Chattopadhyay et al ID #01 Value Added Knits From Ramie-Cotton Blended Yarns Spun Using Short Staple (Cotton) Spinning System ID Number: 01 Sajal Kumar Chattopadhyay1, Shaymal Kumar Dey2, Bindu Venugopal3 and Amar Chaphekar4 1,3,4 Central Institute for Research on Cotton Technology, (ICAR), Adenwala Road, Matunga, Mumbai 400 019, India and 2National Institute of Research on Jute and Allied Fibre Technology, 12 Regent Park, Kolkata 700 040, India [email protected] Abstract In India, many of the natural ligno-cellulosic fibres are considered as low value fibres useful only for manufacturing industrial ropes and fabrics for packaging. Ramie is one such natural ligno-cellulosic bast fibre obtained by decortication of bark from canes of the plant, followed by degumming of ramie fibres. The present paper reports an exploratory study on the possibility of utilizing Indian ramie fibre in blends with cotton using cotton spinning system. A two stage degumming method has been optimised. Ramie fibre could be blended with cotton to an extent of 35% for spinning of acceptable yarn qualities for production of 24.6 and 14.7 tex (30s and 40s Ne) ring yarns. The knitting and garmenting trials of the blended yarns on commercial knitting machines were also found satisfactory. INTRODUCTION In India, many of the natural ligno-cellulosic fibres are considered as low value fibres useful only for manufacturing industrial ropes and fabrics for packaging. However, with the increasing concern world over for ecological preservation, sustainable resources like vegetable fibres originating from plants that are safe, biodegradable and recyclable are gaining importance in recent years. Ramie is one such natural ligno-cellulosic strong, lustrous and fine bast fibre obtained from the inner bark of Boehmeria nivea (L) Gaud. The fibres are embedded in the cells of bast that lies between the outer bark and the woody core of the stem. The spinnable fibres are obtained by decortication and degumming. It is not normally possible to spin the fibre with 2030% adhered gum, which therefore, needs to be removed by the process of degumming. Various methods of degumming have been reported in the literature for the removal of gums from crude ramie fibres. These include both chemical[1-3] and microbial[4-6] methods. Attempts have been made by various researchers to spin ramie in blends with jute, silk, viscose and polyester fibres using jute and woollen spinning systems[7-9]. Any efforts to develop appropriate technologies for the production and processing of ramie either alone or in blends with other fibres for producing finer yarn with improved properties can widen the application of ramie fibre. The present paper reports an exploratory study on the possibility of utilizing Indian ramie fibre in blends with cotton using commercial cotton machinery for producing ring spun blended yarns. The knitting and garmenting trials of the blended yarns on commercial knitting machines have also been reported. 2008 International Conference on Flax and Other Bast Plants (ISBN #978-0-9809664-0-4) 1 Chattopadhyay et al ID #01 DESCRIPTION OF THE ACTUAL WORK The chemical degumming of decorticated ramie fibre (R 67-34 variety) was optimised at NIRJAFT (National Institute of Research on Jute and Allied Fibre Technology). In one set of experiments, decorticated ramie fibre was treated with 1.5% NaOH at 100 °C for 90 minutes. The resultant sample was coded as NIR-1. In a second set, decorticated ramie fibre was first treated with 1.5% NaOH at 100 °C for 60 minutes and then again treated with NaOH of varying concentration, viz., 3.0%, 6.0%, 15.0% and 18.0% at 100 °C for 30 minutes and the resultant fibre samples were coded as Sample NIR-2 to NIR-5. The schematic diagram of various treatments carried out is given in the flowchart (Fig. 1). Ist set Decorticated ramie fibre 2nd Set Decorticated ramie fibre 1.5% NaOH 100 °C 90 minutes 1.5% NaOH 100 °C 60 minutes 3.0% NaOH 100 °C 30 min NIR-1 6.0% NaOH 100 °C 30 min NIR-2 NIR-3 15.0% NaOH 100 °C 30 min NIR-4 8.0%NaOH 100 °C 30 min NIR-5 Fig. 1. Ramie fibre degumming flowchart Gum content of ramie fibre was determined by using test methods as