Publications Search Results

Now showing 1 - 10 of 33
  • Publication
    Printing of µm structures with nano inks using a novel combination of high‐resolution plasma printing and subsequent rotogravure printing
    ( 2019)
    Thomas, M.
    ;
    Herrmann, A.
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    Dohse, A.
    ;
    Borris, J.
    ;
    Weidlich, E.-R.
    In this paper, we investigated reel‐to‐reel area‐selective microplasma treatment of polymer films using the plasma printing technique in combination with subsequent rotogravure printing. The aim was to explore whether and how the plasma printing pretreatment could contribute to increase print resolution with conductive nano inks on flexible polymer substrates. Substrate materials tested included films of biaxially oriented polyester and polypropylene. As the plasma process gas, a nonflammable mixture of 97% N2 and 3% H2 was used. Novel microplasma sources developed during the course of this work achieved satisfactory plasma modification effects for the control of ink‐wetting patterns at process speeds of up to 3 m/min. In the case of biaxially oriented polypropylene (BOPP) film, this value was six times higher than the process speeds using previous microplasma sources. The reproduction accuracy achieved with these process parameters was typically better than 1.5% for structures with widths as low as 10 µm. Organic solvent and water‐based ink systems with silver and PEDOT:PSS as conductive components were tested in the rotogravure process following the area‐selective plasma pretreatment. In the combined plasma printing and gravure printing process, a resolution as good as 50 µm, was achieved using an aqueous PEDOT:PSS‐based ink. Conductive tracks produced on BOPP with this ink also passed the tape test for adhesion.
  • Publication
    Funktionelle Oberflächen für 3-D-gedruckte Polymere
    ( 2019)
    Neubert, T.
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    Borris, J.
    ;
    Lachmann, K.
    3‐D‐Druck kombiniert mit einer Atmosphärendruck‐Gasphasenabscheidungsquelle erlaubt, Beschichtungen mit funktionellen Gruppen auf Polymerbauteilen aufzutragen. Hierdurch lässt sich die Adhäsion steuern.
  • Publication
    Stickstofffunktionalisierung. Sauerstofffreie Plasmajet-Vorbehandlung für die Kunststoffaktivierung bei Umgebungsdruck
    ( 2017)
    Eichler, M.
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    Fischer, V.
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    Paulmann, S.
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    Stammen, E.
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    Thomas, M.
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    Khosravi, Z.
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    Hinze, A.
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    Grishin, A.
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    Lachmann, K.
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    Borris, J.
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    Dohse, A.
    ;
    Nagel, K.
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    Dilger, K.
    ;
    Klages, C.-P.
  • Publication
    Strengthening fibre/matrix interphase by fibre surface modification and nanoparticle incorporation into the matrix
    ( 2013)
    Drescher, P.
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    Thomas, M.
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    Borris, J.
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    Riedel, U.
    ;
    Arlt, C.
    Fibre reinforced polymers (FRPs) generally consist of different phases including the matrix phase, the fibres as the dispersed phase and the fibre/matrix interphase. Of great importance for the FRP properties such as mechanical strength is the contact between the fibre and the matrix. In this work modification of the fibre surface was investigated with the aim to strengthen the contact between fibre and matrix by increasing the surface of fibre and matrix as well as using the atomic forces through nanoparticles. These modifications are to enhance properties of the composite such as tensile strength and interfacial strength. One approach used to achieve this was the modification of the fibre surface by coating it with a resin containing nanoscaled particles including purified carbon nanotubes (CNTs), carbon nanotubes functionalized with carboxyl groups or amino groups as well as boehmite nanoparticles functionalized with taurine. Another approach was to modify the fibres with various treatments. In this approach the fibres were plasma treated, coated using a sizing agent with carbon nanotubes dispersed in it or treated in liquid nitrogen. Properties of the composites produced such as strength and effectiveness of the composites were investigated using the tensile fibre bundle test as well as the single fibre pullout test. Scanning electron microscopy (SEM) was used to examine the homogeneity of the dispersions and fracture areas of samples that underwent fracture testing. Results obtained in this work show that considerable enhancement of the interphase and mechanical strength of the FRP can be achieved with composites that contained suitably treated fibres. Particular improvements were achieved with the plasma treatment of carbon fibres in an Ar/O-2 atmosphere as well as a combination of CNTs and boehmite nanoparticles in the resin.
  • Publication
    Adhesion Improvement by Nitrogen Functionalization of Polymers Using DBD-Based Plasma Sources at Ambient Pressure
    ( 2013)
    Thomas, M.
    ;
    Eichler, M.
    ;
    Lachmann, K.
    ;
    Borris, J.
    ;
    Hinze, A.
    ;
    Klages, C.-P.
