CHAPTER 3 MATERIALS AND METHODS

Transcription

1 CHAPTER 3 MATERIALS AND METHODS 3.1 INTRODUCTION This chapter provides details of cotton fibers, yarns, fabrics used in the study. The work done in this thesis is presented in the following figure3.1 Figure 3.1 Flow chart for the methodology The following figure 3.1 gives the overall methodology adopted in the present study Cotton Fiber-Type A Conventional yarn50ne Compact yarn 50Ne(Suessen Elite) Physical Properties Yarn Tenacity Elongation Evenness Hairiness Imperfections Tested for tenacity and elongation at gauge lengths of 12.7mm, 25.4mm, 76.2mm, 127.0mm and 254.0mm respectively for Weibull modeling 53

2 Production of weft- knitted fabrics using conventional and compact yarns of 50Ne Single Jersey Rib Interlock L1 L2 L3 L1 L2 L3 L1 L2 L3 Com Con Com Con Com Con Com Con Com Con Com Con Com Con Com Con Com con Com-compact, Con-conventional (18 Samples) Spirality 1. Manual method 2. Scanning method ANOVA &Correlation coefficient Scouring Bleaching Dyeing Bio polishing Wicking-Linear Regression analysis, Slope, Intercept Correlation coefficient, Total 72 Samples 54

3 Cotton Fiber-Type B Conventional yarn50ne Compact yarn 50Ne (Suessen Elite) Doubling Conventional + Conventional Conventional + Compact Compact + Compact Five Levels of Twist per inch 16.5, 18.0, 20.5, 22, 24 Testing of doubled yarn Yarn tenacity, elongation, hairiness,imperfections Analysis of Variance 55

4 Materials The materials used in the current research work are discussed below: 3.2 SELECTION OF MATERIAL The experiments were conducted on two Indian cotton varieties (Mcu5 and Mcu5). The fiber parameters are measured with HVI. Both were spun to Ne 50(11.8tex). As seen from Table 3.1 the two cottons differ widely in their characteristics so that they cover a fairly wide spectrum of cottons generally used for spinning. The cotton raw material was considered to produce 50s Ne combed conventional yarn and compact yarn in Suessen Elite Spinning. Type A cotton yarns have been chosen for knitted fabrics and processing of them like, scouring, bleaching, dyeing and biopolishing and the fabric properties have been analyzed. Type B yarns have been doubled (conventional-conventional, compact-conventional, compact-compact) using TFO machine at five levels of twist in S direction and their yarn properties were tested and analyzed. Details of the cotton mixings used for the production of 50s combed yarns are given in Table 3.1. It may be noted that two different types of cottons were used for the production of 50s Ne yarns. Table 3.1 Details of the Cotton Fiber Properties Fiber parameters Unit Mcu5 Mcu5 2.5%Span Length mm Fiber strength gm/tex Micronaire Uniformity ratio

5 Methods 3.3 YARN PRODUCTION Spinning Process parameters for producing Type A yarns below. The sequence of process followed for producing 50s combed yarns is given 1. BLOW ROOM Hcc ventricular speed Vario cleaner // Mono speed rpm Grid bar setting 4/6/ 4/6 Hcc ventricular speed Vario cleaner // Mono speed 650 Hcc ventricular speed 2. UNIMIX Unimix beater speed 630 Lattice speed Feed roller speed Feed roller to beat setting Grid bar setting 1500 rpm 1500rpm 60mm 4.0mm 3mm 5mm Waste plate setting 2,2,3,4,4 3. FLEXI CLEANER Flexi cleaner beater speed- - rpm Feed roller speed Grid bar setting Feed roller to beater mm 5mm 3mm Waste plate setting 2,2,3,4,4 57

6 4. CARDING Chute beater speed-rpm 980 Chute wall distance 130mm Feed plate to licker- in 0.75 Cylinder to flats setting-mm 0.25, 0.25, 0.20, 0.20, 0.20 Cylinder to doffer -mm Licker- in speed-rpm 900 Cylinder speed-rpm 500 Flats speed -m/min 13.3 / 24T Cylinder to SFL C- cleaner Cylinder to SFD C- cleaner LDO/6 Speed hank 0.11 Delivery hank Total draft 5.16 Bottom roll setting 40 // 42 Break draft.51 Speed-rpm LH-10 No. of ends 20 Break draft 1.43 GMS / MTR 69 Total draft Speed-rpm COMBER Table trumpet 4.5mm Top comb index 1 58

