Structure and mechanical properties of vegetable fibres. I. The influence of strain on the orientation of cellulose microfibrils in sisal leaf fibre

Abstract

The relation between the extensibility and the fine structure of sisal fibres has been investi­gated. The spiral arrangement of the cellulose microfibrils in the secondary walls of the fibres undergoes regular change from the base to the tip of the leaf. When fibre bundles are stretched the cellulose spirals steepen in a way analogous to the steepening of a spiral spring. This change in the spiral orientation of the cellulose microfibrils is of reversible character. Formulae are derived for the relative displacement of the microfibrils as the spiral angle changes during stretching.