bluuebunny/crossref_metadata_2025 huggingface dataset:
Solvent/nonsolvent solubility and polarity parameters in fractional separation of oligomers 2. Styrene‐acrylic acid copolymers
Authors: Spychaj Tadeusz , Hamielec Archie E.
Published: April 2003

Styrene‐acrylic acid (St‐AA) low molecular weight copolymers (M̄w < 15,000) synthesized at high temperatures (230 – 300°C) in a continuous stirred tank reactor were fractionally precipitated in solvent/nonsolvent systems. Fractional precipitation experiments were done in the system methanol‐dichloromethane/hexane to remove residual monomers and the lowest molecular weight oligomers (1st step). Solubility limits of St‐AA copolymers as a function of copolymer composition were determined using the same solvent/nonsolvent system in the 2nd step of precipitation tests (cloud point base). GPC on Styragel‐type columns, low‐angle laser light scattering (LALLS), and volumetric titration of carboxylic groups were applied for copolymer characterization. Two solvent‐derived parameters the total solubility parameter δT and the polarity index P′ are used to determine the solubility diagrams of St‐AA low molecular weight copolymers.
A novel method for vinyl grafting onto cotton fabric using ceric‐cellulose thiocarbonate redox system
Authors: Hebeish A. , El‐Sisi F. , Hafiz S. A. Abdel
Published: April 2003

Treatment of cotton fabric with carbon disulphide in presence of NaOH resulted in cellulose thiocarbonate. The latter formed a complex when treated with ceric ammonium nitrate (CAN). After being thoroughly washed, the CeIV cellulose thiocarbonate was capable of initiating vinyl graft polymerization onto cotton fabric without homopolymer formation. The graft yield obtained with methyl methacrylate was found to increase by increasing CAN from zero to 50 mmol/l at temperatures from 60 to 80°C. Grafting was greatly favoured at pH 2; alkaline pH offset grafting. Incorporation of up to 7% of methanol, ethanol, or isopropanol in the aqueous polymerization medium enhanced grafting significantly with the certainty that the highest graft yield was obtained with isopropanol; using higher alcohol percentages decreased grafting. The rate of grafting showed an initial fast rate followed by a slower rate; 60 minutes reaction time proved appropriate for grafting irrespective of the condition used. In addition to methyl methacrylate the ability of CeIV‐cellulose thiocarbonate to induce grafting of acrylonitrile and acrylamide was also examined. The rate of grafting followed the order methyl methacrylate > acrylonitrile > acrylamide.
Interface distribution functions of diluted polymer systems containing core fibrils
Authors: Schöller Thomas , Fiedel Heinz‐Werner , Wenig Werner
Published: April 2003

Interface distribution functions have been evaluated from the equatorial small angle x‐ray scattering of blends of isotactic polypropylene and poly(1‐butene) crystallized in the shear field of the oriented melt. The samples contain core fibrils which represent a diluted system with respect to their distance statistics. It is shown, that interface distribution functions can be calculated from only two interfaces (diffuse phase boundaries between fibrils and amourphous phase). The calculated thicknesses agree well with values determined from other methods.
Saponification kinetic study of mica‐acrylonitrile graft copolymers
Authors: Prasad M. P. , George Anne , Radhakrishnan Ganga , Rao K. Panduranga
Published: April 2003

Kinetics of alkaline hydrolysis of mica‐acrylonitrile graft copolymers was studied. The dependence of alkali concentration and the time of hydrolysis on the degree of saponification was determined. Chemical and spectroscopical techniques were used to determine the mechanism of hydrolysis.
Kinetics and mechanism of inhibited oxidation
Authors: Tüdös Ferenc , Fodor Zsolt , Iring Margit
Published: April 2003

This paper accumulates the mechanism and kinetics of oxidation and the inhibition mechanism of oxidation processes using preventive antioxidants, chain‐breaking antioxidants and deviations from the simple inhibition mechanism.
Pigmented and transparent, highly impact‐resistant PVC for outdoor use
Authors: Hepp Dieter
Published: April 2003

Based on the high standard of quality of EVA‐modified PVC, Hüls has developed an impact‐modified acrylate‐base PVC which can be processed over a wider range, thus meeting the high demands made with regard to processability.

The excellent light stability and resistance to weathering of this material, with its technological properties being retained at the same time, were achieved in white and brown pigmentation within a wide range of stabilizations. This is supported by comprehensive findings from open‐air weathering stations located in various climate zones as well as by findings obtained from Weather‐Ometer and QUV testing.

One phenomenon which has been observed in connection with white‐pigmented PVC, but which has been accorded little attention in the technical literature, is the discolouring of weathered samples when stored in a dark room. This phenomenon, which can also be simulated in a Weather‐Ometer, has an impact on the evaluation of PVC materials for out door usage and of ten leads to false conclusions.

In addition to this pigmented, impact‐resistant PVC Hüls has also developed a highly transparent, impact‐resistant PVC for out door use which is also acrylate‐modified. Here the selection of stabilizers and of the graft copolymer is limited from the beginning due to the high demands made with regard to the technological properties of the final product, i.e. light stability and resistance to weathering, high transparency as well as impact resistance. Despite this, Hüls has been successful in developing an impact‐modified graft polymer which, when suitably compounded, meets the exacting requirements made by the market.
Der einfluß der luftfeuchte bei der verfärbung von PVC während der bewitterung und bei der anschließenden dunkellagerung
Authors: Trubiroha Peter
Published: April 2003

Der Einfluß der relativen Luftfeuchte auf die Lichtechtheit und beim Nachdunkeln von weißem PVC und besondere Veränderungen der bestrahlten Oberflächen werden beschrieben. Die Ergebnisse zeigen, daß das Grenzflächenklima an der bestrahlten Probenoberfläche einen entscheidenden Einfluß auf das Alterungsergebnis hat.
Contribution to polyethylene photooxidation
Authors: Gugumus F.
Published: April 2003