7 Waste% 21% Deliver hank 0.14 Feed length 4.71 Speed(rpm) RSB Speed-rpm 400 Delivery hank 0.14 Break draft Bottom roll setting 39 // 43 Trumpet size 6.2 / 3.5 Scanning roll size 6.4 / 6.7 Scanning roll punnel 6.5mm Draw off roller 4.8 Web tension tube 7 / 7 Count 50 BTS2 Speed 950 Break draft Total draft TPI 1.43 / 1.21 Spacer Green 9. CONDENSOR Inlet Green Middle Green Floating Red Bottom roll setting 35 / 47 / 48 Top roll setting 37 / 49 / 46 Creel draft

8 10. SPINNING Total Draft Break draft Average speed Spacer Traveler 2.5mm 11/OU1UM UDR MAXIMA Spinning Process for producing Type B yarns below. The sequence of process followed for producing 50s combed yarns is given Process Parameters 1. BLOW ROOM Lap weight in Kgs 200 gms 22.0 gms / mtr Lap Hank SPEED MFC Speed 440 MPM Speed 720 RK Speed SETTING IN MM Pedal to Beater setting 8.0 mm Pedal to feed roller mm Beater to stripping plate 1.5 mm 60

9 4. CARDING Sliver Hank Total Draft 5% 88 Tension Draft 1.71 Waste % 2% Carding Setting Feed Plate to licker in Lickerin to cylinder Cylinder to flats Speed in RPM ( 10%) Licker-in-rpm 960 Cylinder 420 Flat inches/min DRAWING Sliver Hank No. of doubling 6 Total Draft 6 Roller setting in mm 38/42 Breaking Draft COMBER Total Draft Noils 1% 19.0 Type of feed Forward Feed Length in mm 4.3 Piecing setting +0.2 Draw Box setting in mm

10 7. SIMPLEX Break Draft 1.21 Total Draft 9.76 Tpi /Tm 1.39/1.2 Spacer size in mm 5.0 mm Roller Setting in mm 44/50/ Doubling and twisting of yarn The 50s count yarns both conventional and compact produced from Type B mixing were doubled in TFO (Two for one twister) employing five levels of twist (16.5, 18, 20.5, 22.0, 24.0) in S direction. Three levels of doubled yarn were made with three combinations, conventional and conventional, compact and compact and conventional and compact (hybrid).this has developed to study the potential of these yarns. 3.4 YARN TESTING The skein (lea) count and strength measurements to compute count strength product were carried out on automated testers. The lea is produced on a wrap reel by wrapping 120 yards of yarn on a 1.5 yard girth reel. As the yarn counts vary from the nominal count spun corrections to the CSP were made using the following formula 2 ActualCSP Actual yarn count Corrected CSP= Nominal yarn count This measurements of lea strength is a rapid test and is very useful in the production environment. Both single and doubled yarn were tested for count, tenacity, elongation, hairiness, imperfections and evenness. The following Table 3.2 gives details of the Yarn tests 62

11 Table 3.2 Yarn Testing and standards Nature of the test Instrument Testing Standard Yarn Count and Count CV% Statex yarn Count system ASTM D Yarn strength and elongation Yarn evenness, imperfections, hairiness Single yarn strength at different gauge lengths Ustertensojet Uster standard test method Uster-5 ASTM D Instron ASTM D Measurements of yarn count: Yarn count and count CV% were measured on Statex yarn count system which is a combination of electronic balance and computer, Using this system, readings were taken from the yarn samples and the mean value was calculated Measurements of yarn Strength and elongation: All the tensile properties of yarn, (breaking strength and elongation) were measured on the UsterTensojet using the single strand method.this instrument works on the CRE principle Measurements of yarn hairiness, evenness and imperfections: The evenness of yarn is one of main indexes to measure the quality of yarns. The unevenness of yarns will deteriorate the mightiness of yarns, and increase the end breakage rate in the spinning, and the increase of the end breakage rate will directly limit the speed of the machines and reduce the productivity. In addition, the unevenness of yarns will seriously influence the 63

12 appearance quality of textiles. Yarn hairiness and evenness were measured on Uster Tester Measurements of single yarn strength at different gauge Length: The gauge length is the distance between the grips. The conventional and compact spun yarn having 50 s count and constructed of 100% cotton were tensile tested using INSTRON tensile tester to determine how their strength varies as a function of gauge length. Twenty tests were performed at each gauge length of 254.0mm, 127mm, 76.2mm, 25.4mm and 12.7mm. 3.5 FABRIC PRODUCTION In this work conventional and compact yarns were used to produce Single jersey, rib and interlock structures with three different loop lengths. The details of machine type and selection of loop length are given in following Tables 3.3 to 3.5. Table 3.3 Knitting Machinery Details Particulars Single Jersey Rib Interlock Machine Falmac Singapore Falmac Singapore Shinta Taiwan Model FSB 3XSK PN1.6XRB DBR4 Diameter Gauge Number of feeders

