bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and properties of acrylonitrile–EPDM–N‐vinylcarbazole graft terpolymer
Authors: Seo Beom‐Doo , Park Duck‐Jei , Ha Chang‐Sik , Cho Won‐Jei
Published: April 2003

A graft terpolymer of acrylonitrile (AN) and N‐vinylcarbazole (NVC) onto ethylene–propylene–diene terpolymer (EPDM) was synthesized in toluene using benzoyl peroxide. The effects of EPDM content, mole ratio of NVC to AN, reaction time, reaction temperature, and initiator concentration in the graft copolymerization were examined. The synthesized AN–EPDM–NVC graft terpolymers (AEVC) were identified by infrared (IR) and 1H‐NMR (nuclear magnetic resonance) spectra. The thermal stability, tensile strength, and light resistance of AEVC were investigated by using a Fade‐o‐Meter, thermogravimetric analyzer, and tensile tester. It was found that the heat resistance of AEVC is considerably better than that of acrylonitrile–butadiene–styrene (ABS) copolymer. © 1995 John Wiley & Sons, Inc.
Preparation and characterization of cellulose acetate organic/inorganic hybrid films
Authors: Shojaie Saeed S. , Rials Timothy G. , Kelley Stephen S.
Published: April 2003

A series of organic/inorganic hybrid (OIH) films were prepared using cellulose acetate (CA) as the organic component and tetraethyl orthosilicate (TEOS) as the inorganic component. The chemical, morphological, and mechanical properties of these films were evaluated with a variety of analytical techniques. The results of these evaluations showed that crosslinked CA OIH films were formed during the sol‐gel reactions. The structure of OIH films was very sensitive to the CA/TEOS ratio and film formation conditions. All of the films with added TEOS were two phase on a molecular level, i.e., inorganic TEOS domains surrounded by a CA matrix. Under some film formation conditions the presence of TEOS, a nonsolvent for CA, led to solvent/nonsolvent phase separation on the micron scale. © 1995 John Wiley & Sons, Inc.
Influence of pentaerythritol triacrylate acrylic carrier swelling on immobilization of enzymes
Authors: Kolarz B. N. , Wojaczyńska M. , Bryjak J. , Łobarzewski J. , Pawłów B.
Published: April 2003

Suspension copolymerization and modification of pentaerythritol triacrylate (PENTA)–butyl acrylate (BA) matrices with ethylenediamine (EtDA) are discussed. It is shown that aminolysis in water solution offers gel structure carriers with small pore radii (about 3 nm). These carriers are characterized by the high swelling and sharp correlation between the pH value and the specific volume. The enzymes (acylase, glucoamylase, and peroxydase) are immobilized by means of the glutaraldehyde method. The best matrix seems to be copolymers modified in a 95% solution of ethylenediamine in water. Preparations do not lose activity after 1 month storage at 4°C. © 1995 John Wiley & Sons, Inc.
Application of syndiotacticity‐rich PVA hydrogels to drug delivery system
Authors: Horiike S. , Matsuzawa S.
Published: April 2003

The preparation of stable syndiotacticity‐rich poly(vinyl alcohol) (s‐PVA) hydrogels is easier in comparison with that of the atactic poly(vinyl alcohol) (a‐PVA) hydrogels. The drug release with use of s‐PVA hydrogels containing indomethacin of 1.5 mg/mL buffer, solution was studied under several conditions: at the gelation temperatures of 20–30°C, the release temperatures of 27–47°C, and pHs of phosphate buffer solutions of 6.6–7.4, for the gels with the concentrations of PVA of 3–8% using the degree of polymerization of 2170–4380. Indomethacin has been released spending 14 h. The diffusion exponents were 0.45–0.50, corresponding to Fickian diffusion. © 1995 John Wiley & Sons, Inc.
Morphology of microporous neosepta ion‐exchange membranes and its effect on separation of biological mixtures
Authors: Tishchenko Galina , Bleha Miroslav , S̆kvor Jir̆í , Bures̆ Ladislav , Mizutani Yukio , Ohmura Nobuhiko
Published: April 2003

Specially prepared microporous Neosepta ion‐exchange membranes were investigated to establish a correlation between their structural characteristics (pore‐size distribution, porosity) and permeability to components of immunoglobulin (Ig) fractions of mouse ascitic fluids. The solutions to be separated contained IgG1 with specificity to horseradish peroxidase or to the heavy chain of human IgM, some other proteins, and a large amount of ammonium sulfate (0.22–0.35M). Analysis of the membrane morphology carried out by scanning electron microscopy and mercury porosimetry showed that the membranes possess a polymodal pore‐size distribution. There are large open pores (400–600 and 200–300 nm in diameter) on the membrane surfaces, but the void volume of the membranes is a system of connected pores of smaller diameters (from 60–100 to 7–10 nm). The main part of the pores in the membranes displaying the best separation ability was 8–17 nm in diameter. It was found that highly porous charged membranes (relative porosity 58–60%) with low ion‐exchange capacity (0.02–0.1 meq/g) made it possible to achieve the desired desalination degree of protein mixture (80–83%) within 5–7 h instead of 5 days needed in the traditional dialysis. Moreover, the amount of separated accompanying proteins reached 25–30% depending on membrane porosity and the quality of specific IgG1 was considerably improved. © 1995 John Wiley & Sons, Inc.
Rheological measurements: Some basic yet vital considerations
Authors: Bafna Sudhir S.
Published: April 2003

