bluuebunny/crossref_metadata_2025 huggingface dataset:
Graft copolymerization onto natural rubber, VIII. Graft copolymerization of methyl methacrylate onto rubber using a potassium bromate/thiourea redox system
Authors: Lenka Subasini , Nayak Padma L. , Mohanty Indu B.
Published: April 2003

The graft copolymerization of methyl methacrylate onto natural rubber (NR) was investigated by varying monomer concentration, initiator concentration, temperature, and using different solvents and substrates. When the potassium bromate concentration increases up to 5 X 10‐3 mol/l the extent of grafting increases and decreases again with further increase of the potassium bromate concentration. The extent of grafting increases with increasing monomer concentration up to 0.9388 mol/1. With further increase of monomer concentration it decreases. With increasing temperature up to 50°C, the extent of grafting increases and with further increase of temperature it decreases. The effect of addition of CuSO4 as well as of different solvents and monomers has been investigated. A suitable mechanism has been suggested and the kinetic rate expression has been derived.
Macromolecular structure of coals. V. Molecular weight distribution of extracted coal chains
Authors: Hill‐Lievense Mary Elizabeth , Lucht Lucy M. , Peppas Nikolaos A.
Published: April 2003

Seven coal samples with carbon contents ranging from 69.95% to 94.17% on a dry mineral matter‐free (dmmf) basis were extracted with pyridine at reflux temperature for two weeks. The liquids obtained (coal extracts) were analyzed for molecular weight distribution by gel permeation chromatography at 35°C using a solution of 10% pyridine and 90% tetrahydrofuran as the mobile phase. Calibration was done by use of anionically‐prepared monodisperse polystyrene and by a series of polynuclear low molecular weight compounds. The number average (M̄Mn) and weight average (M̄w) molecular weights of the coal extracts were found to depend on the carbon content of the initial coal samples. As the carbon content increased, M̄n and M̄w decreased from original values of 640 and 1120 for the lignite sample, passing through a minimum of 600 and 895 respectively and reaching a maximum of M̄n = 725 and M̄w = 1 445 for the anthracite sample with 94.17% C. Previously extracted coal matrices were alkylated by the Sternberg alkylation technique which causes degradation of the macromolecular chains of the coal matrix. Gel permeation chromatographic analysis of pyridine‐extracted liquids of the solid alkylated coal showed average molecular weights smaller than those of the original coal extracts (M̄n = 440–470, M̄w = 445–590).
Immobilisierung von corynebacterium simplex durch einschluß in synthetische vernetzte gele — Biokatalysatoren für die steroidumwandlung
Authors: Manecke Georg , Klussmann Udo
Published: April 2003

Ganze, lebensfähige Zellen von Corynebacter. simplex wurden in ein wasserlösliches Poly[acrolein‐co‐(1‐vinyl‐2‐pyrrolidon)] durch Vernetzung eingeschlossen. Als Vernetzer wurden verschiedene Alkylendioxydiamine und Oxaalkylendioxydiamine synthetisiert. Die Polymer‐Zell‐Konjugate zeigten eine Steroid‐Δ1‐dehydrogenase‐Aktivität, und die Bildung von Prednisolon aus Hydrocortison wurde untersucht. Die Aktivität war abhängig von der Hydrophobie des einschließenden Gels und konnte durch eine Enzyminduktion und eine Behandlung mit einer Pepton‐enthaltenden Nährlösung auf ungefähr das Zehnfache gesteigert werden. Vorteilhafterweise konnte die Steroidumwandlung mit einem Überschuß an mikrokristallinem Hydrocortison durchgeführt werden. In diesem Fall wurden 0.57 g Prednisolon pro Tag und pro g Biokatalysator erhalten.
Vinyl polymerization by carbon black, VI. Physico‐chemical characteristics of poly(N‐vinylcarbazole) prepared by modified and unmodified carbon black
Authors: Biswas Mukul , Haque Shah A. , Basu Sakti P.
Published: April 2003

The polymerization initiating activity of carbon black N220, unmodified as well as modified by pretreatment with various protonic and aprotonic acids has been examined in regards to N‐vinylcarbazole polymerization. The physico‐chemical characteristics of the polymer obtained by these catalyst systems have been investigated by I.R., X‐ray, 1H‐NMR, 13C‐NMR, gel permeation chromatography and thermal analysis measurements. Under certain conditions the resultant polymer shows some partial insolubility in methylethylketone. Contrary to the usual belief, this is not due to any stereochemical difference between the polymeric entities as observed by 13C‐NMR spectrum analysis of the methylethylketone insoluble fraction of the polymer.
Synthesis and characterization of some 2,4′‐dibenzyldiisocyanate ionic polymers
Authors: Buruianǎ Tinca , Beştiuc Ioan , Popescu Valeriu , Caraculacu Adrian
Published: April 2003

Cationic polyurethanes were synthesized by a two step Menschutkin reaction. A prepolymer with tertiary dimethylamino end groups and a dihalide (1,3‐dimethyl‐4,6‐di(chloromethyl) benzene) were used in the first step, and 1,8‐diaza bicyclooctane in the second step. The polymers from flexible and transparent films and their solutions give ionomer dispersions by adding of acetone. The viscometric behaviour of diluted solutions was studied in solvents with different dielectrical constants.
The effect of mixing polymers on their combustion
Authors: Elomaa Matti A. , Salo Simo , Lindberg J. Johan
Published: April 2003

