Interferenzmikroskopische charakterisierung von faserstrukturen, 4. Zusammenhänge zwischen der farbstoffdiffusion und der faserstruktur beim färben von polyethylenterephthalat-fasern mit dispersionsfarbstoffen

Concentration distributions of dyestuffs C. I. Disperse Red 60 and C. I. Disperse Blue 139 in microtomic cuttings of fibers of poly(ethylene terephthalate), (poly(oxyethyleneoxyterephthaloyl)) are discussed. An interpretation of the results in relation to order and orientation along the fiber radius by interferometric investigations gives informations about the diffusion process. It is shown, that the diffusion of dyestuffs in high polymers depends—in a complicated way—on fiber structure (as a function of the diffusion path), fiber history, and experimental conditions: C. I. Disperse Red 60 shows a lower diffusion rate at higher radial orientations, whereas the diffusion rate of C. I. Disperse Blue 139 does not depend on the radial dependence of these structure parameters.     

Interferenzmikroskopische Charakterisierung von Faserstrukturen, 2. Der Einfluß des Schrumpfes beim Thermofixieren von Polyäthylenterephthalat-fasern mit extrem unterschiedlicher radialer Struktur

The change of the radial structure during the thermofixation of poly(ethylene terephthalate), [poly(oxyethyleneoxyterephthaloyl)], fibres with and without shrinkage is studied. The fibre structure is described by interferometric measurements, which allow statements about order and orientation as a function of the fibre radius. The fibre interferograms are interpreted by an analytical model, which has been developed in the first part of this series.     

Interferenzmikroskopische charakterisierung von faserstrukturen, 1. Die ermittlung ortsabhängiger strukturparameter von fasern

The interferometric determination of refractive indices of fibers as a function of the radius of the fiber allows statements about order and orientation along the fiber radius and therefore gives an important contribution to the analysis of the structure of fibers. An analytical model for the interpretation of interferograms of fibers is developed; its application is demonstrated in comparison with a shell model for the example of a poly(ethylene terephthalate) fiber.     

Einfluß einer orientierung der moleküle auf die kinetik der kristallisation von polyethylenterephthalat

Amorphous samples of poly(ethylene terephthalate) were oriented by drawing at 92°C to different drawing ratios as well as by cold drawing. The kinetics of isothermal crystallization was determined in the range from 70°C to 115°C. The orientation of the samples was measured by the birefringence before crystallization. With increasing orientation also the rate of crystallization increases and the Avrami exponent n decreases from 3 to 1. The density obtained at the end of the crystallization process almost is not affected by the orientation. The results also indicate that some sort of order occurs already during the orientation process. The results are discussed. The birefringence does not change monotonically during crystallization.     

Analyse der phasenstruktur von binären polymersystemen

Two sets of polymer blends have been prepared by mixing solutions or melts of polystyrene with polybutene-1(poly(1-ethylethylene)), cellulose acetate, poly(methyl methacrylate), polyisobutylene, atactic polypropylene, poly(vinyl chloride), high pressure polyethylene, and of poly(vinyl chloride) with high pressure polyethylene, ABS, poly(vinylidene chloride), poly(vinyl acetate), vinyl chloride/vinyl acetate copolymer. The phase structure of these blends was analysed by microscopic and differential calorimetric measurements and by determination of the turbidity of the films. Phase diagrams were prepared from the glass transition temperatures and melting points taken from DSC curves. In this analysis all systems show a distinct phase separation ensuing from incompatibility. The only exception is the blend: poly(vinyl chloride) + vinyl chloride/vinyl acetate copolymer.     

