Indian Journal of Fibre & Textile Research Vol. 24, June 1999 , pp. 103-110

Air permeability of jute based needle-punched nonwoven fabrics

S Sengupta, S Samajpati & P K Ganguly'

National Institute of Research on Jute and Allied Fibres Technology, 12 Regent Park, Calcutta 700 040, India

Received 4 December 1997; revised received and accepted 4 June 1998

Cross-laid needle-punched nonwoven fabrics of 80, 120 and 160 punches/crn2 have been prepared from jute, chemically texturized jute(TJ) and their blends with polypropylene having jute or TJ as a major component, and the effects of texturization, blend composition, punch density, depth of needle penetration and jute fibre cut length on fabric thickness, fabric density and air permeability studied. The resistance offered to the flow of air through the fabric is much higher for the fabrics made from texturized jute and its blends compared to that for fabrics made from jute and its blends. Air permeability of fabri cs made from texturized jute and its blends decreases with the increase in punch density, whereas the air permeability of fabrics made from jute and its blends having low polypropylene content (10%, 20%) increases with the increase in punch density. As the polypropylene content is increased to 30% and 40%, the trend is reversed. With the increase in needle penetration and jute fibre cut length, the air permeability decreases with slight deviation for 100% jute fabric. Random-laid jute/polypropylene (60:40) blended fabric exhibits higher thickness, lower density and higher air permeability compared to its cross-laid counterpart. Correlation between sectional air permeability and reciprocal of fabric density is observed in most of the fabrics. However, it is found to be highly significant for fabrics made from jute, TJ and their blends with 30% and 40% polypropylene.

Keywords: Air permeability, Jute, Needle-punched fabric, Polypropylene, Sectional ai r permeability, Texturized jute

1 Introduction Needle-punched nonwoven fabrics, produced by

penetrating barbed needles into a fibrous mat, are essentially a three-dimensional network of fibres enclosing small air pockets . This structure , prepared out of jute and its blends, is suitable for products with wide range of applications 1. The use of jute fibre in the manufacture of nonwoven fabrics is very limited. T;J diversify the use of jute fibre, attempts are being made to deve lop jute- and modified jute-based non.voven fabri c.; alone or in blends vith manmade fibres fo r \'arious applications including filtration I and tloorcoverin g ~ . T hese applicati ons demand air permeabil ity of the fabric as an important property . Ai r permeabi lity of a fabric is the rate of air tlow through a fabric under a differential pressure between the two fabric surfaces' . Mohamed et al. 4 observed hat the need le-punched fabrics are stronger than the

fibrous mats and cheaper than the woven fabrICS , and these may ~e the main reasons for the success of needle-punched fabric s in the above mentioned areas. .-\cc ordin ~ to them, needle-punched fabrics are also superior to woven fab rics In ability to collect fi ne particles and dust loading capaci ty.

"To whom all the correspondence should be addressed.

Sengupta et at. 5 studied the air permeability of hessian reinforced jute nonwoven fabrics. In the present work, needle-punched nonwoven fabrics have been prepared from jute, chemically texturized jute(TJ) and their blends with polypropylene(PP) without any rei nforcing material and the effects of texturization, blend composi ti on, punch density , depth of needle penetration, jute fibre cut length and web laying technique on fabric thickness, density and air permeabil ity have been studied . The mechanical behavior of such fabrics have been reported earlier6

,7.

2 Materials and Methods

2.1 Materials Tossa j uteS of grade TD-5 and polypropylene fi bre

(Denekalon) were used for the preparation of nonwoven fabrics. The staple length and linear density of polypropylene(PP) fibre were 120 mm and 1.7 tex res;jectively. The phys ical properties of jute, texturized jute and PP fibres were measured fo llowing the method of Samaj pati et 0 /.

9 and are given in Table I.

2.2 Chemical Texturization of Jute

The bundles of jute reeds were cut to 30 cm length and then chemicallv texturized 10 w ith I ROt, (~/,,\

104 INDIAN J. FIBRE lEXT. RES., JUNE 1999

NaOH solution at 30DC for 30 min, keeping the jute­to- liquor ratio at I :20. The texturized jute(TJ) was then washed thoroughly in running water, soured with J % acetic ac id solution for 30 min, washed again with water till free from ac id and dried in air.