This article addresses a seemingly trivial question—“Based on rheological measurements, when are two samples different beyond experimental error?”—and proceeds to give a nontrivial answer. The preferred answer requires the application of t statistics to multiple measurements on each sample. The larger the number of multiple measurements made, the lower is the uncertainty in conclusively discriminating between two samples. However, such multiple measurements on every sample are seldom feasible in real life and then it becomes necessary to resort to the use of Z statistics. A stepwise procedure for the application of both, t and Z statistics is given. Knowledge of the measurement precision is a prerequisite for scientifically answering this seemingly trivial question. Hence, the precision of capillary rheometry measurements (apparent viscosity, extrudate swell ratio, and entrance pressure loss) is discussed in detail. The precision of these capillary rheometry measurements improves as the magnitude of the variable measured (force/pressure or swell) increases. This implies that the precision of capillary rheometry measurements can be improved by lowering the experimental temperature. Extensive numerical data on various high‐density polyethylenes generated using two different capillary rehometers are given and are compared with the ASTM round‐robin data. © 1995 John Wiley & Sons, Inc.
Grafting of acrylonitrile onto styrene‐maleic acid copolymer by tetravalent cerium ion
Authors: Vora R. A. , Trivedi H. C. , Patel C. P. , Trivedi M. C.
Published: April 2003

The graft copolymerization of acrylonitrile (AN) onto a styrene‐maleic acid copolymer (SY‐MAc) with ceric ammonium nitrate (CAN) as a redox initiator in an aqueous medium has been studied. The effects of various reaction parameters, including reaction time and temperature, concentrations of initiator, nitric acid, and monomer, on the grafting yields and the rates of polymerization (Rp), graft copolymerization (Rg), and homopolymerization (Rh) were studied systematically. The results are discussed. The kinetic scheme of free‐radical graft copolymerization has been proposed and the equations relating the values of Rp, Rg, and Rh are also suggested. The experimental results are found to be in good agreement with the proposed kinetic scheme. The activation energies of graft copolymerization and total polymerization are calculated. © 1995 John Wiley & Sons, Inc.
Oxygen barrier properties of polypropylene/polyamide 6 blends
Authors: Holsti‐Miettinen R. M. , Perttilä K. P. , Seppälä J. V. , Heino M. T.
Published: April 2003

Effects of composition, compatibilization, and blending procedure on oxygen barrier properties of injection‐molded polypropylene/polyamide 6 blends were investigated. The main attention was paid to the relationships between oxygen permeability, mechanical properties, and blend morphology. The effect of the polypropylene/polyamide 6 ratio was evident in blends with a homogeneous dispersion type of morphology. After the phase inversion, when polyamide became the continuous phase, the barrier properties of the blends were significantly improved and approached those of polyamide 6. Increasing the amount of the compatibilizer, maleic anhydride grafted polypropylene, was found to increase the permeability of the blend. The blending procedure had a significant effect on the permeability of the blends. The injection‐molded blend exhibited a laminar type of morphology when polyamide 6 and the compatibilizer were preblended in a twin‐screw extruder, and polypropylene was added later as a dry‐blend before injection molding. The dispersed polyamide phase formed thin elongated platelets in the polypropylene matrix. This laminar morphology resulted in significant improvement of oxygen barrier properties approaching the level of the theoretical values calculated for corresponding coextruded structures. Moreover, both the tensile and impact properties of this particular blend were exceptionally good. © 1995 John Wiley & Sons, Inc.
An advanced computer algorithm for determining morphology development in latex particles
Authors: Durant Yvon G. , Sundberg Donald C.
Published: April 2003

A new algorithm is presented for the prediction of equilibrium morphology in latex particles. Thermodynamic equilibrium calculations of the interfacial free energies associated with a large array of possible morphologies serve to create a continuous free‐energy surface upon which the preferred morphology is located. When the computations are performed on a 486DX33 PC, the calculations are essentially instantaneous. The graphical output can be refreshed on the monitor screen in less than 2 s. The algorithm is applied to simulate the conversion‐dependent morphology for several latex systems composed of polystyrene and poly(methyl methacrylate) and two very different surfactants. © 1995 John Wiley & Sons, Inc.
Gelation of poly(vinyl alcohol)/phenol/water solutions and gel spinning
Authors: Yamaura Kazuo , Suzuki Masayoshi , Yamamoto Minako , Shimada Rumi , Tanigami Tetsuya
Published: April 2003

The light transmittance of the gels of poly(vinyl alcohol) (PVA)/phenol/water solutions was examined for the entire range of phenol/water content. Excellent transparency was found for the gels with phenol contents of 70–95 vol %. In full consideration of the results for the transparency and melting temperature of the gels and the viscosity and gelation ability of solutions, the PVA solutions of 75 vol % phenol content were selected for the gel spinning. The maximum dynamic moduli of drawn filaments at 25°C (room temperature) were 42 GPa (15x) for atactic PVA and 45 GPa (14x) for syndiotacticity‐rich PVA. © 1995 John Wiley & Sons, Inc.
Stability of aqueous solutions of poly[(maleic acid)‐alt‐styrene] sodium salts in the presence of divalent cations
Authors: Jarm V. , SertiĆ S. , Ŝegudović N.
Published: April 2003

The influence of divalent salts (MgCl2, CaCl2, BaCl2) on precipitation of polyelectrolyte, poly[(maleic acid)‐alt‐styrene]sodium salts, NaMA/St, having two degrees of neutralization (100 mass %, 100NaMA/St and 50 mass % 50NaMA/St) from their aqueous solutions, has been investigated. The experiments were performed by variation of the copolymer concentration, cp = 0.005‐0.04M/L, salt concentration, cs = 0.002‐0.4M/L, and temperature, T 298‐333 K. The critical concentrations of salts, csc, used as a measure of solution stability, were determined from turbidimetric measurements, while viscosity and refractive index measurements were used to indicate the changes in dimensions and hydration of polyions, respectively. © 1995 John Wiley & Sons, Inc.
Preparation of ultrahigh molecular weight polyacrylonitrile and its terpolymers
Authors: Zhang C. , Gilbert R. D. , Fornes R. E.
Published: April 2003