The hydroperoxides formed on thermal oxidation of polyethylene have been used to examine their photolysis. The kinetics and mechanisms of the photolytically induced decomposition of these hydroperoxides are considered. The difficulties encountered with the mechanism based on homolysis of the hydroperoxy bond are discussed. New mechanisms of hydroperoxide photolysis based on bimolecular reactions are proposed. They are in agreement with the products found experimentally ‐ mainly ketones and trans‐vinylene groups ‐ and with the kinetics of the product formation. The mechanisms envisaged are easily adapted to polyolefins other than polyethylene and polymers in general.
Natural ageing of high impact two phase styrene‐copolymer‐systems
Authors: Karaenev S. , Nikolova S. , Dobrewa D. , Tschilingirian M.
Published: April 2003

Die Aufgabe der hier vorliegenden Arbeit ist es, die atmosphärische Alterung der schlagfesten Zweiphasen‐Styrol‐Copolymere in Abhängigkeit von der Monomerzusammensetzung der Matrix sowie der Art und Menge des Kautschuks zu untersuchen. Zu diesem Zweck wurden BS, ABS, MBS und PS, SAN untersucht, die in der Zusanmensetzung des Monomers der Matrix zveim der Zweiphasensysteae entsprechen (BS und ABS).

Aus der Interpretation tier aufgenoi;mienen Daten wurde festgestellt, der eine ßorrelation zwischen den Strukturveränderungen, der Kerbschlagezähigkeit und der ßiegefestigkeit besteht. Die durchgeführten Untersuchungen zeigen den deutlich schwierigen Charakter der Alterungsprozesse der phasenheterogenen Systeme im Vergleich zu den Homopolyneren und homogenen Copolymeren. Die Schlußfolgerungen können zur Vorauswahl des Typs und der Henge des Stabilisators in Abhängigkeit von der Honomer‐ und Phasenzusammensetzung der Systeme herangezogen werden.
Neueste ergebnisse ueber die stabilisierung von polyurethan‐systemen gegen photooxidative einfluesse
Authors: Stohler Felix R. , Berger Kurt
Published: April 2003

After a few general remarks with regard to degradation of polyurethanes under the influence of light, some new results considering the stabilization of such systems will be treated. Apart from a comparison between aromatic and aliphatic one component systems for textile coating, the main subject of this paper is the light stabilization of integral‐PUR foams as well as the stabilization of thermoplastic polyurethane. New fully liquid systems as light stabilizers for PUR may be of special interest.
Simulation des natürlichen hagelschlags an transparenten kunststoffplatten
Authors: Hennig J. , Lehmann J. , Zaengler G.
Published: April 2003

Natural hail impact tests are scarcely available because hailstorms are limited to a small area and cannot be predicted regarding time, place and intensity. Therefore we relied on laboratory tests simulating natural hailstones by polyamide balls (5‐50 mm dia.) whose final velocity could be varied according to meteorological data. So the influence of diameter (weight) and velocity of the artificial hailstones could be taken into consideration independently.

The energy of damage or equivalent natural hailstone diameter were determined for 16 mm double skin sheet from PMMA as 0.2 J (14 mm dia.) for star shaped cracks and 2 J (26 mm dia.) for holes. These values do not significantly decrease after 10 years weathering. 10 mm double skin sheets from PC show an extremly high energy of damage of abt. 10 J (38 mm dia.) which decreases to a medium level of 2 J (26 mm dia.) after several years weathering. This decrease is remarkably reduced by weather resistant protective coating.

As hailstorms consist to more than 80% of hailstones below 10 mm dia. (0.04 J) the mentioned sheet materials are quite hail resistant also after long weathering periods, but they cannot withstand an extreme hail catastrophe as in Munich July 12, 1984.
Some special aspects of thermal ageing of isotactic polypropylene (measuring method: Isothermal long‐term DTA)
Authors: Steiner G. , Koppelmann J. , Schwarz Th.
Published: April 2003

Thermo‐oxidative ageing processes were investigated in films (100 μm thick) made from isotactic polypropylene with different antioxidant concentrations between 0% and 0.1% using isothermal long‐term differential thermal analysis (ILDTA). The end of the oven life of polypropylene coincided with the loss of mechanical properties which was confirmed by tensile tests at temperatures far below the crystallite melting range. Already prior to the beginning of autocatalytic decomposition, ILDTA experiments permits conclusions to be drawn on the thermal history of the specimens and statements made regarding the end of thermo‐oxidative stability of the polymer, which is accompanied by a deterioration in the mechanical properties.

In consequence of the correlation between oxidation time and antioxidant concentration the local antioxidant concentration in sheets or films can be measured by ILDTA. Thus, investigating the diffusion of an antioxidant in polypropylene using ILDTA is possible.
Carbon fibre reinforced bismaleimide composites, I
Authors: Choudhary V. , Fitzer E. , Heine M.
Published: April 2003

The paper deals with the effect of addition of bis(allylphenyl) type (TM 120) monomer on the properties of unidirectionally carbon fibre reinforced 4,4′ bismaleimidodi‐phenyl methane (BM) – 2,4‐tolylene diamine (A) (1:0.3 molar ratio) (BM‐A) composites. The curing and thermal behaviour of the blends was investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) in air atmosphere. A marginal decrease in thermal stability was observed with increasing concentration of TM 120. Flexural, interlaminar, and impact strength of the laminates increased in the presence of this monomer. Optimum mechanical properties were observed at ∼ 20 phr of TM 120.
Reaction of some polymers containing carbonyl groups with phenol in the presence of mineral acids
Authors: Akar Ahmet
Published: April 2003

