Experimental Study on Fabric Surface Wettability based on Contact Angle and Surface Energy

Transcription

1 2017 Asia-Pacific Engineering an Technology Conference (APETC 2017) ISBN: Exerimental Stuy on Fabric Surface Wettability base on Contact Angle an Surface Energy Bingxuan Ni an Peng Zhang ABSTRACT The aer stuies on surface wettability characterization of fabric by using contact angle. Accoring to surface tension of liqui, contact angle between liqui an fabric, base on Owens moel, the surface energy of nonwoven surface that has water reellent finishing (samle 2) is mn/m, an nonwoven surface that hasn t water reellent finishing (samle 1) is mn/m. The essence of water-reellent finishing is to reuce soli surface energy. The surface tension of liqui ro is lower the contact angle of rolet an fabric surface is smaller. INTRODUCTION The surface wettability of fabric is one of imortant characteristics in surface roerties. Incluing of raincoat fabric, out oor clothing, meical rotective clothing, surgical raes, esk clothing an wall clothing, they all nee to evaluate their surface wettability. A rolet ros on fabric surface, rolet contacts fabric surface an reaches to equilibrium state. The intersection angle between gas-liqui interface tangent an soli-liqui bounary line is name contact angle. As shown in Fig. 1, contact angle of liqui an fabric surface is an evaluation inex of surface wettability, an it is a quantitative hysical quantity, not subjective. The contact angle reflects the reaction of affinity between liqui an soli surface, the stronger affinity, the smaller contact angle. If contact angle is less than 90, fabric surface is consiere to be hyrohilic soli. If contact angle is higher than 90, fabric surface is consiere to be hygrohilous, so liqui is ifficult to wet fabric surface. (a) Poor (b) Mile (c) Goo Figure 1. Different shae of rolet on fabric (hyrohobicity). Bingxuan Ni 1, a * an Peng Zhang 1,b 1 Guangzhou Fiber Prouct Testing an Research Institute, No.1-2, Zhujiang Roa, Chaotian Inustrial Park, Panyu District, Guangzhou, China a nibx@gtt.net.cn 1, b zhang@gtt.net.cn 1 *Corresoning author: nibx@gtt.net.cn 428

2 The fabric surface energy originates from atoms or molecular that on the surface of soli is ifferent of inner. Surface energy affects the roerties of surface wettability. The surface tension of liqui can be measure irectly, but so far, we can t measure soli surface energy by using of instrument, only through calculating base on contact angle to estimate. EXPERIMENTAL Test Liqui Distilling water, ethylene glycol, an their mixe liqui. Instrument Otical contact angle measuring instruments, Datahysics OCA 15EC, Germany. Fabric Sunbon nonwoven, incluing of water-reellent-finishing nonwoven (1) an non-finishing nonwoven (2) knitte fabric woven fabric. RESEARCH CONTENTS Contact Angle Using ifferent liquis, research on the relationshi between surface tension an contact angle. Surface Energy Using two ifferent liquis which have ifferent surface tension, two ifferent of contact angle can be measure, an OWRK metho is use to calculate fabric surface energy. EXPERIMENTAL RESULTS Liqui Surface Tension an Contact Angle The surface tension of liqui, incluing of their isersion comonent an olar comonent are as seen from Table 1. TABLE 1. SURFACE TENSION OF MIXED LIQUID. Mass fraction of ethylene glycol /% 0% 10% 30% 60% 90% 100% Surface tension /(mn/m) Dis. comonent /(mn/m) Polar comonent /(mn/m) Seen from Fig. 2, using liqui of Table 1, to water-reellent finishing nonwoven, when surface tension is 72.8mN/m, contact angle is 142, when surface 429