2.3 Fahric Preparation

Jute reeds were subjected to softening treatment with 4% jute batching oil in water emu lsion and then processed in a breaker card. The breaker card sliver and texturized jllte reeds were cut to various lengths (Table 2) and then hand-opened thoroughly. The bl ending of jute and TJ fibres with PP fibres was can'ied in different dry weight proportions following the stack-mixing technique.

A ll the nonwoven fabrics (area density, around 300 g/m2 ) were prepared using a OILO nonwoven plant compri s ing a card . a camel-back crosslapper and needle loom (OILO 00 lJ/6) . Fabrics of different punch densiti es and depth of penetrations were prepared lIsing 3b gauge RB needle. Random-laid

Tahle I- Phys ical properties of fihre

Fihre type Density Linear Tenacity Extension at g/n; density , tex cN/tex hreak, %

JII ! \' 1.4: 2.14 30. 1.55

Texturized .lUl l: lS( 1.% 20 .:: 7.40

Polyprn py lell l.· 0.9: 1.70 38.7 51 .00

web was prepared by air-laying technique using the Callaghan web maker consisting of a hopper feeder and two randomizers and then it was needled as stated earlier. Four sets of nonwoven samples as shown in Table 2 w'ere prepared .

2.4 Measurement of Fabric Thickness and Density The fabric thickness was measured on a Prolific

carpet thickness gauge with a circular pressure foot of 2 em diam. aft~r exerting a pressure of 0 .2 glmm2 for 10 s. This is the minimum pressure available in the tester and it was used because the fabrics are highly compressible II . Fabric density was calculated usmg area weight and mean fabric thickness.

2.5 Measurement of Air permeability A Shirley air permeability tester was used for

measuring the air permeability of nonwovens. The results were expressed as the units of volume of air in cubic centimeter passed per second through 1 cm2 of fabric at a pressure difference of I cm head of water. But in some cases, the high flow rate required for a pressure difference of J em head of water could not be covered by the range of flowmeters available in the instrument. Hence. three layers of nonwoven fabri cs. superimposed on one another, were tested at a time and the fl owmeter reading fo r a single layer wa

Tahle 2--Constructional detaIls of expenmental f abnc~

St:l Fihre Fibre-l ayi ng Jute fibre CU ! Blend composition Runch density eedle penetration

Ill' type: techlllque length . mm Jutc!fJ:PP Punches/em"" mm

J Uk Cross- lai d 70 100:0(1 80.120.160 13

.Ii J[ ~ C ross-laid 710 90 :10 80120.16(\ I'

Jul, Cro~~- I alt 70 80:20 80, I 20,16\1 .J

.I II! '. ' Cross-laid 70 70:30 80,120,1 ('0 1 ~ .l

j l l i ( ross-18iu 7(' 60:4{) 80: 120: I 60 13

'1 ( r",s-i ai u /\i I ()(H)' I 80.120.!61, 13 -ro ss -Ial~ ~. 90: I () 1'0. 120 .1 (,e 'v

'J I: ros, -Ia:' 7:: RO:20 80 120.11i0 U

T' Cr()~' ~-!a ; (' 7(' 7Wi ll RO.1 2U,1 61.' IJ

~ I .. il l .I.: ~-l wr' I ' 60:40 l:IU. 20.1(;(; ,I

.IU! ' ( fos!---bH . 71l 10n'(\1 l\"i,' ~I 1 j ,',

.:u . ......1 O~~- ! a hJ ; v 60:4" ; (; ~. ~)

C ro~~ -JaJL 7[' 60:.11) IMI 4 " c 131:;P

II : lu : . Cross- laiC 60,70,80,90 IOO:(}!' l 20 i'

JU I' Cros~-Iaiu 60.70.80,90 60:40 80

.lU I :, Cro~s- l a i <J 60,70.80,90 60:40 120 , 3

Jull. C ross-laJO 60,70,SO,90 60:40 160 1 .)

