ISSN 2251-838X / Vol, 8 (4): 393-397 Science Explorer Publications
The effect of corona discharge on fabric thickness in
different velocities and rotations
, Mansour Ahmadi Kamarposhti2
1. sama technical and vocational training college, islamic azad university, saribranch, sari, iran 2. Samatechnical and vocational training college, Islamic azad university, qaemshahr, iran.
Corresponding Author email:email@example.com
ABSTRACT: Corona discharge is a kind of gas evacuation activates ionization surrounding the active electrons. Practically, at low-flow about afew if the potential difference increased between two points and the surface, then the electrical discharge will occur from point to surface; this electrical discharge reacts with the surface under radiation and changes the surface properties of the product. In this study, the relationship between number of rotation and linear velocity of corona roller on thickness of cotton fabric would be evaluated. Electrical discharge has happened under 10kv voltage; the distance of top electrode which electrons discharge occurs from there to fabric surface is 3mm from the surface of Corona roller and Corona roller moves on 4 different linear velocities (3,5,6,7)m/min and Corona operation was applied for each velocities in 5 five passages with total rotations (20,30,40.50,70).Some characteristics such as number of rotation and Corona roller velocity have been evaluated by using Analysis of Variance method (ANOVA),Tukey’s multi range Test and determination of correlation coefficients between variables. This study has been used the weft knitting cotton fabric with plain texture and weight of 153 g/mm, and to determine the physical and mechanical characteristics we used thickness gauge machine made by NasjSanj Iran Company and to statistical evaluation we used SPSS software version 13.Based on statistical data obtained from ANOVA method Tukey’smulti range Test, the thickness of cotton fabric was increased in comparison with reference sample or untreated sample in rotation 30 and with velocity of 3m/min maximum of increasing on thickeness has been occurred.
Key words:Corona discharge, Analyse of variance (ANAOVA), Tukey Test, fabricthickness INTRODUCTION
Nowadays, Corona is using in different industries in various ways. Among these usages we can refer to promote shirinkaging and hydrophilic properties of fibers and also due to lack of industrial wastewater and reduction of adverse environmental effects, corona applying is an appropriate way to improve dimensional and mechanical properties of cotton fabric. In this study, according to characteristics of Corona discharge we examined the effects of linear velocity and the number of Corona rollerrotationson cotton fabric thickness.
have examined the effect of Corona discharge on hydrophilic and shirinkage properties on wool fabric surfaces. When samples prepared at normal room condition, they reflected the effect of different voltages of Corona discharge on hydrophilic and shrinkage fabric properties. According to this study, by increasing the voltage, the fabric absorbs the water more quickly and it means that the hydrophilic properties have improved. High voltage corona discharge creates a powerful oxidation reaction and oxygen atoms take place on the wool surface, so hydrophilic properties increased(valipour, 2008).
JangmiRyu et al in 1991 have investigated the effects of Corona discharge on the wool fabric surfaces to reduce shirinkage. Enzyme is an environmentally compatible element which is suitable for reducing woolshirinkage, however, high price and long time for preparation, limited its widespread usage to complete wool products. Jangmi Ryu et al were examined effects of Corona discharge on surface of wool products in order to reduce shirinkage. They proved that the level of surface shirinkage of prepared wool fabrics by Corona discharge is more than the prepared fabric by enzyme. Therefore, they used the combination of both methods to reduce woolshirinkaging (jangmi ryu , 1991).
pre-prepared by Corona discharge under 13kv voltage and then special resin shrinkage is done. The results indicated that resin preparation has improved resistance shirinkagingagainst washing while this kind of preparation has been reduced the touchness properties of fabric, consequently,it has been significantly increased time of water infiltration and this means that the hydrophilic property of fabric surface was reduced. The results indicated when fabric pre-prepared by Corona discharge and set under resin preparation, the shrinkage level is reducing
(stefan Brzezinski, 2009).
WeilinXuet al in 2002 have evaluated modification of polyester fabricsurface by Corona discharge irradiation. Polyester fabric was prepared by Corona discharge irradiation at different voltages. Prepared fabric has been shown to increase hydrophilic properties. These properties can be reserved for a long time. Dyeing rate and color penetration improved by dyeing prepared fabrics (weilin xu, 2002).
GuizhenKe in 2007 has examined the effect of preparation of Corona discharge on surface properties of wool fabric. According to his experiments, some characteristics such as hydrophilic capability and dyeing capability have been examined by use of natural colors which were prepared by Corona discharge. After Corona dischargepreparation, hydrophilic properties of wool fabric and dyeing capability increased. Images of scanning electronical microscope (SEM) showed that some cuticles of epicuticle have been decreased on fabric surface. X Ray photoelectron spectroscopy analysis (XPS) also showed that amount of oxygen in wool increased and amount of sulfur decreased(Guizhen ke, 2007).
