Browsing B6 – LU institūti un aģentūras / Institutes and agencies of the UL by Author "Vaivars, Guntars"
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Composite membranes of sulfonated poly (Ether ether ketone) with active carbon: Composite preparation and investigation of their properties for potential application for co2 electrochemical reduction
Fedorenko, Deniss; Vaivars, Guntars (Kauno Technologijos Universitetas, 2020)In this study, synthesis of sulfonated poly(ether ether ketone) (SPEEK) was performed using sulfonation method with concentrated sulfuric acid. Polymer with three degrees of sulfonation was obtained: 0.87; 0.82 and 0.74. ... -
Corrigendum to Evaluation of radiation stability of electron beam irradiated Nafion® and sulfonated poly(ether ether ketone) membranes
Pajuste, Elina; Reinholds, I.; Vaivars, Guntars; Antuzevics, Andris; Avotiņa, L.; Sprūģis, Einārs; Mikko, R.; Heikki, K.; Meri, R.M.; Kaparkalējs, Reinis (Elsevier, 2022)Proton exchange membranes (PEM), which have been commonly used in fuel cells have raised interest for the application in harsh environments involving ionizing radiation. Therefore, radiation stability and ability to sustain ... -
Critical Evaluation of the Methods for the Characterization of the Degree of Sulfonation for Electron Beam Irradiated and Non-Irradiated Sulfonated Poly(ether ether ketone) Membranes
Pakalniete, Laura Dace; Maskova, Elizabete; Zabolockis, Rudolfs Janis; Avotina, Liga; Sprugis, Einars; Reinholds, Ingars; Rzepna, Magdalena; Vaivars, Guntars; Pajuste, Elina (MDPI, 2023)Sulfonated poly(ether ether ketone) (SPEEK) materials are promising candidates for replacing Nafion™ in applications such as proton exchange membrane (PEM) and direct methanol fuel cells. SPEEK membranes have several ... -
Different approaches in sulfonated poly (ether ether ketone) conductivity measurements
Fedorenko, D.; Vaivars, Guntars (Institute of Physics Publishing, 2019)Ion conductivity of sulfonated poly (ether ether ketone) (SPEEK) membranes with various degree of sulfonation (DS) was investigated using impedance analysis with different measuring cell configuration and ion conductivity ... -
Evaluation of radiation stability of electron beam irradiated Nafion® and sulfonated poly(ether ether ketone) membranes
Pajuste, E.; Reinholds, I.; Vaivars, Guntars; Antuzevičs, Andris; Avotiņa, L.; Sprūģis, Einārs; Mikko, R.; Heikki, K.; Meri, R.M.; Kaparkalējs, R. (Elsevier, 2022)Proton exchange membranes (PEM), which have been commonly used in fuel cells have raised interest for the application in harsh environments involving ionizing radiation. Therefore, radiation stability and ability to sustain ... -
Impact of Helium Ion Implantation Dose and Annealing on Dense Near-Surface Layers of NV Centers
Berzins, Andris; Grube, Hugo; Sprugis, Einars; Vaivars, Guntars; Fescenko, Ilja (MDPI, 2022)The implantation of diamonds with helium ions has become a common method to create hundreds-nanometers-thick near-surface layers of NV centers for high-sensitivity sensing and imaging applications; however, optimal ... -
Modelling IR Spectra of Sulfonated Polyether Ether Ketone (SPEEK) Membranes for Fuel Cells
Vaivars, Guntars; Krūkle-Bērziņa, Kristīne; Markus, Madara (Scientific.Net, 2020)SPEEK (sulfonated polyether ether ketone) membranes have been prepared and characterized. The SPEEK membrane geometry and theoretical vibration spectra calculated using density functional theory (DFT) as depending from ... -
Optimization of the enzyme power source for a nano drug delivery system fuelled by glucose in blood plasma
Naidoo, S.; Thage, L.; Ying, Q.; Vallie, S.; Vaivars, Guntars (Institute of Physics Publishing, 2019)A unique in vivo electrical pulse generator to improve membrane permeability for drugs and simultaneously facilitate self-powered nano devices for nano drug delivery systems (NDDS) was identified. The use of an unsupported ... -
A Study of Mechanical Properties of Polymer Composite Membranes with Various Ionic Liquids at Elevated Temperatures
Sprugis, Einars; Vaivars, Guntars; Merijs Meri, Remo (Kaunas University of Technology Publishing House Technologija, 2019)Ionic liquid/sulphonated poly(ether ether ketone) composite membranes were prepared using following ionic liquids: 1,2,3-trimethylimidazolium dimethylphosphate, 1-hexyl-3-methylimidazolium dimethylphosphate, 1-dodecyl-3- ...