Netzwerkgebundene oxidationsinhibitoren in vernetztem polyäthylen

New antioxidants of improved properties in crosslinked polyethylene are presented. Their molecular structure includes an oxidation inhibiting part and a crosslink-reinforcing part. As a consequence of this structure the stabilizers are chemically bound to the polyethylene matrix during crosslinking. Therefore the stabilizers possess migration stability, are nonvolatile, and show a significantly improved stabilizing effect which is demonstrated by reference to measurements of their oxygen uptake at increased temperatures in comparison with that of the analogous components without a crosslink-reinforcing part.     

Selektivitätsuntersuchungen an einer zweischichtenfraktionierung von polyäthylenterephthalat

The concentration dependence of the selectivity in fractionation experiments with polyethylene terephthalate has been investigated. The values obtained with 0.25% solutions showed close approximation to the SCHULZ-FLORY distribution. Lowering the concentration resulted in an essential increase of efficiency. Almost quantitative fractionation was achieved with various model blends of polyethylene terephthalate samples having different molecular weight.     

Infrarotspektrometrische untersuchungen zur haftstellenzahl adsorbierter polyäthylenglykole

The adsorption of poly(ethylene glycol) of molecular weights of 6 000 and 600 and of the low molecular weight model substance 2-ethoxy ethanol on aerosil is studied at 25°C in CCl₄ solution by IR-spectra. The extinction of the IR absorption band at 3 300 cm^?1, which is caused by hydrogen bridge bonds formed during the adsorption of the substances on aerosil, is measured in dependency of the adsorbed amount. From these measurements evidence can be given upon the conformation of the adsorbed layer. The poly(ethylene glycols) 6 000 and 600 are adsorbed irreversibly, but 2-ethoxy ethanol is adsorbed reversibly.     

Zur struktur von schlauchfolien aus polyäthylen

The crystal orientation and the morphology of a tubular extruded LDPE film and two HDPE films, each of different molecular weight and different blow ratio, were investigated by means of small- and wide-angle X-ray techniques and, after staining, by electron microscopy. Only by combining these methods the structure of the films can be described in detail. In the LDPE film the orientation of the a-axis parallel to the machine direction is dominant. The morphology is more complicated than is usually supposed from X-ray measurements. The lamellae show a variety of orientations. The periodicity of the lamellae is more strongly marked in the machine direction than in all other directions. The morphology of one of the HDPE films consists of biaxially oriented stacked lamellae, their normals preponderantly lying in the plane of the film.In the other HDPE film the normals of the lamellae lie in the film plane, too, but they are oriented preponderantly in the machine direction. The distribution of the crystal orientations as determined from the pole figures corresponds to the electron microscopie results. An essential part of the morphology determining the mechanical properties of the film are the shish-kebabs. They form in the strained melt. The observed greater X-ray periods and radial intensity bridges in the small-angle region of the HDPE-films are due to greater periods along thc shish-kebabs.     

Kurzmitteilung zum Mechanismus der Spannungsübertragung in eigenfaserverstärkten Kunststoffen

Mechanical parameters like Youngs modulus and yield stress have been measured from a set of samples of fiber reinforced polymer composites. The values have been correlated to the lateral diffuse phase boundary thicknesses of the fibers. It has been found, that the phase boundary is an important morphological feature responsible for the transfer of load from the matrix onto the fibers.     

Ellipsometrische charakterisierung der adsorptionsschichten von polyäthylenglycol,polyvinylpyrrolidon und polystyrol an chromoberflächen

In the work presented, the adsorption of polystyrene (PS) from cyclohexane (25°C, 36°C), dioxane (15°C, 36°C) and methylethylketone (15°C, 36°C), the adsorption of polyethyleneglycol (PEG) from H₂O and methanol (25°C) and the adsorption of polyvinylpyrrolidone from H₂O (25°C) was investigated by means of ellipsometry. Chrominium covered glass-slides, prepared by high-vacuum technic, were used as adsorbent. From the thickness, concentration and adsorbed amount measured it can be followed, that the polar PEG is adsorbed in a principle different manner than the unpolar PS. PEG prefers to adsorb in a flat uncoiled manner, while PS is adsorbed in a coil-form conformation.     