Herstellung und antivirale Wirksamkeit von Polyacrylsäure und Polymethacrylsäure

The antiviral activity of a number of fractions of poly(acrylic acid)s and poly(methacrylic acid)s with different tacticities, different molecular weights and molecular weight distributions has been investigated. Isotactic poly(acrylic acid)s are essentially more antiviral active in the whole area of efficacy than the atactic ones. Independent of the tacticity poly(acrylic acid)s with molecular weights smaller than 5000 show no significant effects, polymers with molecular weights greater than 25000 are toxic in the used doses. The optimum of efficacy is between 6000 and 15000. Isotactic poly(acrylic acid)s with narrow molecular weight distributions are more active than those with broad distributions. The atactic poly(acrylic acid)s with lower efficacy do not show this relationship. Atactic poly(methacrylic acid)s are not antiviral active in vivo compared with untreated controls. Isotactic ones have a just detectable efficacy which is essentially lower than the activity of the atactic poly(acrylic acid)s.     

Zur Taktizität von Poly(α-methylstyrol), 5. Die Abhängigkeit der Taktizität von der Reaktionstemperatur und der Anfangsmonomerkonzentration

The tacticity of poly(α-methylstyrene) was measured by ¹H NMR spectroscopy. The polymerisation initiated in tetrahydrofuran by butyllithium gives a dependence on the initial monomer concentration and a S-shaped plot of log(m/r) vs. 1/T, which is not influenced by a stronger reaction medium like 1,2-dimethoxyethane or hexamethylphosphoric triamid or by addition of LiB(C₆H₅)₄. The activation parameters of the two straight lines A and B limiting the experimental curve are according to the equation The temperature dependence of the propagation rate constant k_w measured dilatometricly between ?11°C and ?75°C gives a linear Arrhenius plot. The rate constant of depolymerisation k_d was calculated using the equilibrium monomer concentration. The activation parameters are The influence of ionic dissociation on the tacticity is discussed. The results lead to the conclusion, that the contact ion pair, the solvent separated ion pair, and the free anion generate tacticities, which are undistinguishable by the applied experimental methods.     

Zur theoretischen deutung der temperaturabhängigkeit der relaxationszeiten von polymeren

The free volume theory of Cohen and Turnbull, the results of which are identical with the empirical relationship of Williams, Landel and Ferry (WLF), was compared with the theory of conformational entropy of Adam and Gibbs (AG) using experimental results of measurements of the temperature dependence of the relaxation times of poly(vinyl acetate). In spite of being different in their mathematical form, both theories were found to describe the experiment with similar adequacy. A procedure was also suggested permitting to obtain the AG parameters if the WLF parameters are known. The procedure was applied to 59 compounds, the WLF parameters of which were found in the literature. The results are tabulated.     

Orthophosphorsäuremonoester-Phosphohydrolaseaktivität der repressiblen Pyrohosphat-Phosphohydrolase I von Candida utilis

Two enzymes splitting inorganic pyrophosphate (I and II) have been investigated in Candida utilis. The results indicate that only enzyme I (no considerable thermoinactivation — 10 min, 71 °C-, optimum near pH 2.5, enzyme strongly bound to the cell, high splitting rates in vivo, derepression under phosphate starvation conditions) is also able to split orthophosphoric monoesters. Thus, the enzyme I is an unspecific acid orthophosphoric monoester phosphohydrolase (E. C. 3.1.3.2.).     

Nachweis von teilverträglichkeit in den phasengrenzflächen von polymergemischen mittels IR-spektroskopie

Among the various methods for determining compatibility in polymer blends infrared spectroscopy, especially the FT IR method, because of its sensitivity, is a rather simple tool to detect specific interactions as a necessary condition for compatibility in polymer blends. As a special advantage, in addition to hints for compatibility, from FT IR spectroscopy informations about the functional groups involved are obtained. By means of FT IR spectroscopy in blends of poly(oxymethylene) (POM) and polymers with ester groups like poly(methyl methacrylate) (PMMA) or poly(tetramethylene terephthalate) (PBTP) the existence of intermolecular interactions between carbonyl groups and the oxygen atoms of POM can be shown. This gives a possibility to detect very weak interactions which cannot be seen with the usual compatibility methods. Nevertheless, such weak interactions may enhance properties like processing behavior or toughness by an increased adhesion between the brittle matrix polymer and the dispersed elastomer phase in impact modified polymer systems.     

