Revitalization of Industrial Hemp Cannabis sativa L. var. sativa in Slovenia: a Study of Green Hemp Fibres

The importance of industrial hemp as a source of highly valuable textile fi bres is briefl y presented through its use for textiles and composites and its increasing cultivated areas in the 21 st century.On the territory of present Slovenia, about 160 ha of agricultural area was cultivated with hemp before WWII, then it quickly began to decline and at the end of the 1970s, it was no longer cultivated.Revitalization of industrial hemp in Slovenia with fi eld experiments started already in the years 2000/2001 for producing seeds, whereas hemp fi bres were used only as an insulation for buildings.The textile technological properties of hemp fi bres from diff erent varieties grown in Slovenia have not been examined till now.They are important for using hemp fi bres in highly valuable textile products.The properties of green hemp fi bres extracted mechanically from non-retted hemp stems of Cannabis sativa L. var.sativa (varieties: Novosadska, Juso-11, Bialobrzeskie, Unico-B and Beniko) were determined.All the analysed varieties except Beniko had stem height over 200 cm.The highest yield of green fi bres was 33.1% (Novosadska).The analysed green fi bres' content was 1.24-3.26% of ash, 7.77-8.50% of moisture regain, 10.69-13.92% of water-soluble substances and 8.45-10.83% of pectin.Through a biodegradation process of retting green hemp fi bres in tap water at temperature 35°C, 9.01-18.89% of dry mass was removed after ten days.Average linear density of green hemp fi bres was very high, around 200 tex.Tenacity of fi bres' bundles was in the range of 167-272 MPa, but tenacity of elementary fibres was 548-672 MPa.From the curves of specifi c stress-strain, it is seen that green hemp fi bres from all fi ve varieties had similar superstructure.All analysed green hemp fi bres had high linear density and low mechanical properties.For textile application, they should be further processed into fi ner fi bres in order to increase their tensile stress and become also more fl exible and soft.Keywords: Cannabis sativa, non-retted hemp fi bres, green hemp fi bres, hemp in Slovenia, revitalization of industrial hemp Izvleček V članku sta na kratko predstavljena pomen navadne konoplje kot vira dragocenih tekstilnih vlaken za uporabo v tekstilstvu in v kompozitih in povečevanje kmetijskih površin, zasejanih z navadno konopljo v 21. stoletju.Še pred drugo svetovno vojno je bilo na ozemlju današnje Slovenije s konopljo zasejanih okrog 160 hektarov kmetijskih površin, te površine pa so potem začele hitro upadati in konec 70.let konoplje niso več gojili.Revitalizacija navadne konoplje v Sloveniji se je s poljskimi poskusi začela v letih 2000/2001 za pridelavo semen, pri čemer so se konopljena vlakna uporabljala le za toplotno izolacijo stanovanjskih hiš.Tekstilno tehnološke lastnosti konopljenih vlaken iz različnih sort navadne konoplje, ki so gojene na območju Slovenije, do zdaj še niso Revitalization of Industrial Hemp Cannabis sativa L. var.sativa in Slovenia: a Study of Green Hemp Fibres Tekstilec, 2017, 60(1), 36-48