Fineness and tensile properties of hemp ( Cannabis sativa L.) fibres

Abstract

There is great interest in the use of hemp (Cannabis sativa L.) fibres for to reinforce polymers in composite materials due to the light weight of hemp fibre. In this study, tensile tests of hemp fibre were conducted using a universal tensile strength testing machine. Fibres used in the experiment were from hemp grown at target seeding rates of 50, 100 and 350 plants m−2. The effects of target seeding rate on the fibre fineness and tensile properties of hemp fibre were examined. Before the tensile tests, diameters and finenesses of the fibres were measured. In the tensile tests, the clamping length of fibre specimen was 35 mm, and the load-elongation curves of fibre specimens were recorded. The tensile properties of fibre (specific tensile strength, maximum strain, apparent modulus and work of rupture) were derived from the curves. Increasing the target seeding rate from 50 to 350 plants m−2, decreased the average fibre diameter from 0.28 to 0.25 mm, decreased the average fibre fineness from 150 to 88 tex; increased the average specific fibre tensile strength from 22.9 to 44.0 cN tex−1; decreased the work of rupture from 9.3 to 5.7 mJ. All the properties measured were highly variable. However, the frequencies distribution of the data showed a cluster for most properties. For example, the majority of fibres had fineness within the range of 0–50 tex, had specific tensile strength within the range of 0–20 cN tex−1, and had work of rupture within the range of 0–5 mJ.