Interferenzmikroskopische charakterisierung von faserstrukturen, 3. Die änderung des radialen verlaufes der physikalischen struktur von polyethylenterephthalat-fasern beim färben mit dispersionsfarbstoffen

The change of the radial structure during the diffusion of dyestuffs in fibers of poly(ethylene terephthalate), [poly(oxyethyleneoxyterephthaloyl)], is studied with regard to the relationship between the dyestuff diffusion and the structure of high polymers. The fiber structure is described by interferometric measurements, which allow statements about order and orientation as a function of the diffusion path. The experimental results show that C. I. Disperse Red 60 raises the parameters which describe the order and orientation and that C. I. Disperse Blue 139 lowers these structure parameters.     

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.     

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).     

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.     

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.     

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.     

Polymerisation von fulvenen, 3. Strukturbeweis für kationische polyfulvene durch vergleich mit modellverbindungen

The structure of cationic poly(6,6-dimethylfulvene) ( 2a ) has been confirmed by synthesis of 4 model compounds 6, 7, 8, 9 and comparison of the spectral data with those of the polyfulvene. 5-Isoproylidenetricyclo[5.2.1.0^2.6]dec-3-ene ( 6 ) shows the same sensitivity towards oxygen as 2a . The reaction of 6 with oxygen yields a 1:1-copolymer, for which structure 10 has been proved by means of spectroscopic methods.     

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.     

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.     

Konstitution und lösungseigenschaften von makromolekülen. VIII. Ungestörte dimensionen von polytetrahydrofuran

The numerical value of K₀ = [η]₀/M of a sample of poly(tetrahydrofuran), which is proporational to the unperturbed dimensions, was determined in different solvents by three methods at 25°C. The resulting value of K₀ = 0.202 ml./g. was compared with the corresponding data for polyethylene, poly(ethylene oxide) and polyoxymethylene.     

Katalysatoren beim thermischen Abbau von Polymeren, 1. Über den katalytischen Abbau von Polypivalolacton

The ability of different metal oxides and acetates to catalyze the thermal degradation of poly(pivalolactone) into cyclic oligomers has been investigated. Magnesium oxide was found to be the most active catalyst which converts poly(pivalolactone) completely into oligomers within less than two hours at 547 K. The influence of temperature and catalyst concentration and the distribution of cyclic oligomers is discussed.     

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.     

Centrifugally-spun polyhydroxybutyrate fibres: Effect of process solvent on structure,morphology and cell response

The structure and morphology of a novel form of poly(β-hydroxybutyrate) produced by gel-spinning is described. The entangled fibrous nature of the material, which resembles 'cotton wool' suggests possible functions in wound scaffolding devices. The surface structure and fibre diameter distribution of the fibres have been investigated using phase contrast and scanning electron microscopy. Fibres were found to possess a variety of surface irregularities, such as pores and indentations, with diameters mainly in the range 1-15 μm. Additionally, individual fibres were occasionally found to be fused or forked together with neighbours. The effects of blending with various polysaccharides and of altering the process solvent on fibre morphology were also investigated. Under hydrolytic degradation conditions (pH 10.6, 70°C) the fibres degraded by gradual fragmentation and erosion to fibre fragments, particulate matter and eventually to monomer. Altering the production process influenced both the fibre diameter distributions and surface morphology of the constituent fibres. Mammalian and human epithelial cells were used to study the cellular interaction with the spun fibres. SEM studies show that there is little or no cell adhesion to the unmodified fibres, but surface treatment by means of acid and alkali washes promoted cell proliferation on the materials, probably as a result of the introduction of hydroxyl and carboxyl at the surface. Fabrication of non-woven mats, which were subsequently acid or alkali treated, provided a conventional way of forming a celladhesive matrix which may have potential value as a wound scaffold. Neither cell line exhibited any cytotoxic response to these polymers.     

Centrifugally-spun polyhydroxybutyrate fibres: effect of process solvent on structure, morphology and cell response

The structure and morphology of a novel form of poly(beta-hydroxybutyrate) produced by gel-spinning is described. The entangled fibrous nature of the material, which resembles 'cotton wool' suggests possible functions in wound scaffolding devices. The surface structure and fibre diameter distribution of the fibres have been investigated using phase contrast and scanning electron microscopy. Fibres were found to possess a variety of surface irregularities, such as pores and indentations. with diameters mainly in the range 1-15 microm. Additionally, individual fibres were occasionally found to be fused or forked together with neighbours. The effects of blending with various polysaccharides and of altering the process solvent on fibre morphology were also investigated. Under hydrolytic degradation conditions (pH 10.6, 70 degrees C) the fibres degraded by gradual fragmentation and erosion to fibre fragments, particulate matter and eventually to monomer. Altering the production process influenced both the fibre diameter distributions and surface morphology of the constituent fibres. Mammalian and human epithelial cells were used to study the cellular interaction with the spun fibres. SEM studies show that there is little or no cell adhesion to the unmodified fibres, but surface treatment by means of acid and alkali washes promoted cell proliferation on the materials, probably as a result of the introduction of hydroxyl and carboxyl at the surface. Fabrication of non-woven mats, which were subsequently acid or alkali treated, provided a conventional way of forming a cell-adhesive matrix which may have potential value as a wound scaffold. Neither cell line exhibited any cytotoxic response to these polymers.     