The reaction of polymers containing carbonyl groups such as poly(methyl vinylketone), poly(methyl vinyl ketone‐co‐styrene) and acetylated polystyrene with phenol in the presence of HCI or H2SO4 has been studied in order to produce bisphenol A type structure on the polymer chain. Poly(methyl vinyl ketone) shows intramolecular aldol condensation and acetylated polystyrene results in bisphenol A type structure.
Studies on the electrodeposition of polyimides
Authors: Yang Chin‐Ping , Chen Yahn‐Haur
Published: April 2003

The emulsions of aromatic polyamic acids (PMPE and PBPPM) in DMF and methanol were used to coat uniform films on conductor surfaces by electrodeposition. The deposition yield and quality of the deposited films are dependent on sort of polyamic acid, solvent (DMF), precipitant (MeOH), surfactant (TEA), pH value and solid content. To get maximum deposition yields from PMPE and PBPPM, the best conditions of electrodeposition were required as follows: pH value 5.7 and 5.58, MeOH/DMF weight ratio 3.0 and 2.8, solid content 3.5 and 2.4 wt.‐%. Deposition yield was found to obey Faraday's law of electrolysis, and the higher the equivalent weight of the polyamic acid, the higher the coulombic yield.
Model of double associates for sorption of binary gas mixtures on polymers
Authors: Pyda M. , Jaroniec M.
Published: April 2003

A simple model of double associates is used to represent bilayer sorption of binary gas mixtures on a flexible linear chain of a polymer. The isotherm equation derived in terms of this model is a simple product of the isotherm equation describing bilayer adsorption of binary gas mixtures on a homogeneous solid surface and a function reflecting specific features of sorption on polymers.
Thermosetting mechanism of polyethersulfone
Authors: Wu Zhungwen , Jiang Da Zen , Seki Miharu , Yosomiya Ryutoku
Published: April 2003

Thermosetting mechanism of paint‐use polyethersulfones was studied by utilizing FTIR/PAS and ESCA. As a result, it was confirmed that the oxygen in the air has an effect on the thermosetting mechanism. That is, the polyethersulfone film were baked from the surface, and proceeded according to reaction (4).
Studies on electrical and paramagnetic properties of poly(phenylene sulphide)
Authors: Kreja Ludwik , Rozpłoch Franciszek , Warszawski Andrzej
Published: April 2003

Electrical and paramagnetic properties of poly(phenylene sulphide) synthesized by a direct method from benzene and sulphur were investigated. In darkness dc conductivity of the polymer in its pristine state is of the order 10−10 S/m. Upon doping with iodine it increases by 8 orders of magnitude. For undoped samples the n‐type conductivity and for those doped with iodine the p‐type conductivity was observed. On the basis of ESR experiments the number of spins and g‐value were determined, which for undoped polymer at room temperature are equal to 0.80 · 1017 spins/g and 2.0037, respectively. Next, the changes in spin concentration both for the iodine doped samples and these annealed within the temperature range 513 – 903 K were described. An attempt to discuss the ESR lineshape in a quantitative way was also made.
Synthesis and study of the chelating properties of 3‐carboxy‐4‐hydroxyacetophenone‐formaldehyde resins
Authors: Patel K. Surekha R. , Patel Hasmukh S. , Patel Shanti R.
Published: April 2003

3‐Carboxy‐4‐hydroxyacetophenone (CHAP) was polycondensed with various proportions of formaldehyde using alcoholic alkali as catalyst. The resin samples, designated as CHAP‐F, have been characterized by elemental analyses and IR spectroscopy, by estimation of their number average molecular weights (M̄n), by measurement of intrinsic viscosity, and by TGA. Polymeric metal chelates of one CHAP‐F sample with Cu2+, Fe3+, Co2+, Ni2+, and UO22+ ions have been prepared and characterized.

Ion‐exchanging properties of one CHAP‐F resin sample for Fe3+, Cu2+, and Ni2+ metal ions are studied by the application of the batch‐equilibration method.
Niedermolekulares poly(β‐hydroxybutyrat). Herstllung und anwendungen
Authors: Trathnigg Bernd , Weidmann Volker , Lafferty Robert M. , Korsatko Brigitta , Korsatko Werner
Published: April 2003

Niedermolekulares Poly(β‐hydroxybutyrat) (PHB) kann durch kontrollierte Hydrolyse des auf biotechnologischem Wege hergestellten Polymeren erhalten werden. Die Geschwindigkeitskonstanten des Kettenabbaus wurden in verschiedenen 85prozentigen Säuren bei 90 und 100°C bestimmt. Aus den so erhaltenen PHB‐Fraktionen im Molmassenbereich von 3000 – 500000 wurden Matrixtabletten hergestellt. Es wird gezeigt, daß der Retardeffekt stark von der Molmasse des verwendeten Polymeren abhängt.
On the structure of styrene‐divinyl benzene copolymers as obtained by small‐angle X‐ray scattering
Authors: Włochowicz Andrzej , Sanetra Roman , Kolarz Bożena N.
Published: April 2003

The parameters of the supermolecular structure of styrene‐divinyl benzene copolymers with a degree of crosslinking equal to 5, 10, and 20% were examined. It was found that regions with different electron density occur in the copolymers.

