Steam explosion of woody hemp chènevotte.

This paper concerns the morphology of hemp woody core cells, investigated by optical and scanning electron microscopy, and the chemical analysis of the hemp cells. Steam explosion was investigated as a pre-treatment step for woody hemp 'chènevotte', with the aim of optimizing the separation and delignification of woody fibres. In this study, we report the results of five experiments performed on 'chènevotte' samples impregnated in acid solution (0.1% w/w H2SO4) and steamed at 200, 210, 220, 230 and 240 degrees C for 180 s. The effect of process temperatures on the woody hemp core after acidic impregnation was followed by optical and scanning electron microscopy, by assessment of the chemical composition, and by evolution of the average degree of polymerization (DPv) values of the purified wood fibres. We found that treatment at 200 and 210 degrees C led to samples that were difficult to delignigy because the destructuring and disintegration of lignocellulosic materials were insufficient. A temperature of the order of 220-230 degrees C is required to obtain well-separated fibres. However, at a temperature of 240 degrees C, degradation and fibre damage were noted.