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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Urea-Based Treatments of Unretted Hemp Fibres from Residual Streams

Ortiz Sarasty, Danilo Esteban January 2023 (has links)
More sustainable and efficient degumming methods are required to extract finner bast fibres, especially from agro-industrial waste streams such as stalks from hemp for food purposes. For this reason, in this study, two urea-based treatments were evaluated as degumming alternatives for unretted hemp fibres from residual streams, one at cold and alkaline conditions (CUA) and the other in combination with microwave radiation (MWU). Both approaches reduced fiber bundles diameter, decreasing 61% at -7°C 5 minutes, 12%Urea-5%NaOH, and 44% for microwave-30%urea for 30 minutes. Although both methods resulted in considerable fibre bundle diameter reduction, they resulted in a lower reduction than the 74% obtained for a traditional alkali (TA) degumming. Shorter fibres were obtained after the treatments. CUA and TA treatments obtained similar fibre lengths, while MWU resulted in longer than the other treatments. The chemical and thermal analysis showed that the highest removal of no cellulosic components was achieved by the TA treatment, followed by CUA and MWU. The treatments were applied to nonwovens produced by needle punching, showing no significant differences in tenacity and flexural rigidity compared to non-treated nonwovens. An increase of mass per unit area was identified for the CUA-treated fabrics, attributed to crimp generated in the treatment. Both urea-based treatments showed potential as more sustainable alternatives for degumming unretted hemp fibre bundles extracted from agro-waste.

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