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Effect of enzymatic treatment of flax on fineness of fibers and mechanical performance of composites

De Prez, Jana, Van Vuure, Aart Willem, Ivens, Jan, Aerts, Guido, Van de Voorde, Ilse
Composites 2019 v.123 pp. 190-199
absorption, biocomposites, dew, diffusivity, enzymatic treatment, equilibrium moisture content, fineness, flax, mechanical properties, polygalacturonase, retting, scanning electron microscopy
The application of enzymes as alternative to dew retting of flax was studied in correlation to the characteristics of composites reinforced with these natural fibers. Fiber fineness and mechanical properties of biocomposites were evaluated. Furthermore, moisture absorption by biocomposites was studied and fracture surfaces were investigated using Scanning Electron Microscopy. Compared to dew retted fiber composites, improvements in mechanical performance can be observed for composites impregnated with fibers extracted after enzymatic treatments. All enzymatic treatments resulted in finer fibers than green fibers and led to biocomposites with a reduced equilibrium moisture content and lower diffusion coefficient. This study illustrates the high potential of enzymatic retting, in particular with polygalacturonase. Also, the manual extraction procedure used, produced fibers with an E-modulus up to 84 GPa and strength up to 800 MPa, likely due to reduced fiber damage, which illustrates the hidden potential of flax fibers.