In 1995, the Improvement of wetabilityof fabric evaluated after Corona discharge preparation by Andrea Hesse. Preparation of producing fabrics from artificial fibers with Corona discharge has made changes in chemical and physical reaction in structure of surface layer that have an acceptable effect on stability and functional properties of textiles. They indicated that preparation of producing fabrics with artificial fibers under Corona discharge makes an acceptable increase in fabric wetability. .( andrea hesse, 1995).
In this study, the weft knitting cotton fabric with plain texture and weight of 153 g/mm that made up cotton yarn with yarn count 30nehas beenused, which is spun by open-end spinning machine with following characteristics has been shown in table1.
Table1.the count 30 of cotton yarn properties
Elongation percentage 6.38
Cv percentage 14.66
The thin parts ratio 36.40 The thick parts ratio 60.40
Nep percentage 33.20
Hairness percentage 5.71
Single jerseyweft knitting machine
This knitting machine which is called the King Youngmade in Korea. Diameter of machine is 34inch, gauge 24, and has 4 base needles.
Corona machine is made of a plastic coated roller that the fabric should place on it. The roller will begin to turn around by command of power supply and counter device. In the roller direction, there are aluminum rods which their distance is 3mm from the fabric surface. Practically, if the potential difference between two points increased, electrical discharge will occur from electron surface to fabric surface, in low flow about anew mA. This operation affect son physical and superficial properties of fabric or yarn.
The fabric thickness gauge
Fabric thickness is measured based on the distance between two pressure flats that fabric took place between them. This machine which is used in order to determine the thickness of weft knitting cotton fabric is made in NasjSanj Iran Company.
Cotton fabric is washed before Corona operation by nonionic soup under the 60˚Ctemperature and 30 min, which the ratio of fabric weight tothe bath volume is(1:40).
Electrical discharge is done under 10kv of voltage, and the distance of top electrode from Corona roller surface, which is responsible to discharge electron to fabric surface, is 3mm and Corona roller moves with 4 different linear velocities (3, 5, 6, 7) m/minute and Corona operation was applied for each velocity in 5 five passages with total rotations (20, 30, 40, 50, 70).
Fabric thickness is the distance between two flat surfaces which fabric is placed between them under certain pressure. The thickness of the fabric usually measure by placing a fabric between two metal surfaces. The thickness gauge takes thickness of 10 different points of fabric, finally the total number was average of those 10 points from fabric surface, that has shown amount of thickness.
Statistical analysis of samples
In this section the obtained data were analyzed by Spss software, 13version. The proper testing method for equality of averages is analysis of variance. Analysis of variance is the most helpfultechnic in statistical deduction (D.CMontgomery ,1997). Analysis of variance or in more appropriate words, mean-variance analysis, is the partitioning of all existent variations in a data set into components. Each component is attributed to one variation source. Besides, a component shows the resultant variations caused by uncontrolled factors and random errors (G.K Bhattacharyya ,1997).
According to the ANOVA tables (2,3), if sig is less than 0.05, the significant differences with 95% or more of confidence level would be observed in samples. Table 2 is related to the ANOVA of thickness of cotton fabric thickness with the constant velocity.
Table 2. ANOVA statistical analysis in different velocities of Corona roller on cotton fabric thickness. Sum of
Squares df Mean Square F Sig.
Between Groups .006 5 .001 13.835 .000
Within Groups .001 18 .000
Total .007 23
Table 3. ANOVA statistical analysis with a constant velocity eof Corona roller on cotton fabric thickness. Sum of
Squares df Mean Square F Sig.
Between Groups .004 4 .001 5.837 .003
Within Groups .004 20 .000
Total .008 24
Statistical analysis of samples by use of Tukey Test
In tables 4 and 5 which are about Tukey Test, significant differences can be observed in the confidence level of 95%. In these tables, the differences of untreatsample with other groups affected by Corona can be seen in 95% confidence level which is shown the significant difference in ANOVA related to tables 2, 3.
Table 4. statistical analysis of Tukey Test in different number of Corona roller rotations on cotton fabric thickness. Different number of
corona roller rotations Number of samples
Subset for alpha = .05
1 2 3 4 0 4 .56000 70 4 .57625 .57625 20 4 .58500 .58500 50 4 .59125 .59125 .59125 40 4 .59875 .59875 30 4 .60750 Sig. .016 0.0230 .031 0.0166
velocity of corona roller Number of samples 1 2 0 5 .56000 7 5 .58700 8 5 .59100 3 5 .59400 5 5 .59500 Sig. 0.025 0.0458
According to thetable 4, the maximum of thickness is in rotations 40, 30, 50 and also regarding to table 5, the maximum thickness is at velocities of 3 and 5 m/min.
The effect of Corona discharge on increasing thickness of fabric thickness in different linear velocity and rotations
As mentioned before in fabric thickness measurement method, all the treated and untreated samples with Corona has been measured by 10 times repetition from different points. The average of final number was recorded as thickness of that sample.