Über die kinetik des thermischen und thermooxidativen abbaus von polyäthylenterephthalat

The apparent kinetic parameters of the thermal and the thermal and thermooxidative degradation of poly(ethylene terephthalate) for non-isothermal conditions were evaluated. The dependence of these parameters on the heating rate, the mean molecular weight, and the degree of conversion was also established. It is shown that the degradation in nitrogen probably occurs by a short chain mechanism, while the degradation in air is more complex. In the latter case, the exothermic character of the DTA-curves suggests that the chain degradation reaction is overlapped by oxidation processes.     

Gas permeability of the racemic form of poly(γ-benzyl glutamate)

Sorption of carbon dioxide gas by a film of the racemic form of poly(γ-benzyl glutamate) was observed over the temperature range from 10 to 40°C and the permeability coefficient of carbon dioxide gas through the film was measured over the temperature range from 30 to 120°C. Different sorption isotherms were obtained in the ranges above and below the glass-like transition temperature, respectively. The result indicates that the sorption behavior is influenced by the side chain mobility. The amount of sorption by the racemic form of poly(γ-benzyl glutamate) does not vary with the intermolecular benzene ring stacking, but is similar to that of the form C of poly(γ-benzyl-L -glutamate) which contains no stacking. The breakdown of the intermolecular benzene ring stacking, which was confirmed by X-ray diffraction analysis and differential scanning calorimetry, results in an abrupt increase of the permeability and the diffusion coefficients, and conversely the formation of the stacking leads to an abrupt decrease in the permeability and the diffusion coefficients. Below the transition temperature, the permeability coefficient of the racemic form of poly(γ-benzyl glutamate) is smaller than that of the forms A, B, and C of poly(γ-benzyl-L -glutamate), related to the benzene ring stacking. The diffusion coefficient was estimated from the free volume theory, and the calculated value was compared with the value obtained from the permeability and the solubility coefficients. The fractional free volume was estimated to be about 0,068, when the best fit between the experimental and the calculated diffusion coefficients was obtained by a trial and error method.     

Untersuchungen zur thermodynamik und konformation von makromolekülen in polymermischungen in der nähe von entmischungspunkten durch neutronenbeugung

The structure and the thermodynamics of polymer blends made from two poly(styrene/acrylonitrile) copolymers with a different ratio of styrene/acrylonitrile are investigated by neutron scattering. These systems are endothermic, exhibit a positive value for the Huggins parameter χ and show phase separation at sufficiently large molecular weights. The results are in good agreement with the corresponding states theory of Prigogine and Patterson. Other polymer blends are exothermic, exhibit negative χ-values and are compatible even for infinitely large molecular weights. In these cases one can adapt the theoretical equations to the experiments by the introduction of a suitable parameter for an exothermic contact energy. This is shown for blends from poly(methyl methacrylate) and poly(styrene/acrylonitrile).     

Etude diélectrique de deux copolymères du méthylcyanure de vinylidène avec le 4‐fluorostyrène et le 4‐chlorostyrène

The dielectric properties of 2 copolymers poly[(methyl vinylidene cyanide)‐co‐(4‐chlorostyrene)] and poly[(methyl vinylidene)‐co‐(4‐fluorostyrene)] have been studied. These products are chiefly alternating and have relatively high glass transition temperatures, respectively at 145°C and 160°C. α relaxation phenomena have been characterised around to these temperatures. The values of dielectrical increment Δε have been calculated and compared to those of similar copolymers synthesized from vinylidene cyanide with various substituted styrenes. The low values are due to the steric effect of the bulky aromatic cycles. The orientation abilities of CN dipoles decrease comparatively to that of the copolymer of vinylidene cyanide with vinylacetate and this could explain the low piezo or pyroelectric properties.     

