# Exploring the solid wood modification with preserved hierarchical structure via non-cellulosic substances removal

Yi Hien Chin, Pascal Henry Biwole, Joseph Gril, Rostand Moutou Pitti,

Christophe Vial, Salah-Eddine Ouldboukhitine, Nicolas Labonne, Yoshiki

Horikawa

► To cite this version:

Yi Hien Chin, Pascal Henry Biwole, Joseph Gril, Rostand Moutou Pitti, Christophe Vial, et al. Exploring the solid wood modification with preserved hierarchical structure via non-cellulosic substances removal. 11th European Conference on Wood Modification (ECWM11), Apr 2024, Florence, Italy. .
hal-04585291

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Distributed under a Creative Commons Attribution 4.0 International License
# Exploring the solid wood modification with preserved hierarchical structure via non-cellulosic substances removal

Yi Hien Chin, Pascal Henry Biwole, Joseph Gril, Rostand Moutou Pitti, Christophe Vial, Salah-Eddine Ouldboukhitine, Nicolas Labonne, Yoshiki Horikawa

► To cite this version:

Yi Hien Chin, Pascal Henry Biwole, Joseph Gril, Rostand Moutou Pitti, Christophe Vial, et al. Exploring the solid wood modification with preserved hierarchical structure via non-cellulosic substances removal. 11th European Conference on Wood Modification (ECWM11), Apr 2024, Florence, Italy. . [hal-04585291](https://hal.science/hal-04585291v1)

HAL Id: hal-04585291

https://hal.science/hal-04585291v1

Submitted on 23 May 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

DAGARD

<figure><img src="image_3.png" /></figure>

CAP
20-25

I-SITE
CLERMONT
Clermont Auvergne Project

<figure><img src="image_4.png" /></figure>

国立大学法人
東京農工大学
Tokyo University of Agriculture and Technology

<figure><img src="image_5.png" /></figure>

INSTITUT
PASCAL
sciences de l'ingénierie et des systèmes

<figure><img src="image_6.png" /></figure>

UNIVERSITÉ
Clermont
Auvergne

<figure><img src="image_7.png" /></figure>

# Exploring the solid wood modification with preserved hierarchical structure via non-cellulosic substances removal

CHIN Yi Hien<fnref n="1" />,<fnref n="2" />,<fnref n="3" />, BIWOLE Pascal<fnref n="1" />,<fnref n="4" />, GRIL Joseph<fnref n="1" />,<fnref n="5" />, MOUTOU PITTI Rostand<fnref n="1" />,<fnref n="6" />, VIAL Christophe<fnref n="1" />, OULDBOUKHITINE Salah-Eddine<fnref n="1" />, LABONNE Nicolas<fnref n="2" />, HORIKAWA Yoshiki<fnref n="3" />

## Introduction

Innovations in wood modification technology have led to the development of novel functionalities and enhancements to the existing advantages of wood. The removal of non-cellulosic substances creates a low-density porous cellulose scaffold with reduced thermal conductivity [1]. Despite various top-down wood delignification methods, there has been a lack of comparative analysis. Additionally, scaling up production using freeze-drying technique presents challenges.

### Objectives

<figure><img src="image_8.png" /></figure>

* To evaluate the degree of non-cellulosic substances removal among three delignification techniques

* To identify potential drying techniques for large-scale production

<figure><img src="image_9.png" /></figure>

## Materials & Methods

French poplar wood planks of 100 mm along the grain and 100 mm by 10 mm section in the transversal plane were used.

<figure><img src="image_10.png" /></figure>

## Results & Discussions

### ❖ Degree of lignin removal

* The decreasing intensity of the peaks at 1730 and 1240 cm⁻<fnref n="1" /> assigned to acetyl functional groups was a result of hemicellulose removal [2]. Organosolv & NaClO₂ treatment led to the disappearance of the peaks at 1508, 1465, and 1264 cm⁻<fnref n="1" />, indicating the absence of lignin.

* A higher treatment temperature, treatment duration or delignifying solution concentration may be required for NaOH and alkaline sulfite & H₂O₂ modification.

* The high glucose content was maintained in all modified wood, suggesting that cellulose was not much affected by the treatments, only lignin and hemicellulose were preferentially altered.

<figure><img src="image_11.png" /><figcaption>Fig. 1: FTIR spectra of poplar wood under different modification treatments.</figcaption></figure>

<figure><img src="image_12.png" /><figcaption>Fig. 2: Ratio of chemical components in poplar wood before and after modification treatments.</figcaption></figure>

### ❖ Drying kinetics

* For all drying methods, the drying rate decreases as the moisture content of samples reduces.