1" .1 Cross- laid 60,70,80,90 60:40 120 n 1\ ' ju te. C ross-l aid 70 60:40 120 l3

Random-l aid 70 60:40 120 13 TJ - - Texrurized j ure : ancl PP -Polypropylene

..

r

..,

SENGUPTA et. at.: NEEDLE-PUNCHED NONWOVEN FABRICS 105

es timated by multiplying the results by three ll. Air

permeab ility was calculated by dividing the flowmeter read ing in cels at I cm pressure drop by the test area (5 .07 cm\ The air permeability values were multiplied by the mean thickness (cm) of needle­punched fahrics to obtain the sectional air permeabi lity (SAP)1 2 values. SAP values were used to compare the permeability of different nonwoven fabrics.

Thirty pieces of 10 cm x to cm size were cut from the different parts of each of the 10 sets of fabric being tested and weighed individually. These weights and average of fabric thickness values were used to calcul ate the fabric weight per unit area in glm2 and fabric density in g/cc. The mean thickness, density and air permeability of each set of fabric have been

reported after testing the statistical significance of the difference between the mean values at 5% level of confidence.

3 Results and Discussion Jute, chemically texturized jute (TJ) and

polypropylene(PP) fibres used for the study are significantly different from each other in physical properties. Jute is a strong, coarse and brittle fibre with very low extensibility (0.8-2.0%) . It is meshy in structure. The meshes gradually split up and the filaments are broken into smaller lengths during manufacturing processes . Jute, when chemically texturized, has a considerably higher extensibility, mainly due to its crimped nature. However, TJ looses much of its crimp during opening and carding

Table 3-Effect of blend composi tion and punch density on air permeability of jute-based nonwoven fabrics'

Blend composition Punch density Fabric Fabric density Air permeability Sectional air permeability Punches/em2 thickness glce cc/s/cm2 ec/s/em

mm 100:00 80 2.76 0.109 162.97 44.98

JutelPP 120 2.66 0.112 192.78 51.28

160 2.58 0.117 198.45 51.20

10000 80 2.65 0.113 54.60 14.46

TJ/PP 120 2.57 0.117 51.06 13 .14

160 2.55 0.120 25 .14 6.4 1

90:10 80 3.04 0.098 159.08 48.80

JutelPP 120 2.72 0.110 181.86 49.40

160 2.64 0.114 197.22 52.00

90: 10 80 2.70 0.110 55.68 15.04

TJ/PP 120 2.67 0.113 53.04 14.16

160 2.65 0.112 33.48 8.86

80:20 80 3.29 0.092 148.08 48 .72

Jute/PP 120 2.99 0.101 170.10 50.40

160 2.86 0.106 183.00 52.40 80:20 80 2.86 0.105 61.32 17.56

TJ/PP 120 2.70 0.112 66.72 18.04

160 2.91 0.102 32.28 9.40 70:30 80 3.3 1 0.091 157.56 52.20

Jute/PP 120 3.05 0.098 172.44 52.60 160 2.97 0.100 166.14 49.40

70:30 80 2.77 0.109 111.06 30.76 TJ/PP 120 2.54 0.118 82.44 20.94

160 2.39 0.127 42.48 10.16 60:40 80 4. 13 0.072 137.04 56.60

JutclPP 120 3.79 0.079 152.16 57.72 160 3.31 0.091 134.76 44.60

60:40 80 3.44 0.088 121.74 41.52 TJ/PP 120 2.93 0.103 110.40 32.38

160 2.27 0.132 60.00 13.64 "Net:lllc penetration. 13 mm; and Jute fibre cut length , 70 mm

106 INDIAN 1. FIBRE TEXT. RES., JUNE 1999

operations and hence the fibre becomes vulnerable to the needling operation, leading to fibre breaks during needling. TJ fibre has a better fonn retention characteristic than jute9

. On the other hand, pol ypropylene is a fl exible, highly extensible, strong and tough fibre with a very low density (Table 1).

3.1 Effect of Punch Density and Blend Composition Table 3 and Figs I and 2 show the effects of blend

composition and punch density on air penneability (AP) of nonwoven fabrics based on jute, texturized jute and blends of jute and texturized jute with PP fibre. Fabri c density values have been plotted along with the AP values due to its importance determining

b'I' f f b ' 213 I . III air permea 1 Ity 0 nonwoven a ncs ' . t IS

200 0.14 180 ( a)

160 ._. __ ............................................ 0.13

140 0.12 120

0.11 100 80 0.10 60 0.09 40 Denllty AP

20 - .--. 0.08

0 0.07 N 200 E • 0.14 u 180 -------- ( b) Vi 160 -e---... 0.13 ............... u u

140 --a

0.12 ~ u

.; 120 01 .....