13 Table 3.4 Loop Length Calculation for the Selected Knit Structures Knit Structures Samples Tightness Factor Tex 0.5 cm -1 Loop Length(cm) R1, C Single Jersey R2, C R3, C R4, C Rib R5, C R6, C R7, C Interlock R8, C R9, C Table 3.5 Nomenclature of the samples S.No Samples Yarn Used Knit Structure Loop Length (in cm) 1 R1 Conventional yarns Single jersey R2 Conventional yarns Single jersey R3 Conventional yarns Single jersey R4 Conventional yarns Rib R5 Conventional yarns Rib R6 Conventional yarns Rib R7 Conventional yarns Interlock R8 Conventional yarns Interlock R9 Conventional yarns Interlock C1 Compact yarns Single jersey C2 Compact yarns Single jersey C3 Compact yarns Single jersey C4 Compact yarns Rib C5 Compact yarns Rib C6 Compact yarns Rib C7 Compact yarns Interlock C8 Compact yarns Interlock C9 Compact yarns Interlock

14 3.6 CHEMICAL TREATMENTS With a view to investigating the effects of chemical treatments on the properties of knitted fabrics, they were subjected to chemical treatments and these are described below. Commercially obtained chemicals were used in all treatments The investigator has subjected the conventional and compact spun knitted fabrics to scouring, bleaching, dyeing and finishing processes. The processes were carried out under normal industrial parameters Scouring Scouring is the process in which natural as well as artificial impurities are removed. The ultimate aim of the scouring is to make the material uniformly and highly absorbent in a cost-effective manner so that there are no difficulties in the later processes of dyeing, printing and finishing The scouring solution contained the following ingredients Scouring Recipe: Sodium hydroxide : 3.0 % Sodium Silicate : 0.1% Material: Liquor Ratio : 1: 20 Wetting Agent : 0.1% Reaction Time : 1 Hour Temperature : Boiling The weighed amount of sodium hydroxide was wetted with wetting agent followed by sodium silicate. The calculated amount of water was added to it. The temperature was raised to 100 ºC and was kept for an hour. Then the fabrics were 66

15 taken out and thoroughly washed followed by flat drying for two days. The fabrics were then dried in oven for not more than 70 ºC. After 12 hours, the fabrics were ready for wickability testing Bleaching Bleaching is the process in which we remove the color pigments in order to achieve the degree of whiteness. The bleaching of textile fibers with hydrogen peroxide is certainly the most popular process today because it is 1. Environmental friendly. (Potentially it can decompose into oxygen and Water). 2. It is versatile (it can used hot or cold batch wise and continuous) Bleaching Recipe: Hydrogen peroxide : 3 % Sodium Silicate : 3% Soda Ash : 1 % Sodium hydroxide : 0.5% Material: Liquor Ratio : 1: 20 Reaction time : 1 Hour Temperature : 70 ºC The weighed amount of hydrogen peroxide, sodium silicate and soda ash were mixed with the required amount of water and the temperature of the bath was raised to the boiling point and kept for an hour. Then the samples were taken out and after thorough washing and drying, they were ready for testing Dyeing The reactive dyes offer a wide range of dyes with varying shades, fastness, with high brilliancy, easy applicability and reproducibility. In addition to giving 67

16 high wash fastness on cotton, reactive dyes usually give bright shade. Reactive dyes have moderate to good light fastness and fair- to- poor chlorine fastness. selected Hence the reactive dyes for dyeing the bleached knitted fabrics were Dyeing Recipe: Machine : Soft Flow Machine Dye : Reactive Dye (Yellow-0.08Gpl, Red- 0.05Gpl, Blue-0.2Gpl) Salt : 50gpl (Time- 30 Minutes) SodaAsh : 10gpl (Time- 45 Minutes) Material: Liquor Ratio : 1: 20 Temperature : 60 ºC The dyeing was carried out in industry under normal industrial practices Bio Polishing Finish Biopolishing result in smooth fabrics with enhanced appearance and handle.as mechanical force is involved in scouring, bleaching, it increases the fuzz on cottons knit fabrics. The hairiness or fuzz that produced in the last stage can be reduced when bio polishing is introduced with cellulase enzyme. Acid cellulases enzyme is concentrated, non-gmo based biopolishing enzyme, can achieve desired results at lesser dosage and less processing time. Biopolishing Recipe: Machine Enzymes : Winch and Tumble Dryer : Acid cellulases (Ezysoft GM3) 68