Mean sizes of heterogeneities, 1, thicknesses of transition layers E, and specific areas S/V were determined. It was found that as the degree of crosslinking increases the inhomogeneity of the copolymer structure becomes greater and the separation of the phases is more visible.
Elektrokinetische untersuchungen von chemiefasern
Authors: Pfeifer Stanisław , Włochowicz Andrzej
Published: April 2003

Electrokinetische Parameter wie die elektroosmotische Stromstärke (Qc) und das elektrokinetische Potential (ζ) von Fasern hängen stark von Masse und Struktur der untersuchten proben ab. Anhand von Polyamid‐, Polyester‐ und Polyacrylnitrilfasern wurde der Einfluß dieser Parameter untersucht. Dabei zeigte sich (a), daß es nicht möglich ist, mit Hilfe der elektroosmotischen Methode die echten Werte des Zeta‐Potentials festzustellen und (b), daß für einen relativen Vergleich des Zeta‐Potentials verschiedener Fasern diese Einflüsse nicht bestimmt werden müssen.
Effect of various epoxy fortifiers on the reactivity in curing of epoxy resins
Authors: Patel Rasmika H. , Patel Ranjan G.
Published: April 2003

Diglycidyl ether of ethylene glycol was prepared and used as a reactive diluent in the curing of an epoxy resin, based on diglycidyl ether of bisphenol A. Effect of different fortifiers on the curing reaction of the resin‐diluent system has been investigated using differential scanning calorimetry. The dynamic scans were analyzed using four different relations to evaluate the kinetic parameters, the activation energy and the order of the reaction. The reactions are found to follow first order kinetics with an activation energy in the range of 36 – 84 kJ mol‐1.
Organic solvent treatment of isotactic polypropylene films, 2. Temperature dependence of proton spin‐lattice and spin‐spin relaxation times of the sample treated with tetrachloroethylene
Authors: Tanaka Hiroshi
Published: April 2003

The structural properties of isotactic polypropylene films treated with tetrachloroethylene at high temperatures were characterized by proton spin‐lattice T1 and spin‐spin T2 relaxation times, loss in weight, crystallinity, molecular weight, and melting temperature, and heat of fusion. Two kinds of samples, a quenched and an annealed sample, were employed. There are a considerable loss in weight and large increases in crystallinity and in molecular weight when treated the sample at high temperatures especially in the quenched one. These morphological changes result in a shift of T1 minimum to high temperatures and a decrease in T2a. The effects of the solvent on the annealed sample are qualitatively the same for the quenched one but are relatively mild.
Viscosity‐index and polymer rheology. Comparison of concepts by means of experiments with some of the technically most important systems
Authors: Maderek E. , Wolf B. A.
Published: April 2003

Poly(n‐decyl methacrylate), a statistical copolymer of ethylene and propylene, and a diblock copolymer of styrene and hydrogenated butadiene were studied as representatives of various kinds of viscosity‐index (VI) improvers. Essomarcol 52 and AF 1 from Schindler served as base‐oils, toluene and 1‐phenyl dodecane were also studied. By means of viscosity measurements in the temperature interval from 37.8 to 98.9°C up to a concentration of typically 1 wt.‐% polymer, the viscosity indices of the different systems and the corresponding intrinsic viscosities, Huggins coefficients, and activation energies of flow, E≠, were determined. The discussion of the obtained experimental material demonstrates that the VI of a base‐oil can be raised in two clearly distinguishable ways: (i) via an increase in the viscosity due to the mere presence of the polymer, without a change in E≠ and (ii), less general, via an additional reduction of E≠ as a consequence of thermodynamic interactions. Formulae are given from which these two contributions can be calculated.
Celluloseaustauscher mit glyoxal‐bis‐(2‐mercaptoanil) als ankergruppe für die abtrennung von silber, gold und quecksilber
Authors: Hofmann B. , Lieser K. H.
Published: April 2003

Die Verteilungskoeffizienten von Ag+, Au3+ und Hg2+ and dem Celluloseaustauscher mit Glyoxal‐bis‐(2‐mercaptoanil) als Ankergruppe werden als Funktion des pH‐Wertes in 0,1 M NaNO3 als Grundlösung und unter Zusatz von NaCl, NH4NO3, Na2S2O3 und NaCN bestimmt. Ag+‐Ionen werden mit verhältnismäßig hohen Verteilungskoeffizienten gebunden, auch in Gegenwart von NH4NO3. Sogar in Gegenwart von Na2S2O3 liegen die Verteilungskoeffizienten noch in der Größenordnung von 102 ml/g. Au und Hg werden aus 0,1 M NaNO3 mit Verteilungskoeffizienten von etwa 5 · 103 bzw. etwa 103 ml/g gebunden, während in Gegenwart von 0,5 M NaCl und von NaCN die Verteilungskoeffizienten deutlich niedrigersind.
Biocide polymers, 19. Modification of carboxyl groups containing resins with 3(5)‐methylpyrazole
Authors: Hartmann Manfred , Wermann Kurt , Claußen Frank , Schwachula Gerhard , Feistel Lothar , Krauß Dieter
Published: April 2003

Polymeric inhibitors of nitrification have been prepared by reversible attachment of 3(5)‐methylpyrazole to poly(acrylic acid‐co‐divinylbenzene) and poly(4‐vinylbenzoic acid‐co‐divinylbenzene) containing 86 mol‐% and 88 mol‐% carboxyl groups, respectively.

Pyrazolide bonds between the bioactive agent and crosslinked copolymers were formed by means of aminolysis of reactive derivatives of the resins containing mixed anhydride groups or acid chloride groups. The modified resins had pendantly bound 3(5)‐methylpyrazole residues in the range of 7 to 36.4 wt.‐% and were subjected to hydrolysis in order to study the influence of crosslinking on the release rate of the active ingredient. The results obtained were discussed.
Coupling particle size distribution technique. A new ultracentrifuge technique for determination of the particle size distribution of extremely broad distributed dispersions
Authors: Mächtle Walter
Published: April 2003

The particle size distribution (PSD) of extremely broad distributed dispersions (diameter range 20 < D < 2000 nm) is not possible to be measured by analytical ultracentrifuge (AUC) using the standard technique, i.e. measuring turbidity τ at a single concentration c, because the specific turbidity τ/c varies too much between very small and very large particles. To solve this problem we have developed a new AUC technique, the so‐called Coupling‐PSD‐Technique. Here two different concentrations of the same dispersion are measured simultaneously by one single AUC run with two corresponding curves of light intensity I vs. time t being registered. At a low standard concentration cs, mainly the larger particles are detected, while at a concentration ch 5 to 30 times higher mainly the smaller particles are registered. Both I(t)‐curves are coupled mathematically and transformed into the requested broad distribution curve employing Stokes' law and Mie's light scattering theory for homogeneous isotropic spheres.

