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Fig. 12 Typical cross-sectional images obtained with x-ray tomography for samples with fine components. a Reference with unrefined NBSK and hemp with starch (TP7). The added fine
components included b V-fines (TP8), c CMF (TP9), and d TCNF (TP10). The corresponding stress–strain curves are shown in Fig. 11. Wire side is at the bottom
Acknowledgments Open access funding provided by Technical Research Centre of Finland (VTT). This article was based on the results achieved in the Novel Structural Materials with Multi-scale Fibre Components (NoMa) project. The authors are grateful for the financial support from Tekes (now Business Finland, the Finnish innovation funding, trade, investment, and travel promotion organization), VTT, the participating companies, and Lahti University of Applied Sciences. We are also grateful for the support by the FinnCERES Materials Bioeconomy Ecosystem. We would like to thank Kirsi Immonen and Jari Sirvio¨ for useful discussions. Tuomas Turpeinen, Annika Ketola, Pa¨ivi Sarja, Meiju Sinkkonen, and Timo Rantanen are appreciated for their laboratory and analysis work.
can be compared with theoretical prediction of 3.80. Moreover, the slope was not correlated with material density. This gives further evidence of a buckling mechanism describing the observed stress–strain behaviour at intermediate compression levels, before collective phenomena soften the structure (Ma¨kinen et al. 2020). The resilience of the samples after compression was not affected by the bonding properties but by the dominant fibre type. This suggests that resilience is related to the recovery of fibres from earlier buckling; poor resilience does not necessarily mean that inter- fibre bonds would have failed. These findings will be useful in developing new applications for lightweight cellulose materials, where separate tuning of mechanical behaviour and material density are essential.
Funding
Funding was provided by Tekes and VTT.
Compliance with ethical standards
Conflict of interest conflicting interests.
The authors declare that they have no
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