Abstract

Synthetic structural materials with exceptional mechanical performance suffer from either large weight and adverse environmental impact (for example, steels and alloys) or complex manufacturing processes and thus high cost (for example, polymer-based and biomimetic composites)1,2,3,4,5,6,7,8. Natural wood is a low-cost and abundant material and has been used for millennia as a structural material for building and furniture construction9. However, the mechanical performance of natural wood (its strength and toughness) is unsatisfactory for many advanced engineering structures and applications. Pre-treatment with steam, heat, ammonia or cold rolling10,11,12,13,14,15,16,17,18,19,20,21 followed by densification has led to the enhanced mechanical performance of natural wood. However, the existing methods result in incomplete densification and lack dimensional stability, particularly in response to humid environments14, and wood treated in these ways can expand and weaken. Here we report a simple and effective strategy to transform bulk natural wood directly into a high-performance structural material with a more than tenfold increase in strength, toughness and ballistic resistance and with greater dimensional stability. Our two-step process involves the partial removal of lignin and hemicellulose from the natural wood via a boiling process in an aqueous mixture of NaOH and Na2SO3 followed by hot-pressing, leading to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres. This strategy is shown to be universally effective for various species of wood. Our processed wood has a specific strength higher than that of most structural metals and alloys, making it a low-cost, high-performance, lightweight alternative.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    , & Layered nanocomposites inspired by the structure and mechanical properties of nacre. Chem. Soc. Rev. 41, 1111–1129 (2012)

  2. 2.

    A synchrotron look at steel. Science 298, 975–976 (2002)

  3. 3.

    et al. Ultrastrong and stiff layered polymer nanocomposites. Science 318, 80–83 (2007)

  4. 4.

    & Nanostructured metals: retaining ductility. Nat. Mater. 3, 351–352 (2004)

  5. 5.

    & Nature’s hierarchical materials. Prog. Mater. Sci. 52, 1263–1334 (2007)

  6. 6.

    , , , & Materials become insensitive to flaws at nanoscale: lessons from nature. Proc. Natl Acad. Sci. USA 100, 5597–5600 (2003)

  7. 7.

    , & Structural biological materials: critical mechanics-materials connections. Science 339, 773–779 (2013)

  8. 8.

    et al. Anomalous scaling law of strength and toughness of cellulose nanopaper. Proc. Natl Acad. Sci. USA 112, 8971–8976 (2015)

  9. 9.

    & Wood and Cellulosic Chemistry (CRC Press, 2000)

  10. 10.

    Mechanical Properties of Laminated Modified Wood (US Department of Agriculture, Forest Service, Forest Products Laboratory, 1965)

  11. 11.

    , , , & Densification of wood veneers by compression combined with heat and steam. Eur. J. Wood Wood Prod. 70, 155–163 (2012)

  12. 12.

    , & Properties of plywood manufactured from compressed veneer as building material. Mater. Des. 30, 947–953 (2009)

  13. 13.

    Structure and Properties Relationships of Densified Wood (Virginia Polytechnic Institute and State University, 1999)

  14. 14.

    et al. Comparison of selected physical and mechanical properties of densified beech wood plasticized by ammonia and saturated steam. Eur. J. Wood Wood Prod. 72, 583–591 (2014)

  15. 15.

    & Combined densification and thermo-hydro-mechanical processing of wood. MRS Bull. 29, 332–336 (2004)

  16. 16.

    , & Interactive effect of surface densification and post-heat-treatment on aspen wood. J. Mater. Process. Technol. 210, 293–296 (2010)

  17. 17.

    Improving wood strength and stiffness through viscoelastic thermal compression. Masters thesis, Oregon State Univ., (2007)

  18. 18.

    , , , & Wood densification and thermal modification: hardness, set-recovery and micromorphology. Wood Sci. Technol. 50, 883–894 (2016)

  19. 19.

    & Compression of wood under saturated steam, superheated steam, and transient conditions at 150 °C, 160 °C, and 170 °C. Wood Sci. Technol. 46, 73–88 (2012)

  20. 20.

    et al. The water vapour sorption properties of thermally modified and densified wood. J. Mater. Sci. 47, 3191–3197 (2012)

  21. 21.

    et al. Measuring the thickness swelling and set-recovery of densified and thermally modified Scots pine solid wood. J. Mater. Sci. 48, 8530–8538 (2013)

  22. 22.

    & Improvement in toughness of poly(l-lactide) (PLLA) through reactive blending with acrylonitrile–butadiene–styrene copolymer (ABS): morphology and properties. Eur. Polym. J. 45, 738–746 (2009)

  23. 23.