Pyrolysis and burning experiments were carried out with polypropylene, polystyrene and mixtures of them with cellulose. Polycyclic aromatic hydrocarbons (PAH) were extracted from the soot formed, and the extracts were examined by gas chromatography. The gas chromatograms were compared, like fingerprints, using a computer program developed for this purpose. The amount of benzo(a)pyrene was determined. The pyrolysis of the mixtures was also followed up by thermogravimetry. Under the experimental conditions the mixing of cellulose with hydrocarbon polymers (1:1 w/w) had only a small effect on the products formed during pyrolysis and combustion as compared with the treatment of the corresponding pure compounds.
Effect of copolymers modifying PVC on its physical and mechanical properties and its UV‐radiation resistance. 4. Photodehydrochlorination of PVC in films containing MMA/MA, VC/VAC, MBS or ABS
Authors: Kamińska A. , Kaczmarek H.
Published: April 2003

The process of PVC dehydrochlorination caused by 253.7 nm UV‐radiation in PVC films and its blends with 1% of copolymers MMA/MA, VC/VAC, MBS or ABS has been investigated. The analyses of UV‐VIS spectra pointed out that the increase of concentration of polyene structures, being created as a result of PVC photodehydrochlorination, is smaller in films containing the copolymers than that in films made of pure PVC. It suggests that the presence of 1% of these copolymers in PVC films evidently restrains photodehydrochlorination of this polymer. These copolymers used as modyfiers which help processing of PVC or improve its impact resistance can additionally act as PVC photostabilizers restraining photodehydrochlorination.
Quantitative bestimmung der verteilung von additiven in kunststoffen mit hilfe der neutronenaktivierung und autoradiographie. Grundlagen der untersuchungsmethode
Authors: Krassowski Georg
Published: April 2003

Die quantitative Bestimmung der Verteilung von Additiven in Kunststoffen bereitet in der Kunststofftechnologie derzeit noch Schwierigkeiten, da mit den gebräuchlichen Beurteilungsmethoden häufig nur grobe Klassifizierungen vorgenommen werden können. Mit Hilfe der Neutronenaktivierung von Additiven und der Autoradiographie als registrierendem Verfahren lassen sich dagegen praxisgerechte Mischgrade sehr nachweis‐ und auflösungsempfindlich quantitativ bestimmen. Die Einflußfaktoren dieser Untersuchungsmethode werden systematisch in Form von Gleichungen zusammengestellt und auf die praktische Anwendung übertragen.
Biocide polymers, 14. Modification of polyvinyl alcohol with biologically active N‐phosphorylated 3‐amino‐1,2,4‐triazoles
Authors: Hartmann Manfred , Bauer Hans‐Jürgen , Wermann Kurt
Published: April 2003

N‐Phosphorylated 3‐amino‐1,2,4‐triazoles, prepared from the herbicide amitrole by acylation with phenyl‐ and 4‐nitrophenyl phosphorodichloridate, respectively, as well as with phosphoryl chloride were reversibly linked to poly(vinyl alcohol) designed for controlled release of the active agent.

4‐N,N′‐Dimethylaminopyridine was used as catalyst for the polymeranalogous esterification reactions. IR, 1H‐NMR, and 31P‐NMR analyses of polymers suggest attachment of the herbicide moiety as pendant groups bound via phosphate groups at the ring nitrogen. Comparative hydrolysis studies demonstrated the influence of the substitution degree of PVAL and of the modification of the phosphorus‐to‐triazolide linkage upon the hydrolytic release of amitrole.
Graft copolymers of starch and polyacrylonitrile. 1. Effect of source
Authors: Patel A. R. , Patel K. C. , Patel R. D.
Published: April 2003

Graft copolymers of six cereal starches with polyacrylonitrile have been prepared and investigated. The molecular weights, the frequencies of grafting and the absorbencies of the saponified products are almost independent of the source of granular starches. The percent yield and percent add‐on of graft copolymers from gelatinized starches are almost the same as those from granular cereal starches. However, their molecular weights, corresponding frequency of gelatinized starch graft copolymers have increased five times, while absorbency is doubled. The effects of initiator monomer concentration, and of dilution are discussed.
Synthesis of porous styrene divinylbenzene copolymers
Authors: Poinescu Ignat , Popescu Vespasian , Carpov Adrian
Published: April 2003

The copolymerization of styrene with divinylbenzene in the presence of tri‐n‐butylphosphate or a mixture of di‐2‐ethylhexylphosphoric acid and chlorobenzene was studied in order to perform porous networks, solvent impregnated copolymers, etc. The diluents behave as strong precipitants allowing to prepare permanent porous copolymers having low contents of the crosslinking agent.

The effects of dilution, crosslinking degree, and nature of diluent on the porosity as well as on the uptake coefficients, the specific surface area, and the average pore diameter, were studied to elucidate the manner in which such inert compounds contribute to the formation of porous networks.
Polymérisation induite sous irradiation laser visible. 2. Sensibilisation par les colorants
Authors: Chesneau E. , Fouassier J. P.
Published: April 2003

De nombreux sensibilisateurs et amorceurs ont été testés pour la polymérisation d'un acrylate, sous irradiation visible. Les rôles de chaque constituant du système, des concentrations et des conditions d'irradiation (puissance du faisceau et focalisation) sont reportés. Les meilleurs résultats sont obtenus avec l'éosine, l'amorceur étant PDO + MDEA. La réactivité de ce système est comparée à celle des amorceurs UV pour la polymérisation en film et en solution. Les processus mis en jeu sont discutés.
The effect of molecular orientation on the vapour sorption of cyclohexane in amorphous polyester fibres
Authors: Czerwiński Wojciech
Published: April 2003