We use an AUC together with an 8‐cells‐rotor and a multiplexer. Because very large and very small particles are to be measured simultaneously in one single run, we can no more apply a constant rotor speed N as before, but by means of a time program N(t) we always have to increase the rotor speed from 0 to 40000 rpm within one hour.
Block‐ und Propfcopolymere als Verträglichkeitsvermittler in Polymermischungen
Authors: Lausberg Dietrich , Mühlbach Klaus , Taubitz Christof
Published: April 2003

Zwei chemisch verschiedene Polymere sind im allgemeinen unverträglich, d. h. sie weisen eine hohe Oberflächenspannung und geringe Grenzflächenhaftung auf. Block‐und Pfropfcopolymere können diese unerwünschten Effekte stark verringern. Ein Konzept für Verträglichkeitsvermittler mit chemisch identischen und chemisch unterschiedlichen, aber thermodynamisch mischbaren Blöcken wird vorgestellt. Am System Poly[oxy(1,4‐phenylen)]/Poly(styrol‐co‐acrylnitril) (PPE/PSAN) werden alle möglichen Varianten — identisch‐identisch, identisch‐mischbar und mischbar‐mischbar — getestet. Die Ergebnisse werden diskutiert.
Estimation of polymer fractionation efficiency by comparison of theoretical models and experimental molecular mass distribution
Authors: Mencer Helena J. , Gomzi Zoran
Published: April 2003

In this paper the efficiency of a new modified column fractionation method was presented through the comparison of theoretical models and experimentally obtained molecular mass distribution. Five theoretical functions were used for fitting the experimental data: log‐normal, Tung, Schulz, polynomial, and Flory distribution function. The curve fittings were estimated by the mean square deviation. The mean square deviations in all the theoretical models were of the same order. The least values of mean square deviation and consequentely the best fitting of the gel permeation chromatography (GPC) distribution curve, which deals as a true distribution of the applied polymer sample, were achieved with polynomial and Flory model. These theoretical models were further chosen as a reference distribution function. The experimental fractionation data in two quite different solvent pairs were afterwards fitted to the chosen referent models. Fractionation data of the both applied solvent pairs have been in close agreement with Flory and polynomial model. This confirms the high efficiency of the proposed fractionation method.
Studies on the enhancement of separation characteristics of sulfonated poly(phenylene oxide)/polysulfone thin film composite membranes for reverse osmosis applications. I. Effect of chemical treatment
Authors: Agarwal A. K. , Huang R. Y. M.
Published: April 2003

The effect of chemical treatment on the reverse osmosis (RO) separation characteristics of sulfonated poly(phenylene oxide) (SPPO) thin film composite membranes was investigated. The effects of the concentrations of aqueous solutions of formaldehyde, sulfuric acid, hydrochloric acid, phosphoric acid, sodium hydroxide, and treatment time on the RO separation characteristics of the composite membranes with ion exchange capacity (IEC) of 2.14 and 2.50 meq/g in various combinations are reported in detail. The results indicate some enhancement in RO separation characteristics of the SPPO/polysulfone (PS) composite membrane under the best conditions of the chemical treatment.
Studies on the enhancement of separation characteristics of sulfonated poly(phenylene oxide)/polysulfone thin film composite membranes for reverse osmosis applications. II. Effects of nitromethane and the chemical treatment combined with gamma‐ray irradiation
Authors: Agarwal A. K. , Huang R. Y. M.
Published: April 2003

The enhancement effect of the addition of nitromethane into the coating solution of sulfonated sodium poly(phenylene oxide) (SPPONa) polymer for the synthesis of sulfonated poly(phenylene oxide)/polysulfone (SPPO/PS) thin film composite membranes on reverse osmosis (RO) separation characteristic was studied. The effect of gamma‐ray irradiation on the SPPO/PS thin film composite membranes was also evaluated when the membrane samples were in the wet and dry conditions. The composite membranes were also subjected to a chemical treatment combined with gamma‐ray irradiation in both wet and dry conditions in the hope of obtaining the maximum possible enhancement under each treatment. However, the experimental data of this combined treatment indicated the possibility of some degradation of the SPPO/PS composite membranes.
Modification of epoxy resins with acrylic rubbers containing a pendant epoxy group
Authors: Tomoi Masao , Yamazaki Hideo , Akada Hiroyuki , Kakiuchi Hiroshi
Published: April 2003

New acrylic rubbers with a pendant epoxy group were prepared by copolymerization of butyl acrylate (BA) with vinylbenzyl glycidyl ether (VBGE). The modification of an epoxy system (bisphenol‐A diglycidyl ether/p,p′‐diaminodiphenyl sulfone) with the acrylic rubbers was carried out in order to increase the toughness of the cured epoxy resin. The addition of 20 wt.‐% of the copolymer containing 74% of BA and 26% of VBGE units resulted in a 30% increase in the fracture toughness (KIC) of the cured resin at minimal expenses of strength and modulus of the resin. The modified epoxy resin had two‐phase morphology in which the rubber particles with average diameter of 2 μm are dispersed in the epoxy matrix. The copolymer without the pendant epoxy group, prepared from BA and vinylbenzyl methoxyethyl ether, was ineffective as a modifier, indicating that the reaction of the pendant epoxide with the epoxy matrix resulted in good interfacial adhesion between the rubber particles and the matrix, and in the increased toughness. The epoxide‐containing copolymers with 55 or 86% of BA units were also insufficient modifiers. The addition of the former yielded cured resins with homogeneous structure, whereas that of the latter resulted in macroscopic phase separation between the rubber and the epoxy resin.
Polyurethane ionomers: Effects of emulsification on properties of toluene diisocyanate based polyether polyurethane cationomers
Authors: Chan Wu‐Chung , Chen Show‐An
Published: April 2003

