Metal-plastic composites are promising components for lightweight constructions. The paper deals with metal-plastic composites with an elastic interface layer of polyurethane with different thicknesses. The introduction of such a plane and adhesively bonded elastic interface layer enables the production composites of metals and thermoplastics with very high bond strength. The composites are made by compression moulding, injection moulding or by sandwich injection moulding. The bond strength was characterized by a shear test.

Translation abstract Metal plastic hybrids will become more important as components for lightweight constructions. It is reported about optimisation of making three layer hybrids consisted of a steel plate, an adhesion layer based of uretdione powder coating material and a flexible component polyurethane in model experiments. Hybrid formation is performed in a compression moulding process. The adhesion layer and the polyurethane are modified to increase the hybrid bond strength. Peel test are conducted to quantitatively characterize the bond strength and an apparent energy release rate is calculated based on the peel force. For hybrids with widths of 2 mm polyurethane stripes it is possible to increase the apparent energy release rate for about 30 % to 16 N/mm in comparison with a hybrid with unmodified components. These hybrids have the same high bond strength level as the strongest hybrids reported in literature. Concluding the optimisation results are discussed related to their relevancy for the interpretation of the adhesion mechanisms in the interface between adhesion layer and polyurethane.

Metall‐Kunststoff‐Verbunde werden als Bausteine für Leichtbaulösungen immer mehr an Bedeutung gewinnen. In dieser Arbeit wird über Modellversuche zur Optimierung der Herstellung von Dreischichtverbunden aus Stahlblech, einer Adhäsionsschicht aus einem Uretdionlack und der flexiblen Weichkomponente (thermoplastisches Polyurethan (TPU)) berichtet. Die Verbundbildung erfolgt in einem Pressverfahren. Es erfolgt sowohl eine Modifizierung der Adhäsionsschicht, als auch die Modifizierung der Weichkomponente mit dem Ziel einer Erhöhung der Verbundfestigkeit. Als quantitatives Maß dafür wird aus der im Schälversuch gemessenen Schälkraft ein „scheinbarer GIc‐Wert“ berechnet. Für Verbunde mit einer thermoplastischen Polyurethan‐Streifendicke von 2 mm wird der GIc‐Wert gegenüber dem Verbund mit unmodifizierten Komponenten um ca. 30 % auf 16 N/mm erhöht. Damit weisen diese Verbunde ähnlich hohe Verbundfestigkeiten auf wie die stabilsten Verbunde aus der Literatur. Abschließend werden die erzielten Optimierungsergebnisse hinsichtlich ihrer Bedeutung für die Interpretation des Haftungsmechanismus in der Grenzschicht Adhäsionsschicht‐thermoplastisches Polyurethan diskutiert.

Polytetrafluoroethylene (PTFE) powder is used as a solid lubricant in commercial antifriction coatings. However, most of the matrix polymers are usually not compatible with virgin PTFE resulting in low dispersion and mechanical film stability and adhesion. In our research PTFE TF 2025 was irradiated by g-beam generating PTFE micropowder with persistant radicals and functional groups. These functional groups are able to perform a chemical grafting (cg) of polyamideimide (PAI) and modified PTFE-micropowder by reactive extrusion in melt. Based on grinded extrudates PAI-PTFE-cg dispersions were formulated followed by characterizing dispersion as well as film properties. It was found, that PAI-PTFE-cg dispersion comprises very small PTFE-particles at higher g-irradiation doses in homogeneous dispersions. In addition, all samples showed outstanding film flexibility. Basic tribological properties under mixed lubrication were studied by using a ring-on-disk tribometer. Finally, diluted dispersions were applied to a multi-surface sliding bearing (four segments) for testing in a hydrodynamic plain test bench.

