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  • 92

    CHAPTER 5

    WICKING BEHAVIOUR OF MANMADE CELLULOSIC FIBRES

    LIKE VISCOSE, MODAL, TENCEL AND BAMBOO FIBRES

    5.1 INTRODUCTION

    This chapter is concerned with the study of properties of viscose, modal,

    bamboo and tencel staple fibres and also their wicking behaviour.

    5.2 MATERIALS AND METHODS

    These have been already discussed in Chapter 3

    5.3 RESULTS AND DISCUSSION

    Table 5.1 shows the various properties of fibres together with their

    variability.

    Table 5.1: Fibre properties

    Fibre Parameters

    Fibres Viscose Modal Tencel Bamboo

    Length (mm) 39.3 51.5 38.8 38.7

    CV% 2.6 4.94 3 2.6

    Fineness (dtex) 1.38 1.28 1.24 1.23

    CV% 15.10 14.80 10.70 9.20

    Tenacity (g/d) 2.66 3.72 4.22 2.64

    CV% 8.10 11.70 10.80 10

    Elongation (%) 18.70 15.80 10.70 18

    CV% 11.20 11.40 15.90 12.60

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  • 93

    From Table 5.1, it is clear that the modal fibres had longer length and

    higher CV% compared to other fibres. Viscose fibres showed higher fineness and

    the variability was found to be higher in viscose ,modal and tencel. Tencel fibres

    displayed higher tenacity compared to other fibres. This agrees with the findings

    of Kreze et al., (2002). The elongation values are higher in the case of viscose and

    bamboo. Tencel fibres showed greater variability. Following figures 5.1 – 5.4

    illustrates the differences in their properties.

    Figure 5.1: Figure 5.2:

    Fibre length and CV% Fibre fineness and CV%

    Figure 5.3: Figure 5.4:

    Fibre tenacity and CV% Fibre elongation and CV%

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  • 94

    Figure 5.5: Stress strain curves of tencel, modal, bamboo and viscose fibres

    Tencel Modal

    Bamboo Viscose

    The presence of yield point has been noticed in other fibres except tencel.

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  • 95

    WICKING RESULTS

    Data on wicking height and time were analysed by four methods

     Plotting height vs time and carrying out linear regression analysis.

     Plotting height and square root of time so that the curve follows Lucas

    Washburn trend. This is based on the method followed by Kamath et al.,

    (1994).

     Plotting H2 vs time and carrying out regression analysis as per the analysis

    followed by Sharabathy et al., (2008) and Mazloompour et al., (2011).

     Plotting logarithm of height vs logarithm of time and carrying out linear

    regression analysis.

    Figures 5.6, 5.8, 5.10 and 5.12 illustrate the wicking behaviour of fibres and

    the respective tables are presented in Appendix 1.

    Figure 5.6: Wicking behaviour of viscose, modal, tencel and bamboo fibres -

    Height and Time

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  • 96

    Tables give the relevant data on slope and intercept. Table 5.2: Regression equation and correlation coefficient for various fibres

    (Height and Time)

    Fibres Slope(cm/min) Intercept(cm) Correlation Coefficient

    (R2)

    Tencel 0.143 1.4733 0.9356

    Modal 0.1333 1.3467 0.9549

    Bamboo 0.1279 1.1867 0.9713

    Viscose 0.1055 0.86 0.9929

    Figure 5.7: Slope values (Height and Time)

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  • 97

    Figure 5.8: Wicking behaviour of viscose, modal, tencel and bamboo fibres -

    Log Time and Log Height

    Table 5.3: Regression equation of the form log (h)=k log t + constant and

    correlation coefficient for various fibres

    Fibres Slope (K) Intercept (C)

    Correlation Coefficient

    (R2)

    Tencel 0.2989 0.3452 0.9955

    Modal 0.2991 0.2619 0.9988

    Bamboo 0.3064 0.1528 0.9944

    Viscose 0.32 -0.1416 0.9826

    Figure 5.9: Slope values versus intercept values (Log Height and Log Time)

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  • 98

    Figure 5.10: Wicking behaviour of viscose, modal, tencel and bamboo fibres -

    Square root of Time and Height

    Table 5.4: Regression equation of the form H=Kt 1/2 + constant and

    correlation coefficient for various fibres

    Fibres Slope(cm/min1/2 ) Intercept(cm) Correlation Coefficient

    (R2)

    Tencel 0.6263 0.8523 0.9858

    Modal 0.5803 0.7756 0.994

    Bamboo 0.5528 0.6475 0.9974

    Viscose 0.4494 0.4299 0.9908

    Figure 5.11: Slope values (Square Root of Time and Height)

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  • 99

    Figure 5.12: Wicking behaviour of viscose, modal, tencel and bamboo fibres -

    Square of Height and Time

    Table 5.5: Regression equation of the form h2/t and correlation coefficient and correlation coefficient for various fibres

    Fibres Slope(cm)2/min) Intercept(cm) Correlation Coefficient

    (R2)

    Tencel 0.6195 1.8807 0.9736 Modal 0.5355 1.5347 0.9858 Bamboo 0.4696 1.128 0.9933 Viscose 0.3004 0.514 0.9959

    Figure 5.13: Slope values (Square of Height and Time)

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  • 100

    In the first method of analyzing wicking, the wicking time was plotted

    against the wicking height and the regression equation and correlation coefficient

    were computed and shown in Table 5.2.Tencel fibres show higher values of slope

    and intercept followed by modal, bamboo and viscose fibres. The correlation

    between height and time was found to be good. This is due to the molecular

    structure of tencel which consists of fine crystalline micro fibrils with fine pores.

    The space between these micro fibrils acts like capillaries giving rise to enhanced

    capillary effect. Also such crystalline arrangement of micro fibrils is uniformly

    distributed in tencel unlike viscose, bamboo and modal. Hence tencel fibres

    showed maximum wicking behaviour compared to other fibres In the second

    method of analyzing wicking, the logarithm of wicking time was plotted against

    the logarithm of wicking height. Values of the time exponent (K) and intercept

    values were computed and shown in Table 5.3. Higher values of ‘C’ and lower

    values of ‘K’ indicate good wickability and vice versa. Slopes and intercepts

    obtained from log h –log t values were plotted to illustrate the trend as shown in

    Figure 5.9. There was a negative correlation between slope K and intercept C as

    suggested by Laughlin and Davies (1961) which has to be considered for

    interpreting wickability. It is clear that there is an interdependency between K

    and C.

    In the third method , the wicking height was plotted against the square root

    of time which is based on the Kamath et al.’s procedure adopted for the studies.

    Table 5.4 shows the slopes and intercept values (Model assumed Kt ½ + constant,

    where K is the slope) whereas the h2/t values are shown in Table 5.5. In this

    method, square of height was plotted against time. In both the cases, tencel fibres

    with higher values of slopes and intercepts exhibited good wickability and the

    correlation was found to be good. Slope values obtained from height and time,

    height and square root of time, square of height and time were plotted to illustrate

    the trend as shown in Figures 5.7, 5.11 and 5.13.

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  • 101

    5.4 CONCLUSION

    Among the fibres studied for wickability, it has been noticed that tencel

    exhibits maximum wicking behaviour. The tenacity was also found to be higher

    compared to other fibres.

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