17 Material: Liquor Ratio : 1: 15 Reaction time : 1 Hour Temperature : 55 ºC The biopolishing requires equipment such as washing machine or winch machine. The machine was filled with water, material liquor ratio was taken as 1:15, then bio wash liquid and softener was added to the winch. The ph was maintained between 4.5 and 5.5; the bio wash was carried out for 1 hour. Cold rinse for 5 10 minutes was followed by hydro extraction and tumble dry. 3.7 FULL RELAXATION In order to achieve the fully relaxed state, all the treated knitted samples were subjected to static wetting in water containing wetting agent for 24h at room temperature, followed by gentle agitation in water heated up to 70 o C which is maintained for 30 min (laundering). The sample were then tumble dried at 80 o c for about 1 hr, The cycle of laundering, hydro extraction and tumble drying was carried out for five times. This method was considered to fully relax the samples in view of the results of Knapton et al. (1985).The desired fabric parameters were subsequently measured and recorded after conditioning the samples at 25 o C,65%RH for several days. 3.8 FABRIC TESTING After full relaxation, the properties of the processed fabrics were analyzed at standard atmosphere conditions of 65% relative humidity and at 27± 2 C. The geometrical fabric properties tested were loop length, wales per cm, courses per cm, area density and thickness. Bursting strength, spirality and wickability were also tested. 69

18 3.8.1 Measurement of wales per cm The samples of 10 cm x 10 cm size were marked at ten different places in the fabric, using the pick glass, the numbers of wales were counted and the result was divided by 10 to determine the number of wales in 1 cm. Number of wales in 10 cm. Wales per cm = Measurement of Courses per cm The samples of 10 cm x 10 cm size were marked at ten different places in the fabric. Using the pick glass, the numbers of courses were counted and the result was divided by 10 to determine the number of course in 1 cm. Number of course in 10 cm. Course per cm = Stitch density: (ASTM D 3887) Stitch density is the number of loops per unit area, which can be obtained by multiplying the number of Wales and courses per unit length; Stitch density in sq. cm = Wales per cm x Course per cm Measurement of Loop length The loop length is the length of yarn used in one knitted loop.100 Wales are counted from each dry relaxed knitting sample. 10 courses were unraveled from these samples and every course average length was measured using a scale. These average lengths were divided by 100, which is the total wale number and the loop length is calculated. 70

19 Measurement of fabric weight (ASTM 3776) Calculating the mass per unit area and expressing as g/m 2 (GSM) is customary for knitted fabric. A circular specimen of size 100 cm 2 was cut rapidly and accurately by using sample cutter. Sample cutter for GSM is a specialized instrument to determine the GSM of the fabric. GSM states the determination of weight per unit area, which is exactly 1/100 th of a sq. meter. The results in grams, multiplied by 100 gives the GSM. GSM = Specimen weight in grams x Measurement of Wickability Sample size The sample size for wicking measurement was 1" Wide and 10 " long. The samples were cut in both wales wise and course wise directions in conventional spun and compact spun scoured, bleached, dyed and finished single jersey, rib and interlock structures. Wicking instrument The wicking instrument was developed which is made of wood. It consists of two pillars on either side with a flat rod at the top for easy hanging of the sample and the bottom edge of the sample is faced towards the beakers containing distilled water, acidic solution and alkaline solution. (Plate I) 71

20 72

21 Wicking measurement The wicking behaviour of all the samples was analyzed by the vertical wicking strip test. Measurements were taken out by ordinary capillary rise method on all the samples. On all fabric strips (scoured, bleached, dyed and finished), three lines after each cm were made to indicate the height of the capillary ascension. To initiate the test, end of the samples were immersed into the beakers containing distilled water, acidic solution and alkali solution. Wicking property was tested according to the rise in the level of the water and other solutions. Lesser the time taken to climb, better the wicking property of the fabric. Every time the front liquid reaches a line, time is recorded. The tests were carried out at the same atmospheric conditions (65 % ± 2 % Relative humidity and 27 ºC ± 2 ºC Temperature) on all the samples. (Plate II) Measurement of spirality Several standards are available for determining the spirality of knitted fabrics, eg. ASTM D British standard 2819 (1990) IWS test method No. 276, AATCC test method The spirality was measured according to the IWS 276 standard test method (Degirmenci and Topalbekiroglu, 2010). According to this method, 5 different places are chosen for each sample. First a wale is marked by pen, and the course linked wale is then marked, as seen in Figure 3.2. By using a protractor, the angle different from the normal of the wale is measured. 73