"~ 0.11 ...

100 >-~

80 0.10 'iii a: . c:: E 60 III

... 40

0.09 Cl <II a. 0 .08 ... 20 ~ 0 0.07

200 0.14 180 -- (e ) -.... __ .

160 ......... ... . 0.13

.......

140 0.12 120

0.11 100 80 0.10 60 0.09 40 20 0.08

0 0.07 100:0 90:10 80:20 7030 60:40 Blend co m posit ion (J u te : P P)

Fig I-Eft'eel o f blend composition on air permeability and fabric density of jute/PP blended nonwoven fabri cs prepared wiih (a) 80 punches/cm'; (b) 120 punches/cm2 ; and (c) 160 punches/cm2

observed that at all the punch density levels studied, air penneability decreases very slowly with the increase of PP component in the jutelPP blended fabric. Density, on the other hand, decreases relatively sharper, apparently due to the lower bu lk density of PP. However, at 160 punches/cm2, the rate of fall of density with the increase of PP component in the blend is lower than that at 80 and 120 punches/cm2, implying the higher consolidation of the web. It is also observed that for each blend composition

200 r-----------, 0.14 (a ) Density 180

160

140

AP .. .. 0 .13

0.12

~!~~~:: 40 1 20 0.08

o I....I..-.----'-_----'--_---L __ U' _ 0 .07 100:0 90:10 80:20 70:30 60:40

N 200 0.14 E 180 (b ) u ~ 160

0.13

-;:; 140 u.. 120

u u

0.12 -0'1

0.11 ... >-~100 '

~!~~/ 0. 10 .~ c

E 40 ~ 20

0.09 ~

Q.

\...

<i:

0.08

o 0.07 100:0 90:10 80:20 70:30 60;40

200 r:(:-c):------- ----, 0,14 180 160 0.13

140 '----.. 0.12 120 100

80

0. 11

0.10

60 ..-- 11 0.09 40 .-• .... 20 .--.-~Dr---... · .. ·· 0.08

o _-.l..--->...l 0.07 100:0 90:1 0 80:20 70:30 .60:40

Blt>nd com posi t io n (TJ: P p)

Fig 2- Effect of blend composition on aI r permeabili ty and fabric density of TJIPP blended nonwoven fabri cs prepared with (a) 80 puncheslcm2; (b) 120 punches/cm2; and (c) 160 puncheslcm2

SENGUPTA et. at.: NEEDLE-PUNCHED NONWOVEN FABRICS 107

studied, fabri c density quite expectedly increases with the increase in punch density . However, the AP values of jute and jute/PP fabrics show an increasing trend in spite of the improvement in fabric density wi th the increase in punch density . This is apparently due to the formation of permanent holes in the fabric accompanied by expansion of fabric width during needling of webs in which jute (a brittle and inextensible fibre) is the major component. However, as the PP component of the web is further increased to 40%, successi ve increase in punch density to 160 punches/cm2 tends to lower the AP of fabrics, and during needling the web contracts in width and the incidence of hole formation is also less evident. This is apparently due to the presence of large number of finer, ex tensible and e lastic PP fibres per unit area of the fabrics, the importance of which has been emphasized by Kothari and Newton II.

TJ and TJ/PP blended fabrics show consistently lower air permeability and higher density compared to jute and jute/PP blended fabrics at all the three levels of punch density (Table 3, Fig. 2). Besides, AP shows a decreasing trend with the increase in punch density for all the blend compositions studied. These are apparently due to lower linear density and crimped nature of TJ which leads to better form retention of the web. As a result, very little lateral expansion of the web and hole formation are evident during needling and the fabrics based on TJ are far more compact and denser than the fabrics based on jute. Increase of PP component in the TJIPP blended fabrics, though enhances the number of fibres per unit

area of the fabric , tends to increase the AP of the fabric , the extent of which is reduced with the successive increase in punch density level. This is expected because with the increase of PP component in the blend, the number of fibres per unit area of the web increases and so does the requirement of needling to achieve consolidation.

