Magnetization studies of polystyrene/multiwall carbon nanotube composite films

Lappeenranta University of Technology School of Technology Technical Physics Evgenii Zhukov MAGNETIZATION STUDIES OF POLYSTYRENE/MULTIWALL CARBON NANOTUBE COMPOSITE FILMS Master’s thesis 2015 55 pages, 41 pictures, 9 Tables. Examiners: Professor Erkki Lähderanta D.Sc. Ivan Zakharchuk Keywords: polystyrene, multi-walled carbon nanotubes, MWCNT, composite, magnetization, SQUID. In this thesis magnetic properties of polystyrene/multiwall carbon nanotube (MWCNT) composites are investigated with Quantum Design SQUID magnetometer (MPMS XL). The surface of the composite films is studied via BRUKER Multimode 8 Atomic Force Microscope, as well. The polystyrene/MWCNT composites have been prepared by the group of professor Okotrub (Physics Chemistry of Nanomaterials laboratory, Nikolaev Institute of Inorganic Chemistry, Russia). The composite films have been prepared by solution processing and stretching method. The approximate length and inner diameter of the MWCNTs used in fabrication are 260 μm and 10 nm, respectively. The content of MWCNTs is 1 and 2.5 contents percent (wt%) for studied samples. The stretching of the samples is 30% for samples with 1 and 2.5 wt% content, and one sample with 1 wt% loading of MWCNTs is 100% stretched. MWCNTs aligned perpendicular to a silicon substrate are used as a reference sample. The magnetization field dependencies of the samples exhibit hysteresis behavior. The values of saturation magnetization of composite films are much less compared to that of the reference sample. The saturation magnetization coercitivity field value drops with decrease of MWCNT content. At high magnetic fields strong presence of diamagnetism is observed. Measurements in magnetic field parallel and perpendicular to the composite plate display anisotropy with respect to the direction of stretching. Temperature dependences of magnetization for all samples display difference between zero-field cooled and field-cooled curves of magnetization. This divergence confirms the presence of magnetic interactions in the material. The atomic force microscopy study of the composites’ surfaces revealed that they are relatively smooth and the nanotubes are aligned with the axis of stretching to some extent. 

Possibility of press forming wood films into primary packaging

In recent times the packaging industry is finding means to maximize profit. Wood used to be the most advantageous and everyday material for packaging, worktables, counters, constructions, interiors, tools and as materials and utensils in the food companies in the world. The use of wood has declined vigorously, and other materials like plastic, ceramic, stainless steel, concrete, and aluminum have taken its place. One way that the industry could reduce its cost is by finding possibilities of using wood for primary packaging after which it can be safely recycled or burned as a carbon source for energy. Therefore, the main objective of this thesis is to investigate the possibility of press-forming a wood film into primary packaging. In order to achieve the stated objectives, discussion on major characteristics of wood in terms of structure, types and application were studied. Two different wood species, pine and birch were used for the experimental work. These were provided by a local carpentry workshop in Lappeenranta and a workshop in Ruokolahti supervised by Professor Timo Kärki. Laboratory tests were carried out at Lappeenranta University of Technology FMS workshop on Stenhøj EPS40 M hydraulic C-frame press coupled with National Instruments VI Logger and on the Adjustable packaging line machine at LUT Packaging laboratory. The tests succeeded better on the LUT packaging line than on the Stenhoj equipment due to the integrated heating system in the machine. However, there is much work to be done before the quality of a tray produced from the wood film is comparable to that of the wood plastic composite tray.