The synthesis of high molecular weight (in excess of 106 million Daltons) poly(acrylonitrile) and poly(acrylonitrile‐co‐methylacrylate‐co‐itaconic acid) is described. An inverse emulsion polymerization formulation with AIBN as the initiator was used. However, polymer precipitation occurred early in the polymerization. In each case, the molecular weight distribution was surprisingly narrow (M̄w/M̄n ∼ 1.5). Conversion vs. time plots with monomers containing the inhibitor had the “S” shape typical of emulsion polymerizations. The terpolymer composition and molecular weight were quite uniform throughout the polymerization. With inhibitor‐free monomers, the initial molecular weights were very high (∼ 3 × 106 Daltons), but gelation occurred at ca. 50% conversion. There was an inverse relationship between the monomer inhibitor content and the polymer molecular weight. It is suggested that the growing polymer radicals are occluded in the precipitated polymer particles and are terminated by inhibitor diffusing into the particles, accounting for the narrow molecular weight distribution. © 1995 John Wiley & Sons, Inc.
Sulfur vulcanization of polyisoprene accelerated by benzothiazole derivatives. II. Reaction of 2‐mercaptobenzothiazole and its zinc salt with sulfur and ZnO in polyisoprene
Authors: Gradwell M. H. S. , Mcgill W. J.
Published: April 2003

Compounds of polyisoprene with sulfur and bis(2‐mercaptobenzothiazole)zinc(II) (Zn(mbt)2) or ZnO and 2‐mercaptobenzothiazole (MBT) were vulcanized by heating in a differential scanning calorimeter. The reaction was stopped at points along the thermogram and the product analyzed. ZnO and MBT readily react, the reaction going to completion during compounding. The presence of Zn(mbt)2 delays the onset of crosslinking compared to compounds without zinc. It is suggested that the induction period prior to crosslinking is occasioned by the inactivity of Zn(mbt)2, which must breakdown to MBT before it can participate in the vulcanization process. Such decomposition results from attack by anions generated when polysulfidic crosslinks, formed in the unaccelerated sulfur that occurs in the early stages of crosslinking, undergo scission. The effect of MBT, not bound to zinc, on the mechanism of the reaction is discussed. © 1995 John Wiley & Sons, Inc.
Adsorption behavior of Cu2+ and UO ions on crosslinked poly[2,2‐bis(acrylamido)acetic acid]
Authors: Rivas B. L. , Maturana H. A. , Ocampo X. , Peric I. M.
Published: April 2003

The synthesis of a water‐insoluble metal ion complexing resin was carried out by radical polymerization of 2,2‐bis(acrylamido) acetic acid. The resin was characterized by elemental analyses, FTIR spectroscopy, and thermal analyses. The ability to bind copper(II), iron(II), iron(III), and uranium(VI) as well as the elution of the metal ions from the loaded resins were studied. For uranyl ions, pH 5 was the optimum sorption pH value. Sorption selectivity from the binary mixture Cu(II) + U(VI) was studied at pH 2. The thermal stability is increased by adsorption of UO. According to these results a coordination mechanism is suggested for sorption of copper and uranium. © 1995 John Wiley & Sons, Inc.
Development of poly(vinyl alcohol) hydrogel for waste water cleaning. I. Study of poly(vinyl alcohol) gel as a carrier for immobilizing microorganisms
Authors: Okazaki Masaki , Hamada Tosihiro , Fujii Hiroaki , Mizobe Akio , Matsuzawa Shuji
Published: April 2003

The structures and properties of poly(viny1 alcohol) (PVA) hydrogel prepared by the freezing and thawing method and poly(ethy1ene glycol) and polyacrylamide hydrogels prepared by polymerization were compared in view of immobilizing microorganisms. Observation in a scanning electron microscope and measurement of the physicochemical properties revealed that the frozen PVA gel is superior in water content and oxygen permeability than the other gels. The PVA hydrogel has a high tensile and folding strength and good handleability and processability. The durability against abrasion and chemical resistance of PVA gel were also studied. Activated sludge was immobilized and fixed on PVA gel particles and incubated. This gel had a treating capacity for synthetic sewage of about two to three times that with the standard activated sludge process. © 1995 John Wiley & Sons, Inc.
Multiobjective optimization of an industrial semibatch nylon 6 reactor
Authors: Sareen Rajiv , Gupta Santosh K.
Published: April 2003

Multiobjective Pareto optimal solutions have been generated for three grades of nylon 6 being produced in an industrial semibatch reactor. The optimal operating conditions (called preferred solutions) for these three batches are easy to implement and lead to substantial improvements over current practice. The technique used is quite general and can easily be applied to improve the operation of other industrial polymerization reactors or design better (new) reactors. Good mathematical models, which account for the important physicochemical aspects actually operative in a reactor and which have been tested on industrial data, are a prerequisite for such optimization studies. © 1995 John Wiley & Sons, Inc.
Phagocytosis and peroxidase release by seabream (Sparus aurata L.) leucocytes in response to yeast cells
Authors: Rodríguez Alejandro , Esteban M. Ángeles , Meseguer José
Published: April 2003

A flow cytometric method was adapted to evaluate phagocytosis by gilthead seabream leucocytes after incubation with yeast cells (Saccharomyces cerevisiae). Head‐kidney leucocytes were incubated in vitro for different times in different proportions with heat‐killed fluorescein isothiocyanate (FITC)‐labeled yeast cells to study the kinetics of phagocytosis. Attached and internalized yeast cells were differentiated by quenching FITC‐labeled S. cerevisiae with trypan blue dye. Only internalized cells kept their FITC fluorescence after quenching. Monocyte‐macrophages and acidophilic granulocytes showed phagocytic activity, as demonstrated by transmission electron microscopy (TEM). From the ultrastructural features of the phagocytic process, it was observed that cytoplasmic granule membranes fused with the phagocyte membrane at the point where the yeast cell was attached to the phagocyte surface. This observation led us to adapt a colorimetric method to study peroxidase (myeloperoxidase and eosinophil peroxidase) release, since both are considered to be markers of the degranulation that occurs in seabream head‐kidney leucocytes in response to yeast cells. Head‐kidney leucocytes were incubated with calcium ionophore (CaI), phorbol myristate acetate (PMA), or yeast cells for different periods of time (0–30 min) to study the kinetics of peroxidase release. The results obtained indicate that CaI and yeast cells, but not PMA, stimulate the degranulation (by about 44.51% and 21.04%, respectively, at 30 min) of seabream head‐kidney leucocytes. Anat Rec Part A 272A:415–423, 2003. © 2003 Wiley‐Liss, Inc.
A proposal of monitoring and testing for distributed object oriented systems
Authors: Terashima Yoshiaki , Imai Isao , Shimotsuma Yoshiki , Sato Fumiaki , Mizuno Tadanori
Published: April 2003

