Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Apr 14;13(8):1844.
doi: 10.3390/ma13081844.

A New Strategy to Produce Hemp Fibers through a Waterglass-Based Ecofriendly Process

Aurelio Bifulco  1 , Brigida Silvestri  1 , Jessica Passaro  1 , Luca Boccarusso  1 , Valentina Roviello  1 , Francesco Branda  1 , Massimo Durante  1
Affiliations

A New Strategy to Produce Hemp Fibers through a Waterglass-Based Ecofriendly Process

Aurelio Bifulco et al. Materials (Basel). .

Abstract

Natural fibers such as kenaf, hemp, flax, jute, and sisal have become the subject of much research as potential green or eco-friendly reinforcement composites, since they assure the reduction of weight, cost, and CO2 release with less reliance on oil sources. Herein, an inexpensive and eco-friendly waterglass treatment is proposed, allowing the production of silica-coated fibers that can be easily obtained in micro/nano fibrils through a low power mixer. The silica coating has been exploited to improve the chemical compatibility between fibers and the polymer matrix through the reaction of silanol groups with suitable coupling agents. In particular, silica-coated fibers easily functionalized with (3-Aminopropyl) triethoxysilane (APTS) were used as a filler in the manufacturing of epoxy-based composites. Morphological investigation of the composites through Scanning Electron Microscopy (SEM) demonstrated that the filler has a tendency to produce a web-like structure, formed by continuously interconnected fibrils and microfibrils, from which particularly effective mechanical properties may be obtained. Dynamic Mechanical Analysis (DMA) shows that the functionalized fibers, in a concentration of 5 wt%, strongly affect the glass transformation temperature (10 °C increase) and the storage modulus of the pristine resin. Taking into account the large number of organosilicon compounds (in particular the alkoxide ones) available on the market, the new process appears to pave the way for the cleaner and cheaper production of biocomposites with different polymeric matrices and well-tailored interfaces.

Keywords: ecofriendly production; epoxy composites; hemp fibers; silica coating; waterglass; web-like structure.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Overall scheme of the new fiber modification strategy to produce APTS functionalized filler.
Figure 1
Figure 1
Percentage change as a function of the number of soaking–drying cycles.
Figure 2
Figure 2
Micrographs of the fibers at different magnifications: (a) general overview at 300 µm (b) and increasing details at 40 µm (c) and 3 µm.
Figure 3
Figure 3
Micrograph of hemp fiber after APTS functionalization and EDX spectrum.
Figure 4
Figure 4
Spectra of (a) hemp fabric after functionalization with waterglass (Hemp_SiO2 sample), (b) the spectrum recorded after the functionalization with APTS (Hemp_SiO2_ APTS sample).
Figure 5
Figure 5
Micrographs of the composites epoxy/APTS functionalized hemp fibers: (a,c) 50 µm scale and its detail, (b) region at 10 µm.
Figure 6
Figure 6
Glass transformation temperature of the composites epoxy/APTS functionalized hemp fibers as a function of composition.
Figure 7
Figure 7
Comparison between the experimental values of Tanδ (calculated as storage and loss modulus ratio) for different volumetric percentage of filler content in the epoxy resin.
Figure 8
Figure 8
Storage moduli of the different specimens measured by DMA.
Figure 9
Figure 9
The difference between the experimental and theoretical values of moduli for different volumetric percentages of filler content in the epoxy resin.
See this image and copyright information in PMC

References

    1. Eichhorn S.J., Dufresne A., Aranguren M., Marcovich N.E., Capadona J.R., Rowan S.J., Weder C., Thielemans W., Roman M., Renneckar S., et al. Review: Current international research into cellulose nanofibers and nanocomposites. J. Mater. Sci. 2010;45:1–33. doi: 10.1007/s10853-009-3874-0. - DOI
    1. Holbery J., Houston D. Natural-fiber-reinforced polymer composites in automotive applications. Jom. 2006;58:80–86. doi: 10.1007/s11837-006-0234-2. - DOI
    1. Siqueira G., Bras J., Dufresne A. Cellulosic biocomposites: A review of preparation; properties and applications. Polymers. 2010;2:728–765. doi: 10.3390/polym2040728. - DOI
    1. Alves C., Silva A.J., Reis L.G., Freitas M., Rodrigues L.B., Alves D.E. Ecodesign of automotive components making use of natural jute fiber composites. J. Clean. Prod. 2010;18:313–327. doi: 10.1016/j.jclepro.2009.10.022. - DOI
    1. Nechyporchuk O., Belgacem M.N., Bras J. Production of cellulose nanofibrils: A review of recent advances. Ind. Crop. Prod. 2016;93:2–25. doi: 10.1016/j.indcrop.2016.02.016. - DOI

LinkOut - more resources