Consequntly there is little decrease in tensile strength, for the chain lenght remains unchanged ,but there is a considerable increase in reducing power because of the increase in the percentage of aldehyde groups.
A further treatment with alkali, however, causes breakage of the chin to give product F, which possesses the same reduced tensile strenght because the mean chain length is shortened.
If the alkil treatment is carried out with exposure to air , simultane-our oxidation takes place to give a proportion of substances of the type of product G , which , compared with product D , possesses a much- reduced viscosity in cuprammonium, a lowered reducing power because the aldehyde groups are reduced in percentage, and an increased absorption for basic dyes because there are many more COOH groups present. Product G compared with product F shows little change in viscosity of solutions, a lower reducing power , and an increased absorption for basic dyes such as methylene bule . As normal alkali treatments are carried out in presence of air , it is invariably the case that a proportion of product G is formed along with the main quantity of product F.Sisal Hemp:
Botanical: fibres from the leaves of agave rigida. colour : light yellowish. Staple: cells 1.5-4 mm. Diameter: cells 20-32 microns' much thicker in the middle than at the ends. Surface: smooth:
peculiar spiral vessels are present. Lumen: wider than the cell wall,
polygonal in cross section, but with very rounded angles. cell ends: broad, blunt, thick, seldom forked. Cross section: Cells are polygonal thick walled fibres are present, with narrow lumen and distinct surface pores . Cbemical reactions: as a lignified fibre. The calcium ocalate crystals found clinging to the fibre bundles, which are sometimes large enough to be seen with the naked eye; these usually occur in longitudinal series.