The sorption and transport of cyclohexane in poly(ethylene terephthalate) (PETP) fibres with various molecular orientations below the glass transition have been studied. The results have been analyzed in terms of the dual sorption model which has been successfully employed for glassy polymers. It has been shown that the capacity of the Langmuir mode of sorption inherent to glassy polymers is connected with the molecular orientation in the fibres of PETP. The increase of molecular orientation in the fibres has caused the decrease of the Langmuir capacity of PETP. This postulates a decrease in the free volume as a consequence of gradually increasing molecular orientation. Observations on the diffusion coefficients and activation energies for cyclohexane‐PETP fibres system have been discussed.
Versuche zur stufenweisen epoxid/methacrylat‐photopolymerisation mit diaryliodoniumsalz‐photoinitiatoren
Authors: Klemm Elisabeth , Flammersheim Hans‐Jürgen , Märtin Rolf , Hörhold Hans‐Heinrich
Published: April 2003

DSC‐Untersuchungen bestätigen das präparative Ergebnis, wonach eine selektive, zeitlich aufeinanderfolgende Photopolymerisation von Methylmethacrylat und Phenylglycidether aus einer Mischung beider Monomeren möglich ist mit Diaryliodoniumtetrafluorborat/Benzoinmethylether als Photoinitiator. Die Trennung beider Polymerisationsprozesse ist abhängig von der Bestrahlungsintensität und von der Zusammensetzung der Monomermischung. Aus einer Monomermischung (80 Gew.‐% Methylmethacrylat [MMA]/20 Gew.‐% Phenylglycidether [PGE]) polymerisiert bei einer Bestrahlungsintensität von I = 0,7 mJ/s cm2 bis zum Eintreten des Geleffektes nur MMA (etwa 30 Minuten). Die Epoxidpolymerisation kann danach mit dem ungefilterten Licht einer Quecksilberhochdrucklampe innerhalb von 10 Minuten durchgeführt werden. Die zeitliche Trennung beider Prozesse gelingt nur, wenn MMA Hauptbestandteil der Monomermischung ist.
Interaction of copoly(L‐lysine · HBr γ‐methyl‐L‐glutamate)s with 2‐(4′‐hydroxyphenylazo) benzoic acid
Authors: Kuramoto Noriyuki , Aoyama Tomoyuki , Yamaguchi Mieko , Nagai Katsutoshi , Hayama Shigeru
Published: April 2003

Copoly(Nε‐benzyloxycarbonyl(Cbz)‐L‐lysine γ‐methyl‐L‐glutamate)s of different amino acid composition were obtained from the mixture of N‐carboxy anhydride (NCA) of Nε‐Cbz‐L‐lysine and NCA of γ‐methyl‐L‐glutamate of different molar ratio. Interactions of copoly(L‐lysine · HBr γ‐methyl‐L‐glutamate)s with 2‐(4′‐hydroxyphenylazo) benzoic acid were evaluated by means of difference visible absorption spectroscopic measurement using the Benesi‐Hildebrand equation. With an increase in residue mole of L‐lysine in the copolymers, the binding constants per residue mole of L‐lysine in the copolymers were reduced.
Water‐insoluble polyacrylamides, IV. Polychelates based on poly(o‐N‐acryloyl amino benzoic acid)
Authors: Patel Kishore , Suthar Bhikhu
Published: April 2003

Polychelates of Fe(II), Co(II), Ni(II), Cr(III) UO2(II), and Zn(II) were prepared from poly(o‐N‐acryloyl amino benzoic acid). All these polychelates are intensely coloured and insoluble in all common organic solvents. They are characterized by electronic reflectance spectra, magnetic susceptibility measurements, elemental analyses, and infrared spectral studies. All the polychelates show six coordinated structure and suggest the octahedral geometry. Conductometric studies indicate these polychelates as non‐electrolytes. From thermogravimetric analyses, the thermal stability of all these polychelates was determined.
Gemeinsame kondensation von harnstoff, melamin und formaldehyd. I. Einfluß der reaktionsparameter
Authors: Braun Dietrich , Abrão Maria de Lourdes , Ritzert Hans‐Josef
Published: April 2003

Die Abhängigkeit der gemeinsamen Kondensation von Harnstoff, Melamin und Formaldehyd von den Reaktionsparametern wurde mit Hilfe chromatographischer und spektroskopischer Methoden untersucht. Dabei zeigte sich, daß bei Erniedrigung des pH‐Werts die Reaktivität sowohl von Melamin als auch von Harnstoff gegenüber Formaldehyd ansteigt. Eine kontrollierbare Reaktion von Harnstoff, Melamin und Formaldehyd ist nur im neutralen und alkalischen Medium möglich. Bei Erhöhung des Anteils an Harnstoff im Reaktionsgemisch steigt der Kondensationsgrad an.

Ein Vergleich der Mischharze mit den entsprechenden Harnstoff‐Formaldehyd‐und Melamin‐Formaldehyd‐Harzen mit Hilfe chromatographischer und spektroskopischer Methoden ergab Hinweise auf die Bildung von Cokondensaten aus Harnstoff und Melamin. Zum selben Befund gelangt man beim Vergleich der Acetonverträglichkeiten und der Trübungspunkte der Dreikomponentenkondensate mit den reinen Harnstoff‐ und Melaminharzen.
Bestimmung von phenyl‐, alkylphenyl‐ und benzoyl‐endgruppen in bisphenol‐a/polycarbonaten
Authors: Horbach A. , Freitag D. , Müller H.
Published: April 2003

Für unter Verwendung von Kettenabbrechern hergestellte Polycarbonate auf Basis von Bisphenol‐A wird ein neues Analysenverfahren zur Bestimmung des Gehaltes an Phenyl‐ und 4‐tert‐Butylphenyl‐Endgruppen vorgestellt, das zusätzlich auch zur Analyse von 4‐Kresyl‐, 4‐Isooctyl‐ und 4‐Cyclohexylphenyl‐ sowie von Benzoyl‐Endgruppen geeignet ist.