Über die Wechselwirkung zwischen Polycaprolaktam und Polyäthylenglykolterephthalat in Gegenwart von Stabilisatoren

There has been investigated the effect of copper phthalocyanine (I) and basic lead phosphite (II) on the exchange interaction in a joint thermal processing in a melt of polycaprolactamide (PCA) and polyethylenglycolterephthalate (PÄT). Added in a quantity of 0,05 mass-% with regard to the mixture of I and II, they inhibit the exchange reactions between the two polymers. It was found that above a definite degree of exchange interaction, the high melting block polyesteramide contains a fraction which is soluble in 85% formic acid. This is confirmed by the thermograms of the samples after triple extraction with 85% formic acid. The only peak of melting therein, referring to the high melting block polyesteramide, is considerably narrowed and moved on to higher temperatures. The addition of 1 mass-% of II of the mixture accelerates the exchange interaction between PCA and PÄT, in which is expressed the double action of II.     

Nachweis von ω-Aminocarbonsäuren und Carbonylverbindungen in thermooxidativ abgebautem Polycaprolactam

After oxidation and subsequent hydrolysis homologous series of alkyl amines and ω-amino carboxylic acids were proved to be further degradation products of polycaprolactam. The formation of these substances cannot be explained by an attack on the N-vicinal methylene group which is the most reactive site of this polymer. Considering the low and nearly equal amount of nitrogen containing degradation products a statistical attack on the remaining methylene groups takes place besides the preferred N-vicinal reaction. The CO-vicinal site is not particularly activated. The formation of likewise isolated substances with carbonyl groups cannot be explained by a uniform mechanism.     

Blends aus polyvinylchlorid und chloriertem polyäthylen. III. Untersuchungen von dynamischen eigenschaften,schlagzähigkeit,transparenz und fließverhalten

The modul of the polymeric two phase system poly(vinylchloride)/chlorinated poly(ethylene) is dependent on manufacturing conditions during melt blending. We have compared experimentally determined moduls of these blends with calculated moduls according to the models of Davies and Nielsen. The calculated moduls are in agreement with morphological findings by electron microscopy. An interpenetrating network of the two phases or a sphere-in-matrix morphology is found dependent on concentration and on manufacturing conditions during melt blending. Optical properties of the modified PVC were determined by light scattering. Correlation of impact properties of these blends with morphological observations confirms the interpenctrating network structure as optimal to achieve good mechanical properties. This morphology has also the lower melt viscosity compared to the spherematrix-morphology. These rheological results are compared with the particle flow of PVC being demonstrated with two samples of emulsion PVC.     

Untersuchungen der strukturänderungen in polyäthylenmischungen niederer und hoher dichte bei bestrahlung mit γ-strahlen

Structural changes are investigated which occur in mixtures of polyethylene with low and high density by radiation with γ-rays. It is established by electron microscopy that up to certain doses the rays cause structuring in the clean polymers and also in the mixtures. At greater radiation doses (10 Mrad) degradation and crazes are obtained. These processes are in direct dependance on the contents of the mixtures and are connected with their crystal structure. By X-ray investigations the change in the crystal structure of the mixture is studied. The destruction of the polymer chains is proved by IR-spectroscopy.     

Die bestimmung der maschenweite von netzwerk-lösungen aus fließkurven,Kurzmitteilung

Aspects of crosslinking cotton-cellulose are given in view of structure and processing by means of informations from literature. From results found there, crosslinking agents and methods were selected (underlying the similarity of the structure and reactivity of native and regenerated cellulose), which seemed to be optimal for studies of the influence of crosslinking cellophane to the resulting gas-permeability. Various fixed crosslinking agents are found to have a quite different influence on the permeability (P

1 FA = Formaldehyd; DMH = Dimethylol urea; DMÄH = Dimethylolä ethylene urea; DMDHÄH = dimethylol dihydroxyë-thylene urea.