3.2 Effect of Depth of Needle Penetration The effect of needle penetrati0t:! on air

permeability, sectional air permeability and fabric density is shown in Table 4 . It is evident that with the increase in depth of needle penetration, fabric thickness decreases while the density increases due to higher entanglement and consolidation of the fibres in the web. This leads to decrease in the air permeability and SAP of jutelPP and TJIPP(60 :40) blended fabrics. In case of 100% jute fabric , initially the air permeability and SAP decrease up to 13 mm needle penetration and thereafter they increase with further increase in needle penetration. It appears that too deep a needle penetration results in fibre rupture and also creates channels in the nonwovens. All these factors combine to result in higher air permeability when the needle penetration exceeds an optimum limit. This has also been reported by Sengupta et a/5

•

3.3 Effect of Jute Fibre Cut Length It is expected that the longer the fibre, the more

effective would be the needling operation, resulting in higher entanglement of fibres in the web. Table 5 shows that in case of 100% jute fabrics, there is

Table 4-Effect of depth of needle penetration o~ air permeability of jute-based nonwoven fabrics'

Blend Needle penetration Fabric thickness Fabric density Air permeability Sectional air composit ion mm mm gicc cclslcm2 permeability, celslem

100:00 9 3.10 0.098 108.44 64.70

JutelPP 11 2.80 0.108 208.00 58.24

13 2.59 0.117 197.94 51 .20

15 2.77 0.111 204.06 56.46

17 2.88 0.105 221.70 6p8

60:40 9 3.50 0.085 141.54 4~.50

JutelPP 11 3.52 0.084 129.66 45 .60

13 3.31 0.091 134.76 44.60

15 3.21 0.094 137.25 44.04

17 3.12 0.096 134.94 41.78

60:40 9 2.72 0.112 76.58 20.32

TJ/PP 11 2.59 0.117 67.50 17.50 13 2.27 0.132 60.00 13.64 15 2.15 0.141 56.34 12.10 17 2.08 0.146 53.28 11.1 0

"Punch density, 160 punches/cm2; and Jute fibre cut length, 70 mm

103 INDIAN 1. FIBRE TEXT. RES., JUNE 1999

Table 5-Effect of fibre cut length on air permeability of jute-based nonwoven fabrics'

J ute fibre cut Fabric Fabric density Air permeability Sectional air Blend composition

100:00

JutelPP

Punch density punches/cm2 length~ mm thickness, mm glcc cc/s/cm2 permeability, cds/cm

60:40

JuteIPP

60:40

TJIPP

do

80

120

160

120

"Needle penetration, 13 mm

60

70

80

90

60

70

80

90

60

70

80

90

60

70

80

90 60

70

80

90

2.74

2.66

2.70

2.89

3.97

4.13

3.64

3.63

4.00

3.79

4.08

3.72

3.16

3.31

2.86

2.91

3.05

2.93

2.90

2.78

hardly any difference in density and thickness of fabrics prepared from 60-80 mm cut length. However, there is a significant decrease in fabric, density and increase in fabric thickness when the fibre cut length is further increased to 90 mm. This is apparently due ':0 the fibre breakage at this cut length which is reflected in the deterioration of mechanical properties as reported in our earlier communication7

• However, air permeability and SAP do not exhibit any significant change. In case of juteIPP and TJIPP :60:40) blended fabrics, higher fibre cut length results in higher fabric density and lower thickness and consequently resulting in lower air permeability and SAP.

3.4 Efr~ct of Fibre Laying Technique It is observed from Table 6 that random-laid web

produces bulkier fabric. Moreover, due to random alignment of fibres, the number of pores in the random-laid fabrics is also higher as compared to that in the cross-laid web, resulting in higher air permeability and SAP.