Toluene diisocyanate based polyether polyurethane cationomer solutions are prepared and then emulsified by adding water. Properties of films cast from the solutions and emulsions are studied using infrared spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, wide‐angle X‐ray diffraction, and tensileelongation testing. It is found that the use of the asymmetric chain extender, N‐methyl‐diethanolamine, also leads to a polyurethane (PU) with detectable order in the hard domains as in the PU with symmetric chain extender such as 1,4‐butandiol. After quaternization with glycolic acid, the PU cationomers have increased elongation and tensile strength and modulus. These can be attributed to the proper Coulomb interaction between two neighboring hard segments. The emulsification of the PU ionomer solution results in an increased mixing between the soft segments and the hard segments with asymmetric 2,4‐urethane isomers originally located in the hard domains, and therefore make the hard domains containing a higher concentration of symmetric 2,6‐isomer. The hard domains then become more ordered. Such increased order and phase mixing leads to an increase of the three tensile properties. During the emulsification conductivity and viscosity variations show that water is firstly adsorbed on the surface of the hard segment microionic lattices and then enters into the disordered and ordered hard domains successively.
Nonlinear programming methods to determine surface free energy components of polymers using harmonic mean approximation
Authors: Erbil H. Yildirim , Meriç R. Alsan
Published: April 2003

The dispersion and polar surface free energy components, γ and γ, and the critical surface free energy, γc, of polymers were determined from contact angle data by the application of a nonlinear programming method using harmonic mean approximation.

The surface free energy components of the probe liquids, γ and γ, which reflect the conditions of the maximized interaction parameter, Φ, were also simultaneously determined by this method.
Excimer formation in solution and molecular aggregation of polyethersulfone
Authors: Wu Zhongwen , Zhang Luifang , We Qingyang , Yosomiya Ryutoku
Published: April 2003

Formation of intermolecular excimers in polyethersulfone (PES) dichloromethane solutions were observed at a PES concentration about 2.7 × 10−2 mol/l by the fluorescence analysis. External light energy irradiation enabled the formation of intramolecular excimers in the PES dichloromethane solution. These chains can gain an access to each other in parallel though the molecular chains are considerably rigid. The electron micrograph of the PES film, heat treated at 200°C for 72 hours, presented a diffraction micrograph, which suggests that the PES molecular aggregation is changed from a randomly coiled amorphous phase to an ordered one.
Poly(N‐vinylpyrrolidone‐co‐styrene)s: Extraordinary catalysts in two‐phase reactions
Authors: Kondo Shuji , Ozeki Masashi , Nakashima Nobuo , Suzuki Kenji , Tsuda Kazuichi
Published: April 2003

Poly(N‐vinylpyrrolidone‐co‐styrene)s possess extaordinary activity as catalysts for several substitution reactions in organic‐aqueous two‐phase systems, although the monomeric analogue does not show this catalytic effect. The catalytic activity is affected remarkably by the composition of copolymer, indicating the importance of hydrophobic environment around the active site. It was also found that poly(N‐vinylpyrrolidone‐co‐styrene)s employed here extract potassium ions more effectively than the monomeric analogue and the extraction ability increases with increasing density of the pyrrolidone unit. It is reasonable therefore to assume that the catalytic activity is caused by both effects, cation extraction ability by the polymer and activation of anions by desolvation in hydrophobic region of polymers. Insoluble polymers, poly(N‐vinylpyrrolidone‐co‐styrene)s crosslinked by divinylbenzene also exhibit high activity as phase transfer catalysts.
Kurzmitteilung zum Mechanismus der Spannungsübertragung in eigenfaserverstärkten Kunststoffen
Authors: Wenig Werner , Schöller Thomas
Published: April 2003

An aus der orientierten Schmelze kristallisierten, eigenfaserverstärkten Polymerlegierungen aus isotaktischem Polypropylen (iPP) und isotaktischem Poly(1‐buten) (PB‐1) wurden mechanische Parameter (E‐Modul, Fließspannung) gemessen und mit aus äquatorialen Röntgenkleinwinkelstreukurven bestimmten lateralen Grenzschichtdicken korreliert. Die Kurvenverläufe von E‐Modul, Fließspannung und Grenzschichtdicke als Funktion der Komponentenzusammensetzung stimmen qualitativ überein. Es wird gezeigt, daß die Morphologie der Grenzschicht von besonderer Bedeutung für die Übertragung der Spannungen von der Matrix auf die Fasern ist.
Effect of thermal history on crystallization behavior of polyetheretherketone studied by differential scanning calorimetry
Authors: Wu Zhungwen , Zheng Yu Bin , Yu Hong Xe , Seki Miharu , Yosomiya Ryutoku
Published: April 2003

The crystallization behavior of polyetheretherketone (PEEK) was investigated by differential scanning calorimetry (DSC). The glass transition temperature of PEEK shifts to higher temperatures with an increase in crystallinity. Heat‐treated PEEK showed double peaks in their DSC curves, which is a characteristic phenomenon of PEEK. These double peaks were caused by the formation of incomplete crystal structures according to the conditions of heat‐treatment.
Styrene divinylbenzene copolymers. Influence of diluent mixture on matrix structure
Authors: Poinescu I. C. , Beldie C.
Published: April 2003

In order to prepare porous beads with good characteristics mixtures of diluents were used. The influence of the δ‐parameter values of the two diluents was investigated which constitute the mixture of diluents on the macroporous features.