reported earlier[10]. The ramie fibre samples were evaluated for fibre fineness and bundle strength following standard test procedures. The degummed ramie fibres were cut into 40 mm staple length on a staple cutter machine and blended with DCH.32 cotton having 2.5% span length of 33 mm, micronaire value of 2.9 µg/inch (0.114 tex), bundle tenacity of 26.6 g/tex and uniformity ratio of 45%. The Improved Microspinning Technique developed at CIRCOT was adopted for carrying out spinning optimisation trials. The degummed ramie sample was blended in the proportions of 35%, 50% and 65% with DCH.32 cotton adopting flock-blending method. All the blends were spun to 14.7 tex (40s Ne) yarn using the ring spinning system. The list of spinning trials is given in Table I. 2008 International Conference on Flax and Other Bast Plants (ISBN #978-0-9809664-0-4) 2 Chattopadhyay et al ID #01 TABLE I. List of Spinning Trials on Cotton-Ramie Blends (14.7 Tex Ring Yarn) S.No. 1 to 5 Blend Code NIR-1 to NIR-5 6 7 8 MP-1 MP-2 MP-3 Fibres Used In Blends Ramie degummed under chemical conditions:Cotton Ramie (NIR-3):Cotton Ramie (NIR-3):Cotton Ramie (NIR-3):Cotton different Blend Composition (%) 35:65 35:65 50:50 65:35 Based on the results of these optimisation trials, bulk blending trials were undertaken keeping the cotton each to ramie blend ratio of 65:35 and spun to 24.6 and 19.7 tex (24s and 30s Ne) yarn on the ring spinning system. Pure cotton sample was also spun to identical count for comparison purpose. Further, yarn samples were suitably waxed and identically knitted into single jersey fabric on a 25.4 cm (10 inch) diameter, 8 feeder knitting machine at 37 rpm with 9 needles per cm. This was followed by commercial knitting, finishing and garment making trials. TESTING OF YARN AND FABRIC SAMPLES All the yarn samples were tested for lea strength and linear density on a computerised lea tester. They were tested for various tensile properties by using Uster Tensorapid automatic tensile tester. Yarn unevenness (U%) and imperfections were tested on an electronic evenness tester. The knitted fabrics were evaluated for various dimensional properties, such as courses per cm (C), wales per cm (W) and loop length (l). The loop shape factor and stitch density were calculated as, Stitch density = C x W C W Tightness factor = Loop shape factor = (1) (2) yarn tex (3) l Tightness factor11 (TF) of the knitted fabrics was determined by the following formula. Besides, fabrics were tested for bursting strength with a diaphragm type bursting tester as per the standard method. Shrinkage testing was done after wet relaxation using a wetting agent (0.5%) at room temperature as per CIRCOT procedure. Air permeability was determined by Prolific Air Permeability tester as per the standard procedure and the results were expressed in terms of m3/m2/min. RESULTS i) Effect of Degummed Ramie Fibre Properties on Blended Yarn Quality Five degummed ramie fibre samples prepared by various chemical treatments were used in the study. The properties of fibres are given in Table II. It can be seen from the table that with decrease in residual gum content, the fibres become finer and weaker. The sample NIR-1 has the highest bundle tenacity of 47.5 g/tex, but the fibres remained the coarsest (1.06 tex), while sample NIR-5 having the lowest bundle tenacity of 19.1 g/tex was the finest (0.67 tex). The properties of cotton-ramie blended yarns produced using the above ramie fibres are presented in Table III. It can be seen that initially the lea CSP and single yarn breaking tenacity increase due to increase in fibre fineness, reach optimum values (for 2008 International Conference on Flax and Other Bast Plants (ISBN #978-0-9809664-0-4) 3 Chattopadhyay et al ID #01 sample NIR-3) and, there after drop down (Fig. 2). As the gum is removed, fibres become finer resulting in higher realisation of the blended yarn strength due to increase in the number of fibres in the yarn cross-section. However, this will be offset by the fall of fibre strength resulting from the decreased interfibre cohesion. Thus, the optimum degumming treatment will be determined by the combined effect of fibre fineness and