Published March 10, 2021 | Version v1
Journal article Open

Impact of Alkali and Silane Treatment on Hemp/PLA Composites' Performance: From Micro to Macro Scale

  • 1. Department of Material and Environmental Technology, Tallinn University of Technology
  • 2. InnoRenew CoE; Andrej Marušič Institute, University of Primorska
  • 3. Pulp and Paper Institute, Bogišićeva 8, 1000 Ljubljana
  • 4. Department of Mechanical and Industrial Engineering, Tallinn University of Technology


This study investigated the effect of hemp fiber pretreatments (water and sodium hydroxide) combined with silane treatment, first on the fiber properties (microscale) and then on polylactide (PLA) composite properties (macroscale). At the microscale, Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy investigations highlighted structural alterations in the fibers, with the removal of targeted components and rearrangement in the cell wall. These structural changes influenced unitary fiber properties. At the macroscale, both pretreatments increased the composites’ tensile properties, despite their negative impact on fiber performance. Additionally, silane treatment improved composite performance thanks to higher performance of the fibers themselves and improved fiber compatibility with the PLA matrix brought on by the silane couplings. PLA composites reinforced by 30 wt.% alkali and silane treated hemp fibers exhibited the highest tensile strength (62 MPa), flexural strength (113 MPa), and Young’s modulus (7.6 GPa). Overall, the paper demonstrates the applicability of locally grown, frost-retted hemp fibers for the development of bio-based composites with low density (1.13 to 1.23 g cm−3 ).


The authors wish to make the following two corrections to this paper [1]: the graphical abstract on the website contains an image wrongfully labeled, and Figure 11 depicts the same data as Figure 12 in the original version of the published article. We apologize for the original errors. The graphical abstract and Figure 11 should be updated to correct this oversight.



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InnoRenew CoE – Renewable materials and healthy environments research and innovation centre of excellence 739574
European Commission