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Hardness of chemically densified Yellow birch in relation to wood density, polymer content and polymer properties

Juliette Triquet ORCID logo, Pierre Blanchet ORCID logo and Véronic Landry ORCID logo
From the journal Holzforschung


Density of wood can be increased by filling its porous structure with polymers. Such densification processes aim to increase hardness of wood and are particularly interesting for flooring applications. This study aims to evaluate efficiency of different polymers for chemical densification based on the polymer properties. Yellow birch (Betula alleghaniensis Britt.) was chemically densified with seven monomer mixtures through acrylate monomer impregnation and electron beam in-situ polymerization. Chemical retention and polymer content of densified woods were recorded. Hardness of treated and untreated Yellow birch was measured and compared to hardness of Jatoba (Hymenaea courbaril L.). All densified woods showed higher or comparable hardness to Jatoba. Hardness of densified wood was analyzed in relation to initial density of wood and polymer content of the material using multivariable linear mixed models. Efficiency of polymers for chemical densification was evaluated through effect of polymer content on hardness with interaction coefficients. Polymer films corresponding to monomer impregnating mixtures were prepared through low energy electron beam and characterized by their glass transition temperature, micro hardness, indentation modulus and crosslinking density. Polymers showed statistically significantly different efficiencies and were separated in two main groups. Overall, polymer efficiency increased with increasing glass transition temperature of polyacrylates.

Corresponding author: Juliette Triquet, Wood and Forest Sciences Department, Faculty of Forestry, Geography, Geomatics, Université Laval, 2405 rue de la Terrasse, Quebec City, Québec G1V 0A6, Canada; and NSERC Canlak Industrial Research Chair in Interior Wood-Product Finishes (CRIF), Université Laval, 2425 rue de l’université, Quebec City, Québec G1V 0A6, Canada, E-mail:

Funding source: Natural Sciences and Engineering Research Council of Canada (NSERC)

Award Identifier / Grant number: RDCPJ 500157 – 16

Award Identifier / Grant number: PCISA 514917 – 16


The authors are grateful to the industrial partners of the NSERC-Canlak Industrial Research Chair in Finishes for Interior Wood Products (CRIF) for their help and support. Many thanks to Prof. Roberto Uribe-Rendon from Kent State University (Kent, Ohio, USA) for his help with electron beam irradiation. The authors would also like to thank collaborators who provided technical support: Dr Zhao Chen for micro indentation testing, Pascale Chevalier and the Research Center for Advanced Materials (CERMA - Université Laval) for SEM imaging, as well as the whole technical team at the Renewable Materials Research Center (CRMR - Université Laval).

  1. Author contribution: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: This work is part of the research program of Natural Sciences and Engineering Research Council of Canada (NSERC) Canlak Industrial Research Chair in Finishes for Interior Wood Products (CRIF) through programs CRD (RDCPJ 500157 – 16) and PCI (PCISA 514917 – 16).

  3. Conflict of interest statement: The authors declare no conflicts of interest regarding this article.


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Received: 2020-03-24
Accepted: 2020-06-18
Published Online: 2020-08-25
Published in Print: 2021-02-23

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