c=0,2.10—3—1,4.10—3 g/cm3) at 25°CC is investigated. The results are compared with measurements on poly(γ‐benzyl‐L‐glutamate), PBLG, (poly[L‐imino‐1‐(2‐benzyloxycarbonylethyl)‐2‐oxoethylene]), (1c) under the same conditions. A transition from a rigid hydrogen bonded helix to a random solvated coil occurs in two stages for both: PBPLG (first stage 0—55%, second stage 55—100% dichloroacetic acid) and PBLG (first stage 0—70%, second stage 70—100% dichloroacetic acid).

Therefore, the introduction of a p‐phenyl substituent in PBLG leads to a less stable helix in benzene/dichloroacetic acid mixtures.

The stability and viscosity behavior of PBLG in benzene/dichloroacetic acid mixtures (c=0,2.10—3—1,4.10—3g/cm3) is quite similar to the behavior of PBLG in m‐cresol/dichloroacetic acid mixtures (c=1,0.10—3—4,0.10—3 g/cm3).
Polymerisationskinetische und konduktometrische messungen an polystyrylionenpaaren in einem größeren temperaturbereich
Authors: Schmitt B. J. , Schulz G. V.
Published: April 2003

Messungen der Bruttogeschwindigkeitskonstante von Polystyryl‐Natrium in 3‐Methyltetrahydrofuran (3‐Me‐THF) in Abhängigkeit von der Konzentration der “lebenden” Kettenenden und der Natriumionen ergeben, daß die Monomeraddition wie in anderen polaren Lösungsmitteln nach einem Mehrwegmechanismus erfolgt. Der Übergang vom Kontakt‐ zum solvatgetrennten Ionenpaar wird in einem Temperaturbereich von — 110 bis +85°CC mit Hilfe kinetischer Messungen im Strömungsrohr und durch Leitf ähigkeitsmessungen verfolgt. Analog zu entsprechenden Untersuchungen in Tetrahydrofuran kann dabei die Polymerisation über jeweils eine Art von Ionenpaaren fast vollständig isoliert beobachtet werden. Die thermodynamischen und kinetischen Parameter der Polymerisation werden mitgeteilt.
Modellrechnungen zur Lösungsmittel‐ und Polymerenabhängigkeit der thermodynamischen Eigenschaften von Polymerlösungen
Authors: Lechner Manfred D.
Published: April 2003

Umfangreiche Messungen an Polymerlösungen haben gezeigt, daß eine deutliche Korrelation zwischen chemischem Potential, Entropie und Enthalpie besteht. Es wurden verschiedene Modelle (quasi‐chemische Näherung, Theorie der 1‐2 Kopplung, Theorem der übereinstimmenden Zustände u. a.) durchgerechnet und mit den experimentellen Werten verglichen. Hierbei ergab sich, daß das Theorem der übereinstimmenden Zustände den breitesten Anwendungsbereich hat, wohingegen die anderen Theorien für spezielle Probleme brauchbare Resultate liefern.
Der Ablauf der Rekristallisation in verstreckten Polyäthylenfilmen
Authors: Cayrol Bertrand , Kubát Josef , Petermann Jürgen
Published: April 2003

Das Gefüge und die Orientierungen von kalt‐ und warmverstreckten Polyäthylenfilmen werden in Abhängigkeit von der Temperzeit mittels Transmissionselektronenmikroskopie untersucht. Die Kristallitlänge (Dimension senkrecht zur Molekülrichtung) wächst stetig von ca. 100 Å direkt nach der Kaltverformung auf 3000 Å nach einer Temperzeit von 8 Wochen bei 122°C an. Die Orientierung der Filme ändert sich während des Temperns von einer Fasertextur über eine b‐Textur zu einer (110)‐Textur. In warmverstreckten Filmen ist die Kristallitlänge nach der Verformung ca. 500 Å und wächst dann mit ähnlicher Geschwindigkeit wie bei kaltverstreckten Filmen. Im Unterschied zu den kaltverstreckten Filmen tritt die b‐Textur direkt nach der Verformung auf und geht in eine (110)‐Textur über. Diese Beobachtungen werden mit Hilfe der Rekristallisation gedeutet.
Studies on hydrolysis reaction of model substances of cellulose in the presence of polymer catalysts, 1. Hydrolysis reaction of dextrin in the presence of poly(vinylalcohol‐co‐vinylsulfonic acid)
Authors: Arai Kenichiro , Ise Norio
Published: April 2003