Das Polycarbonat wird in üblicher Weise durch alkalische Totalhydrolyse in die Grundbausteine abgebaut. In der sauer gestellten Hydrolyselösung werden anschließend die aus den Endgruppen gebildeten Mengen an Phenol, 4‐tert‐Butylphenol, 4‐Kresol, 4‐Isooctylphenol, 4‐Cyclohexylphenol bzw. an Benzoesäure über Reversed‐Phase‐Hochdruckflüssigkeitschromatographie bestimmt. Im Gegensatz zu den literaturbekannten Verfahren zur Analyse von Phenyl‐ und 4‐tert‐Butylphenyl‐Endgruppen kann auf spezielle Anreicherungs‐ bzw. Abtrennungsschritte verzichtet werden.

Bei guter Reproduzierbarkeit und Richtigkeit der Ergebnisse zeichnet sich das neue Verfahren durch einen relativ geringen Arbeits‐ und Zeitaufwand aus.
Untersuchung der reaktionen von alkydharzen mit melaminvernetzern
Authors: Pohl Horand Uwe , Traenckner Hans‐Joachim
Published: April 2003

Bei der anwendungstechnischen und analytischen Untersuchung der Vernetzungsreaktionen von Alkyd‐ mit Melaminharzen sind Effekte zu beobachten, die nicht mit den bekannten Reaktionen zu erklären sind:

Die filmmechanischen Eigenschaften (Pendelhärte, Eindringtiefe, Dehnung) erreichen bei der 130°C‐Einbrennung bereits nach ca. 5 min ihr endgültiges Niveau, die Filmbeständigkeitseigenschaften (Xyloltest, MEK‐Wischtest) dagegen erst nach ca. 30 min.

Die Abhängigkeit des Quellgrades von der Einbrenndauer geht durch ein Minimum.

Die Abhängigkeit der OH‐Menge von der Einbrenndauer geht durch ein Minimum.

Im Abgas wird weniger iso‐Butanol wiedergefunden, als nach den IR‐Ergebnissen aus dem Melaminharz abgespalten wird.

Alle diese Effekte lassen sich durch eine Solvolyse der Alkydestergruppen durch das aus dem Melaminharz abgespaltene iso‐Butanol erklären.
Flameproofing of cellulose and several synthetic polymers by substituted N‐[(phosphinyl) methyl]‐2‐imidazolidinones
Authors: Mikroyannidis John A.
Published: April 2003

Substituted 1‐[(phosphinyl)methyl]‐2‐imidazolidinones were used for development of a novel finishing process referring cotton fabric fire and crease resistant. The process involves treatment of cotton fabric with an acidic solution of substituted 1‐[(phosphinyl)methyl]‐3‐hydroxymethyl‐2‐imidazolidinones and tris (N‐hydroxymethyl) melamine followed by curing. The fire resistance, the crease resistance, and the mechanical strength of the treated fabric were determined in order to evaluate the process. Particularly, the fire resistance of the specimens was determined by measuring their char length, the afterflame time, and the afterglow time. All treated specimens were selfextinguishing. The crease resistance and the mechanical strength of the specimens were determined by measuring their recovery angle and breaking load, respectively. In addition, substituted 1,3‐bis[(phosphinyl)methyl]‐2‐imidazolidinones were used as fire retardant additives in several synthetic polymers such as nylon 66 and polyethylene with significant increase of their limiting oxygen index (LOI) value.
Curing of new trimellitimide glycidyl ester derivatives with aromatic diamines
Authors: Martínez Pedro‐Alberto , Cádiz Virginia , Serra Angels , Mantecón Ana
Published: April 2003

The cure behaviour of new epoxy resins containing a preformed imide ring with m‐phenylenediamine (mPDA) and diaminodiphenylmethane (DDM) was investigated. The progress of polymerization was followed by recording IR and 13C‐NMR spectra at time intervals. The curing proceeded mainly by chain extension at low temperatures, the reaction being not very fast, whereas crosslinking occurred as the gel point was reached (about 15 h at 60°C) by reaction of secondary amino groups with epoxides. Impurities influence, playing the part of catalysts, could be determined from the reaction rate of glycidyl and amino groups. So a kinetic study was made. The thermal behaviour of these cured epoxy resins was also studied.
Evaluation of the glass transition temperature of polymers
Authors: Patel K. C. , Patel R. D.
Published: April 2003

An attempt has been made to determine the glass transition temperatures, Tg, of two series of polymers ((a) polymethacrylates and (b) amylose esters) from the chemical structure of the repeating unit applying the contribution of each element as well as the molecular interaction. A fairly good agreement has been achieved between the theoretical and experimentally reported values of Tg involving the error ranging from 0.5 to 7%.
Adjustment and control of weathering conditions in accelerated tests of polymer materials for better correlation
Authors: Kockott Dieter
Published: April 2003

The principal possibilities of acceleration will be discussed. Technical polymers are a complicated system of several components exposed to the various influencing factors of the weather which themselves are often in interaction. A decisive technical presupposition concerning the comparison of accelerated weathering and outdoor weathering as well as reproducibility of accelerated weathering results are adjustment, measurement and control of the most important influencing parameters in the weathering device. This will particularly be discussed for the following parameters: Spectral energy distribution, irradiance/radiant exposure, relative humidity/water, and concentration of various industrial pollutant gases.
The importance of spectral distribution and intensity of artificial light sources in UV and IR region of radiation for accelerated ageing of polymers
Authors: Boxhammer Jörg , Rudzki T.
Published: April 2003

In recent years increasing importance has been attached to modified, extended and new kinds of test tasks, such as

‐ the action of radiation at a simultaneous extreme thermal stress;

‐ synergistic influence of the climate (primarily radiation) and e. g. mechanical stress;

‐ testing of structural parts and systems (with the requirement of large irradiation surfaces).