Recently, the development of systems consisting of objects developed with different installation methods has been expanding rapidly. In such development, systems become more complicated and reliability is decreased. Hence, it is important as the final stage of testing to verify the behavior of each object during the behavior of the entire system. In this paper, a system functionality test is proposed that evaluates object behavior during an operation without dependence on the installation architecture by using the IDL (Interface Definition Language) for interoperability. First, the weight reduction in the test and the treatment of the object behavior are explained. A test configuration for resolving these and a method of analyzing the trace of the effect and cause of object behavior by message tracing are explained. Also, the practicality of the test is described. It is shown that the individual installation architecture can be concealed in the development flow of the testing environment from the IDL specification. Finally, a quantitative evaluation and discussions are presented and effectiveness of the proposed method is verified. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(10): 33–44, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10059
Efficient representation of short‐time phase based on time‐domain smoothed group delay
Authors: Banno Hideki , Lu Jinlin , Nakamura Satoshi , Shikano Kiyohiro , Kawahara Hideki
Published: April 2003

A method for representing the short‐time phase of speech efficiently is proposed. In this paper, we attempt to represent the short‐time phase using a time‐domain smoothed group delay (TSGD) obtained by scaling the inverse Fourier transformed speech group delay by an appropriate order. The results of tests using segmental SNRs show that information regarding the shapes of waveforms is concentrated at TSGDs of orders less than 100. In addition, subjective evaluation tests show that high‐quality speech almost indistinguishable from the original speech is synthesized when the order of the TSGD is about 30 and the short‐time phase can be represented efficiently by the proposed scheme. In addition, since the proposed scheme also suppresses degradation due to errors associated with speech–no speech decisions, which has been a problem in past analysis‐synthesis schemes, it is considered to be useful in applications such as speech coding and speech quality transformation. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(10): 56–64, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10120
Driver model based on reinforced learning with multiple‐step state estimation
Authors: Koike Yasuharu , Doya Kenji
Published: April 2003

In this study the authors proposed a method for reinforced learning using multistep state estimation based on internal model of control object. It offers a discussion of learning results obtained by application of this model to a vehicle running on a road including various curvatures, for evaluating whether the vehicle would wander off the road. The vehicle's dynamic model acquired by learning was used for estimating rewards and determining the control outputs, based on the estimated states at multiple time intervals. Results of simulation confirmed that safe driving was possible even with road shapes containing nonlearned curvatures and speeds. Since in this control method external information varies depending on the employed control patterns and environmental conditions, it is possible to consider a model with changing view in order to obtain necessary information for driving control. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(10): 85–95, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10123
Inhibition of phosphatidylinositol 3‐kinase signaling negates the growth advantage imparted by a mutant epidermal growth factor receptor on human glioblastoma cells
Authors: Klingler‐Hoffmann Manuela , Bukczynska Patricia , Tiganis Tony
Published: April 2003

In de novo glioblastoma multiforme, loss of the tumour suppressor protein PTEN can coincide with the expression of a naturally occurring mutant epidermal growth factor receptor known as ΔEGFR. ΔEGFR signals constitutively via the phosphatidylinositol 3‐kinase (PI3K)/protein kinase Akt and mitogen‐activated protein kinase pathways. In human U87MG glioblastoma cells that lack PTEN, ΔEGFR expression enhances tumourigenicity by increasing cellular proliferation. Inhibition of PI3K signaling with the pharmacologic inhibitor wortmannin, or by the reconstitution of physiological levels of PTEN to dephosphorylate the lipid products of PI3K, negated the growth advantage imparted by ΔEGFR on U87MG cells. PTEN reconstitution suppressed the elevated PI3K signaling, without affecting mitogen‐activated protein kinase signaling and caused a delay in G1 cell cycle progression that was concomitant with increased cyclin‐dependent protein kinase inhibitor p21CIP1/WAF1 protein levels. Our study provides insight into the mechanism by which ΔEGFR may contribute to glioblastoma development. © 2003 Wiley‐Liss, Inc.
Characterization of proteins by means of flocculation with propanol
Authors: Jirgensons B.
Published: April 2003

The results of this investigation indicate that proteins in solution may be characterized by causing them to flocculate in mixtures of propanol‐water in which the propanol concentration is gradually increased, and other conditions, namely PH, temperature and concentration of the protein are maintained constant. When trubidity is measured and the values are plotted against the concentration of propanol, characteristic curves are obtained which serve as diagnosis of type and homogeneity of the protein. Lysozyme, human and bovine serum albumin and egg albumin, for example, yielded simple flocculation curves; the curve obtained for γ‐globulin had at least one maximum; various samples of Bence‐Jones protein yielded trubidity curves which had maxima at low concentrations of propanol if the flocculation was carried out at 37°C.

The method seems to be amenable to further application, particularly as a clinical method to detect abnormalities in blood proteins.
Über die ausscheidung und speicherung von radioaktiv indizierten xylanschwefelsäureestern. II. Entwicklung der methode prüfung der abhängigkeit vom polymerisationsgrad
Authors: Hoffmann von E. G. , Husemann E. , Lötterle R. , Wiedersheim M. , Hertlein W.
Published: April 2003

Es wird eine Methode beschrieben zur Untersuchung der Ausscheidung und Speicherung von blutgerinnungshemmenden Xylanschwefelsäureestern durch Indizierung mit S35. Eine spezifische Speicherung finder insbesondere in Leber, Niere und Milz statt. Der gespeicherte Xylanester verbleibt lange im Organismus. 14 Tage nach der letzten Injektion ist nahezu die gleiche Menge in den Organen vorhanden wie nach 24 Stunden. Bei Präparaten kürzerer Kettenlänge ist das Ausmaß der Speicherung geringer, das der Ausscheidung entsprechend höher.
Chromatographische untersuchungen zur säurehydrolyse der kartoffelstärke
Authors: Ulmann von M.
Published: April 2003