The hydrolysis of dextrin was studied in the presence of poly(vinyl alcohol‐co‐vinylsulfonic acid). The reaction was slightly accelerated by the copolymer in comparison with sulfuric acid. Mixtures of poly(vinyl alcohol) and poly(vinylsulfonic acid) retarded the reaction. Although the reaction rates tended to increase with decreasing molecular weight of the substrate, the reaction rates in the presence of the copolymer were always larger than in the case of sulfuric acid at the same molecular weight of the substrate. Both the enthalpy and entropy of activation in the presence of the copolymer were smaller than those for sulfuric acid or ethanesulfonic acid; the acceleration observed was due to the decrease of ΔH≠ as was noted earlier for a variety of reactions in the presence of polyelectrolytes. All of these activation parameters satisfied well the isokinetic relationship, indicating that the reaction mechanism was not changed by the presence of the copolymer.
Kinetics of 1,3,5‐trioxacycloheptane formation in the electro‐initiated copolymerization of 1,3‐dioxolane with trioxane
Authors: Mengoli Giuliano , Furlanetto Ferdinando
Published: April 2003

The kinetics of 1,3,5‐trioxacycloheptane (1,3,5‐trioxepane) formation in the electroinitiated copolymerization of 1,3‐dioxolane with trioxane was investigated, using 1,2‐dichloroethane as solvent and tetrabutylammonium perchlorate as background electrolyte. It was found that at temperatures between 50 and 70°C 1,3,5‐trioxepane is the main product of 1,3‐dioxolane/trioxane interaction till it reaches an equilibrium concentration in the system and that afterwards 1,3,5‐trioxepane can take part itself in the copolymerization which involves 1,3‐dioxolane and trioxane.

1,3,5‐Trioxepane formation with respect to the copolymerization process, was unfavoured by decreasing temperature and increasing trioxane concentration, whereas it seemed largely independent from solvent and catalyst nature.
Determination of long‐chain branching distribution in polyethylene by combination of gel permeation chromatography and viscometry
Authors: Servotte André , Bruille Roland De
Published: April 2003

Direct measurement of intrinsic viscosity on gel permeation chromatography effluent was combined with use of the universal calibration concept in order to determine long‐chain branching in polyethylene. The experimental procedure, involving an axial dispersion correction for the limited resolution of our chromatographic system, is presented. Results obtained for three branched polyethylene samples are compared with those provided by the well‐established method of preparative fractionation by column elution and examination of the fractions by viscometry and light scattering.
Polymere brenzcatechin‐derivate, 1. Über die Copolymerisation von 4‐Propenylbrenzcatechin‐Derivaten mit Vinylmonomeren durch Tributylboran
Authors: Iwabuchi Susumu , Kojima Kuniharu , Hosoya Hiromichi
Published: April 2003

Die Copolymerisation von 4‐Propenylbrenzcatechin‐Derivaten, wie Eugenol (1), Isosafrol (2), und Safrol (3), mit Vinylmonomeren, wie Acrylnitril (AN), Maleinsäureanhydrid (MA), und Methylmethacrylat (MMA), durch Tributylboran (TBB) wurde in Cyclohexanon bei 30°C unter Stickstoff untersucht. Die Propenylverbindungen copolymerisierten mit AN und MA, während MMA mit ihnen nur Homopolymeres ergab.

Für die Systeme AN/Propenylbrenzcatechin‐Derivat/TBB wurden die folgenden Copolymerisationsparameter erhalten (M1 = AN): AN/1/TBB‐System: r1 = 2,2 und r2 = 0, AN/2/TBB‐System: r1 = 0,28 und r2 = 0, AN/3/TBB‐System: r1 = 1,8 und r2 = 0. Dieses Resultat entspricht der Tatsache, daß die Propenylverbindungen 1–3 unter diesen Reaktionsbedingungen nicht homopolymerisierten.

Das MA/2/TBB‐System ergab 1:1‐Copolymere; die Copolymerisation verlief wahrscheinlich über einen CT‐Komplex‐Mechanismus.
Potential antiradiation polymers, 1. Isothiouronium salts, thiosulphates and dithiocarbamates
Authors: Barnes John , Esslemont George , Holt Paul
Published: April 2003

Polymers were synthesized that contain isothiouronium, thiosulphate or dithiocarbamate residues, which occur in known radioprotectors of low molecular weight. By copolymerizing a monomer containing the radioprotective residue with 1‐vinyl‐2‐pyrrolidone or acrylic acid, polymers were formed that were soluble in water. Polymers containing isothiouronium residues were obtained directly from an ethylenic isothiouronium salt and 1‐vinyl‐2‐pyrrolidone, and by the reaction of an intermediate halogen‐containing polymer with thiourea. Polymers containing thiosulphate or dithiocarbamate residues were obtained by copolymerization of the appropriate monomer with 1‐vinyl‐2‐pyrrolidone. Molecular weights (GPC), determined for three of the copolymers, did not exceed 12000. In preliminary tests in mice, poly[S‐(2‐acryloylaminoethyl)isothiouronium chlorideco‐1‐vinyl‐2‐pyrrolidone] (4b) and poly(N,N‐diethyl S‐vinyldithiocarbamate‐co‐acrylic acid) (6) showed some radioprotective activity.
Über Darstellung und die Bromierungseigenschaften polymerer N‐Brom‐(phenyl‐4‐vinylphenyl)methanimine
Authors: Manecke Georg , Stärk Michael
Published: April 2003

