Ljubljana, Slovenia
Ljubljana, Slovenia

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Burja K.,CO PoliMaT | Segedin U.,Helios Domzale D.d. | Skale S.,Helios Domzale D.d. | Berce P.,Helios Domzale D.d. | And 4 more authors.
Progress in Organic Coatings | Year: 2015

High-solids styrene-hydroxyl-acrylic copolymer resins were synthesized in different solvents above their boiling points in a high-pressure reactor and compared to the same resin synthesized at ambient pressure. High-solids acrylics, prepared in a closed high pressure reactor at temperature above solvent's boiling point, have lower molecular weight, narrower molecular weight distribution and consequently a lower viscosity compared to resins with the same chemical composition and content of solids prepared at ambient pressure. Syntheses were monitored calorimetrically and by in situ ATR-FTIR spectroscopy using an RC1e™ reaction calorimeter. All synthesized resins were tested in two-component polyurethane metal topcoats. Coatings based on resins synthesized in a pressure reactor cure faster according to Model Free Kinetics studies and display improved anticorrosion properties, determined by electrochemical impedance spectroscopy, when compared to the resin synthesized at ambient pressure. © 2014 Elsevier B.V.

Devetak M.,Co PoliMaT | Skoporc N.,University of Ljubljana | Rigler M.,University of Ljubljana | Persin Z.,Co PoliMaT | And 7 more authors.
Materiali in Tehnologije | Year: 2012

We investigated water sorption in viscose nonwoven fibres manufactured by Tosama d.d. with the surface density of 175 g/m 2. A comparison between untreated fibres and by oxygen plasma treated fibres was made using optical polarization microscopy. Plasma treatment was done for 10 minutes at pressure of 75 Pa at current of 250 mA at the power of 500 W. Swelling was characterized by measurements of fibre diameter. Modifications of intensity of the polarized light transmitted through the fibre were measured as a function of time of exposure to water. Characteristic swelling and intensity modification times were resolved for untreated and oxygen plasma treated fibres. The swelling time of oxygen plasma in comparison to untreated plasma is reduced by the factor of 0.54 and intensity change time by the factor of 0.4. From the characteristic swelling and intensity change times it was concluded that oxygen plasma treatment of viscose increases the speed of water sorption.

Kurecic M.,University of Maribor | Kurecic M.,CO Polimat | Smole M.S.,University of Maribor | Smole M.S.,CO Polimat
Tekstilec | Year: 2013

Electrospinning is a method based on the use of electrostatic forces for producing continuous fibres with the diameter from between ten nanometres to some micrometres. Such fine fibres cannot be produced with conventional methods for the production of nonwovens. The nanofibres formed with electrospinning have an exceptionally large active surface area per mass unit (fibre surface at diameter of 100 nm equals 40 m2/g) and the spinning process itself enables a planned formation of the web structure (e.g. planned size of pores in the web by adjusting the nanofibre diameter and fibre thickness). Nanofibres can be electrospun from synthetic or natural polymers and their blends, from polymers with various nanoparticles (metal, ceramic etc), active substances etc. We can fabricate individual fibres, as well as webs with a random or planned fibre arrangement. Fibres with a complex structure, e.g. core shell or hollow fibres, can be produced with a special electrospinning method. Regarding the advantages demonstrated by the nanofibres fabricated with electrospinning, this procedure has become an important part of research in seve ral fields of use of technical textiles, e.g. shielding materials, air and oil filters in the car industry, agrotextiles and most of all medical textiles. The method can also be used in the production of batteries and photovoltaic cells. Apart from the apparatus designed for the research purpose in laboratories, pilot devices and the devices designed for the use in the industry can be found on the market. The paper comprises the introduction of the preparation procedure of nanofibres on an electrospinning apparatus, the morphological characteristics of fibres and the characteristics of electrospun webs in dependence of the conditions when forming fibres.

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