During the irradiation of high molecular weight poly (tetrafluoroethylene) (PTFE) in presence of oxygen perfluoroalkyl (peroxy) radicals and functional groups are formed which allow chemical coupling reactions (cc = chemical compatibilized) with oils and plastics. The micropowder resulting from the irradiation of PTFE are used in base oils to improve the tribological properties significantly if oil molecules are covalently linked to primary PTFE particles in the oil dispersion. These oil-PTFE-cc-dispersions show primarily anti-wear (AW) properties. The use of additional reactive groups (e.g. phosphite groups) in the oil gives the dispersions extreme pressure (EP) properties additionally. This article demonstrates the usefulness of the oil-PTFE-cc-dispersions in rolling bearings and in ropes using phosphite-modified PTFE products as additive in lubricants. The investigations are completed by wear tests with different contact geometries. A model is shown to explain the effect of phosphite groups on 100Cr6 metallic surfaces.Keywords: PTFE, high performance lubricant, oil-PTFE-cc dispersion

Irradiation modified PTFE (polytetrafluoroethylene) micropowder was processed with PAI (polyamideimide) by reactive extrusion to a chemically grafted and compatibilized PAI-PTFE-cg material which was dissolved in NMP to form a lubricant varnish dispersion. After application and curing on a substrate the anti-friction coating was characterized in terms of mechanical and tribological properties. It could be shown that the PAI-PTFE-cg material is an effective substitute for the white alloy used in hydro-dynamically lubricated floating bearings.

This article gives an attention to the development, processing and tribological characterization of special semi-finished products, so-called tribo-patches, for integration into complex structures from thermoplastic fiber composites. These patches are made of three different textile reinforced slides on the basis of chemically coupled/compatibilised thermoplastic (PP, PA6 and PEEK)-PTFE-compounds. The performed friction and wear analyses show that these maintenance-free foil bearings possesses very good tribological properties.

During the irradiation of high molecular poly(tetrafluoroethylene) (PTFE) in presence of oxygen perfluoroalkyl(peroxy) radicals and functional groups are formed which allow chemical coupling reactions with oils and plastics. The micropowder resulting from the irradiation of PTFE are used in base oils to improve the tribological properties significantly if oil molecules are covalently linked to PTFE particles. Surface charge and the size and distribution of PTFE particles in the oil affect the resulting properties, e.g., stability of PTFE particles in the oil phase and, therefore, their tribological efficiency. Tribological properties of oil-PTFE-cc dispersions (cc = chemical compatibilized) are discussed and specific performance parameters from practically oriented tests are presented.

In the prevailing paper we report the production and testing of multi component composites based on the high performance polymer PPS. Both flexible two component rigid-flexible-composites and rigid composites with a functional polymer are produced. In the case of the two component composites TPU is used as flexible component whereas it is used as a flexible inter layer in the rigid composites. A new adhesive layer consisted of polyallophanate powder coating material is used in all composites between PPS and TPU. The multi component composites are manufactured by injection moulding or compression moulding. The flexible composites are tested with a peel test to measure the peel force determining the Glc value. The rigid composites are tested in compression shear test.

Micropowder of poly(tetrafluoroethylene) (PTFE) can be used in base oils to improve the tribological properties significantly, if oil molecules are covalently linked to primary PTFE particles in the dispersion. Enhanced properties are not only determined by the amount of PTFE micropowder added to the oil but as well by the surface charge, radical concentration, and the size and distribution of PTFE particles in the oil phase.The chemical compatibilization (=cc) between PTFE micropowder and ester oil by the use of two types of PTFE micropowder, which differ in radical concentration and the amount of functional groups is shown. The concentration of PTFE micropowder in the dispersions was varied from 5 to 20 wt%. Both the pure PTFE micropowder and the oil-PTFE-cc dispersions were characterized by ESR and FTIR spectroscopy as well as by zeta potential measurements. Rheological and tribological tests were performed on the ester oil and the oil-PTFE-cc dispersions. Qualitative differences are discussed in terms of particle interactions, dispersion stability, chemical compatibilization efficiency and the amount of functional groups.A correlation between flow properties and surface charge of the PTFE particles within the dispersions was obtained. The influence on tribological properties is discussed as well. (C) 2014 Elsevier B.V. All rights reserved.

