Ružica Čunko

Application of AFM for identification of fibre surface changes after plasma treatments

Abstract The application of low pressure argon and oxygen plasma treatment as an eco-friendly process of Lyocell textile modification was investigated. Using atomic force microscopy, the changes in nanomorphology induced by plasma treatments were recorded. The chemical groups of the outer fibre layer treated with plasmas and silver compounds (AgNO3 and AgCl) were analysed using Fourier transform infrared-attenuated total reflectance spectroscopy. The viscosimetric method was used to determine possible changes of the cellulose polymer molecular weight after plasma treatments. The experimental results provided data useful for better understanding the art of plasma action on the fibre surface, depending on the nature of gases. They also indicate different mechanisms of silver nanoparticle binding and their distribution on the surface of the treated Lyocell fabric, depending on the parameters of the applied plasma process.

Reducing fibrillation tendency of man-made cellulose fibres employing ultrasound treatment

Abstract The impact of 30 kHz frequency ultrasound waves on man-made cellulose fibres after a thirty-minute treatment in an aqueous medium at room temperature, was investigated. The impact of ultrasound treatment on the fibrillation tendency of viscose and lyocell fibres was determined using a modified and developed microscopic method. Based on fibrillation appearance, fibres were assessed and sorted into seven grade groups, according to the criteria for individual numerical assessments based on the fibre microscopy performed. Characteristic images of fibrillation for each fibre type were made. Fibrillation degree (D F) was calculated and fibre fibrillation tendency assessed according to the criteria established. Reduced tendency to fibrillation was recorded for all the fibres after ultrasound treatment. Investigation results of the ultrasound impact on viscosity average molecular mass of fibre samples are also presented. (Paper was presented at the 5th International Conference TEXCI 2003, Liberec, Czech Republic, June 16–18, 2003.)

Influence of Ozone as an Air Pollutant on Polypropylene Fiber Properties

Ever increasing ozone concentrations in the earths atmosphere polluted by photochem ical smog raise the question of possible ageing of fibers in such an environment. This paper investigates polypropylene fibers characterized by pronounced ageing in the natural environment under the impact of sunlight. Fibers are exposed to ozone for varying times and temperatures in a concentration range that can be expected in a heavily polluted urban industrial environment. Changes in the level of chemical composition and molecular configuration are investigated, together with morphological characteristics and end-use properties. Results indicate that, even under relatively mild ozone conditions, hydroper oxide groups are created, morphological surface changes occur, fibers become more brittle and lose strength, and the isotacticity of the configuration is pronounced, but there are some rather positive effects as well.