3 tension is 48.2mN/m, contact angle is 112. With the liqui surface tension is bigger, contact angle is bigger. The exerimental results are in accor with Young s equation. Comare with two curves, the contact angles of water-reellent finishing nonwoven are all bigger than non-finishing nonwoven it can show that the effect of water-reellent finishing is goo. Figure 2. Relationshi of surface tension an contact angle. Contact Time an Contact Angle When rolet on fabric surface, to reach an equilibrium state, it nee some time, the molecular of fabric an liqui will interact until equilibrium. We can see from Fig. 3(a), (b) an (), with contact time is increasing, contact angle will be smaller, an eventually reaches a stale state, contact angle remains unchange basically, this contact angle is name static contact angle or equilibrium contact angle. To Fig. 3(a), (b) an (), after 16 secons of contact time, contact angles of four ifferent fabric reach to equilibrium state. To Fig. 3(c), it can be seen that non-finishing nonwoven is wette when rolet contact fabric surface, so its contact angle is 0, The contact angle of knitte fabric at the time of 24s-28s, contact angle reuce from 100 to 0, which inicates that the interaction between liqui ro an fabric surface is longer, an finally, fabric is wette. The woven fabric is wette at the time of 8s-10s. Seen from four figures, we know that it nee some time of contact angle between liqui ro an fabric surface becomes equilibrium, when reach equilibrium, the equilibrium contact angle can be obtaine. It is very imortant to choose reasonable contact time to measure equilibrium contact angle. If the time is too short, the interaction between rolet an fabric is not balancing, the time is too longer, an the evaoration of the rolets will affect the shae of the rolet. So it will affect the measurement of equilibrium contact angle. From all test, to fabric, in general, 60s contact time is aroriate. Surface Energy Through contact angles from two kins of liquis with ifferent surface tension, surface energy can be calculate. The Young s thermoynamic equilibrium equation is as follows: 430

4 cos sl. Among them, reresents soli surface energy, reresents liqui surface tension, sl interfacial tension between liqui an soli.. An θ can be measure by instrument, but an sl can t. Therefore, we nee another equation from some theory moel, in this aer, Owens moel is use for calculating surface energy, an it assumes that isersion an olar force of molecular can be ae ineenently. 431

5 Water-reellent finishing nonwoven Knitte fabric Woven fabric Non-water-reellent finishing nonwoven Figure 3. Relationshi between contact time an contact angle. sl 2 From above equation, we can get follow equation: cos 1 2 cos 1 y 2 x a b mn/m, To non-water-reellent finishing nonwoven, when liqui uses water, =21.80 mn/m =72.80 =51.00 mn/m, =93. When uses glycol, 432

6 =50.46 mn/m, =19.13 mn/m =31.33 mn/m, =75. Accoring to above, the surface energy of fabric is: =43.99mN/m. To water-reellent finishing nonwoven, when liqui uses water, =72.80 mn/m, =21.80 mn/m =51.00 mn/m, =145. When uses glycol, =50.46 mn/m, =19.13 mn/m =31.33 mn/m, =131. Accoring to above, the surface energy of fabric is: =29.54mN/m. From above calculation result, the surface energy of water-reellent finishing nonwoven is 29.54mN/m, an non-finishing nonwoven is 43.99mN/m. So it exlains that essence of water or oil-reellent finishing is to reuce soli surface energy. If only consier surface energy, in theoretically, in orer to wet fabric surface, surface tension of liqui shoul be less than soli surface tension. Through fabric surface energy, so we can estimate surface wettability situation of fabric using a liqui which has known surface tension. CONCLUSIONS The following conclusions can obtaine from above exerimental results: (1) With the liqui surface tension is bigger, contact angle between liqui ro an fabric surface is bigger. We can estimate water-reellent finishing effect through contact angle of fabric which has water-reellent finishing. (2) Contact time will affect the measurement of equilibrium contact angle. From all test, to fabric, in general, 60s contact time is aroriate. (3) The surface energy of water-reellent finishing nonwoven is 29.54mN/m, an non-finishing nonwoven is 43.99mN/m. So it exlains that essence of water or oil-reellent finishing is to reuce soli surface energy. REFERENCES [1] Liu Yongming, Shi Jianyu, Lu Qinqin, Guo Yunzhu, Chen Ruiqing, Yin Dachuan. Research Progress on Calculation of Soli Surface Tension Base on Young's Equation[J]. Materials Review,2013,27(11): [2] Di Jianfeng. Treatment of Water-reellent an Oil-reellent Fabric Finishing an the Test Metho[J]. Shanghai Textile Science & Technology,2003,31(4):