The influence of the mixtures of 2‐ethyl hexyl alcohol/polystyrene (M̄w = 172000), 2‐ethyl hexyl alcohol/toluene, and gasoline (bp 110–125°C)/polystyrene on the styrene‐divinylbenzene macroporous copolymer features was investigated. It was found that the specific surface areas or the porosities of the macroporous copolymers were very sensitive to the modifications of the δ‐parameter values and the monomer composition.
Ein modell zur quantitativen beschreibung der morphogenesis von PVC‐S, I. Modellierung der inneren morphologie — wissensstand
Authors: Weickert Günter , Klodt Rolf‐Dieter , Platzer Bernd , Weißenborn Klaus‐Dieter , Henschel Ines
Published: April 2003

Die morphologischen Eigenschaften von PVC‐S‐Pulver (Teilchengrößenverteilung, Schüttdichte, Porosität u. a.) beeinflussen maßgeblich seine Verarbeitungseigenschaften. Das Ziel des ersten Teiles der vorliegenden Arbeit besteht in der kritischen Bewertung wesentlicher Ergebnisse des in der Fachliteratur publizierten Erkenntnisstandes zum PVC‐Kornbildungsprozeß. Einige Autoren untersuchen chemische und physikalische Details dieses Prozesses, während andere Autoren einfache mathematische Modelle zur Pulvercharakterisierung ableiten. Für den praktisch arbeitenden Ingenieur ist jedoch ein Mangel an Informationen zur Modellierung der Morphogenesis von PVC‐S nicht zu übersehen.

Die PVC‐S‐Morphogenesis wird als 6‐Stufen‐Prozeß detailliert betrachtet, wobei bisherige Modellvorstellungen ergänzt werden.

In den nächsten Teilen dieser Arbeit wird ein praktikables neues Modell zur Berechnung der Größe und Zahl der Teilchen von den Mikrodomänen bis zu den Agglomeraten in den Monomertropfen abgeleitet.
Some aspects of graft copolymerization on holocellulose
Authors: Okieimen Felix , Idehen Kevin
Published: April 2003

Graft copolymers of acrylonitrile and methyl methacrylate on unmodified holocellulose and holocellulose containing between 0.3 and 4.6% thiol groups were prepared by the use of Ce4 + initiator in aqueous medium at 29°C. It was found that although the extent of graft polymer formation on the holocellulose was appreciably reduced by the presence of thiol groups, thiolation showed little influence on the frequency of grafting. The molecular weight of grafted PMMA chains was higher than for PAN grafts; but the latter were more frequently grafted on the backbone polymer. The observed low frequency of grafting is thought to indicate that radicals formed on the cellulosic substrate may not be very reactive towards graft polymer formation.
Effect of thermal history on the crystallization behaviour of polyetheretherketone by the dynamic viscoelastometer
Authors: Wu Zhungwen , Zheng Yu Bin , Ni Zhuo , Nakamura Tomoki , Yosomiya Ryutoku
Published: April 2003

The effect of thermal history on the crystallization behaviour of PEEK is investigated by the dynamic viscoelastometer. The crystallization behaviour of PEEK shows significant influence on the α peak in the tan δ and the storage modulus. The α peak temperature is rapidly increased at shorter times with the annealing temperature at 160°C or higher, and is then constant. The storage modulus is more gently reduced in the α transition region as the annealing temperature is higher, and becomes then a constant value. It is suggested that the reduction in the storage modulus corresponds to some defect in the crystal structure of PEEK.
Effect of the viscosity of components on the phase structure and impact strength of polypropylene/ethylene‐propylene elastomer blends
Authors: Fortelný Ivan , Kamenická Danuše , Kovář Josef
Published: April 2003

The concentration dependences of particle size of the dispersed phase on rheological properties of the components were investigated by scanning electron microscopy for blends of polypropylene and ethylene‐propylene elastomers obtained by melt mixing. At very low concentrations the minority component is dispersed the more finely the lower its viscosity is. With increasing concentration of the dispersed phase the size of its particles in the given matrix increases the more quickly the lower the viscosity of the dispersed phase is.

With increasing viscosity of the matrix the particle size of the minority phase decreases at all compositions of the blend. The results obtained were interpreted as a result of dynamic equilibrium between the break up and coalescence of particles in flow. At elastomer concentrations higher than 15% the differences between impact strength values of the blends are determined by the size of inclusions of the elastomeric modifier. Dispersions finer than the optimal one with respect to impact strength can be reached only with the polypropylene matrix possessing high viscosity.
The mechanism and kinetics of reactions in the initial stage of thermally initiated oxidation of caprolactam
Authors: Lánská B. , Šebenda J.
Published: April 2003

In the induction period of the autocatalytic, thermally initiated oxidation of caprolactam (90–155°C) the role of the catalyst is played by the primary oxidation product, caprolactam hydroperoxide.

With increasing concentration of hydroperoxide the probability of its association by hydrogen bonds to a dimer also increases. This dimer is cleaved by a somewhat different mechanism than the monomeric form, or its associate with caprolactam; the oxidation of caprolactam assumes a stationary rate, with adipimide as the oxidation product. Its presence by no means affects the further oxidation course and adipimide alone is neither oxidized nor hydrolyzed.

Similarly to the oxidation of N‐alkyl amides, carboxylic groups arise in the oxidation of caprolactam via an alkoxy radical formed by the homolysis of hydroperoxide. We found that the carboxylic groups are formed autocatalytically due to their cooperative effect in the decomposition of caprolactam hydroperoxide into adipic acid monoamide. With increasing concentration of carboxyl groups the rate of this decomposition increases so much that adipic acid monoamide becomes the predominant oxidation product. The rate of radical homolysis of hydroperoxide, i.e. of the initiation reaction and of the oxidation in general, also decreases.