3.5 Relationship between Sectional Air Permeability and Reciprocal of Fabric Density

Previous workers 11 -13 have emphasized the influence of fabric density on the air-permeability of

0.110 182.10 49.93 0.112 192.78 51.28 0.110 186.24 50.28 0.104 182.22 52.66 0.075 158.52 62.94

0.072 137.10 56.60

0.081 137.10 57.04

0.082 154.50 56.18

0.075 142.26 56.96

0.079 152.16 5'7.72

0.073 107.10 43.76

0.080 102.54 38.13 0.09~ 142.74 45.06

0.091 134.76 44.60

0.105 123.12 35.26

0.103 102.06 29.70

0.098 112.80 34.44

0.103 110.40 32.38 0.104 94.38 27.34

0.109 92.34 25.64

Table ~Effect of fibre-laying technique on air permeability

Fibre-laying Fabric Fabric Air Sectional air technique thickness density permeability permeability

mm glcc cc/s/cm2 cds/cm

Cross-laid 3.79 0.079 152.16 57.72

Random-laid 4.38 0.069 191.55 83.89

JuteIPP, 60:40; Punch density, I 20 punches/cm2

nonwoven fabrics. In the present investigation, an attempt has been made to investigate the relationship between sectional air permeability (SAP) and reciprocal of fabric density. For this, all the SAP values have been divided into ten groups on the basis of fibre type and blend. The correlation coefficient between SAP and reciprocal of fabric density for each group has been calculated and shown in Table 7. The significance at probability 0.05 for each group has been analyzed. It is observed that the group 4 comprising all the fabrics based on jute, TJ and their blends with PP show a correlation with high significance between the said parameters. Therefore, in general, it can be said that the SAP and reciprocal of fabric density are highly correlated. However, when groups 2, 5, 6 & 7 comprising 100% jute and jutelPP blended fabrics have been analysed for significance of correlation between the respective SAP and reciprocal of density, it has been found that

SENGUPTA ~t. al.: NEE.Dl.E-PuNcHm> NONWOVEN FABRICS t09

Table 7-Relationship between sectional air-permeability and reciprocal of fabric density

No Group Sample size

I 100% jute & 100% TJ 15

2 100% jute & all juteIPP blends 43

3 100% TJ & all TJIPP blends 24

4 100% jute. 1000TJ. all juteIPP blends & all 67 TJIPP blends

5 100% jute 12

6 100% jute & juteIPP blends (90: 10 and 80: 20) 18

7 100% jute & juteIPP blends (70:30 and 60: 40) 37

8 JuteIPP blends (70:30 and 60:40) 25

9 100% TJ & TJIPP blends (90: 10 and 80:20) 9

IO ,TJIPP blends (70:30 and 60:40) 15

the co~elations are either insignificant (groups 6 & 7) or significant at a very low level (groups 2 & 5). Similarly, when TJ and TJIPP (90: 10 and 80:20) fabrics are considered together (group 9), the correlation is found to be insignificant. Higher proportion of PP in the blends improves the correlation (groups 8 and 10). Group 10 c.omprising TJIPP (70:30 and 60:40) blended fabrics shows very high correlation.

The above findings indicate that incorporation of finer fibre (PP) and crimped fibre (TJ) in the jute based nonwoven fabrics improves the correlation between SAP and reciprocal of density because of the higher number of fibres per unit area, as reported by Kothari and Newton I' and better web uniformity.

The correlations with best fit lines for groups 8 and 10 are shown in Figs 3a and· 3b respectively. The relationship between SAP and fabric density can be represented as:

[ Ps=P.t ]

where, Ps is the sectional air permeability(SAP)in cels/cm; P, the air permeability in cc/slcm2

; D, the fabric density in glcc; t, the mean fabric thickness in cm; and K, & K2, the constants .

The values of constants K, and K2 are as follows: For group 8, K, = 5.24, K2 =-32.68, and t =

0.354 cm For group 11, K, = 7.59, K2 =-165.42, and t =

0.265 cm

4 Conclusions 4.1 TJ and TJ/PP blended nonwoven fabrics create a

much higher resistance to air flow compared to jute and jute/PP blended fabrics.