    Nitrogen-bearing chemical functional groups have been generated on the surfaces of various polymers by plasma treatment using dielectric barrier discharges (DBDs) or AC corona discharges stabilized by a dielectric barrier. Investigations on the role of these functional groups for adhesion control are reported in this paper. The experiments were carried out under an almost oxygen-free atmosphere with nitrogen, forming gas and ammonia as process gases. It was possible to establish more than 10 primary amino groups per nm2 on polyethylene (PE) or biaxially oriented polypropylene (BOPP) with forming gas and optimized hydrogen content depending on the energy density. Adhesion experiments carried out on BOPP with natural rubber adhesives show a close relationship between the number of primary amines and adhesion improvement. Poly(ethylene terephthalate) (PET) functionalized by DBD treatments with forming gas and ammonia shows a strong improvement in adhesion with natural rubb er adhesives up to values typical of wet-chemically treated reference samples. Overtreatment effects become obvious for energy densities above 100 W-min/m2, resulting in a marked decrease of adhesion. In the case of PET other functional nitrogen groups may also play an important role in adhesion and this will need to be clarified in further investigations. In addition, treatment of the high-performance polymers poly(vinylidine fluoride) (PVDF) and poly(ether ether ketone) (PEEK) was investigated. It was found that energy densities of more than 3000 W-min/m2 are necessary to obtain a strong adhesion. For PVDF a strong improvement in adhesion to steel was achieved using hot-melt adhesives. The maximum value was 1.7 N/mm. It was possible to functionalize the PEEK in particular with forming gas in an AC corona discharge in such a way that there would be a cohesive failure in the PEEK after bonding with different epoxy adhesives.
  • Publication
    Plasma printing and related techniques - Patterning of surfaces using microplasmas at atmospheric pressure
    ( 2012)
    Thomas, M.
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    Borris, J.
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    Dohse, A.
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    Eichler, M.
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    Hinze, A.
    ;
    Lachmann, K.
    ;
    Nagel, K.
    ;
    Klages, C.-P.
    The interest in applications of atmospheric-pressure plasmas to solve surface-technological tasks was originally motivated primarily by the expectation that major cost savings could be achieved if plasma-based processes, conventionally run below 1?mbar, could now be performed at ambient pressure. However, it was soon recognized that, working at 1 bar, also completely new techniques are made feasible by the utilization of microdischarges, thanks to strongly reduced mean free paths of plasma constituents. The present contribution gives an overview of a number of possibilities, studied in the recent years, to apply atmospheric-pressure microplasmas for the patterned coating or surface modification of two- and three-dimensional substrates.
  • Publication
    Reduction of plasticizer leaching from PVC by barrier coatings deposited using DBD processes at atmospheric pressure
    ( 2012)
    Cerezuela Barreto, M.
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    Borris, J.
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    Thomas, M.
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    Hänsel, R.
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    Stoll, M.
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    Klages, C.-P.
    Barrier coatings against plasticizer leaching are deposited on flexible polyvinylchloride (PVC) films typically used in flooring or in the automotive industry. Octamethylcyclotetrasiloxane (OMCTS) and hexamethyldisiloxane (HMDSO) are plasma polymerized using plasma-activated CVD (PA-CVD) based on an atmospheric pressure (AP) dielectric barrier discharge (DBD). A reduction in plasticizer leaching higher than 80% is achieved with these coatings. The effect of the monomer flow rate, discharge power, and oxygen flow rate on the barrier efficiency is investigated. The coating composition of the best barrier coating has been identified and the long-time barrier efficiency in contact with an organic solvent has been studied.
  • Publication
    Kostengünstige und ressourceneffiziente Herstellung flexibler Leiterplatten, RFID-Antennen und Biosensoren mittels Plasma Printing & Packaging Technologie
    ( 2011)
    Borris, J.
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    Thomas, M.
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    Dohse, A.
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    Lachmann, K.
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    Hochsattel, T.
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    Weidlich, E.-R.
    ;
    Klages, C.-P.
    In dem BMBF-Verbundprojekt "P3T - Plasma-Printing & Packaging Technology" entwickelt das Fraunhofer IST zusammen mit Partnern aus der Industrie und Wissenschaft eine neuartige Rolle-zu-Rolle-Technologie zur kostengünstigen und ressourceneffizienten Herstellung von flexiblem Leiterplatten, RIFD-Antennen und Biosensorgrundstrukturen. Die P3T-Prozesskette beginnt mit dem Plasma-Printing, bei dem eine Direktstrukturierung der Folie durch eine ortsselektive Plasmamodifizierung mit Mikroplasmen bei Atmosphärendruck erfolgt. Dann folgen nasschemische ortsselektive Metallisierung, Bestückung und Verlötung. Zu den Vorteilen dieser Technologie zählt, dass auf Vakuum- und lithographische Prozesse verzichtet werden kann.
  • Publication
    Plasma-Printing: Strukturierte Oberflächenfunktionalisierung und selektive nasschemische Metallisierung
    ( 2011)
    Thomas, M.
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    Borris, J.
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    Dohse, A.
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    Weidlich, E.-R.
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    Elbick, D.
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    Klages, C.-P.
    Plastics lend themselves especially well to the use of simple forming processes for manufacturer of high-volume components. At the same time however, not only the shape of such components but also additional functionality is demanded. This is especially the case for integration of electrical and electronic applications. By combining atmospheric plasma-treatment and chemical metallising, it is possible to achieve such functions. This opens the door to a large number of new areas of application.
  • Publication
    Micropatterning using atmospheric pressure plasma processes
    ( 2011)
    Thomas, M.
    ;
    Borris, J.
    ;
    Eichler, M.
    ;
    Klages, C.-P.
    Cost-efficient technologies for patterned surface functionalization or coating are of great interest within the glass and plastic industry. In collaboration with partners from industry and academia the Fraunhofer Institute for Surface Engineering and Thin Films IST has developed area-selective ambient pressure plasma treatment processes for pattering surfaces of materials such as silicon, glass or plastic. In the so-called plasma printing process structures with widths down to 20 um were produced. Different types of equipment have been developed to carry out plasma printing batch processes on silicon or glass and reel-toreel processes on flexible substrates such as polymer films.