Durch Trennung der Amylose und des Amylopektins der Stärke, wie auch der durch Säureeinwirkung aus diesen hervorgegangenen Abbauprodukte Vermittelst einer Al2O3‐Adsorptionssäule und ihre Sichtbarmachung nebeneinander, gelingt es, eine Reihe neuer Einblicke in das Angangsstadium des Verlaufes der Säurchydrolyse der Stärke zu gewinnen. Die Säure wirkt auf die in nativem Zustande nebeneinander vorliegenden etwa 80% Amylopektin und 20% Amylose der Kartoffelstärke ganz verschieden ein. Das viel empfindlichere Amylopektin wird als erstes desaggregiert und dann zu einem Dextrin abgebaut, während die viel stabilere Amylose erst angegriffen wird, wenn die Hauptmenge des ursprünglich vorhandenen Amolopektins verschwunden ist.
Molekulargewicht und viskositätszahl bei polystyrolen mittlerer molekülgröße
Authors: Kern von W. , Rugenstein M.
Published: April 2003

An einer polymerhomologen Reihe von fraktionierten Polystyrolen (Molgewichte zwischen 15 000 und 60 000), die zum Zwecke der chemischen Endgruppenbestimmung mit Brombenzoylperoxyd bei verschiedenen Bedingungen hergestellt worden waren, wurden viskosimetrische und osmotische Messungen ausgeführt. Die Ergebnisse werden mit denjenigen anderer Autoren verglichen.
Über die verdünnungsentropie der lösungen von fadenmolekülen
Authors: Schulz von G. V.
Published: April 2003

Es wird versucht, auf breiter experimenteller Basis, einen allgemeinen überblick über die Wechselwirkung zwischen Polymeren und Lösungsmitteln (LM) in mäßigen Konzentrationen (bis 3%) zu gewinnen. Zu diesem Zweck wird der osmotische Druck in Abhängigkeit von der Konzentration und der Temperatur für 2 verschiedene Polymere in einer größeren Anzahl von Lösungsmitteln gemessen und daraus die Virialkoeffizienten und die thermodynamischen Funktionen Δμ1, Δh1und Δs1berechnet.

Der 1. Virialkoeffizient (VK) A hängt, wie zu erwarten war, nur vom Molekularge which des Polymeren ab. Der 2. und der 3. VK werden in der Größe B̄ zusammengefaßt, die ein Maß für die „Güte”︁ des LM ist. Die differentielle Verdünnungswärme Δh1variiert in einem breiten Bereich von negativen bis zu positiven Werten. Die differentielle Verdünnungsentropie Δ s1variiert bei den verschiedenen LM und Polymeren wesentlich weniger.

Der 2. VK B̄ wird in einen Energie‐ und einen Entropieterm B̄Hund B̄Szerlegt. Der Entropieterm wird mit dem theoretisch für athermische Lösungen berechneten Bath. Es ist wahrscheinlich, daß für Polymere, die nur ein statistisches Fadenelement enthalten; Bs= Bath.ist.
Über die Darstellung einheitlicher Polypeptide
Authors: Schramm Von Gerhanrd , Restle Heinz
Published: April 2003

Die Kondensation des AlaGlyGly‐Methylesters wurde untersucht. Mit Hilfe der Pa‐pierchromatographie gelang es, alle entstehenden Reaktionsprodukte einderutig zu identifizieren. Die Molgewichte der Polypeptide wurden auf spektroskopischem Wege an den DNP‐Derivaten bestimmt. Beim Erwärmen des Tripeptidesters ohne Lösungsmittle entstehen offene Peptide mit 6, 9, 12, 15, 18, 21 usw. Aminosäure‐Resten. Das höchstmolekulare Produkt enthielt 42 Aminosäurereste. Neben diesem Aufbau findet gleichzeitig ein Abbau statt, bei dem Diketopiperazine aus der Peptidkette abgespalten werden. Dieser Abbau tritte besonders bei längerer Kondensationsdauer in Erscheinung.

Auch bei der Kondensation in Lösung läßt sich ein Abbau nicht vermeiden. Der AlaGlyGly‐Thiophenylester ist wesentlich reaktionsfähiger als der Methylester, beitet aber keine präparativen Vorteile bei der Darstellung der Polypeptide.
Über die autoxydation ungesättigter verbindungen. III. Mit. Die katalyse der autoxydation des linolsäuremethylesters durch metallverbindungen und durch kombinierte katalysatorsysteme
Authors: Kern Von W. , Willersinn H.
Published: April 2003

Es wird die Katalyse der Autoxydation des Linolsäuremethylesters durch Metallverbindungen und durch verschiedene kombinierte Katalysatorsysteme untersucht. Bei der metallkatalysierten Autoxydation werden die zugesetzten Metallverbindungen nur in Verbindung mit dem entstehenden Substratperoxyd wirksam; ihre katalytische Wirkung beruht auf einer Aktivierung des radikalischen Zerfalls des Substratsperoxydes und der damit verbundenen Steigerung der Autokatalyse der Autoxydation. Weiterhin ergibt sich, daß nur Peroxyde mit einer Hydroperoxy‐Gruppe allein durch Metallverbindungen vom Typ des Cu++‐Oktoates aktivierbar sind, nicht dagegen Dialkylperoxyde und Diacylperoxyde. Der Mechanismus der Peroxyd‐Aktivierung wird diskutiert. Die Beschleunigung der Autoxydation durch Redoxsysteme und Metallredoxsysteme wird beschrieben.
Kinetics of the polymerization of styrene catalyzed by benzoyl peroxide and dimethylaniline. VIII. On vinyl polymerization
Authors: Imoto Minoru , Otsu Takayuki , Ota Tadatoshi
Published: April 2003

