Water and Oil Repellent Finishing of Textiles by UV Curing: Evaluation of the Influence of Scaled-Up Process Parameters
In this work, various textile fabrics were coated with silicone and fluorocarbon-based resins by photo-curing using ultraviolet irradiation. A great number of large fabric samples were impregnated by padding with commercial finishing agents and then irradiated in air with a high power, semi-industrial UV source. The add-on of various finishing agents was kept low to reduce the treatment cost. White and dyed samples of different textile composition were treated and evaluated in terms of conferred repellency, yellowing, or color changes. Most relevant process parameters were investigated, utilizing the thermal process normally adopted at industrial level as reference. The results were statistically evaluated by ANOVA using Minitab 16 software, in order to identify the most influential parameters and to evaluate the real possibility of replacing the thermal treatment with UV curing.
UV-curable PDMS-containing PU system for hydrophobic textile surface treatment
Polydimethylsiloxane (PDMS) is a super-hydrophobic material with low surface energy. UV-curable PDMS-containing polyurethane (PU) oligomer (UV-PDMS-PU), having a PDMS moiety is designed for textile (PET and Nylon) surface treatment with a long lasting hydrophobic property. UV-PDMS-PU was prepared by an addition of 2-hydroxyethyl methacrylate (2-HEMA) to NCO-terminated PDMS-containing PU pre-polymer (NCO-PDMS-PU). NCO-PDMS-PU was obtained from an addition reaction of alkyl hydroxyl-terminated PDMS with an excess amount of isophorone diisocyanate (IPDI). UV-PDMS-PU system consisted of 1% (w/w) photo-initiator that was coated either on glass plate or textile and then cured by UV-radiation. The UV-cured PDMS-containing PU films were evaluated by the measurements of thermal and physical properties. The hydrophobic characters and silicone content were remained on textile surface after water washing cycles, which indicating that UV-curing process can help the PDMS moiety to anchor onto textile fibers.
A new method of near field analysis
The problem of the accurate determination of the total electromagnetic field produced by a current distribution on a circular disc type aperture is examined. For comparison of the near and Fresnel region solutions, an exact Maxwellian integral is used as the starting point. Aperture and space coordinates are separated by the use of Bessel function addition theorems, allowing the field to be expressed as a sum of terms containing radial and angular integrals. The radial integrals involve only the disc (aperture) distribution and coordinates while the angular integrals involve only the elevation angle. The distance from origin appears implicitly in the series coefficients. These integrals are suitable for high speed computations and have been evaluated for a number of cases. The results are compared with the small angle and general Fresnel formula values for various observation angles, distances from the aperture, and aperture distributions.