Role of microwave in processing of hemp fibre

Authors: Nair, G, Y Gariepy, D Rho, Gsv Raghavan
Description: Hemp is cultivated commercially in Canada. Hemp fibre, which is processed from hemp stem, can be used as a replacement for synthetic fibres in various applications like, biocomposites, papers, etc. Retting is the separation or loosening of bast fibres from other non-fibre fractions and is a major problem in processing hemp. The natural methods of retting (water retting, dew retting, etc.) are time consuming (2 - 4 weeks) and produces environmentally unacceptable fermented wastes. The newer methods like the enzyme-assisted retting reduce time to 8 - 24 hours, which involves the use of enzymes which are expensive and not reUSAble. The project aims at introducing an electro-technology in hemp fibre processing, especially in retting. Microwave assisted retting of hemp stem was conducted by varying parameters like initial soaking time of the hemp stem, microwave power and the residence time in the microwave chamber. Non-retted flax stem was subjected to water soaking for 12, 24, and 36 hours. Those soaked stems were placed in a microwave chamber for residence times of 10, 15, and 20 min. The microwave powers were fixed at 1.0, 1.5, and 2.0 W/g. The volumetric heating of microwaves allows the water molecules inside the hemp stem to move outwards. Consequently, it helped in the breaking of the weaker covalent bonds which kept the pectino-cellulosic structure to hold the bast fibre to stick to the stem wall. The combined effect of microwave and the heat generated during the microwave treatment eased the separation of the cellulose-rich fibres. The experiments are ongoing now and results are not yet analyzed. NIR analysis, Fibreshape analysis, color and tensile strength analysis are used to analyze the fibre characteristics (work is in progress and it will be included in the final submission).
Keywords: microwave, retting,hemp, fibre
Technical field: Bioprocess Systems Engineering
Session name: Food and bioprocess engineering
Date: 2012
Identifier: CSBE12042
Coverage: Canada

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