Institute of Textile Architecture, Faculty of Material Technologies and Textile Design, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
Prof. Zbigniew Stempien
Institute of Textile Architecture, Faculty of Material Technologies and Textile Design, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
This work is a follow-up study for a recently-proposed 3D radiochromic gel dosimeter that contains a tetrazolium salt and a physical gel matrix made of poly(ethylene oxide)- block -poly(propylene oxide)- block -poly(ethylene oxide) (Pluronic F-127). Several tetrazolium salts were examined in this work, including tetrazolium violet, blue tetrazolium chloride, nitro blue tetrazolium chloride (NBT), tetranitro blue tetrazolium chloride (tNBT) and thiazolyl blue tetrazolium bromide (TBTB). The salt-containing gel dosimeters were compared with the first Pluronic gel composition that contained 2,3,5-triphenyltetrazolium chloride (TTC) as the radiation-sensitive component (dose sensitivity of 0.0023 (Gy cm) −1 ). The Pluronic gels with NBT and tNBT outperformed the other gels, including the TTC-containing gel, with respect to their dose sensitivity and low dose-response. The NBT gels were found to have better stability over time than tNBT gels. Sensitization of the gels to ionizing radiation was examined by addition of tert-butyl alcohol and sodium formate. The best composition was 0.0818% NBT (1 mM), 25% Pluronic F-127 and 0.136 × 10 −2 % sodium formate. This gel dosimeter was insensitive to changes in dose rate for photons of different energies. The mean dose sensitivity amounted to 0.0047 ± 0.1 × 10 −4 (Gy cm) −1 . A diversion in the dose-response was observed for the gel irradiated with electrons. Additional characteristics of the NBT gel were a linear-dose range and a dynamic-dose range between <1 and ⩾150 Gy and a dose threshold of <1 Gy. The dose distribution registered for the NBT-Pluronic gel was stable after irradiation for over 7 d with no visible diffusion of the irradiated part, which is analogous to the original TTC-Pluronic gel.
The inkjet-printing technique was used to deposit a commercial silver nanoparticle ink in order to fabricate the electro-conductive layers directly on the different natural, synthetic, blend and mineral textile fabric surfaces with simultaneous sintering at 130℃ during printing process. This modification eliminated the necessity of sintering of silver prints in a box oven and significantly minimised ink spreading over the fabric. The silver nanoink used was characterised by means of ultraviolet-visible spectrometry, dynamic light scattering and transmission electron microscopy. The changes in surface resistance of the fabrics with the silver-deposited layers have been measured by means of the four-probe method. The morphology of the silver layers has been observed by optical microscopy and scanning electron microscopy. The conducting layers were also characterised chemically by means of energy dispersive spectroscopy. The changes in surface resistance of the silver inkjet-printed textiles were evaluated in the bending tests and after the rubbing, washing and dry-cleaning processes. The obtained results proved that the proposed shape-programmed inkjet-printing method was very simple, giving an excellent adhesion of the inkjet-printed silver layers to the substrates and ensuring a very low surface resistance. The studies have confirmed the usefulness of the ink applied for inkjet printing of silver electrodes and their good tolerance to bending, washing and dry-cleaning processes.
The paper presents the results and analysis of interdisciplinary research concerning electromagnetic field shielding, conductive polymers printed on textiles and numerical simulation using the finite element method (FEM). The use of conductive, layered textiles for shielding electromagnetic interference (EMI) has been proposed. After establishing the optimal conditions for deposition of polyaniline (PANI) and polypyrrole (PPy) on polyacrylonitrile (PAN) fabric, conductive composites were made by means of reactive inkjet printing. For this purpose, polyacrylonitrile (PAN) fabrics were coated with polyaniline or polypyrrole, obtained by chemical oxidation of aniline hydrochloride and pyrrole by ammonium peroxydisulfate. The morphology of the obtained coatings was observed using a scanning electron microscope (SEM). The conductive properties (surface resistance) of the fabrics were measured using the four-wire method, and the tests of the effectiveness of electromagnetic shielding were carried out using the waveguide method in the frequency range from 2.5 to 18 GHz. The results of experimental shielding effectiveness (SE) tests and numerical simulation showed that the composites of polyacrylonitrile with polyaniline PAN/PANI and polyacrylonitrile with polypyrrole PAN/PPy achieved very good and good EMI shielding efficiency, respectively. Moreover, the obtained measurement results were verified by numerical modeling with the use of FEM–ANSYS HFFS software.