Durch Reaktion von vernetzten und unvernetzten Copolymeren aus p‐Lithiumstyrol und Styrol mit Benzonitril und nachfolgende Umsetzung mit Methanol wurden polymere (Phenyl‐4‐vinylphenyl)methanimine (5) erhalten, die auf verschiedenen Wegen am Stickstoffatom bromiert wurden.

Mit den so hergestellten polymeren N‐Brom‐(phenyl‐4‐vinylphenyl)methaniminen (7) ließen sich geeignete monomere Substrate in der Seitenkette und in Allylstellung bromieren. Die auf diese Weise entbromierten makromolekularen Substanzen konnten durch erneute Bromierung am Stickstoffatom regeneriert werden.
Synthese, Charakterisierung und Halbleitereigenschaften eines polymeren Indopheninhomologen
Authors: Kossmehl Gerhard , Manecke Georg
Published: April 2003

Durch Kondensation von 2,3,7,8‐Tetraoxo‐2,3,7,8‐tetrahydropyrrolo[2′,3′:1,2]naphtho[5,6‐b] pyrrol (4) mit Thiophen entsteht ein polymeres Indopheninhomologes (2). 2 ist ein Küpenfarbstoff und besitzt auf Grund seines koplanaren konjugierten π‐Elektronensystems ausgeprägte Eigenschaften eines polymeren organischen Halbleiters. Es ist ein p‐Leiter mit einer spezifischen elektrischen Leitfähigkeit von σ298k=1,8.10−5 Ω−1 cm−1 bei einer thermischen Aktivierungsenergie von E=0,34eV (≈0,54.10−19J), bei einem Druck von p=1500kp cm−2 (14700 N cm−2). 2 besitzt eine spezifische Spinkonzentration von 5.6.1019 spins g−1.
Gelchromatographie, 12. Gelchromatographisches Verhalten von Polyvinylalkoholgelen
Authors: Heitz Walter , Bier Peter
Published: April 2003

Durch Hydrolyse von Copolymeren aus Vinylacetat und 1,4‐Bis(vinyloxy)butan werden vernetzte Polyvinylalkoholgele hergestellt und ihre Eignung als hydrophile stationäre Phase bei gelchromatographischen Trennungen mit Dextranen, Poly(äthylenoxid)en und Proteinen als Testsubstanzen geprüft. Die Gele sind druck‐ und biostabil und zeigen keine störende Adsorption. Je nach Herstellungsbedingungen werden Ausschlußmolekulargewichte bis zu 106erzielt.
Zur Struktur des Polybutadiens, 3. Das 13C‐NMR‐Spektrum des cis‐1,4‐1,2‐polybutadiens
Authors: Elgert Karl‐Friedrich , Quack Günther , Stützel Bernhard
Published: April 2003

Das 13C‐NMR‐Spektrum eines Polybutadiens aus cis‐1,4‐ und 1,2‐Struktureinheiten wird interpretiert und zugeordnet. Die Verschiebung der Resonanzsignale der Doppelbindung der cis‐1,4‐Verknüpfung als Folge benachbarter 1,2‐Einheiten kann durch einen Satz empirischer Shiftparameter berechnet werden.
Thermal behaviour of poly[imino(1‐oxooctamethylene)], nylon 8
Authors: Ceccorulli Giuseppina , Manescalchi Francesco , Pizzoli Maria
Published: April 2003

The thermal behaviour of nylon 8 was studied by differential scanning calorimetry (DSC). Glass transition temperatures (Tg) were measured over the molecular weight range 1,7·103 – 3,4·104 in order to determine a Tg‐Mn dependence. A small decrease in the Tg values was observed for the lowest molecular weight samples which, however, were obtained by polymerization in presence of a chain terminator.

The origin of multiple melting endotherms, found during DSC analysis of samples crystallized under different conditions, was also investigated. The effects of heating rate, of cooling rate from the melt, and of isothermal crystallization at various crystallization temperatures (Tc) on melting behaviour were consistent with the hypothesis of a meltrecrystallization process during heating.