Spontane polymerisation von 2-vinylpyridin in gegenwart von polymethacrylsäure

The polymerization of 2-vinylpyridine in the presence of poly(methacrylic acid) of varying tacticity was studied in an aqueous medium. The reaction systems were heterogeneous with poly(2-vinylpyridine) and polymethacrylic acid almost exclusively in the precipitated phase. The overall rate of conversion was found to depend on the poly(methacrylic acid) tacticity only to a very little extent. The poly(2-vinylpyridine)/poly(methacrylic acid) mixture of the insoluble phase could be separated only in a strong acid medium. NMR measurements indicated the products to be predominantly syndiotactic, quite independent on the tacticity of the poly(methacrylic acid) used.     

Five-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside attenuates poly (I:C)-induced airway inflammation in a murine model of asthma

BACKGROUND: Asthma can frequently be induced or exacerbated by respiratory viral infections. Oxidative stress might also play an essential role in the pathogenesis of allergic airway diseases, indicating that antioxidant therapy may have a potential effect in controlling allergic airway diseases. Recent studies showed that 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR) has the potential ability to modulate NADPH oxidase activity, indicating the antioxidant activity of AICAR. This study investigated the inhibitory effects of AICAR as an anti-inflammatory modulator on allergic airway inflammation in murine animal models. METHODS: The anti-inflammatory effects of AICAR were evaluated in two experimental asthma models: (1) an ovalbumin (OVA)-induced experimental asthma model and (2) an OVA plus polyinosinic-polycytidylic acid [poly (I:C)]-induced experimental asthma model to mimic respiratory viral infections. The inhibitory effects of AICAR in poly (I:C)-mediated signalling for NF-kappaB activation and production of TNF-alpha were analysed in vitro. RESULTS: AICAR was shown to have a marginal inhibitory effect in an OVA-induced asthma model. Interestingly, AICAR significantly attenuated poly (I:C)-induced airway hyperresponsiveness and airway inflammation, as shown by the attenuation of the influx of total inflammatory cells and soluble products into bronchoalveolar lavage fluid, such as macrophages, eosinophils, IL-5, IL-13, TNF-alpha and IFN-gamma. AICAR also significantly reduced the serum levels of OVA-specific IgE and IgG2a antibodies. Histologic and flow cytometric studies showed that AICAR inhibited poly (I:C)-induced lung inflammation and the infiltration of CD11b+CD11c+ dendritic cells into the lung. Moreover, AICAR effectively inhibited poly (I:C)-mediated activation of NF-kappaB and the production of TNF-alpha. CONCLUSION: These findings suggest that AICAR may be a novel immunomodulator with promising beneficial effects for the treatment of respiratory viral infection in airway allergic diseases.     

Reaktive träger zur immobilisierung von enzymen ausgehend von polyacrolein

Polyacrolein ( 1 ) was transformed into poly(allyl alcohol) ( 2 ), poly[1,1-bis(hydroxymethyl)ethylene] ( 5 ) and N-substituted poly(vinylmethanimine)s 8, 9a–c and 10 . By subsequent reactions on these polymers reactive carriers with isothiocyanato-, diazo-, and azido groups were formed or by reaction with BrCN activated carriers were obtained which are able to bind enzymes covalently. The binding abilities of some reactive carriers were investigated for papain and trypsin. The effect of the pH-value during the coupling reaction, the amount of offered enzyme, the content of the reactive groups per g carrier and the effect of different reactive groups on the binding ability of the carriers were investigated. For immobilized papain and trypsin the enzymatic activity, the pH-optimum of their activity, and the apparent Michaelis constant K_M(app) were determined. The dependence of the activity on the temperature was also investigated.     