bundle tenacity resulting in optimum tenacity realisation in the blended yarn. Unevenness of all the cottonramie blended yarns is on a higher side compared to similar cotton yarns probably due to migration of coarser ramie fibre to the surface. This explanation is supported by SEM photographs of the blended yarn sample (Fig. 3). Table II. Fibre Properties of Chemically Degummed Ramie Fibre Sample Code Properties NIR-1 NIR-2 NIR-3 NIR-4 NIR-5 Fibre Fineness (Tex) Bundle Tenacity, 3.2 mm gauge (g/tex) Residual Gum Content (%) 1.06 47.5 4.45 0.85 34.1 5.23 0.83 25.7 5.08 0.70 20.7 4.97 0.67 19.1 4.82 Table III. Properties of Cotton-Ramie Blended Yarns (14.7 Tex Ring Spun) Blend Code CSP 1 2 3 4 5 NIR-1 NIR-2 NIR-3 NIR-4 NIR-5 1758 1853 1951 1924 1902 Uneven ness (U%) 18.9 18.4 20.5 19.6 19.1 Breaking Work (gf.cm) 200.2 197.5 223.8 279.5 238.2 Breaking Force (gf) 171.5 183.8 189.1 185.2 174.8 2000 Breaking Tenacity (gf/tex) 11.6 12.5 12.8 12.5 11.8 Breaking Elongation (%) 4.40 4.15 4.62 5.61 4.80 13 12.5 Lea CSP 1900 12 1800 11.5 CSP Br. Tenacity (gf/tex) S. No. Tenacity (gf/tex) 1700 11 NIR-1 NIR-2 NIR-3 NIR-4 NIR-5 Chemical Treatment Code Fig. 2. Effect of Degumming on Lea CSP and Breaking Tenacity of Cotton-Ramie Blended Yarn (14.7 tex ring) 2008 International Conference on Flax and Other Bast Plants (ISBN #978-0-9809664-0-4) 4 Chattopadhyay et al ID #01 Fig. 3. SEM Depicting Longitudinal View of Cotton-Ramie Blended Ring Yarn ii) Effect of Blend Proportions on Cotton-Ramie Blended Yarn Quality The optimised degummed ramie fibre sample, NIR-3 was used to study the effect of proportion of ramie fibre in the blended yarn. The properties of various blended yarns are presented in Table IV. It can be seen that as the proportion of ramie fibres in the blend increases, various tensile properties, elongation and evenness of the blended yarns decrease (Fig. 4 (a) and 4 (b)). This is due to the increase in the number of coarser and stiffer ramie fibres in the yarn cross-section. It is to be noted that ramie can be added to an extent of 35% in the blend for production of 14.7 tex (40s Ne) yarn suitable for knitting. Table IV. Properties of Cotton-Ramie Blended Ring Yarns (14.7 Tex) S. No. Blend Code 1 2 3 MP-1 MP-2 MP-3 Blend Composition (R:C) 35:65 50:50 65:35 CSP Unevenness (U%) 1850 1326 858 19.6 23.7 25.6 Breaking Work (gf.cm) 232.6 165.0 82.5 Breaking Force (gf) 180.3 144.5 92.5 Breaking Tenacity (gf/tex) 12.2 9.79 6.25 Breaking Elongation (%) 4.81 4.12 3.28 1850 12 10 Lea CSP 1600 8 1350 6 1100 4 850 Lea CSP Br. Tenacity (gf/tex) 600 5 (50R:50C) MP2 Blend Code 4.5 4 3.5 Br. Elongation (%) 2 0 ( 35R:65C) MP1 Br. Elongation % 14 Br. Tenacity (gf/tex) 2100 (65R:35C) MP3 (a) Unevenness (U%) 3 ( 35R:65C) MP1 (50R:50C) MP2 26 25 24 23 22 21 20 19 18 17 16 Unevenness (U%) R=Ramie, C=Cotton (65R:35C) MP3 Blend Code (b) Fig. 4. Effect of Ramie Fibre Proportion on (a) Lea CSP and Br. Tenacity and (b) Br. Elongation and Unevenness (14.7 Tex) of Blended Yarns 2008 International Conference on Flax and Other Bast Plants (ISBN #978-0-9809664-0-4) 5 Chattopadhyay et al iii) a) b) c) ID #01 Bulk Trials on Blending Ramie with Cotton Based on the results of these optimisation trials, bulk blending trials were undertaken keeping the cotton each to ramie blend ratio of 65:35 and spun to 24.6 and 19.7 tex (24s and 30s Ne) yarn on the ring spinning system. Pure cotton sample was also spun to identical count for comparison purpose. Yarn properties of the samples are given in Table V. The following measures were adopted during bulk trials. A thorough opening of stiffer ramie fibre component was more effectively achieved by the use of improved beaters in the blowroom. These are better suited than the conventional beaters for cotton ramie processing. Conventional beaters necessitate the ramie component to be passed thrice for acceptable level of fibre opening. During carding, the use of improved apron doffing system reduced the instances of card web sagging and shedding of fibres as compared to doffing with the conventional doffer comb. Ramie fibre in blended sliver was observed to give more resistance during drafting operation. This is due to the higher stiffness of ramie fibre. Hence, higher drafting pressure was needed for satisfactory processing of ramie fibre blends. Table V. Yarn Properties of Cotton-Ramie Blended Yarns and 100% Cotton Yarns (Bulk Trials) Materials Properties 100% Cotton 65% Cotton:35% Ramie (NIR-3) Blend Code C1 C2 RC1 RC2 Nominal Tex (Ne) Corrected CSP Breaking Tenacity (g/tex) Breaking Elongation (%) Unevenness (U%) Thick Places/km Thin Places/km Neps/km Total imperfections/km 24.6 (24s) 2416 12.4 8.8 15.5 1532 216 1764 3512 19.7 (30s) 2385 15.3 5.6 17.4 1440 295 1614 3349 24.6 (24s) 2047 12.0 4.8 19.6 2780 981 2964 6725 19.7 (30s) 1956 11.7 4.4 20.8 3109 1494 4525 9127 iv) Knitting Behaviour in Bulk Trials Though the CSP of blended yarns were significantly lower, the knitting performance was almost identical for all the yarn samples. No needle breakage occurred during knitting and hence mechanical faults were almost absent in the knitted fabrics. The single jersey fabric properties are given in Table VI. No mechanical fault was observed in blended fabrics indicating that there was no damage to knitting elements. Cloudiness and accumulation of trash particles resulting in spots were found more in blended fabrics. This was mainly due to significantly higher U% and more imperfections in the blended yarns. These spots were frequently observed in the blended fabrics, which may be due to presence of considerably higher number of thick places in the blended yarns. Bursting strength of blended fabric was much lower than that of the cotton fabric. This was mainly because of weaker yarns from cotton/ramie blends. The area shrinkage of blended fabric was much higher than 100% cotton of the same yarn count. It may be due to quick relaxation of cotton fabric because of higher extensibility and pliability of cotton yarn. Air-permeability of blended fabric was higher than 100% cotton indicating the suitability of cotton/ramie blends for apparel fabrics. 2008 International Conference on Flax and Other Bast Plants (ISBN #978-0-9809664-0-4) 6 Chattopadhyay et al ID #01 Table VI. Properties of Single Jersey Cotton-Ramie Blended Knitted Fabrics Code Yarn Tex C (No./ cm) W (No./ cm) Loop length (cm) Stitch density (No./ 2 cm ) Fabric wt (g/m2) Area Shrinkage (%) Bursting strength (kg/ 2 cm ) Air permeability (m3/m2/ min) Skewness (%) RC1 RC2 C1 C2 24.6 19.7 24.6 19.7 14.9 14.1 16.1 15.4 13.9 15.2 13.7 13.6 0.334 0.339 0.327 0.342 206 214 221 210 165 162 196 165 2.43 1.65 1.89 1.54 100 88 106 88 72 96 56 86 3.9 7.3 5.3 3.4 RC = 65% Cotton: 35% Ramie, C= 100% Cotton (v) Circular Knitting, Printing and Garment Making Trials Commercial knitting trials of the cotton-ramie (65:35) blended 19.7 tex yarn was successfully carried out. The knitting was done on a 24-gauge double jersey circular knitting machine. In addition to plain and interlock design, a peanut design was also produced. The plain and interlock designs were made on a 76 cm (30 inch) diameter machine equipped with 36 feeders and running at 20 rpm, while the peanut design was knitted on a 61 cm (24 inch) diameter machine having 24 feeders. The working of all the yarns was quite satisfactory. The knitted fabric samples were subjected to chemical finishing optimisation experiments. Scouring, bleaching and softening treatments were optimised and carried out in a single bath process. The following chemical processing was found suitable for the type of garments (Fig. 5) produced in the study. (a) Scouring and bleaching Application steps: (i) Water-7 litres, ALLENDENT (wetting agent)-NI-0.5 g/l, temp-40°C, time-15 min, drain the bath. Water-7 litres, LUBASSIST-JET (Lubricating agent)-1 g/l, Acetic acid-0.5 g/l, (ii) MADSCOUR-BL (Scouring agent)-2.5 g/l, time-30 min, Hydrogen peroxide-9 g/l, Caustic soda-3.0 g/l, temp-95°C, time-45 min, drain the bath. (iii) Water-7 litres, Acetic acid-1 g/l, time-10 min, temp-85°C, drain the bath. (iv) Water-7 litres, time-10 min, temp-70°C, drain the bath. Water-7 litres, Acetic acid-1 g/l, ARAPLEX-PH-0.5 g/l, time-10 min, drain the bath. (v) (vi) Water-7 litres, White Tinopal 2B-0.3 g/l, temp-60°C, time-20 min, drain the bath. (vii) Rinsing and drying of fabric. (b) Softness treatment Application by pad. The following softeners were attempted, DERMASIL-3780 (i) HYDROSIL (ii) (iii) MICRODERM 8865 2008 International Conference on Flax and Other Bast Plants 10 g/l 0 g/l 10 g/l (ISBN #978-0-9809664-0-4) 7 Chattopadhyay et al ID #01 Dermasil softness treatment was found better for such fabrics. It creates softness coupled with smooth and silky hand while retaining the original water absorbency of fabric. Fig.5. Assorted Knitwear Collection made from Cotton-Ramie Blended Yarns CONCLUSIONS In the present study, finer cotton-ramie blended yarns were successfully produced by adopting commercial cotton spinning system, where the jute/flax spinning machines had failed. A blend ratio of 65% cotton and 35% ramie produced 14.7 tex (40s Ne) ring yarn with adequate strength. Knitting performance of the blended yarns on a laboratory scale was satisfactory. The following main conclusions were made from the study: Decorticated ramie fibre contains 20-30% gum. It is not possible to spin the fibre with (i) this adhered gum, which therefore, needs to be removed. In the present study, ramie fibre was chemically degummed by an improved method. The optimum degumming treatment (sample NIR-3) is determined by considering the (ii) combined effect of fibre fineness and bundle tenacity resulting in optimum tenacity for the blended yarn. (iii) A blend ratio of 65:35 for cotton each to ramie was found to give adequate CSP for spinning to 14.7 Tex (40s Ne) ring yarns. Though the CSP of blended yarns was significantly lower, the knitting performance was (iv) almost identical for all the yarn samples. No mechanical fault was observed in blended fabrics that were knitted, indicating that there was no damage to knitting elements. Air-permeability of blended fabric was higher than 100% cotton fabric, indicating the (v) suitability of cotton/ramie blends for apparel fabrics. The area shrinkage of blended fabric was higher than that made from 100% equivalent (vi) cotton yarn. (vii) Dermasil softness treatment was found better for such fabrics. It creates softness coupled with smooth and silky hand while retaining the original water absorbency of the fabric. Thus, by improved degumming method coupled with appropriate modification of the spinning process and proper selection of cotton, finer cotton-ramie blended yarns can be produced by adopting commercial cotton spinning system. These yarns can be used for production of knits on commercial machines and variety of outerwear garments. 2008 International Conference on Flax and Other Bast Plants (ISBN #978-0-9809664-0-4) 8 Chattopadhyay et al ID #01 ACKNOWLEDGEMENTS This report forms a part of the R & D work carried out jointly by CIRCOT and NIRJAFT under an AP cess fund project. The authors are thankful to Indian Council of Agricultural Research, New Delhi for necessary financial support. The authors are also thankful to Director, CIRCOT, Mumbai and Director, NIRJAFT, Kolkata for their valuable suggestions during the course of the work. REFERENCES 1. P.C. DASGUPTA, K. SEN and S.K. SEN, Cellular Chemical Technology, 10, p. 285 (1976). 2. B. LUNIAK, Textile Quarterly, 4 (4), p. 92 (1954). 3. T. HOEFER, Melliand Textilber, 47 (6), p. 615 (1966). 4. A. KUNDU and A.B. ROY, Jute Bulletin, 25 (5), p. 150 (1962). 5. N.B. PAUL and S.K. BHATTACHARYYA, Journal of Textile Institute, 70 (12), p. 512 (1979). 6. R.H. BALASUBRAMANYA, P.B. IYER, K.M. PARALIKAR and K.K.R. IYER, Proceedings, International Seminar on Jute and Allied Fibres: Changing Global Scenario (NIRJAFT, Kolkata), p. 195 (1998). 7. M.C. MAZUNDER, S.K. SEN and P.C. DASGUPTA, Indian Textile Journal, 85 (8), p. 135 (1975). 8. Annual Report of Jute Technological Research Laboratories, Calcutta, p. 21 (1974). 9. Annual Report of Jute Technological Research Laboratories, Calcutta, p. 36 (1978). 10. An Insight into Some Ligno-Cellulosic Fibre Structure and Properties (CIRCOT, Mumbai), p. 89 (1999). 11. D.T. SPENCER, 'Aspects of Knitting', Knitting Technology (Pergamon Press Ltd, UK), p. 254, (1983). 2008 International Conference on Flax and Other Bast Plants (ISBN #978-0-9809664-0-4) 9
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