Correlation Statistical analysis Remark coefficient (r)

0.648 rc:orO.648 > rO.05. 13=O·514 Significant

0.331 rc:orO.331 > ro.05 .. 41=O.300 Significant

0.719 r caI=O. 719 > ro.05.2(f=O·423 > rO.05.22 Significant

0.638 r c:orO.638 >rO.05.6~=O.235 Significant

0.633 r caI""-o.633 > ro.05.IO=O.576 Significant

0.125 r c:orO.125 < rO.05.16=O.468 Insignificant

0.320 r c:orO.320 < rO.05.3~=O.325 Insignificant

0.706 .rcal=O·706 > r005.zo=O·423 > rO.O~.23 Significant

0.248 r caI=O.248 < rO.05.7=O.666 Insignificant

0.958 rc..=O·958 ro.o~.I3=O .514 Significant

1 E

10 45 (0) (b)

l II) 40

15 ,. 70

== :a JO a 10 t 25 • SO Q, 20

'0 40 15 a. c JO 10 0

u 5 .. 20

'" • 10 11 .2 IS •• IS • 10 11 12

Fig 3-Relationship between sectional air permeability and reciprocal of fabric density of nonwoven fabrics: (a) juteIPP blends (pP =30% and 40%); and (b) TJIPP blends (pP = 30% and . 40%)

4.2 The air permeability of fabrics made from jute and its blend havmg low PP content (10% and 20%) increases with the increase in punch density, whereas the air permeability of fabrics made from texturized jute and its biend with PP decreases with the increase in punch density in all the blend proportions studied.

4.3 With the increase in PP content, air permeability decreases in jutelPP blended fabrics and increases in TJIPP blended fabrics for all the punch densities studIed.

4.4 In case of 100% jute fabric, air permeability decreases initially up to 13 mm needle penetration and thereafter it increases with further increase in needle penetration. In jutelPP and TJIPP(60:40) blended fab . cs, air permeability decreases with the increase in depth of needle penetration.

4.5 In TJ and jutelPP (60:40) blended fabrics, air permeability decreases as the cut length of jute fibre increases. 100% jute fabric at 120 puncheslcm2, does not show any significant difference in air permeability with increase in fibre cut length.

4.6 Random-laid juteJPP (60:40) fabric exhibits higher air permeability than its cross-laid counterpart.

11 0 INDIAN J. FIBRE TEXT. RES. , JUNE 1999

4.7 Fabrics based on TJ and its blends with 30% and 40% polypropy lene show highly significant correlati on between the rec iprocal of fabric density and sec ti onal air permeability. The number of fibres per unit area and the uniformity of the web appear to be the main factors goveming this correlation .

Acknowledgement The authors are grateful to Dr B C Mitra, Director,

and to Dr P Sengupta, both of NIRJAFT, for their keen interest thi s work. They are also thankful to Mr A Majumder of NIRJ AFf for his suggesti ons.

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2 Scngupta A K. Sinh a A K & Debn ath C R. Indian J Text Res, 10 ( 1985) 9 1.

3 ASTM:D7 37-1975 .

4 Mohamed M H, Afify E M & Volger J W. Needle-punched fabrics in fil tration , paper presented at the technical symposium on Nonwoven Product Techno logy, Washington D.C., 5-6 March 1974.

5 Sengupta A K, Sinha A K & Debnath C R, Indian J Text Res, 10 (1985) 147.

6 Ganguly P K, Sengupta S & Samajpati S, Indian J Fibre Text Res. 22 ( 1997) 169.

7 Ganguly P K. Sengupta S & Samajpati S, Indian J Fibre Text Res. 24 ( I) (1999)34.

8 Indian standards specification IS :271 (Bureau of Indi an Standards, New Delhi), 1975.

9 Samajpati S, Majumder A & Das Gupta P C , Text Res J, 49 ( 1975) 8.

10 Majumder A, Samajpati S, Sinha A K, Debnath C R, Das P K. Ghosh S K, Ganguly P K & Kumar G S, Chemical texlllrization of jute and its effect on the proccssibility and properties of jute nonwoven, paper presented at the sil ver jubilee seminar on jute, Calcutta, November 1979.

II Kothari V K & Newton A, J Textlnst, 65 (1 974) 525.

12 Clayton F H, J Text blSt, 26(1935 ) TI7!.

13 Dent R, Nonwovens 71, edited by P Lennox·-Kerr ( Textile Trade Press, Manchester), 1971 .