This aspect as well as primarily ergonomic reasons in the field of the conventional accelerated light exposure and weathering tests in machines have stimulated the discussion about alternative light sources beside the time‐tested Xenon radiation appropriate for the simulation of solar radiation, they have initiated quite a number of scientific investigations, and have now found their first realization in the correspondig machines and equipment.

New findings in the application of special metal halide lamps and fluorescent tubes as alternative light sources for Xenon radiation are being discussed on the basis of some typical results.

The importance of the infrared part in the artificial radiation to simulate particular phenomena of deterioration is shown with the help of an example of specific problems in the automobile industry, and the transfer of these findings into especially developed and problem‐oriented machine and equipment technology will be discussed.
Coating polycarbonate with acrylics will improve its weatherability
Authors: Hennig Jürgen
Published: April 2003

A problem of protecting polymers against weather influences is to concentrate the protective agents (UV‐absorbers, antioxidants etc.) in the adequate place: the surface layer where photocxidative reactions primarily set in. The outstanding properties of polycarbonate (PC) are high levels of toughness and heat resistance whereas polymethylmethacrylate (PMMA) exhibits brilliant transparency and excellent weatherability. Mainly because of its higher spectral energy absorption from global radiation in the critical range from 300 to 400 nm wavelength PC is inferior to PMMA in weatherability: yellowing and erosion within a 20 μm surface layer of PC become visible after 5 years natural weathering. So the idea suggested itself to combine the favourable properties of these two polymers by coating PC with acrylics. As far as weathering results are available today this idea turned out to be very useful: the improvement in weatherability by coating PC regarding the yellowness index, light transmittance and surface erosion is a factor 2–3 in time and even more.
Stabilization of polyamides against degradation caused by heat and light
Authors: Stohler Felix R.
Published: April 2003

The stabilization of polyamides or nylons, considered the oldest engineering plastics, has been the subject of many patents in the last 50 years. Most of these patents refer to attempts to improve the resistance of polyamides against the negative influence of heat and oxygen. Light stability, however, was always of certain interest as well, and more so in recent years when polyamide producers started to search seriously for new fields of application.

Some general remarks will be made on how to test the heat stability of this substrate group. The three different types of heat stabilizing systems with their advantages and disadvantages will be discussed briefly. Among these three systems ‐ copper halides, secondary aromatic amines and phenolic antioxidants ‐ the latter will be dealt with in some depth.

Some information will cover investigations on stabilization of polyamides in general. Another study will be presented that deals with the behavior of polyamide 6 at various elevated temperatures. The results of an extraction of polyamide 66 with boiling water will be explained including discussion of the consequences.

An example will also be given for the heat stabilization of polyamide 12.

Some general remarks on testing polyamides under the influence of light lead to several considerations concerning light stabilizer systems for polyamides. Examples will be given for polyamides 6, 66 and 12.

A short survey of the status quo with regard to polyamide stabilization and an outlook for the future will conclude this paper.
Cold‐drawing behaviour of naturally aged poly(ethylene terephthalate)
Authors: Avramova Nadka , Fakirov Stoyko
Published: April 2003

The cold‐drawing behavior of naturally aged poly(ethylene terephthalate) (PET) is investigated and an attempt is made to compare the mechanical behavior of unaged commercial PET and material which has been naturally aged for 11 years. Mechanical, viscometric, DSC and IR measurements are applied. The previously observed unusual ability of fresh PET bristles to be cold drawn up to 15:1 is not achieved for the naturally aged material. This fact is related to chemical cross‐linking occuring on the surface of bristles after drawing and thermal treatment. The cross‐linking skin is unsoluble, infusible and uncrystallizable. The naturally aging defeats the ability of PET to respond to external treatments which would otherwise change the internal structure. Such a “stabilization” of material properties is a result of the transformation, during natural aging, of the original physical network into a chemical network consisting of covalent bonds.
Heat stabilization of segmented copoly(ether ester)s
Authors: Zeilstra Job J.
Published: April 2003

Oxidative degradation of segmented copoly(ether ester)s can be suppressed by interference of the following basic processes:

a. degradative radical chain reactions. Effective inhibition is possible by means of primary antioxidants.

b. initiation of the radical chain reactions by means of hydroperoxides formed. Such initiation reactions can be suppressed by inactivation of the hydroperoxides with the aid of secondary antioxidants.

c. polyester segmental chain scission by formic acid formed during oxidative degradation of the polyether segments. By scavenging the formic acid, or its precursor formaldehyde, this serious process can be restricted.

Combined addition of stabilizers, simultaneously influencing the basic processes a., b. and c. can lead to synergism. Examples of the activity of the different stabilizers are given.
The photooxidative gelation of cis‐1,4‐ polybutadiene in solution
Authors: Jovanović Dragiša
Published: April 2003

Irradiation of dilute solution of cis‐1,4‐polybutadiene in carbon tetrachloride with UV light in the presence of air causes fast formation of white precipitate—insoluble gel. It has been shown that carbon tetrachloride was effective photosensitizer for oxidation of cis‐1,4‐polybutadiene. Separated sol and gel fractions were analysed by infrared spectroscopy for better understanding of gelation process and structure of the gel. Three stages were detected in the process of oxidative photogelation of cis‐1,4‐polybutadiene in carbon tetrachloride solution: pre‐gelation(sol‐stage), gelation (sol/gel‐stage) and post‐gelation (gel‐stage). In the first stage intensive photooxidative reactions between cis‐1,4‐polybutadiene, carbon tetrachloride and oxygen take place, giving products with high content of hydroperoxide and bounded chlorine. When hydroperoxide and chlorine content reached critical value, precipitation‐gelation takes place. It is proposed sequence of free radical reactions which involves: photolysis of carbon tetrachloride to free radicals, addition of solvent radicals to the double bonds of rubber followed by combining of resulting radicals with oxigen to chlorinated polymeric peroxy radicals. Initially formed gel is peroxidic in nature, which photolyses to the more stabile ether gel by prolonged irradiation.
Ageing of rubber modified thermoplastics and elastomers
Authors: Bach J. , Braun D. , Müller I. , Wendorff J. H.
Published: April 2003