22 Determination of angle of wale spirality: Manual method The following steps were included to determine the spirality The fabric samples were relaxed at room temperature for 72 hours to test the spirality. The specimen was spread on a flat surface without any tension. Place the protractor along the course line PQ so that the line AB is perpendicular to PQ. Determine accurately the path of the wale line A that intersects with the bottom of 90º line on the protractor. The angle between the 90º line and wale line <ie AA > is measured and direction of spirality (right left) is recorded. Repeat this process 10 times. Finally the mean is calculated. The percentage of spirality is calculated with the following equation. PS% = AB-BA = x AB X 100 Where x is the angle of spirality. Figure 3.2 Measurement of spirality by manual method A A 90 P 180 B 180 Q 74

23 Determining the spirality by CorelDraw software Tools used - Pick Tool - Pen Tool - Zoom Tool - Dimension Tool The cotton-plain-knitted fabric samples used in this study have been dry relaxed and prepared as 5 x5 square. Image of the sample have been acquired via a scanner with 1200 resolution. Image was opened with corel draw graphics suite 12 version. The following steps were framed to measure the angle of spirality. Step: 1 The first step is to magnify the knitted structure to 3-5 times larger using zoom tool. After magnifying the knitted structure of single jersey fabric with wale and course is clearly shown. Step: 2 In the second step the pen tool is selected to draw a horizontal line and then the angular dimension tool is used to measure the angle of spirality. The dimension tool is dragged from bottom of the horizontal line to draw a vertical line upto 2 and then it is dragged towards the direction of wale line that intersects the course line. The angle is automatically displayed on the screen which periodically 75

24 represents the wale s angle (Figure 3.3) and it is to be recorded. The percentage of spirality was calculated with the following equation: PS% = 90-MV = x 90 X 100 Where MV is the mean value x is the percentage of spirality. Figure 3.3 Knitted fabric sample showing spirality 76

25 3.8.8 Measurement of bursting strength (ASTM D 3786) The bursting strength of the single jersey, rib, and interlock knitted fabrics was tested with hydraulic bursting strength tester. The fabric specimen was clamped by a ring over a thin flexible rubber diaphragm which itself was clamped over a circular hole in the upper face of a reservoir. The pressure in the liquid was increased by valves and due to increase in pressure the diaphragm bulges and the fabric bursts and the pressure at that point was indicated by the pressure gauge. The tests were carried according to ASTM standard. The readings were noted in kg/cm Measurement of thickness (ASTM D 1777) Thickness is the distance between one surface to its opposite in textiles, the distance between the upper and lower surface of the material, measured under a specified pressure. Thickness is one of the basic physical properties of textile materials. Bulk and warmth properties of textile materials are often estimated from their thickness values, and thickness is also useful in measuring some performance characteristics, such as before and after abrasion and shrinkage. The thickness value of most textile materials will vary considerably depending on the pressure applied to the specimen at the time the thickness measurement is taken. MAG Thickness tester was used to measure thickness. The pressure foot was lifted with the help of the lifting lever fixed on the top of the dial gauge. Then the specimen was placed on the anvil and the pressure foot was lowered down gently onto the specimen. Then the readings were noted on the dial gauge to get the thickness of the specimen. The above procedure was repeated to obtain the value of thickness and the average thickness was reported. 77

26 3.9 STATISTICAL ANALYSIS Weibull software was used to obtain the values of shape and scale parameters for tenacity and elongation at different Gauge length of 12.7mm, 25.4mm, 76.2mm, 127.0mm and 254.0mm. The doubled yarn with three combinations, (conventional and conventional, compact and compact and conventional and compact) were analyzed statistically by Analysis of Variance. The test results were analyzed statistically, with the view to finding out the samples having better wicking. Correlation is a statistical device which helps us in analyzing the association of two or more variables, says Gupta (2008). The slope is the vertical distance divided by horizontal distance between any two points on the line, which is the rate of change along the regression line. Intercept calculates the point at which a line will intersect the y-axis by using existing x- values and y- values. The standard error is the measure of the amount of error in the prediction of y for an individual x. Confidence intervals display 95% confidence intervals for each regression coefficient tests. Analysis of variance and correlation coefficient were applied to find out if there is statistically significant difference between conventional and compact single jersey fabric data obtained from two methods (Manual method and CorelDraw method) of measuring spirality. 78