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Lynne Wong's PhD thesis

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3.5.3 Fibre/pith ratios in cane component parts and in cane<br />

Bernhardt (1998) in characterising the particle properties of bagasse suggested that not<br />

only the mean fibre length obtained by sieving with an assembly of sieves of apertures 6.7,<br />

4.0, 2.8, 2.0, 1.4, 0.85, 0.60, 0.425 and 0.30 mm was important, but it was also important<br />

to have the coarse to fine ratio of bagasse, which he defined as the mass of particles<br />

retained by the sieves with apertures of 2 mm and higher, divided by the mass of particles<br />

that pass through the 0.85 mm sieve.<br />

In this work it was found much simpler to separate the fibres into two fractions, namely,<br />

one that is retained by a 1.18 mm sieve and one that passes through it. The former is<br />

referred to as fibre and the latter as fines in the case of dry leaf, green leaf, top and rind,<br />

and as pith in the case of stalk, if the hard fibre is not rendered brittle and breaks into short<br />

pieces.<br />

Results of the fibre/fines ratios of dry leaf, green leaf, top, rind and stalk in cane samples<br />

are given in Tables 3.8 – 3.11. It can be seen that irrespective of the cane variety and age,<br />

stalk has the lowest fibre/pith value, followed by dry leaf, rind, green leaf and top.<br />

By combining the mass of fibre or pith in both rind and stalk, and expressing the hard<br />

fibre, pith and total fibre in terms of % cane, some meaningful results, including the<br />

fibre/pith ratio in cane were obtained and are presented in Tables 3.14 – 3.16 for the four<br />

cane varieties of three ages. The change in these parameters due to the presence of<br />

extraneous matter, namely dry leaf, green leaf and tops, was also calculated and presented<br />

in Tables 3.14 – 3.16. Again, since the nodes had been excluded from the fibre extraction,<br />

the mass of cane was taken to be the mass of stalk plus rind only.<br />

3.5.3.1 Effect of cane age on fibre and pith contents of cane<br />

As the cane matures, the hard fibre % cane is expected to increase, so does the total fibre<br />

% cane.<br />

Moodley (1991) tested two cane varieties aged 6 months and 19 months; with one variety,<br />

the fibre/pith ratio did not vary to a large extent, it was 2.22 and 2.27 for the 6-month and<br />

19-month samples respectively, whereas with the other, it was 2.94 and 3.45 respectively.<br />

100

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