) of foils at equal molare concentrations of this agents. Effectivity for lowering P depends, within a certain (medium) molare concentration of crosslinking units in cellophane, from the order: DMDHÄH>FA>DMÄH>DMH whereas this order is: DMDHÄH∽HFA>DuH>DMH at lower molare concentrations. Comparing the effectivity on lowering P of crosslinking agents in reference to their weight-content in cellophane within the medium to lower range of concentration, the order is: FA>DMDHÄH>DMÄH> DMH . At higher concentrations DMDHÄH shows a further strong and progressive effect in decreasing values of P , whereas FA shows this effect reversed by increasing these values. These results are referred to various functions of chemical and morphological structures and to the different ability of the crosslinking-compounds to homopolymerize during crosslinking, which follows the order of: DMDHÄH 相似文献   

Charakterisierung der langkettenverzweigung von polyäthylen in abhängigkeit vom molekulargewicht durch kopplung gelchromatographie/automatische viskosimetrie bei hohen temperaturen

The molecular weight dependence of long-chain branching of polyethylene was measured with a high temperature gel permeation chromatograph coupled to an automatically recording capillary viscometer. With the viscometer the effluent times of the fractions elued from the gel permeation chromatograph are measured after being collected in the syphon. A special construction of the inlet tubes of the viscometer prevents errors of the times measured which may otherwise be caused by droplets of liquid getting into the viscometer during the measurement. Thereby an accuracy of the effluent times of ±3·10^?2s could be achieved. With four polyethylenes made by different procedures it was found that—with the exception of one sample—the number of trifunctional branch points per unit molecular weight is different between the polyethylenes but practically independent of the molecular weight.     

Darstellng räumlich vernetzter Polymer aus difunktionellen Monomeren und reaktiven polyfunktionellen Mikrogel- und Gelpartikeln. Kurzmitteilung

The preparation of addition products from liquid cis-polybutadiene and phenol in the presence of 70% aqueous perchloric acid is described. The percentage of phenol as ortho- and para-substituted phenol and as phenylether is quantitatively determined by IR-analysis. Part of the double bonds of the polybutadiene is used up by cyclisation by which mainly condensed cycloaliphatic 6-ring-systems are formed. Coatings from the addition products have excellent hardness, elasticity and adhesion. On aging they undergo crosslinking. Analysis shows this to be an oxidativ process.     

Comportement électrique des interfaces polyéthylène-métal en liaison avec l'adhésion

Some routes to synthetize covalently bound chelating groups as 8-hydroxyquinoline or 8-hydroxyquinoline-5-sulfonic acid to cellulose are given. The products show a capacity of 500–800 μmol/g, fast kinetics of exchange and good stability against the eluent. The apparent stability constant of the complexes with Zn²⁺ are around 2 · 10⁵ mol^?1 dm³.     

Etude par chromatographie liquide haute pression de polyoléfines et de polyéthylènes modifiés

The high speed liquid chromatography behaviour of polyolefins with different crystallinities, of various branched chain polyolefins (high and low density polyethylene, ethylene-propylene copolymer, polypentene) as well as modified polyethylenes either in bulk (chlorination) or on the surface (chlorination, chlorophosphorylation, oxidation) was studied. The samples consisted of glass beads (44–50 μm) which were coated by deposition of the polymers. The study was carried out on one hand in an apolar mobile phase (cyclohexane) with phenol, ortho-, meta-, and para-nitrophenol as solutes, on the other hand in a polar mobile phase (water-methanol mixtures) with benzene, chlorobenzene, and orthodichlorobenzene as solutes. The influence of a swelling agent for the polymer and the temperature effect were investigated. The obtained results show the possibility of liquid chromatography to study interactions between polymers and a given solventsolute.     

Wärmeübergang in kurzen,wandgängig gerührten Apparaten

Scraped surface heat exchanger are often used in industrial settings for the treatment of systems with solid particle formation or higher viscosities. In reactors with a small length‐diameter ratio, the backmixing has thereby a significant influence on the heat transfer. In the experiments presented here, it can be shown that the heat transfer coefficient strongly depends on the flow pattern within the laminar flow regime, and that, depending on the running conditions, an increased rotor speed may have a negative effect on the heat transfer rate.