Beiträge zur polymerisation von 2-isopropenylnaphthalin, 3. Anionische homopolymerisation von 2-isopropenylnaphthalin

The anionic homopolymerization of 2-isoprenylnaphthalene with butyllithium in tetrahydrofuran at –78°C is described. The refractive index increment amounts to dn/dc = 0,2084 ml/g for these polymers in toluene at 25°C and wavelength λ = 436 nm. Determination of the molecular weights by light scattering yielded values between 13 000 and 270 000. The second virial coefficients also determined by light scattering measurements are comparable with the corresponding data of poly(α-methylstyrene). A calibration curve is given for gel permeation chromatography of the poly(2-isoprenylnaphthalene)s, whose polymolecularity indexes M_w/M_n lie between 1,06 and 1,2. Their intrinsic viscosity/molecular weight relationship is [η] = 1,43·10^?2 M^0,663. From ¹H NMR of the α-methyl group fractions of isotactic triads between 30 and 55% are evaluated. The glass transition temperature extrapolated to infinite molecular weight is T_g∞ = 221°C. Above 300°C fast degradation by monomer formation is observed.     

Untersuchungen von polymeren im massenspektrometer, 4. Abbaureaktionen von polybenzylen

The degradation reactions of unsubstituted poly(1,4-phenylenemethylene)s ( A ) (polybenzyls), poly[(2,5-dimethyl-l,4-phenylene)methylene] [poly(2,5-dimethylbenzyl)] ( B ), poly[(2,3,5,6-tetramethyl- 1,4-phenylene)methylene] [poly(2,3,5,6-tetramethylbenzyl)] ( C ), and poly( 1,4-phenylenethylene) [poly(a-methylbenzyl)] (D) were investigated by direct pyrolysis in the mass spectrometer. Mass pyrograms of polybenzyls made under different reaction conditions were compared in order to obtain direct informations on structural differences, such as branching and different linkages of the benzyl units; degradation products indicating a branched polymer could be found in one example. The thermal degradation of the unsubstituted polybenzyls and the poly(2,5-dimethylbenzyl) occurs mainly by disproportionation and transfer of hydrogen from the CH₂-groups, yielding monomeric and oligomeric degradation products with saturated (phenyl-, alkyl-) and unsaturated (quinonemethid-) endgroups; whereas on the degradation of poly(α-methyl-benzyl) pyrolytic products with vinyl endgroups were also found. The degradation behaviour of poly(2,3,5,6-tetramethylbenzyl) was found, however, to be greatly different, caused by the steric hindrance of the substituents at the phenyl groups. Besides a lower thermostability we found the mass spectral pattern indicating a different mechanism of thermal degradation. “a-benzyl-”, “β-benzyl”-, and “alkyl-cleavage”, as well as ortho-rearrangement were found as the main fragmentations of the ionized pyrolytic products.     

Anti-viral activity of single-stranded homopolynucleotides against encephalomyocarditis virus and Semliki Forest virus in adult mice without interferon induction.

Single administrations of poly C or poly I are anti-viral against infections of encephalomyocarditis (EMC) and Semliki Forest virus (SFV) in mice but poly U and poly A are not. The degree of protection is dose-dependent and mice which die do so at a later time when untreated controls even in a strain of mouse in which the time of death is not dependent on the dose of virus given. No circulating interferon is found after treating mice with poly C or poly I even at polynucleotide doses which give the same degree of protection as the interferon inducer, poly I:C. Several additional features distinguish the protection by poly C and poly I from interferon induction: the effect is low 24h before infection and maximal 6 h before infection, the effect is short-lived and mice do not show hypo-reactivation to repeated treatment. Limited treatment of mice with poly I:C, interferon or poly C before infection itself results in additional protection when poly C is also administered after infection, indicating that poly C has an effect after onset of virus replication. After infection poly C and poly I are both more effective by the intravenous route but before infection they are most effective when administered by the same route as the virus. Quantitative comparisons of the protective effects of poly C, poly I and the interferon inducer, poly I:C, are possible from dose response curves of the polynucleotides at different times relative to infection and by different routes of administration. The results are considered in relation to the presence of homopolyribonucleotide tracts in the viral genomes and effects on the reticulo-endothelial system of the mice.