A study of the polymerization of styrene catalyzed by benzoyl peroxide in the presence of dimethylaniline at 50° has been made. It was proved that the initial rate of polymerization (R0) could be expressed by the equation, R0= k (Bz2O2)1/2 (DMA)1/2, where (Bz2O2) and (DMA) are the initial concentrations of benzoyl peroxide and dimethylaniline respectively. In the polymerization by the system benzoyl peroxide‐dimethylaniline, the initiator efficiency of benzoyl peroxide was measured kinetically. The value obtained was a small value (i. e., 0,25). Moreover, the decomposition of benzoyl peroxide with dimethylaniline in styrene was investigated according to Horner's procedure. From these results, it seems possible that one‐half of benzoate radical which is produced through the reaction of benzoyl peroxide with dimethylaniline is contributed the polymerization of styrene.
Rates of initiation and chain transfer constants in the polymerization of methyl acrylate
Authors: Mahadevan V. , Santhappa M.
Published: April 2003

By a study of bulk polymerization of methyl acrylate at 55°–75°C with benzoyl peroxide, ditertiary butyl peroxide, methyl ethyl ketone peroxide and tertiary butyl hydroperoxide as catalysts, rates of initiation, chain transfer constants for the monomer and the catalyst have been evaluated. Determination of temperature coefficients for all the rate constants have been made. Values for the catalyst efficiencies and thermal rate constants for initiation are given. Calculated and experimentally determined chain lengths are compared. Certain aspects of polymerization of methyl acrylate are compared with styrene and methyl methacrylate.
Kritische betrachtung und verallgemeinerung der auf die baker‐gleichung zurückführbaren viskositäts‐konzentrations‐beziehungen. I. Mitteilung über den physikalischen zustand und das physikalisch‐chemische verhalten hochmolekularer stoffe.
Authors: Frind Von H. , Schramek W.
Published: April 2003

Eine große Anzahl der bekannten Viskositäts‐Konzentrationsbeziehungen verschiedener Autoren, die auf die Baker‐Gleichung (1) zurückgeführt werden können, werden nach Umwandlung in eine allgemeingültige Formulierung [2] kritisch betrachtet und nach Untersuchung und Verallgemeinerung der von den Autoren vorgeschlagenen „Korrekturglieder”︁ in zwei Gruppen geteilt.

In der einen Gruppe tritt eine neue Konstante als Faktor des einen Summanden des Korrekturgliedes auf. Für sie wird die Herstellung gegenseitiger mathematischer Beziehungen nur angedeutet.

In der anderen Gruppe, deren „Korrekturglied”︁ eine Exponentialfunktion darstellt, ist die Konstante a im Exponenten enthalten. Es wird gezeigt, daß a abhängig ist von der Größe des Exponenten der verallgemeinerten Baker‐Gleichung [2], so daß die dieser Gruppe angehörigen Gleichungen mit Hilfe einer aufgefundenen allgemein gültigen hyperbolischen Beziehung auf den gleichen Funktionswert zurückgeführt werden können. Es werden die Gültigkeitsbereiche der erwähnten, Beziehungen untersucht und festgestellt, daß nur in Ausnahmefällen ηre1 = 6 überschritten wird.

Zum Schluß wird die physikalische Bedeutung der Konstanten der verschiedenen Korrekturglieder diskutiert, wofür ein umfangreiches Experimentalmaterial mit mehreren Tabellen und Diagrammen verwertet wird.
Ein versuch, die „grenzviskositätszahl”︁ anschaulich zu machen und eine bemerkung zur nomenklatur der viskosität verdünter lösungen von kettenmolekülen
Authors: Signer Von R.
Published: April 2003

Die „Grenzviskositätszahl”︁ wird anschaulich gedeutet. Es wird auf eine Analogie in ihrer Definition und derjenigen des Elastizitätsmoduls hingewiesen. Als neue Bezeichnung der „Grenzviskositätszahl”︁ wird „Staudinger‐Einheit”︁ vorgeschlagen.
Polyamides from tetrahydrofuran‐2,5‐dipropionic acid: The effects of the tetrahydrofuran ring inserted in the chain of polyamide molecule
Authors: Hachihama Yoshikazu , Hayashi Izumi
Published: April 2003

A homologous series of polyamides from tetrahydrofuran‐2,5‐dipropionic acid and polymethylenediamine (nylon nT, n = 2, 4 ∼ 10) and two series of copolyamides (nylon 66/6T and 69/6T) have been prepared. Based on studies of the properties of these polymers the effects of tetrahydrofuran ring on polymer properties have been discussed.

The introduction of tetrahydrofuran ring into polyamide chain has little influence on melting point and christallinity of the polymer, but fairly increases the solubility, moisture regain, and receptivity towards dyes. The copolyamide 66/6T (wt. ratio 4 : 1) gives a fibre having good mechanical properties and greatly improved dyeing properties.
Branching and grafting reactions on polyvinylbenzoate
Authors: Smets G. , Hertoghe A.
Published: April 2003

La polymérisation du benzoate de vinyle se caractérise par la formation de polymères ramifiés par suite de réactions de transfert de chaine affectant le noyau aromatique. Dans la première partie du présent travail, la ramification du benzoate de polyvinyle a été mise en évidence par la saponification et la transacidification des polymères initiaux; les poids moléculaires osmotiques du benzoate de polyvinyle et des alcool et acétate de polyvinyle obtenus à la suite de ces réactions ont été comparés entre eux.