In the table 6 you can see the thickness of treated samples under Corona compared with untreated samples, has been increased.
Table 6. the effect of Corona discharge on fabric thickness in different velocities and rotations. Number of passage (rotation) 20 30 40 50 70 Linear velocity (m/min) 3 5 7 8 3 5 7 8 3 5 7 8 3 5 7 8 3 5 7 8 Cotton(mm) Untreated sample 56 5 7 58 59 60 62 61 60 60 61 60.5 60 59 59 58 57.5 57 57.5 57 56.5 56.5
As shown in table 6, the cotton fabricthickness has increased under Corona operation compared with untreated sample. The maximum thickness in treated samples by Corona electrical discharge is in 30 rotations and velocities of 3m/min.
Here should be explained that all the operations related to Corona electrical discharge is done in difference potential of 10kv (10000v).
Figure 1 shows the effect of Corona electrical discharge on cotton fabric in all rotations and velocities due to the potential difference of 10kv. In this diagram, we can see that there is a substantial increase in rotation 20 compared with untreated sample on cotton fabric thickness, so when the rotations increased, this amount will significantly decrease. As you can see in figure 1, there isn’t any fixed and constant order in the diagram, which is due to the burnings sometimes happened during Corona electrical discharge test especially on cotton fabrics. By increasing the number of rotations in Corona roller, controlled reduction will occur in thickness, but there is only exception in rotation 20. It seems that the porous form happened under the effect of electrical discharge, so the more rotation of Corona roller increase and the more thickness increase significantly too. Except rotation 20 which has increased at first and decreased when rotations increased, which is more than untreated sample in comparison. If we consider the diagram in terms of velocity, we can see that after rotation 20, by increasing linear velocity of Corona roller, the thickness will decrease, because in a constant rotation, by increasing the velocity, the product haven’t had enough time to meet the electrical Corona discharge, while at low velocities, which effect of Corona Irradiation increased with constant rotation and Corona roller rounds in lower velocity, and in this velocity reduction, the roller gives enough time and opportunity to fabric to affect by Corona operation, this is why in low velocities the rate of thickness increasing in cotton fabric is more than other velocities. As the figure 1 shows, by increasing the rotation and velocity, the thickness will decrease.
According to figure 1 you can see, rotation 30 with 3m/min of velocity has more increase in thickness in contrast with other situations.
Figure 1. the effect of linear velocity and number of rotation in Corona roller under 10000vdifference potential on weft knitting cotton fabric thickness.
After complete statistical analysis of samples, the results have been shown as tables of ANOVA, Tukey and correlation coefficient. According to obtained data, you can see that in rotation 20 the thickness had an increase in cotton fabric compared with untreated sample, so when the rotation increased, this amount will significantly decrease.
By increasing the number of rotations of Corona roller, a controlled reduction will happen in thickness, except in rotation 20 that it seems due to the porosity resulted from electrical discharge, so if the Corona roller rotation increase, the reduction of thickness will be more visible.
After rotation 20, when linear velocity of Corona roller increased, the thickness decreased. In this reduction, the Corona roller gives enough time and opportunity to fabric to get affected by Corona operation. This is why in low velocities, the thickness increases more than other velocities in cotton fabric.
Andreahesse and Helga thamas and hatwighocker . 1995. zero – aox shrink proofing treatment for wool top and fabric , trj 65 (6) Bhattacharyya GK, Johnson RA. 1997.statistical concept and method, John Wiley&Sons,
Brzezinski S, polowinski S, Dorotako W, Iwonakarbowhik , Grczynamalinowska. 2009.effect of the corona discharge treatment of polyester fabrics on their adhesive properties , trjvol 17,no4 (75)
Guizhenke and weidongyu and weilimxu and weigarg cui and xiaolinshen .15 desember 2007. effects of corona discharge treatment on the surface properties of wool fabrics , journal of materials processing technology 207 (2008)
jangmiryu and tomijuwakidi and torutakagishi . octaber 1991. effect of corona discharge on the surface of wool and its application to printing , trj,vol.61 (10)
Montgomery DC . 1997.Design and Analysis of Experiment,4the Edition.,JohnWieley&Sons,NewYork,
Valipour P, Nourbakhsh S, Maboudi M, Ebadi AJ, Taravati A. 18 march 2008. study of chemical and physical behavior cotton fabrics treated by corona discharge after several laundering, African journal biotechnolojy, vol 76
Weilinxu, xinliu . 27 may 2002.surface modificatian of polyester fabric by corona discharge irradiation , European polymer jourral 39 (2003) 0.4 0.45 0.5 0.55 0.6 0.65 0 20 30 40 50 70
Passage irradiation by corrona discharge (rpm)
V1=3 m/min V2=5 m/min V3=7 m/min V4=8 m/min