Eulalia Gliścińska

Sound-absorbing green composites based on cellulose ultra-short/ultra-fine fibers

In this paper studies on sound absorption of the thermoplastic composites on the basis of waste natural fibers are presented. Cotton fibers and cellulose ultra-short and ultra-fine fibers obtained from flax fibers following enzymatic and additional mechanical treatment were used as the components of polylactide composites, and their influence on sound absorption behavior was investigated. The composites were obtained from a pressing process of fibrous multilayer structures. The sound absorption properties of three types of composites were compared: composites reinforced by cotton fibers, composites reinforced by cellulose ultra-short and ultra-fine fibers, and composites reinforced by cotton fibers and cellulose ultra-short and ultra-fine fibers. The role of cellulose ultra-short and ultra-fine fibers in changing the sound absorption properties of composites was determined. It has previously been shown that using natural fibers with a thermoplastic polymer results in increased sound absorption. The best improvement of sound absorption can be obtained by combining cotton fibers and cellulose ultra-short and ultra-fine fibers, especially nanofibers, as a reinforcement.

Sound absorption property of nonwoven based composites

Abstract Sound absorbing materials used to provide optimal conditions in rooms can be applied in the form of textiles with a special structure such as nonwovens or fibre-containing composites. Nonwovens can be successfully used to make thermoplastic composites by thermal pressing. This paper presents the comparison of the sound absorbing properties of needled nonwovens and composites made from them. Composites with various densities can be made of nonwovens with various percentage contents of filling and matrix fibres. The sound absorption by composites with similar thickness, about several millimetres, is slightly lower than that by the laminar nonwoven packs used for their making. The optimal content of the filling fibres in the composite, when its sound absorption coefficient reaches the highest values, is at the level of 10 wt.%. With the increase in the content of filling fibres the composite density decreases. In the case of the composite with 10 wt.% of filling fibres, its density is the highest among the composites investigated, and the increase in absorption of high-frequency sounds is the highest. Imparting a relief with a protrusion diameter over 10 mm to the composite surface, we can increase the sound absorption of that composite.

Solvent Vapour-Sensitive Activated Carbon Submicrofibres Based on Electrospun Polyacrylonitrile Fibre Mat

Lodz University of Technology, Department of Material and Commodity Sciences and Textile Metrology, Center of Advanced Technologies of Human Friendly Textiles PRO HUMANO TEX, ul. Żeromskiego 116, 90-924 Łodź, Poland E-mail: klata@p.lodz.pl Abstract Precursor polyacrylonitrile submicrofibres with a diameter of about 900 nm, electrospun from polyacrylonitrile/dimethyl sulfoxide (PAN/DMSO) solution, were carbonised and chemically activated. These submicrofibres, characterised by a porous structure more developed than in the case of standard fibres, were investigated as solvent vapour sensors. Sensitivity to vapours of four different fluids: methanol, acetone, benzene & toluene at a low concentration of 200 ppm, was studied directly for fibres and for ones in a prototype textile multilayer system. In experiments the electrical conductivity of carbon fibres was utilised. The response time and sensority coefficient, indicating quantitative changes in electric resistance due to contact with the solvent vapours, were estimated. The activated carbon submicrofibres are characterised by sensitivity, a very short response time not longer than 20 s, stability, and selectivity in relation to vapours of polar and non-polar solvents. The sensitivity to vapours of polar solvents is higher than that to those of non-polar solvents.

3-dimensional computer model of electrospinning multicapillary unit used for electrostatic field analysis

Abstract Electrospinning is an experimental method of the polymer super thin fibres formation using the electrostatic field. The distribution of electrostatic field affects the effectiveness of the electrospinning. In order to analyse the electrostatic field for given technological parameters the 3-D computer model of an electrospinning device must be applied.

Bio-Based Composites for Sound Absorption

The acoustic thermoplastic composites and a method for their production with the participation of the bio-components were presented. To form composite matrix polylactide fibres (PLA) were used. Natural fibres (flax (LI) and cotton (CO)), straw and cellulose ultra-short/ultra-fine fibres obtained from biomass were used as a reinforcement. Cellulose ultra-short/ultra-fine fibres were obtained from the flax fibres or straw by enzymatic treatment and optionally modified by silane. The tensile stress at maximum load of composites with the sub-microfibres obtained from waste flax fibres after silane modification is twice higher than that of the composite with the submicrofibres without the silane modification. The effect of different kinds of natural materials on the acoustic composites was studied. The addition of the straw increases the values of the sound absorption coefficient are higher because of the additional voids caused by the particles of straw. If as a reinforcement the CO fibres and cellulose sub-microfibres are used, the sound absorption of the composite is higher than for composite with only CO fibres. In the case of sub-microfibres obtained from the waste flax fibres the highest sound absorption and tensile stress of the composites gives the modification by solution of silane in ethanol and water.