The effect of ozone exposure on several polymers is investigated. From the chemical point of view the consequence of ozone attack on several polybutadienes in solution and as solid polymers is studied. Ozonization of polybutadiene solutions causes a strong decay in the intrinsic viscosity. The behavior of solid polymers was investigated by electron paramagnetic resonance. In the second part of the paper the influence of ozone on Solprene 406, a SBS‐elastomer, and a rubber modified polystyrene on the stress strain behavior is studied. In both cases ozone causes a strong increase of the magnitude of stress relaxation. The dependence of the stress relaxation on the deformation, on the ozone concentration, and on the temperature is described.
Influence of tackifier resins storage stability on EVA based hot melt adhesives
Authors: Hinsken Hans
Published: April 2003

Rosin (colophony) ‐based resins are a major class of tackifying resins for hot melt adhesives (HMA). These resins are very prone to oxidation. Under ambient storage conditions all types oxidize to varying degrees. As a result of this autoxidation process, considerable concentrations of hydroperoxides can accumulate. The properties of the tackifier resin are significantly effected by these hydroperoxides. When the resin is eventually used in EVA HMA production, these hydroperoxides also adversely effect the HMA properties. Autoxidation of the tackifier resin, under ambient storage conditions, can be effectively suppressed by an appropriate antioxidant. The storage stability of the resin can therefore be improved dramatically, minimizing changes in tackifiers properties.
Relative ultimate strain in white pigmented polymers after ageing
Authors: Skledar Štefan
Published: April 2003

Three series of pigmented polymeric films of various pigment volume fractions were prepared. The first series of unsupported films was exposed to ultraviolet radiation and the second to demineralized water, the third series of films being unexposed for comparison. The ultimate tensile properties of all three film series were measured according to ASTM D 2370 standard method. The obtained experimental data follow the equation containing a pigment‐polymer interaction parameter based on the Ziegel's concept. In vinyl acetate‐butyl acrylate copolymer system, the ultraviolet radiation causes an increase of relative ultimate strain at lower pigment volume fractions, where the interaction parameter diminishes. On the contrary, water provokes a decrease of relative ultimate strain in this system by magnifying the interaction parameter at low pigment concentration. In ethyl acrylate‐methyl methacrylate copolymer system, neither ultraviolet radiation nor water affect greatly the relative ultimate strain and the interaction parameter. The results obtained prove good resistance to ageing of this copolymer system, where the thickness of immobilized interfacial polymer region represents a logarithmic function of pigment volume fraction. On the other hand, in poly(vinyl acetate) system both ultraviolet radiation and water diminish the interaction parameter at low pigment concentrations, the thickness of immobilized interfacial polymer region being still the logarithmic function of pigment volume fraction in first approximation. It can be concluded that ageing effects on the relative ultimate strain in white pigmented polymers depend not only upon pigments and their concentration but also upon the nature of polymer matrix.
Comparative study of complex mechanisms of various polystyrene degradations and oxidations
Authors: Kovačević Vera , Bravar Mladen , Hace Drago
Published: April 2003

Comparative investigations of the polymeric residues remained after degrading polystyrene by heat or by UV irradiation reveal numerous profound changes of the structural and molecular parameters of the polymer when subjecting it to either of these main types of degradation.

The polymeric residues of the commercial and of the prepared polystyrene samples were investigated in view of the following characteristics: discolouration, IR, UV and 13C NMR spectra, DSC‐analysis, GPC‐elution curves and X‐ray patterns.

The results show pronounced heterogeneity of the degradative reactions occuring in the framework of the thermal and photochemical degradation of polystyrene, including the existence of crosslinking processes and producing thus very inhomogeneous polymeric material.

The presumption of the existence of different mechanism paths occuring in various polystyrene structural fractions was confirmed and further promoted, especially from the standpoint that the lower‐molecular fractions of the polymer should behave more sensitively against the degradative attacks.

Many‐sided meanings of the informations obtained by analysing degraded polystyrene samples allow to postulate the present degradative mechanism by comparing among them various types of de gradative processes.

The gained informations about the locations and ranges of absorption bands in UV, IR and 13C NMR spectra, as well as the complementary evidence from other determinations enabled the claim that polystyrene thermo‐oxidative degradation would preferentially take place in the way to produce acetophenone structures near the chain ends. In the initial degradation periods this would be related with substantial lowering of the molecular mass.

The photo‐oxidative degradation mechanisms cause the build‐up ketone and aldehyde structures and ring‐opening reactions concurrent with chain crosslinking reactions.

Comparing long‐wave and short‐wave UV irradiations of polystyrene does not only show the existence of inequal induction times, but additionally the presence of two sets of similar reactions leading to the production of many oxidized structures.