Poly(tetrafluoroethylene) (PTFE) micropowder is used as a lubricant in thermoplastic high-performance polymers, for example, in poly(ether ether ketone) (PEEK) to improve their tribological properties regarding friction and wear significantly. The achievable effect for improving such properties by using PTFE is not only determined by the added amount of PTFE micropowder in the PEEK-PTFE compound but rather by the possibility to couple and compatibilize the PTFE with the matrix material chemically that has a direct influence on the distribution of the PTFE particles in the polymer matrix and causes improved tribological and mechanical properties. The proof of a chemical reaction between PTFE and PEEK is difficult because the high-molecular weight PEEK is insoluble in all common solvents. The evidence of chemical coupling reaction between PEEK and irradiation-modified PTFE is shown by model studies using reactive OH-terminated PEEK oligomers. The use of diphenyl sulfone as a high-boiling reaction medium was necessary for the precondition to melt both reactants. In this way, qualitative differences have been achieved and confirmed using Fourier transform infrared spectroscopy. Thus, a safer and indirect detection of the chemical coupling (cc) between PEEK and PTFE (PEEK–PTFE–cc) was achieved.

For the first time, blends of melt processable polytetrafluoroethylene (MP PTFE) with polyetheretherketone (PEEK) in the MP PTFE/PEEK ratio of 100/0, 80/20, 50/50, 20/80, and 0/100 w/w were prepared and characterized. MP PTFE/PEEK blends are attractive materials due to the combination of low coefficient of friction and universal chemical resistance of MP PTFE with good wear resistance and mechanical strength of PEEK while maintaining high thermal stability of both. Miscibility, phase morphology, and mechanical properties of the new MP PTFE/PEEK blends were investigated. To improve their end-use properties, an attempt of reactive compounding with the electron beam irradiated MP PTFE (e-beam MP PTFE) was made. The reactive compounding was done in two steps, that is, the preparation of a masterbatch (MB) consisting of e-beam MP PTFE/PEEK (50/50 w/w) and subsequent melt blending of MP PTFE/PEEK with varying concentrations of MB. The e-beam irradiation of MP PTFE carried out in air atmosphere and at room temperature with a dose of 50 kGy results in its chain scission associated with formation of COF and COOH functional groups. Such modified MP PTFE can be used to compatibilize MP PTFE/PEEK blends. Reactive compatibilized blends exhibit improved phase morphology and mechanical properties. Especially for MP PTFE/PEEK 50/50 blends, a great improvement of almost 250% in strain at break, 40% in stress at break, and more than 600% in toughness was achieved. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

ABSTRACT This contribution describes the effect of absorbing materials on the functionalization and the concentration of radicals of poly(tetrafluoroethylene) (PTFE) during the γ‐irradiation compared to the results without absorbing materials. Different absorbing calcium‐based materials were used to study their efficiency to avoid the release of fluorinated gases that occur within the irradiation procedure in the environment. It was found, that the type of the absorbing material had a significant effect on the formation and concentration of functional groups (carbonyl fluoride, carboxylic acid) and persistent radicals within the radiation‐treated PTFE samples. In addition, by means of wide angle X‐ray scattering (WAXS) the quantitative determination of fluorine (F − ) concentration after irradiation in the absorbing materials could be followed. It may be used for scientific investigations of radiation induced PTFE chain scission mechanisms as well as for the monitoring of industrial γ‐irradiation processes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1787–1793, 2013

A method is described, that allows a quick and simple testing of the burning behaviour of plastics. It takes into account ignition time as well as afterflame time; properties that are characteristic for the burning behaviour of a particular plastic material. The procedure is easy to perform, it does neither require injection-moulded samples nor expensive equipment. The method provides a classification of the burning behaviour. It is especially suitable for a screening of plastic materials complementing established methods like UL-94, GWFI and LOI, and may find application in the development of flame retardants.

In this paper first results about processing and properties of metal plastic hybrids are reported. As metal component were used powder coated steel sheets using a tailor-made uretdion powder. The coated sheets were overmoulded with a variety of thermoplastics in an injection moulding machine. Both soft and flexible as well as rigid and hard thermoplastics were investigated. The modified climbing drum peel test showed that the hybrids based on soft and flexible thermoplastic polyurethane exhibit significant adhesion. Metal plastic hybrids with rigid hard plastics showed no adhesion. This problem was overcome by preparation of three component hybrids containing a thin flexible TPU-layer between coated metal and rigid thermoplastic. Two proposals are given to explain the adhesion results adequately.