    & A strategy for enhancement of mechanical and electrical properties of polycarbonate/multi-walled carbon nanotube composites. Carbon 47, 1126–1134 (2009)

  24. 24.

    , , & A review on the tensile properties of natural fiber reinforced polymer composites. Composites B 42, 856–873 (2011)

  25. 25.

    The conflicts between strength and toughness. Nat. Mater. 10, 817–822 (2011)

  26. 26.

    , , & High tensile ductility in a nanostructured metal. Nature 419, 912–915 (2002)

  27. 27.

    & Recent developments in advanced aircraft aluminium alloys. Mater. Des. 56, 862–871 (2014)

  28. 28.

    & Microstructures and mechanical properties of high-strength Fe-Mn-Al-C light-weight TRIPLEX steels. Steel Res. Int. 77, 627–633 (2006)

  29. 29.

    , , & The effect of cooling rate on the cyclic deformation of beta-annealed Ti-6Al-4V. Mater. Sci. Eng. A 349, 150–155 (2003)

  30. 30.

    , & Brittle intermetallic compound makes ultrastrong low-density steel with large ductility. Nature 518, 77–79 (2015)

Download references

Acknowledgements

We thank R. Briber for suggestions and R. J. Bonenberger for help with mechanical tests. We acknowledge the support of the Maryland NanoCenter and its AIMLab. J.S. acknowledges financial support from the China Scholarship Council.

Author information

Author notes

    • Jianwei Song
    • , Chaoji Chen
    • , Shuze Zhu
    •  & Mingwei Zhu

    These authors contributed equally to this work.

Affiliations

  1. Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA

    • Jianwei Song
    • , Chaoji Chen
    • , Mingwei Zhu
    • , Jiaqi Dai
    • , Yiju Li
    • , Yudi Kuang
    • , Yongfeng Li
    • , Yonggang Yao
    • , Amy Gong
    •  & Liangbing Hu
  2. Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, USA

    • Shuze Zhu
    • , Upamanyu Ray
    • , Nelson Quispe
    • , Hugh A. Bruck
    • , Zheng Jia
    •  & Teng Li
  3. Department of Aerospace Engineering, University of Maryland, College Park, Maryland 20742, USA

    • Ulrich H. Leiste
  4. Forest Products Laboratory, USDA Forest Service, Madison, Wisconsin 53726, USA

    • J. Y. Zhu
  5. Department of Mechanical Engineering, University of California Merced, Merced, California 95343, USA

    • Azhar Vellore
    •  & Ashlie Martini
  6. Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, USA

    • Heng Li
    •  & Marilyn L. Minus

Authors

  1. Search for Jianwei Song in:

  2. Search for Chaoji Chen in:

  3. Search for Shuze Zhu in:

  4. Search for Mingwei Zhu in:

  5. Search for Jiaqi Dai in:

  6. Search for Upamanyu Ray in:

  7. Search for Yiju Li in:

  8. Search for Yudi Kuang in:

  9. Search for Yongfeng Li in:

  10. Search for Nelson Quispe in:

  11. Search for Yonggang Yao in:

  12. Search for Amy Gong in:

  13. Search for Ulrich H. Leiste in:

  14. Search for Hugh A. Bruck in:

  15. Search for J. Y. Zhu in:

  16. Search for Azhar Vellore in:

  17. Search for Heng Li in:

  18. Search for Marilyn L. Minus in:

  19. Search for Zheng Jia in:

  20. Search for Ashlie Martini in:

  21. Search for Teng Li in:

  22. Search for Liangbing Hu in:

Contributions

J.S., C.C., S.Z. and M.Z. contributed equally to this work. L.H., J.S., C.C. and M.Z. contributed to the initiating idea. J.S. and C.C. contributed to the wood densification and mechanical measurements. Yo.L., U.R., Z.J., N.Q., U.H.L., H.A.B. and T.L. contributed to the mechanical tensile and ballistic tests. J.D. and Y.K. contributed to the 3D illustrations. Yi.L., C.C., Y.Y. and A.G. contributed to characterization via SEM. J.Y.Z. performed the compositional analysis. A.V. and A.M. contributed to the indentation and scratch hardness tests. S.Z. and T.L. contributed to both mechanical simulations and analysis. H.L. and M.L.M. contributed to XRD measurement and analysis. T.L., L.H., J.S. and C.C. contributed to the writing of the paper. All authors contributed to commenting on the final manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Teng Li or Liangbing Hu.

Reviewer Information Nature thanks A. Cloutier, S. Eichhorn and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Supplementary information

Videos

  1. 1.

    High-speed slow motion videos of ballistic tests

    Top: natural wood; Middle: monolayer densified wood; Bottom: laminated densified wood.

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature25476

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.