Zur entschmierung der röntgenkleinwinkelstreukurven von hochpolymeren

A method for slit-hight corrections is described, in which the experimental X-ray small angle scattering curve is represented by a cubic spline function. This method is applied on the theoretical scattering curve of spherical particles with homogenious electron-density and on scattering curves of poly(hexamethylene adipate).     

Utilisation de l'analyse viscoélastique dynamique à l'étude de la cristallisation isotherme du poly(téréphtalate d'ethylène) amorphe. Application à des composites unidirectionnels avec fibres de verre

Dynamic viscoelastic analysis was used to continuously follow the “cold crystallisation” of poly(ethylene terephthalate) (PET) test bars. Samples which were cut from an amorphous PET sheet were heated to a given temperature in a hot cell. The evolution of the real part of the modulus not only allows the kinetic crystallisation parameters but also the nucleation and growth characteristics to be determined. This method was applied to unidirectional PET/glass fibre composite strips. Thus, the influence of the glass fibres on the morphological and kinetic characteristics of the matrix crystallisation has been investigated.     

Haupt- und seitenkettenkristallinität bei isotaktischen poly(alkylethylen)en, 4. Die abhängigkeit des kristallinitätsgrades bei den höheren homologen von der thermischen vorbehandlung

Crystallization of the higher homologues of poly(alkylethylene)s containing 12, 13, 14, 16 and 20 C-atoms in the side chains is investigated varying the temperature and duration of crystallization. On cooling the samples slowly from the melt to about 5 to 10 K below the melting temperature, the modification is formed which was first reported by Turner-Jones: The main chain conformation is a quaternary helix, the side-chains crystallize by forming the orthorhombic polyethylene structure. Degrees of crystallinity were determined by X-rays using the method of Hermans and Weidinger. The degree of crystallinity increases up to a limiting value with increasing duration of crystallization at constant temperature. The limiting value grows by increasing the number of C-atoms in the side-chains.     

Physical and biocompatibility properties of poly-epsilon-caprolactone produced using in situ polymerisation: a novel manufacturing technique for long-fibre composite materials

Preliminary investigations into a novel process for the production of poly-epsilon-caprolactone (PCL) to be used as a matrix material in a bioabsorbable composite material are detailed. This material is primarily being developed as a bone substitute for use in maxillofacial reconstructive surgery, however, the technique described could be adapted to other areas where bioabsorbable composite materials may be used. The development of a totally bioabsorbable long-fibre composite material would allow a two-stage degradation to occur with the matrix material degrading first leaving a scaffold structure of degradable fibres which would be absorbed at a later stage. Caprolactone monomer was polymerised in situ within a tool cavity to produce a net shape moulding. Inclusion of a fibre preform within the tool cavity which was impregnated by the liquid monomer produces a long-fibre composite material. PCL with a range of molecular weights has been produced using this liquid moulding technique to assess the physical and biocompatibility properties compared to commercially available PCL. Osteoblast-like cells derived from human craniofacial bone (CFC) have been used to assess the in vitro biocompatibility of the PCL. The results show that high-quality PCL with a narrow molecular weight distribution and properties similar to commercially available PCL can be produced using this technique. Polymerisation of the monomer around a woven fibre preform made of a poly(lactic acid) (PLA)/poly(glycolic acid) (PGA) copolymer (vicryl mesh) produced a bioabsorbable long-fibre composite material. Further work is ongoing to develop this system towards a method for improving craniofacial bone reconstruction.     

Mechano-chemischer abbau bei der schwingmahlung von poly(ε-caprolactam) in gegenwart von sebacoylchlorid und nachfolgende polykondensation mit aromatischen diaminen

Mechano-chemical degradation of poly(ε-caprolactam) {poly[imino(1-oxohexamethylene)]} in the presence of sebacoyl chloride, carried out by vibratory milling, gave polyamide acid chlorides. Subsequently, these products, also by vibratory milling, were condensed with p-phenylenediamine to obtain polymers with aromatic amino groups which by diazotation and coupling reaction were transformed into coloured polymers. The use of some specially selected coupling components (i.e. containing itself primary amino groups) allowed to regulate the colour intensity of the final product when the diazotation and coupling reaction was carried out gradually.