Dans une seconde partie, la réactivité du noyau aromatique a été utilisée à la production de copolymères greffés aux dépens de benzoate de polyvinyle, et de monomères vinyliques, à savoir le méthacrylate de méthyle et l'acétate de vinyle. Les copolymères greffés sont solubles et ont été isolés par la technique de fractionnement par précipitation; leur teneur en benzoate de polyvinyle a été déterminée par spectrométrie infrarouge. Les variations de poids molécularies résultant de ces réactions de greffage ont été déterminés par la méthode osmotique et une dégradation partielle du benzoate de polyvinyle en présence de radicaux a été démontrée.
Struiduruntersuchungen an nachchloriertem polyvinylehlorid
Authors: Fredriksen Von Odd , Crowo Jan. A.
Published: April 2003

Das Nachchlorieren von Polyvinylchlorid, PVC, führt in überwiegendem Maße zur Bildung von 1,2‐Dichloräthylenstrukturen; das heißt, daß die Chlorsubstitution an den CH2‐Gruppen bevorzugt wird. Die Untersuchungen der hier vorliegenden Arbeit zeigen, daß die Verteilung der Chloratome an den CH2‐ und den CHCI‐Gruppen der Polymerkette statistisch durch die Anzahl der zur Verfügung stehenden Wasserstoffatome bestimmt ist. Das bedeutet, daß sich die Wahrscheinlichkeit der Chlorierung der CH2‐Gruppen zu der Chlorierung der CHCI‐Gruppen wie 2:1 verhält. Verschiedene Typen von suspensions‐ chloriertem. PVC wurden untersucht. Dabei wurde gefunden, daß das Verhältnis zwischen dem Gehalt an 1,2‐Dichloräthylen‐ und 1,1‐Dichloräthylenstrukturen von der Chlorierangs‐ methode unabhängig ist.
Mechanism of volatile production during pyrolysis of polystyrene
Authors: Cameron G. G.
Published: April 2003

A simple theory is employed to show, that volatiles are evolved from chain‐end initiation but not from random initiation during pyrolysis of polystyrene. The termination reaction is shown to be a first order process. Mechanisms to explain these facts are considered.
Structure and properties of polyvinylchloride. 1. Molecular structure of chlorinated PVC
Authors: Petersen Jörgen , Rånby Bengt
Published: April 2003

A commercial PVC sample was chlorinated in water suspension under UV irradiation. The chlorine content increased gradually from one to two chlorine atoms per monomer unit indicating an apparent saturation. No significant degradation of the polymer occurred. High resolution NMR‐analysis showed that the initial stage of the reaction was a formation of CHClCHCl‐groups. At later stages CH2CCl2‐groups were also formed but not adjacent to each other along the chains.
Preparation of block copolyamides
Authors: Saotome Kazuo , Sato Kenichiro
Published: April 2003

Block copolyamides have been prepared by polymerization of amino‐ and carboxyl ended propolyamides of relatively low molecular weights. The structures of the block copolyamides were ascertained from the melting point vs. composition curves, the solubilities in methanol, and by dilatometry, in which two breaks, each corresponding to the melting temperature of one type of block segments, were observed. The amide interchange reaction, which disturbs the block regularity, is depressed at temperatures below 250°C. No practical differences in the thermal properties were observed between the two block polymers prepared by prepolyamide polymerization and by amide interchange of homopolyamides.
1,2‐Siloxacyclopentane1 3. Mitt. Über die depolymerisation des polymeren 1‐äthoxy‐1‐methyl‐1,2‐siloxacyclopentans
Authors: Koerner Von Götz , Rossmy Gerd
Published: April 2003

Polymeres 1‐Äthoxy‐1‐methyl‐1,2‐siloxacyclopentan depolymerisiert beim Auflösen in CCl4 unter Entstehung des Monomeren. Die Bildung des Monomeren erfolgt nach einer Reaktion nullter Ordnung mit einer Aktivierungsenergie von 12,0 ± 1,2 kcal/Mol. Daraus folgt, daß die Depolymerisation ausschließlich vom Kettenende her erfolgt, und zwar unter Erhaltung der Endgruppenkonzentration.
Löusungsverhalten niedermolekularer polydimethylsiloxane mit methylendgruppen
Authors: Adank Von Georg , Elias Hans‐Georg
Published: April 2003

Polydimethylsiloxane mit Methylendgruppen sind in Chloroform und Toluol nach dampfdruckosmotischen Messungen assoziiert. Die in Bromcyclohexan gemessenen Virialkoeffizienten sprechen für die Struktur einer gestörten Helix in diesem Lösungsmittel. Die [η]/M0,5‐Werte fallen entsprechend bei niedrigen Molekulargewichten sehr steil ab.
Polykondensationen mit α‐aminocarbonsäureestern. V. Kondensation des L‐leucinäthylesters
Authors: Elias Von Hans‐Georg , Römer Urs
Published: April 2003

Die mit SnCl4 katalysierte Polykondensation des L‐Leucinäthylesters läft im Vergleich zur Kondensation des Glycinäthylesters langsamer ab und führt zu niedrigeren Polymerisationsgraden und Ausbeuten sowie zu weit höheren Dioxopiperazin‐Gehalten. Bei der Reaktion wird eine beträchtliche Racemisierung beobachtet. Intermediär gebildetes Dioxopiperazin wird durch SnCl4 allein nicht, wohl aber mit α‐Aminocarbonsäureestern als Cokatalysatoren polymerisiert. Chloroform als Lösungsmittel hat einen starken Einfluß auf die Racemisierung, und die DOP‐Ausbeute. In Blindversuchen ohne Katalysator wurde nur Racemisierung, nicht aber die Bildung von Oligopeptiden oder Dioxopiperazin beobachtet. Für die katalysierte Polykondensation der α‐Aminocarbonsäureester, die Polymerisation der Dioxopiperazine und die Racemisierung werden Mechanismen vorgeschlagen.
Polymerization of tetrahydrofuran: By the system triethylaluminum/water. I. General kinetic studies
Authors: Imai H. , Saegusa T. , Matsumoto S. , Tadasa T. , Furukawa J.
Published: April 2003

Kinetic studies have been carried out on the polymerization of tetrahydrofuran with the ternary catalyst system Al(C2H5)3H2O‐epichlorohydrin at 0°C. It has been found that this is a stepwise addition polymerization, i.e., the propagating species is formed mostly in an induction period and during the subsequent second stage of polymerization the propagating species of an almost constant concentration continues to grow without being interrupted by chain transfer or termination.

Based upon the above polymerization mechanism, the concentration of propagating species, [P*], was determined from the amount and the molecular weight of polymer. [P*] in the second stage was found to be proportional to the amounts of Al(C2H5)3 and of epichlorohydrin.
Der thermooxydative abbau von polyformaldehyd
Authors: Sedlář Von Jiří , Kučera Miloslav
Published: April 2003

Eine Apparatur für das Studium des thermooxydativen Abbaus von Polyformaldehyd wurde entwickelt. Durch Analyse der gasförmigen Abbauprodukte wurde bestätigt, daß CH2O und HCOOH die Hauptprodukte sind.

