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Properties Of Viscose Vortex Yarns Depending On Technological Parameters Of Spinning

Moučková E., Mertová I., Jirásková P., Krupincová G., Křemenáková D.

Autex Research Journal

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2015

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Vol. 15, no. 2

138--147

EN

This paper analyzes the relationship between technological parameters of spinning of 100% CV Vortex yarns of different counts and its selected geometrical parameters (a lead of helix of wrapping fibre ribbon, yarn diameter) as well as yarn properties. The number of twist of wrapping fibre layer is determined. The effect of the yarn delivery speed, hollow spindle diameter, and the main draft on the hairiness, mass irregularity, tenacity, elongation, resistance to abrasion and bending rigidity of Vortex yarn is observed. The yarn properties are compared with the properties of open-end rotor spun yarns. Slivers of the same spinning lot were used for the production of both kinds of yarn. The results showed that the delivery speed in combination with spindle diameter affects yarn diameter, hairiness and abrasion resistance. Mass irregularity and imperfections of yarn is mainly affected by the main draft of drafting unit. Technological parameters of spinning do not affect the level of bending rigidity of the Vortex yarn. Tested rotor spun yarns had a larger diameter, higher hairiness, lower tenacity and higher elongation, lower mass irregularity and number of imperfections, higher abrasion resistance and lower bending rigidity compared to tested Vortex spun yarns.

2

Flex Fatigue Behavior Of Plastic Optical Fibers With Low Bending Cycles

Huang J., Křemenáková D., Militký J.

Autex Research Journal

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2015

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Vol. 15, no. 2

112--115

EN

Flex fatigue behaviour of plastic optical fibres (POFs) with the diameters of 0.2 and 0.3 mm under different pretensions is measured with fatigue life curve by flexometer. The fatigue sensitivity coefficient is calculated by the linear fitting curve of normalised stress versus logarithm of bending cycles. The residual modulus is investigated during the flex fatigue processes. The results exhibit the exponential relationship between applied pretension and numbers of bending cycles at break. It is indicated that the flex fatigue of POFs might be sensitive with high swing angle or swing speed. There is an evident loss of modulus for two POFs with pretensions of 4 and 10% of ultimate tensile strength during 10-times bending cycles. The values of residual modulus of two POFs almost keep constant after 10-times bending cycles.

3

Evaluation of Illumination Intensity of Plastic Optical Fibres with TiO2 Particles by Laser Treatment

Huang J., Křemenáková D., Militký J., Zhu G., Wang Y.

Autex Research Journal

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2015

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Vol. 15, no. 1

13--18

EN

CO2 laser treatment can increase the surface roughness of plastic optical fibres (POFs) with the diameter of 0.5 mm and enhance the input intensity and attenuation coefficient accordingly, which is supposed to weaken the side emission of POFs in long distance above 375 mm. TiO2 particles were applied to improve the increasing optical loss of POFs by laser treatment. POFs were first modified with fine TiO2 particles and then treated by CO2 laser with the pixel time from 30 to 120 ìs. The surface morphology was observed by scanning electron microscopy to investigate the changes of micro-structure before and after laser treatment and the distribution of TiO2 particles. The illumination intensity and attenuation coefficient were calculated and compared in two methods. It is visible that the evaluation by model LLF2 with two parts is more suitable for the fitting of experimental data and shows higher input intensity and lower attenuation than that by standard power function. Both the evaluation methods exhibit that the utilization of TiO2 particles could play an active role in the enhancement of side emission of POFs treated by CO2 laser.

4

Mechanical characteristics of cottonized flax fibers

Militký J., Křemenáková D., Kovačič V., Bajzík V.

Zeszyty Naukowe. Włókiennictwo / Politechnika Łódzka

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2000

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z. 59

203-210

EN

The basic properties of bast fibers are discussed with respects of differences between flax and hemp fibers. The main part is devoted to description of influence of enzymatic cottonization on the selected mechanical properties of ultimate flax fibers. For characterization of ultimate strength the Weibull distribution is used. The initial modulus and deformation work are estimated from experimental data.

5

Geometrical characteristics of cottonized flax fibers

Militký J., Kovačič V., Křemenáková D.

Zeszyty Naukowe. Włókiennictwo / Politechnika Łódzka

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2000

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z. 59

239-244

EN

The main aim of this contribution is description of influence of enzymatic cottonization on the selected geometrical properties of ultimate flax fibers. For characterization of cross section shape changes the shape factor is used. The fineness is computed from area of cross section and gravimetric measurements. The length distribution of ultimate flax fibers is characterized by the robust median measure. The frequency of bundles exceeding some limit sizes are computed.