The investigations would show that oxidative polystyrene degradation is a very complex phenomenon in which the prefered courses of chemical reactions are in the relations to the initial reaction steps, namely they do depend on structures formed in the early stages of the thermal and photo‐degradative processes.
Studies on the thermal stability of poly/vinyl chloride/ and vinyl chloride ‐ carbon monoxide copolymers
Authors: Orbán Sylvia
Published: April 2003

Thermal stability of vinyl chloride/carbon monoxide copolymers synthetized in the presence of different proportions of carbon monoxide was studied in nitrogen, oxygen or air stream at 180°C. Dehydrochlorination rate increases proportionally to the incorporated carbonyl content. Effect of air and oxygen on acceleration of the decomposition is higher for PVC samples of regular structure than for the vinyl chloride/carbon monoxide copolymers. In the infra‐red spectra recorded after the thermal oxidative decomposition, a broad absorption band appears between 1600 and 1800 cm−1. Two peaks show the most emphasized increase: one at 1720 to 1730 cm−1 assigned to the carbonyl group and another at about 1770 cm−1 of unidentified origin. Additional oxidation products from the polyene yield a “shoulder” in the spectrum between 1600 and 1690 cm−1.
Ageing and recycling of plastic crates
Authors: Vink P. , Rotteveel R. T. , Wisse J. D. M.
Published: April 2003

Plastic crates will deteriorate and ultimately fail due to brittle fracture if, either during use or storage, they are exposed to sunlight. The time to failure depends on the UV stability of the polymer used, but in particular also on the conditions of use, such as time of exposure, height of the stack during stocking, rate of circulation and manner of transportation.

Because of differences in the conditions of use, the time to failure of creates of the same batch will be different. The decrease of the size of a particular batch in time can be described by a Weibull‐function, an empirical, statistical function. Knowledge of this function for a batch provides the possibility to predict reliably the number of crates to be rejected in forthcoming years.

The UV stability of recycled, degraded high density polyethylene (HDPE) create material appears to be hardly dependent on the degree of degradation, although it is lower than the UV stability of the type of HDPE originally used for production of the creates. The UV stability can, however, be markedly enhanced by the addition of a proper stabiliser system.

The tensile impact strength and the meltindex of recycled HDPE depend also hardly on the degree of degradation and are, in general, sufficient for crate material.

It is concluded that recycling of degraded crates, even of embrittled crates, and reuse of the material for the production of new crates, is worthwile to be considered.
Die dimensionen der kristallinen bereiche in fasern aus regeneratcellulose
Authors: Lenz Jürgen , Schurz Josef , Wrentschur Erich , Geymayer Wolfgang
Published: April 2003

Die Dimensionen der kristallinen Bereiche von Regeneratcellulosefasern wurden mittels Transmissionselektronenmikroskopie, Röntgenkleinwinkelstreuung und Röntgenweitwinkeldiffraktion bestimmt. In befriedigender Übereinstimmung wurden nach allen drei Methoden folgende Abmessungen gefunden: Länge: 120–140 Å, Breite: 80–100 Å, Dicke: 30–40 Å. Die breite Ebene der blättchenförmigen Kristallite verläuft parallel zur 101‐Netzebene, die schmale Kantenebene parallel zur 101‐Netzebene. Die Kristallite bilden Ketten mit einer Länge von 1500 bis 5500 Å, die teilweise zu Clustern mit einem Durchmesser von 300 bis 600 Å gebündelt sind, teilweise durch Zonen geringerer Dichte voneinander getrennt sind. Die Abstände zwischen den kristallinen Bereichen betragen in Längs‐ und Querrichtung 20 bis 40 Å.
Porous bead aliphatic‐aromatic methacrylate copolymers V. Grafting of acrylic monomers onto MMA‐DMN copolymers
Authors: Wójcik Anna B.
Published: April 2003

Porous methyl methacrylate‐di(methacryloyloxymethyl)‐naphthalene (DMN) copolymers were subjected to superficial grafting processes with engagement of double bonds present in the polymer structure. Grafting monomers were acrylic and methacrylic acids, acrylonitrile, acrylamide, and glycidyl methacrylate. Grafted copolymers were investigated by elemental analysis, infra‐red measurements, adsorptiondesorption isotherms of nitrogen and scanning electron microscopy. Irrespective of low grafting efficiency, the changes due to grafting with respect to the parent copolymers were easy to observe.
Thermal properties of chlorendic acid based polyester resins
Authors: Bansal R. K. , Ghogare A. B.
Published: April 2003

Polyester resins were prepared from chlorendic acid, maleic anhydride, and ethylene‐ and/or propylene‐glycol. The resins were cured at room temperature with two different crosslinking agents including styrene and methyl methacrylate. The thermal behaviour of these polyester resins and their cured products was studied. From the thermogravimetric data it was observed that the polyester resins cured with styrene are thermally more stable than the methyl methacrylate cured products. It was also observed that the polyester resin prepared from propylene glycol is thermally more stable relatively than the ethylene glycol based polyester resin. The activation energies of thermal degradation of the resins and their cured products were calculated. The implications of these results are discussed.
Synthèse de monomères acryliques et méthacryliques derivés de biocides. Etude de leur homo et copolymérisation
Authors: Potin C. , Pleurdeau A. , Bruneau C. M.
Published: April 2003

En vue de la mise au point de biocides macromoléculaires destinés à être utilisés en tant que liants dans des formulations peinture, divers agents biocides, principalement des phénols, ont été transformés en monomères acryliques et méthacryliques. L'aptitude de ces monomères à l'homopolymérisation et à la copolymérisation avec des comonomères classiques (styrène, esters acryliques) a été étudiée par processus radicalaire. Les monomères actifs, leurs homo et copolymères ont été caractérisés par les méthodes habituelles de spectrographie infra‐rouge, RMN1 H et 13C, analyse élémentaire et chromatographie d'exclusion.
Thermal decomposition of petroleum and coal tar pitches by thermogravimetry
Authors: Eder Marek , Włochowicz Andrzej
Published: April 2003

Thermogravimetry was used to investigate petroleum and coal tar pitches undergoing pyrolysis in an atmosphere of air and nitrogen at three different heating rates.

Pyrolysis of pitches in air is a three‐stage process, whereas in nitrogen two stages were found.