Aus den experimentell ermittelten Gleichungen für die Zeit‐Umsatzkurven ergibt sich, daß der Abbau erster Ordnung bezüglich Sauerstoff ist. Die Aktivierungsenergie wurde zu (19 ± 3) kcal/Mol bestimmt.

Durch Analyse des Depolymerisationsrückstandes wurde festgestellt, daß es zur Bildung von Hydroxyengruppen kommt, deren Konzentration wahrscheinlich die Geschwindigkeit des Gewichtsverlustes bestimmt. Eine Gleichung für die Zeitabhängigkeit von P̄n wurde abgeleitet.

Die Kinetik der Ameisensäürebildung wurde studiert.
Kondensation von D‐glucose mit aromatischen kohlenwasserstoffen. III. Mitteilung
Authors: Micheel Von Fritz , Licht Helmut
Published: April 2003

Die Strukturformel des hochpolymeren Kondensationsproduktes aus Fluoren und D‐Glucose in flüssigem Fluorwasserstoff wurde bewiesen. Es wurden weitere hochpolymere Kondensationsprodukte aus Diphenylmethan, Diphenyläthan, Triphenylmethan, Diphenyl Sowie Diphenylenoxid und D‐Glucose synthetisiert. Tetraphenylmethan läßt sich mit Glucose nicht Kondensieren.
The solution polymerization of butadiene and isoprene catalyzed by cobalt(III)‐acetylacetonate
Authors: Riches Von K. M.
Published: April 2003

The solution polymerization of butadiene and isoprene catalyzed by Co3+‐acetylacetonate has been investigated at 130°C. by dilatometric techniques. A half order dependence on the catalyst concentration and an approximate first order dependence on the monomer concentration have been found. Apparent activation energies of 13 and 20 kcal.·mole−1 were found for isoprene and butadiene respectively. Diphenylpicrylhydrzayl and p‐benzoquinone had no significant effect on the rates of the diene polymerization although the styrene polymerization was strongly inhibited under similar conditions.
Über das vorkommen von azeotropen bei copolymerisationen mit mehr als zwei comonomeren
Authors: Wittmer Von Paul , Hafner Ferdinand , Gerrens Heinz
Published: April 2003

An Hand von aus der Literatur entnommenen Copolymerisationsparametern wurde mit Hilfe einer Rechenanlage überprüft, ob in Copolymerisationssystemen mit mehr als zwei Comonomeren Azeotrope vorkommen. Dabei wurden 37 Dreierazeotrope, 2 Viererazeotrope und 1 Fünferazeotrop gefunden.
Estimation of relative reactivity ratios in radical alternating copolymerization by means of terpolymerization
Authors: Iwatsuki Shouji , Yamashita Yuya
Published: April 2003

We studied the estimation of relative reactivity ratios of the alternating copolymerization by means of terpolymerization technique either in the free propagating mechanism or in the complex mechanism. Ter‐systems studied were 2‐chloroethyl vinyl ether/fumaronitrile/maleic anhydride as one donor/two acceptor monomer system, and maleic anhydride/2‐chloroethyl vinyl ether/p‐dioxene as one acceptor/two donor monomer system. All these monomers have no radical homopolymerizability.

It was found that these ter‐systems coincide with the theoretical treatments and give the relative reactivity ratios in the former tersystem, k12/k13 is 2.73 by the treatment of the free propagating mechanism and rI(K1/K2) is 2.5 ± 0.2 and is 0.2 ± 0.2 by the treatment of the complex mechanism and in the latter tersystem, rII(K2/K1) is 2.23 by the treatment of the free propagating mechanism and rI(K1/K2) is 2.23 and rII(K2/K1) is 0.45 by the treatment of the complex mechanism.

Therefore we have concluded that the terpolymerization technique is useful for the measurement of the relative reactivity of the alternating copolymerization.
Poly‐(α‐methyl benzyl methacrylate). Preparation and preliminary observations
Authors: Liu Kang‐Jen , Lignowski J. S. , Ullman Robert
Published: April 2003

Poly‐(α‐methyl benzyl methacrylate) (PMBMA) polymers were prepared in isotactic, syndiotactic, and atactic forms using both optically active and racemic monomers. The isotactic material was prepared by anionic polymerization in a hydrocarbon solvent at a low temperature (∼−60°C), the syndiotactic and atactic polymers were synthesized by ultraviolet initiated free radical polymerization at –65 and 32°C, respectively. From the proton magnetic resonance spectrum, it could be determined that the isotactic polymer was of high stereochemical purity. The syndiotactic material was less pure, and the atactic polymer was largely syndiotactic. Racemic and optically active α‐methyl benzyl pivalates were prepared to serve as monomeric analogues of the polymer. The optical activity of the isotactic polymer in dioxane is one‐third greater than that of the monomeric analogue at 5890 Å; the syndiotactic polymer is slightly less optically active than the monomeric analogue, and the atactic polymer is between the syndio‐ and iso‐polymers but much nearer the syndio material. The enhancement or decrease of the optical activity is associated with the orientation correlation of successive chain segments, the specific chemical structure of the optically active group, and on solvent‐polymer interactions. The orientation correlations persist over a short range only.
Über die synthese und das redoxverhalten molekular‐einheitlicher hydrochinon‐phenol‐formaldehyd‐konden‐sate. IV
Authors: Manecke Von G. , Mölleken R.
Published: April 2003

Es wird die Darstellung niedermolekularer, molekulareinheitlicher Hydrochinon‐Phenol‐Formaldehyd‐Kondensate beschrieben. Die aromatischen Bausteine sind über Methylenbrücken ausschließlich in 2.5‐Stellung verknüpft. Das Redoxverhalten dieser als Modellsubstanzen für Redoxharze dienenden Verbindungen wurde durch potentiometrische Titration untersucht.