TY - JOUR A1 - Tran, V. C. A1 - Nguyen, V. H. A1 - Tuma, Dirk A1 - Shim, J.-J. T1 - Ionic liquid mediated synthesis of poly(2-hydroxyethyl methacrylate-block-methyl methacrylate)/Fe3O4 core–shell structured nanocomposite by ATRP method JF - Colloid and Polymer Science N2 - A hybrid nanocomposite of magnetic nanoparticles (Fe3O4) and poly(2-hydroxyethyl methacrylate)-blockpoly(methyl methacrylate) (PHEMA-b-PMMA) was synthesized successfully by the atom transfer radical polymerization (ATRP) in an ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6). Fe3O4 nanoparticles were first surface-modified with the initiator, 2-bromoisobutyryl bromide (BiBBr), in dimethylformamide (DMF) solvent, which produced the macro-initiator, Fe3O4-BiB, to initiate the polymerization reactions for the synthesis of the block polymer, PHEMA-b-PMMA. After immobilizing the Initiator on the surface of Fe3O4, the block polymer chains were grafted successfully onto the Fe3O4 surface, causing the Formation of a core-shell nanostructure. The incorporation of Fe3O4 in the nanocomposite was confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The thermal stability and magnetic properties increased with increasing amount of Fe3O4 in the nanocomposite. KW - Nanocomposite KW - Block copolymer KW - Fe3O4 nanoparticles KW - Ionic liquid KW - Atom transfer radical polymerization PY - 2016 DO - https://doi.org/10.1007/s00396-016-3835-5 SN - 1435-1536 SN - 0303-402X VL - 294 IS - 4 SP - 777 EP - 785 PB - Springer International Publishing AG CY - Berlin AN - OPUS4-35893 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tran, K. V. A1 - Woracek, R. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Abou-Ras, D. A1 - Puplampu, S. A1 - Förster, C. A1 - Penumadu, D. A1 - Dahlberg, C. F. O. A1 - Banhart, J. A1 - Manke, I. T1 - Torsion of a rectangular bar: Complex phase distribution in 304L steel revealed by neutron tomography JF - Materials & Design N2 - Metastable austenitic stainless steel (304L) samples with a rectangular cross-section were plastically deformed in torsion during which they experienced multiaxial stresses that led to a complex martensitic phase distribution owing to the transformation induced plasticity effect. A three-dimensional characterization of the phase distributions in these cm-sized samples was carried out by wavelength-selective neutron tomography. It was found that quantitatively correct results are obtained as long as the samples do not exhibit any considerable preferential grain orientation. Optical microscopy, electron backscatter diffraction, and finite element modeling were used to verify and explain the results obtained by neutron tomography. Altogether, neutron tomography was shown to extend the range of microstructure characterization methods towards the meso- and macroscale. KW - Neutron tomography KW - Phase distribution KW - Rectangular cross-section KW - Torsion KW - Geometrical effect PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569101 DO - https://doi.org/10.1016/j.matdes.2022.111037 VL - 222 SP - 1 EP - 13 PB - Elsevier Ltd. AN - OPUS4-56910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ghantous, R.M. A1 - François, R. A1 - Poyet, S. A1 - L’hostis, V. A1 - Bernachy-Barbe, F. A1 - Meinel, Dietmar A1 - Portier, L. A1 - Tran, N.-C. T1 - Relation between crack opening and extent of the damage induced at the steel/mortar interface JF - Construction and Building Materials N2 - Cracks are inevitable in reinforced concrete structures and promote the diffusion of aggressive agents towards the reinforcement. In Eurocodes, for some exposure conditions, a threshold not to be exceeded for crack width near the rebar is recommended in order to limit risks of corrosion development and ensure structure durability. On the other hand, several studies show that the steel/mortar interface quality at the intersection with a crack strongly influences corrosion development. The aim of this study was therefore to test whether a relation exists between the extent of mechanical damage at the interface and the corresponding residual crack opening. To this end, specimens were cracked using three point bending test apparatus and the evolution of crack opening was determined on the outer surface and deep within the specimen. It was observed that the crack opening measured on the outer surface of the specimen was very close to that measured at various depths within the specimen at the same height level. In addition, the length of the mechanically damaged interface was determined for each residual crack opening. It was deduced that cracks induced significant steel/mortar Interface damage independently of the size of their openings. The length of the mechanically damaged interface increased proportionally to the residual crack opening without showing marked variation after a certain crack opening value. Based on the observed results, it is deduced that defining thresholds on crack openings is logical for esthetic reasons but is not articularly relevant for corrosion risk assessment. KW - Reinforced concrete KW - Cracks KW - Load-induced damage KW - Micro-CT PY - 2018 DO - https://doi.org/10.1016/j.conbuildmat.2018.10.176 VL - 193 SP - 97 EP - 104 PB - Elsevier Ltd. CY - Oxford, GB AN - OPUS4-46623 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ho, K.K.C. A1 - Kalinka, Gerhard A1 - Tran, M.Q. A1 - Polyakova, N.V. A1 - Bismarck, A. T1 - Fluorinated carbon fibres and their suitability as reinforcement for fluoropolymers JF - Composites science and technology N2 - The interaction between direct fluorinated carbon fibres and various fluoropolymers (ethylene-chlorotrifluoroethylene, poly vinylidene fluoride, fluorinated ethylene propylene copolymer and tetrafluoroethylene-perfluoro alkoxy vinyl ether copolymer) was studied by means of direct wetting measurements between fibres and the polymer melts and single fibre pull-out tests. The results of both techniques allow the adhesion behaviour between the fibres and the matrices to be predicted. The results obtained show that a low degree of surface fluorination of carbon fibres leads to an improved wettability between the fibres and fluoropolymer melts and this is an indicator for an improved thermodynamic work of adhesion. The apparent interfacial shear strength as measure of practical adhesion, determined by the single fibre pull-out test, increases with increasing degree of surface fluorine content up to a maximum, which depends on the degree of fluorination of the matrix used. The improved interaction between the fibre and the matrix is due to an enhanced compatibility at the fibre/matrix interface. KW - Adhesion KW - A. Carbon fibres KW - B. Debonding KW - B. Interfacial strength PY - 2007 DO - https://doi.org/10.1016/j.compscitech.2007.02.012 SN - 0266-3538 VL - 67 IS - 13 SP - 2699 EP - 2706 PB - Elsevier CY - Barking AN - OPUS4-15814 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -