A K Samanta Institute of Jute Technology. 35 Ballygunge Circular Road. Calcutta. 70() 0\ 9. India

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1 Indian Journal of Fibre & Textile Research Vol. 22, June 1997, pp Some studies on jute/ polypropylene blended fabric characteristics K N Chatterjee. A Mukhopadhyay & B Mitra The Tcchnological lnstitutc of Textile and Sciences, Bhiwani , India and A K Samanta Institute of Jute Technology. 35 Ballygunge Circular Road. Calcutta. 70() 0\ 9. India Received 15 January 1990; revised received 10 October 1990; accepted 4 February 1997 The physical and mechanical properties of the jute/polypropylene blended fabrics are governed by the constituent fibres, texturing and raising treatment. Fabric tenacity, breaking extension, compression, compliance ratio and abrasion resistance increase but compressional recovery and flexural rigidity decrease with increase in polypropylene in weft yarn. On texturing, the fabric tenacity, abrasion resistance, flexural rigidity and compressional recovery decrease although compression, compliance ratio and breaking extension increase. On raising, a similar phenomenon as above is observed except in case of flexural regidity. Textured raised samples possess higher thermal resistivity as compared to untextured raised samples with maximum value for 60:40 PP/Jute blended weft yarn fabrics. It appears that 60% polypropylene in weft yarn may result into most suitable fabric for semi-apparels. Keywords: Abrasion resistance, Compliance ratio, Compressibility, Flexural rigidity, Jute/polypropylene fabric, Raising, Tenacity, Texturing, Thermal resistivity 1 Introduction The general properties of a fabric used for semi-apparel (blanket, jacket, lining fabric, etc.) are normally judged by the way in which it feels, looks and functions. The usual characteristics describing the above factors are handle (stiffness, softness, compliance ratio, drape, compressibility, etc.), appearance (pilling, lustre, colour, etc.), comfortability (moisture property, air permeability, thermal insulation, etc.) and durability (tensile strength, abrasion resistance, washing performance, etc.). Fabric made out of 100% jute fibre possesses poor handle, appearance, comfortability and durability characteristics. However, on chemical texturing of jute fabrics by NaOH, handle and comfortability can be improved': It has been reported+' that aqueous NaOH treatment on jute fibre is accompanied by loss in weight, longitudinal shrinkage, decrease in breaking strength and an increase in extension at break. A recent study" reveals that the treatment of jute with alkali of higher concentration (12% and above) results in decrease in crystallinity index and deterioration in overall molecular orientation alongwith the change in crystallinity lattice from cellulose-i to cellulose-ii, which are responsible for crimp development in jute. Earlier, a number of attempts have been made to study the Jute/PP blended yarn characteristics and the effect of texturing on fabrics":", But little insight has been made about the change in properties on texturing and raising performed on Jute/PP fabric. In the present study, evaluation of different jute/polypropylene blended fabrics has been done through their physical and mechanical properties. 2 Materials and Methods 2.1 Preparation of Fabric Samples The physical properties of the jute and polypropylene fibres used are given in Table 1. Yarns were prepared using conventional jute spinning sequence. For the blends, the polypropylene sliver and finisher card jute sliver were passed through Table l+physical properties of jute and polypropylene fibres Fibre type Density Linear Av. Single Breaking glcc density staple fibre extension tex length tenacity % mm gltex Tossa Daisee (4th Grade) Polypropylene (Commercial grade)

2 CHA ITERJEE et al.: JUTFJPOL YPROPYLENE BLENDED FABRlC CHARACTERISTICS 113 Characteristics Fahric weight loss; Area shrinkage on texturing Test equipment Mettler electronic balance Table 2- Test standards Principle As per IS: No. of observations 5 each Fabric thickness; Compressibility Essdiel cloth thickness tester Compliance ratio Zwick (1445) CRE tensile tester IOS,;,' - 5S :,' each 15 each Bending length; Flexural rigidity Sasmira stiffness tester BS: I 20 each Tensile properties Zwick (1445) CRE tensile tester Load and elongation at constant rate of extension 10 tests Abrasion resistance C.S.!. abrasion tester Cycles to failure 10 tests Thermal resistivity Togmeter Double plate method 10 tests S10 and S5are the stress values at 10% and 5% fibre extension respectively. the finisher card in combination according to blend proportion. Seven different fabric samples 212 twiii with 33 ends/ern and 38 picks/em were produced using 2 ply x 6.5 Ib/spyndle (2/124 tex) jute yarn as warp and jute/polypropylene blended yarns (265 tex) of various blend ratios as weft yams. 2.2 Texturing and Raising Texturization of fabrics was carried out with 18% (w/w) sodium hydroxide solutions for 30 min at 30 C under slack conditions. The fabrics were then washed, neutralized with 2% acetic acid, again washed and dried. Raising was performed on a raising machine. 2.3 Tests Various tests were performed, the details of which are presented in Table 2. 3 Results and Discussion Analysis of un textured and textured fabrics was made both in raised and unraised states. The mechanical properties of the fabrics were studied along the weft direction, whereas the thermal resistivity of the fabrics was observed in raised state only. 3.1 Weight Loss, Area Shrinkage and Fabric Weight It is observed from Table 3 that with the incr~ase of jute component in weft yarn, percentage weight loss of the fabric increases after chemical Table 3-Gain in fabric weight, area shrinkage and weight loss on unraised fabric after texturing Blend ratio PPI Jute % Gain in Area fabric weight shrinkage g/rn? % Weight loss 0: : : : : : : texturing. This is expected due to the loss of the hemicellulose and lignin matters from the jute structure, and also the removal of batching oil from the jute component during texturing. On the other hand, percentage area shrinkage of the fabric decreases with the increase of polypropylene component in weft, as it is a hydrophobic fibre. It is also observed that fabric weight increases after chemical treatment, but the percentage gain in weight/unit area decreases with the increase of PP component in weft yarn. The above phenomenon may be viewed under the combined effect of area shrinkage and weight loss, where the former plays predominent role. 3.2 Thickness and Compressional Parameters It is observed from Table 4 that with the increase of PP component in the weft yarn, the 010

3 114 INDIAN J. FIBRE TEXT. RES., JUNE 1997 Table 4- Thickness values (mm) for unraised and raised untexturedltextured fabrics Blend ratio Untextured Textured PPI Jute Unraised Raised Unraised Raised 0:100 20:80 40:60 50:50 r ~II (~IIWI t~n t~iltlll l:w 120.(111 t:!,u (Wiltl L 1.64 l.ll U 1.43 \.II L I U L U L I.4R U L \ :40 U I.RI L :20 U L :0 U 1.59 \ U and Iwuu indicate the thickness values at 20 gf/crn- and 200Q,gflcm' respectively. L-During loading; and U-During unloading (Initial value of thickness was taken at 2000 gf'/ em') thickness of the fabric gradually increases (up to 80:20 PP/Jute blended weft yarn). The increase in thickness may be due to the lower density of polypropylene fibre. However, in the case of fabric having 100% PP weft yarn, there is a drop in thickness which may be attributed to greater packing of yarn, predominating the effect of fibre density. A similar trend is observed after texturing, but with the maximum value for 60:40 PP/ Jute weft yarn. After raising of textured and untextured samples, the thickness values follow the same trend as above. Table 5 shows that both the compression and compressibility increase with the increase of polypropylene component in weft. The increase in compressibility may be due to the greater flexibility and extensibility of polypropylene fibre as compared to Jute, It is again observed that the compressional recovery gradually decreases with the increase of polypropylene component in weft yarn. This may be attributed to the increased packing coefficient with the increase in PP component. Higher surface contact between fibres and thus higher packing leads to greater resistance on the fibre to recovery during unloading. From Table 5, it is also observed that in case of textured sample, the total compression and compressibility increase up to 60:40 PP/ Jute blended weft yarn fabric and then decrease upto 100% PP weft yarn fabric. After texturing, the extensibility of jute fibre increases due to crimp development, leading to corresponding improvement in fabric compressibility, However, with increase in PP component in blend, the material becomes less susceptible to alkaline attack which may tend to reduce compression and compressibility after text- ' uring. Thus, the present observation may he due to the interaction of above two phenomena. The compressional recovery of the textured samples decreases gradually with the increase of PP component in weft, which may be due to the change in the morphology of jute fibre, resulting in reduction of elastic recovery. It is also observed that compressibility increases after texturing, whereas compressional recovery decreases. The increased value of compressibility after texturing at a comparable blend may be due to improvement in the extensibility of jute fibre after texturing. In case of raised un textured sample, the total compression increases up to 40:60 PP/ Jute and

4 CHA TIERJEE et al.: JUTFlPOL YPROPYLENE BLENDED FABRIC CHARACTERISTICS 115 Table 5-Compression, compressibility and compressional recovery Weft Un textured Textured blend ratio Unraised Raised Unraised Raised PP/Jute Compo CompbIty CR Compo CompbIty CR Compo CompbIty CR Compo CompbIty CR mm % % mm % 0/0 mm % % mm % % 0: : : : : : : C ompression. (C) omp., mm = C.. ( )' I'll - 1,""" ; ornpressibility compbity, % = - - x 100 Compressional recovery (CR), % = I Rlo - I lootl X 100 t where 12 and (,''"'' are the thickness values during loading at the pressure of 20 gt/cm? and 2000 gf/crn? respectively; and (R211' tlitevalue of thickness during unloading at 20 gf'/ em? pressure. Table o-compliance ratio and weight loss on raising Weft blend Compliance ratio Weight loss. % ratio PP/ Jute Untextured Textured Untextured Textured Unraised Raised Unraised Raised 0: : R : : : : I.R RI : then decreases, whereas the compressibility does not show any definite trend and the compressional recovery decreases with the increase in PP component in weft. In case of textured raised sample, however, both compression and compressional recovery do not exhibit any trend, whereas the compressional recovery decreases with the increase of PP component in weft yarn. It is interesting to note that the raised textured samples exhibit higher compressional recovery than untextured raised samples. 3.3 Compliance Ratio Compliance ratio, which indicates the degree of flattening of the stress-strain curve in the region between 5% and 10% extension of the material, can be related with the handle property of the material. It is observed from Table 6 that the compliance ratio improves with the increase of PP component in weft yarn which is expected due to the higher extensibility of the PP fibre. From Table 6 it is also evident that texturing improves the compliance ratio with greater impact on jute-rich blended fabric. The above phenomenon is attributed to the improvement in extensibility of jute fibre after texturing. After raising, there is an improvement in the compliance ratio both in case of textured and untextured fabrics and the value is greater in case of raised textured fabric as compared to raised untextured fabric. This phenomenon may be expected due to the increase in the extensibility of fabric as inter-yarn space usually increases after raising. The above fact indicates that raising of texturized sample can improve the feel which is better then that of raised untexturized sample.

5 116 INDIAN J. FmRE TEXT. RES., JUNE 1997 Table 7-Bending length and flexural rigidity Weft Bending length, em Flexural rigidity, kgf m blend ratio Untextured Textured % Change after Untextured Textured % Change after PP/Jute raising raising BR AR BR AR BT AT BR AR BR AR BT AT 0: : : : : : : BR-Before raising; AR-After raising; BT-Before texturing; and AT-After texturing. Table 8- Tenacity and breaking extension Weft Tenacity, N/mm Breaking extension, % blend ratio Untextured Textured % Loss after Untextured Textured % Gain after PP/Jute raising raising BR AR BR AR BT AT BR AR BR AR BT AT 0: : : : : : : { BR-Before raising; AR-After raising; BT-Before texturing; and AT-After texturing. 3.4 Bending Length and Flexural Rigidity From Table 7 it is apparent that with the increase of polypropylene content, the bending length gradually decreases in case of unraised textured and untextured fabrics, as expected. It is interesting to note that the bending length increases with the increase of PP component in weft after raising. The above phenomenon may be due to the increase in thickness value after raising. The flexural rigidity values also follow the similar trends. It is also observed from Table 7 that after texturing, there is a decrease in bending length in both raised and unraised samples. The above phenomenon may be due to the increase in the extensibility of jute fibre after texturing. Apart from this, reduction in fabric weight also contributes to decrease in bending length. Although after texturing, the thickness increases but the above factors may be dominating in decreasing the fabric bending length. A similar phenomenon has been observed in case of fabric flexural rigidity. In case of textured and untextured samples the percentage change in bending length decreases up to 50:50 PP/ Jute blend and thereafter an increasing trend is observed after raising. In case of % change in flexural rigidity, a similar phenomenon is observed with the trend diversion at 60:40 PP/ Jute blend in case of unraised and raised samples. 3.5 Tenacity and Breaking Extension Tahle 8 shows that as the proportion of polypropylene increases in weft yarn, the tenacity also increases which may be due to the better packing of yarn consisting of higher PP fibre length (Table 1). It is also observed from Table 8 that when these fabrics are chemically textured, a substantial drop in tenacity results in all the cases, the extent of drop in tenacity being greater for fabrics having

6 CHAITERJEE et al.: JUTEIPOL YPROPYLENE BLENDED FABRIC CHARACTERISTICS 117 Table 9-Abrasion resistance and thermal resistivity Weft blend Abrasion resistance, cycles to break % loss after raising Thermal resistivity, tog ratio PP/Jute Untextured Textured Untextured Textured Untextured Textured Unraised Raised Unreaised Raised 0: : : S : : : : higher proportion of jute. The above phenomenon is expected due to the partial dissolution of the hemicellulose and lignin components from jute fibre. After raising, the tenacity decreases and the decrease in tenacity is lower with the increase in polypropylene content, which may be due to decrease in loss of jute fibre with the increase in polypropylene component in weft (Table 6). Again, from Table 8 it is apparent that loss in tenacity is higher in the case of raised textured fabric compared to raised untextured fabric. In case of raised textured and untextured samples, the percentage drop in tenacity decreases with the increase in PP component up to 60:40 PP/Jute blend and then it declines. Table 8 shows that the breaking extension of fabric increases with the increase of PP component in weft. After chemical texturing, increase in breaking extension is about 73% for 100% jute yarn fabric and it follows a downward trend with increase in PP content in weft and becomes insignificant for fabric having 100% PP weft. The above phenomenon may be attributed to crimp development on jute fibre with high longitudinal contraction as polypropylene remains chemically inert. It is also observed from Table 8 that after raising, there is an increase in breaking extension of both the textured and untextured samples. Again, the textured sample shows higher percentage gain in extension value in.comparison to untextured sample. Although on raising the yarn strength decreases but fabric breaking extension increases which may be due to the greater possibility of yarn extension up to the state of jammed construction as the yarns get finer. 3.6 Ahrasion Resistance It is observed from Table 9 that in the case of untextured and textured fabrics, abrasion resistance gradually increases with the increase of polypropylene component in weft. This may be due to greater weft-way strength and surface smoothness of the fabric with increase in polypropylene component. After texturing, the abrasion resistance decreases due to decrease in fabric strength. On raising, the abrasion resistance of both textured and untextured samples decreases, the decrease being more with the increase of jute component in weft. On raising, consolidation of fibres in the constituents yarns deteriorate and the extent of deterioration is expected to be higher with increase of jute component in the fabric, leading to above phenomenon. Again, when textured and untextured samples are compared, percentage loss of abrasion resistance on raising does not exhibit any definite trend. 3.7 Thermal Resistivity From Table 9 it is apparent that with the increase of polypropylene component in weft, the thermal resistivity of the fabric increases up to 60:40 PP/Jute blend and then decreases. The above phenomenon can be explained from the thickness values with maximum thickness for 60:40 PP/Jute blended weft yarn fabric. The higher the thickness, the more will be the amount. of entrapped air within the fabric structure, giving rise to higher thermal resistivity. However, thermal resistivity is higher for textured raised fabric compared to untextured raised fabric in most of the cases. Here also, the maximum thermal resistivity has been observed in case of 60:40 PP/Jute blended weft yarn fabric. 4 Conclusions Fabric tenacity, breaking extension, compression, compliance ratio and abrasion resistance increase whereas compressional recovery and flexural rigidity decrease with the increase of PP con-

7 118 INDIAN J. FIBRE TEXT. RES., JUNE 1997 tent in weft yarn. On texturing, the fabric tenacity, abrasion resistance, flexural rigidity and compressional recovery decrease although there is an appreciable improvement in compression, compliance ratio and breaking extension. On raising, breaking extension, compression and compliance ratio increase but tenacity and abrasion resistance decrease. Textured raised fabric samples exhibit higher thermal resistivity with maximum value for 60:40 PPI Jute blended weft yarn fabric. Among the produced fabrics, 60:40 PP/Jute blended weft yarn fabric may be considered as most suitable fabric for semi-apparel uses. Acknowledgement The authors wish to thank Shri R C D Kaushik, Director, TIT&S, Bhiwani, for providing the facilities to carry out this work. They are greatful to the Principal, IJT, Calcutta, for advice and help during this work and to the Head and staff members of the Department of Textile Technology, IIT- Delhi, for permission and help in testing the samples. References 1 Ganguli P K, Mazumdar A K & Sur D, Indian J Fihre Texl Res, 20 (1995) Macmillan W G, Sengupta A B & Mazumdar S K. J Text Inst, 45 (1954) T RoyMM,}Textlnst,44(1953)T44. 4 Sao K P & Jain A K, Indian} Fibre Text Res, 20 (1995) Sinha A K, Mathew M D & Roy D, Indian} Text Res. 13 (1988) Gupta N P, Mazumdar A K, Mathew M D, Sur D, Roy D & Dasgupta P C. Text Res}, 55 (1985) Sinha A K, Mathew M D & Roy D, Text Res), 60 ( Mazumdar A K. Samajpati S, Ganguli P K, Sarkar D & Dasgupta P C. Text Res), 50 (1980) Gupta N P & Kalsy S S, Indian} Text Res, 2 (1977) 53.