Consequently, the effect of carboxylic groups on the rate of oxidation of caprolactam is an inhibiting one. The reactions mentioned above describe the thermally initiated oxidation of caprolactam to the stage which corresponds to the conversion of 2% of caprolactam.
Systematic study of ion‐exchange properties and ligating behaviour of respropiophenone‐formaldehyde copolymers
Authors: Patel B. K. , Patel M. M.
Published: April 2003

Respropiophenone‐formaldehyde copolymers (RPP‐F) were synthezised by the condensation of 2,4‐dihydroxypropiophenone (respropiophenone (RPP)) and formaldehyde (F) in the presence of NaOH or H2SO4 as catalyst with varied molar ratios of reacting monomers. The copolymers were characterized by elemental analysis, IR spectra, viscosity, and TGA studies. Their M̄n was determined by nonaqueous conductometric titrations and vapour pressure osmometry (VPO). Chelation ion‐exchange properties have also been studied employing the batch equilibration method. Polychelates of Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(II), and UO2(II) with RPP‐F‐AI copolymer were prepared. The analytical data agree with 1 : 2 metal‐ligand stoichiometry. Elemental analysis, magnetic, spectral, and thermal properties of polychelates have been studied and probable structures are assigned to the polychelates. All the polychelates are amorphous powders, insoluble in common organic solvents.
Blends of chlorinated isotactic polypropylene with poly(ethylene‐co‐vinyl acetate) II. Phase studies of the miscible blends
Authors: Lee Seung Soo , Chung Ki‐Hyun , Kim Kwang Soo , Jung Jin Chul
Published: April 2003

By measuring Tg, Tm and Tc (cloud point) phase diagrams for the four miscible blends of chlorinated isotactic polypropylenes (chlorine content 39.2 (CPP‐40) and 49.8 wt.‐% (CP‐50)) with Poly(ethylene‐co‐vinyl acetate)s (vinyl acetate contents 40 (EVA‐40) and 45 wt.‐% (EVA‐45)) were investigated. The blend of CPP‐50 with EVA‐40 was the most compatible of the four blend pairs.
Radical concentration and efficiency of secondary photochemical reactions in modified polystyrene
Authors: Kamińska A. , Kaczmarek H.
Published: April 2003

The influence of acrylonitrile‐butadiene‐styrene‐terpolymer (ABS) and methyl methacrylate‐butadiene‐styrene‐terpolymer (MBS) modifying the polystyrene (PS) films on its resistance to UV radiation were investigated.

On the basis of the results of ESR, IR, UV, mass spectroscopy, viscosimetric and solubility measurements it was found that 3% of ABS or MBS in polystyrene films have a clear influence on the course of photochemical processes. After UV‐irradiation of the samples, at the presence of this terpolymers, a greater concentration of free radicals with shorter half‐life times was observed.

Both terpolymers increase the productivity of photooxydation of polystyrene as well as its crosslinking and decrease its dehydrogenation.
The hydrogenation of HO‐terminated telechelic polybutadienes in the presence of a homogeneous hydrogenation catalyst based on tris(triphenylphosphine)rhodium chloride
Authors: Bouchal Karel , Ilavský Michal , Žůková Eva
Published: April 2003

The hydrogenation kinetics of multiple bonds in HO‐terminated telechelic polybutadienes was investigated using two types of these prepolymers prepared by the anionic and radical polymerization. The rate of addition of hydrogen to the π‐bonds of these polydienes in the presence of tris(triphenylphosphine) rhodium chloride as a homogeneous hydrogenation catalyst was determined by the chemical structures of the starting polydienes, their concentration in the solvent, the partial hydrogen pressure, the concentration of the catalyst, and the temperature.

The effect of kinetic parameters given above on the rate of hydrogenation reaction can be interpreted in the sense of Wilkinson's reaction mechanism of the hydrogenation of alkenes in the presence of the Rh(I)‐complex. Due to the predominant 1,2‐structural units, the anionic prepolymer reacted twice as quickly with hydrogen (k = 0.093 mol−1 dm3 s−1) compared with the radical prepolymer (k = 0.045 mol−1 dm3 s−1). During the hydrogenation of multiple bonds there is a partial loss of hydroxy groups in modified telechelic prepolymers; the extent of this reaction depends on reaction conditions of the hydrogenation reaction.
Structure and molecular dynamics of highly mobile polymer membranes
Authors: Fahmy Tarek , Wesser Joachim , Spiess Hans Wolfgang
Published: April 2003

The function of lipid bilayer membranes crucially depends on their mobility and their ability to incorporate components that, e.g., can change molecular order and dynamics or form channels. Since polymerization increases the stability of model membranes at the expense of their mobility a compromise must be sought. Therefore, the effect of different polymerization schemes on the structure and dynamics of polymer membranes has to be checked. To this end X‐ray scattering, DSC‐thermal analysis and a variety of spectroscopic techniques probing the dynamics on largely different time‐‐‐ and length scales were employed, i.e. 2H‐NMR, ESR, fluorescense anisotropy and FRAP. These studies showed that in model membranes polymerized in the hydrophylic region the head group mobility can be controlled by the length and the nature of the spacer connecting it to the polymer backbone. The head group region is much less affected, if the polymerization is achieved in the hydrophobic region. By use of a lipid analogue carrying a polymerizable group on only one of its two alkyl chains, membranes retaining high mobility in the hydrophobic region can be generated. Typical membrane constituents, i.e. cholesterol, gramicidin and ubiquinone can be incorporated and the mixtures show a behaviour similar to natural model membranes, although lateral diffusion of the lipids is frozen as a consequence of the polymerization.