مطالعه تجربي جريان مويينگي در نخ هاي مغزي-غلاف

چكيده انگليسي :

ABSTRACTThe spontaneous liquid penetration in fibre networks is due to capillary forces Interfibre spacein a fibrous structure is in the form of capillaries that can be occupied by liq id Thesecapillaries are much better defined in continuous filament yarns under tension than in stapleyarns with twist and liquids can wick into these structures spontaneously because of capillarypressure Capillary flow analysis i e spontaneous liquid wicking is more adapted to yarnstructure The control of capillary penetration kinetics in textiles is an important practical needin many processes and applications such as finishing dyeing printing coating and incomposite processing The technique used in this research consists of observing and measuring the capillary flow ofacolored liquid Such analysis consists in the measurement of the liquid height h as a functionof time t This experimental system is based on the analysis of digital handycam images takenduring the capillary rise of a colored liquid in the yarn As the yarn structure is heterogeneous during capillary wicking at each time there is not a unique position of the liquid Thus a mean level of liquid in the yarn is measured Nylon Cotton core spun yarns have been chosen to make all the wicking experiments Theseyarns have a sheath of cotton with the same count and a core of nylon multifilament with different counts These yarn samples were produced under conditions of different pretensions of core component and different twists of core spun yarn In addition 36 yarn samples with different construction features were produced The liquid used for the wicking measurementswas single distilled water with 0 2 non ionic detergent All the wicking measurements wereperformed at room conditions For observing the height of the water wicked a solution of 0 05 acidic dye in water was used At short experimental times t 60 s the dye and thewater diffuse at the same rate After these times the water moves faster than the dye in yarnsand the effect of chromatography phenomenon was seen clearly In this research the influence of core spun yarn t ist core component count and pretensionof core component on the capillary rate coefficient ias determined In our study the Lucas Washburn law f t h2 AJ is followed in all cases However this law can be applied aslong as gravity forces are negligible h hel he being the height at equilibrium When t 60 s gravity forces can be neglected With plotting h2 versus t the capillary ratecoefficient A given by the slope of the straight line In general at zero pretension of core component the decrease in wieking rate is due to areduction in arrangement of the eore component filaments The speed of travel of liquid incapillaries is readily reduced by the presence of random I arranged filaments in the core spunyarn The capillary rate coefficient increases with the increase of pretension from 0 to 30 gf which it is due to orderly arrangement of filaments gives rise to a increase in the raie of liquidwicking The capillary rate coefficient decreases with the increase of pretension from 30 to60 gf again This is attributed to a reduction of capillary size In general the capillary ratecoefficient decreases with the increase of core spun yarn twist The change in the capillaryrate coefficient with yarn twist is due to a reduction of capi lary size and continuity Ingeneral the capillar rate coefficient increases ith increase in linear density of the corecomponent i e when the number of filaments increases This is understandable in view of itseffect on capillaries radius which in turn affects the rate ofwicking I J 1r iJ l VI

دعا خوان، صفيه

مطالعه تجربي جريان مويينگي در نخ هاي مغزي-غلاف

سينتيك مكش , متلب , يانگ-لاپلاس , معادله لوكاس- واش برن , اشباع منافذ -فشار مويينگي , نخ هاي مغزي-غلاف , تصاوير شدت، باينري، RGB