A kinetic analysis of the thermogravimetric data has been made. The orders and activation energies have been determined for each stage of decomposition using the methods of Kissinger, Freeman, and Hüttinger.
Oligomeric 1,4‐phenyleneterephthalamide. Synthesis by interfacial polycondensation and structural properties
Authors: Cum Giampietro , Gallo Raffaele , Severini Febo , Spadaro Agatino
Published: April 2003

The synthesis of a fully aromatic oligoamide by low temperature interfacial polycondensation between terephthaloyl chloride and 1,4‐phenylenediamine is reported. The reaction product was characterized with respect to its physical properties and chemical structure by infrared, X‐rays, electron spectroscopy for chemical analysis (ESCA), and mass spectroscopic techniques. Elemental and thermal analysis, as well as viscosimetric and titrimetric methods were applied to evaluate the average molecular weight of the oligomer, whose chain length consists mainly of 3 to 4 monomeric units.
Morphology property relationships in poly (2‐methoxy)cyanurate of bisphenol‐C (PMCBC)/polystyrene (PS) blends — dynamic modulus
Authors: Parsania Purshottam H. , Shah Praful P. , Patel Kanti C. , Patel Raman D.
Published: April 2003

The dynamic mechanical, thermal, and morphological properties of poly(2‐methoxy)cyanurate of bisphenol‐C (PMCBC), polystyrene (PS), and their blends have been investigated. Dynamic mechanical data show that there is appreciable adhesion at the PMCBC/PS interface but that the PMCBC/PS blends are incompatible. Morphological and thermal analysis results indicate that the PS appears as inclusions in the PMCBC matrix and as a result of interfacial adhesion contributes substantially to the sample's overall modulus. Theories based on perfect adhesion are found to be applicable to the PMCBC/PS blends.
Permeability of alkali chlorides through charged cellulosic membranes
Authors: Kimura Yuzi , Lim Han‐Jin , Iijima Toshiro
Published: April 2003

The permeation of alkali chlorides through charged cellulosic membranes was investigated. The membranes used were partially carboxymethylated and carboxyethylated cellulose with various degrees of substitution. The permeability coefficients were found to increase in a sequence of LiCl < NaCl < CsCl < KCl. This sequence is explained by considering the partition and the hydration of the ions in these hydrophilic membranes. The dependence of the permeability on the salt concentration was interpreted by means of Teorell‐Meyer‐Sievers (TMS) theory. The effectiveness of the charged groups in the membranes is explained by the counterion binding mechanism.
Coordination polymers. 7. Synthesis and characterization of some polychelates derived from bisphenolic complexes
Authors: Spiratos Mihaela , Airinei Anton , Voiculescu Nicolae
Published: April 2003

Chelate polyesters and polysiloxanes derived from bisphenolic complexes with some bivalent ions as copper, nickel, cobalt, iron, zinc have been synthesized. The polychelates are studied in terms of spectral, thermal, magnetic, and electrical properties; the probable structures of these polymers have been proposed.
Rheologische eigenschaften von ethoxylierte amine enthaltende polycapronamidschmelzen
Authors: Peev G. , Garvanska R. , Draganova K.
Published: April 2003

Es wurde eine rheologische Charakterisierung von Polycapronamidschmelzen vorgenommen, die 2 bis 10 Masse‐% zweistufig ethoxylierte Ethylendiamine und Diethylentriamine mit einer Molmasse von 983 bis 8660 enthielten. Diese Amine sind geeignete Zusatzstoffe zur Gewinnung von Polycapronamidfasern mit dauerhaften antielektrostatischen Eigenschaften.

Es wurde festgestellt, daß die Zusatzstoffe die scheinbare Viskosität senken, ohne daß der nichtlineare Charakter des viskosen Fließens wesentlich verändert wird, und daß die Viskosität von Art und Menge der ethoxylierten Verbindungen nicht abhängt.
Investigations of electrokinetic properties of dyed polyamide fibres
Authors: Pfeifer Stanisław , Włochowicz Andrzej
Published: April 2003

Changes of the electrokinetic flow intensity Qv and the zeta potential for polyamide fibres colourless and dyed with Polan dyes were analyzed.

Essential differences in determined quantities were found for fibres dyed with dyes of different steric structure.
Analytical studies on surface damage of PVC sheets
Authors: Jayabalan M.
Published: April 2003

Analytical studies on surface damage of PVC sheets due to weathering were carried out. PVC sheets which contain embossed and smooth surface which were subjected to cyclic weathering conditions of humidity and temperature were analysed. PVC sheets prepared with di‐2‐ethylhexyl phthalate as plasticizer undergo leaching of plasticizer; the leaching being high in smooth and less in embossed surface. The presence of plasticizer on the surface was detected by Attenuated Total Internal Reflectance Infrared Spectrophotometry (ATIR). The higher the leaching in smooth surface, the higher the surface damage in the embossed surface. The higher damage is ascribed to surface brittleness whereas the lower damage is ascribed to the surface plasticization. The surface damage was assessed by photomicrography.
Photoconductivity properties of zinc oxide encapsulated in polymers
Authors: Haga Yutaka , Inoue Syouzo , Sato Takanori , Yosomiya Ryutoku
Published: April 2003

Zinc oxide encapsulated in various polymers was studied concerning its effect on photoconductivity. Consequently, zinc oxide encapsulated in polystyrene (C‐St‐ZnO) showed a marked light sensitization effect. Further, the tendency was observed that the light sensitization effect was increased in proportion to an increase of the encapsulation ratio. Furthermore, in the composite films of C‐St‐ZnO and polystyrene, the film in which 5% of polystyrene is blended showed a remarkable light sensitization effect. Some studies were carried out with respect to the light sensitization mechanism of this encapsulated zinc oxide by examining the dark current property and the initial rising rate of the sensitized photocurrent.