* Dielectric heating (microwave and radio frequency) is the fastest drying technique, yet it causes great dimensional shrinkage despite organic solvent exchange.

<figure><img src="image_13.png" /><figcaption>Fig. 3: Moisture content evolution of NaOH modified wood by different drying techniques.</figcaption></figure>

<figure><img src="image_14.png" /><figcaption>Fig. 4: Drying rate at logarithmic scale of different moisture contents for each drying technique.</figcaption></figure>

## Conclusions & Perspectives

* Organosolv & NaClO₂ modification, alkaline sulfite & H₂O₂ modification and NaOH modification appear to be the most to the least lignin removal efficiency respectively.

* Dielectric heating has the highest drying rate across all moisture contents whereas convective blow drying exhibits the lowest sectional shrinkage.

* The information reported allows a better understanding of wood modification and drying mechanisms for the design of appropriate manufacturing procedures.

* Future investigations should focus on the effects of delignification on the thermal, mechanical, and hygric properties of the French poplar wood.

## Acknowledgments

This work is supported by the French National Research Agency (ANR) and the company Dagard, under the « France Relance » plan. The research visit to Japan was co-funded by the I-Site project CAP 20-25 and the Tokyo University of Agri-culture and Technology.

## References

[1] Li T, Song J, Zhao X, et al (2018) Anisotropic, lightweight, strong, and super thermally insulating nanowood with naturally aligned nanocellulose. Sci Adv 4:eaar3724.

[2] Horikawa Y, Hirano S, Mihashi A, et al (2019) Prediction of Lignin Contents from In-frared Spectroscopy: Chemical Digestion and Lignin/Biomass Ratios of Cryptomeria japonica. Appl Biochem Biotechnol 188:1066-1076.

<footnote n="1">¹Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut Pascal, F-63000 Clermont-Ferrand, France.</footnote>

<footnote n="2">²Dagard Company, F-23600 Boussac, France.</footnote>

<footnote n="3">³Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchū, Tokyo 183-8509, Japan.</footnote>

<footnote n="4">⁴MINES Paris, PSL Research University, PERSEE - Center for Processes, Renewable Energies and Energy Systems, France.</footnote>

<footnote n="5">⁵Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France.</footnote>

<footnote n="6">⁶CENAREST, IRT, BP 14070, Libreville, Gabon.</footnote>

<footnote>yi_hien.chin@uca.fr</footnote>
<figure><img src="image_2.png" /></figure>

DAGARD

<figure><img src="image_3.png" /></figure>

CAP
20-25

I-SITE
CLERMONT
Clermont Auvergne Project

<figure><img src="image_4.png" /></figure>

国立大学法人
東京農工大学
Tokyo University of Agriculture and Technology

<figure><img src="image_5.png" /></figure>

INSTITUT
PASCAL
sciences de l'ingénierie et des systèmes

<figure><img src="image_6.png" /></figure>

UNIVERSITÉ
Clermont
Auvergne

<figure><img src="image_7.png" /></figure>

# Exploring the solid wood modification with preserved hierarchical structure via non-cellulosic substances removal

CHIN Yi Hien<fnref n="1" />,<fnref n="2" />,<fnref n="3" />, BIWOLE Pascal<fnref n="1" />,<fnref n="4" />, GRIL Joseph<fnref n="1" />,<fnref n="5" />, MOUTOU PITTI Rostand<fnref n="1" />,<fnref n="6" />, VIAL Christophe<fnref n="1" />, OULDBOUKHITINE Salah-Eddine<fnref n="1" />, LABONNE Nicolas<fnref n="2" />, HORIKAWA Yoshiki<fnref n="3" />

## Introduction

Innovations in wood modification technology have led to the development of novel functionalities and enhancements to the existing advantages of wood. The removal of non-cellulosic substances creates a low-density porous cellulose scaffold with reduced thermal conductivity [1]. Despite various top-down wood delignification methods, there has been a lack of comparative analysis. Additionally, scaling up production using freeze-drying technique presents challenges.

### Objectives

<figure><img src="image_8.png" /></figure>

* To evaluate the degree of non-cellulosic substances removal among three delignification techniques

* To identify potential drying techniques for large-scale production

<figure><img src="image_9.png" /></figure>

## Materials & Methods

French poplar wood planks of 100 mm along the grain and 100 mm by 10 mm section in the transversal plane were used.

<figure><img src="image_10.png" /></figure>

## Results & Discussions

### ❖ Degree of lignin removal

* The decreasing intensity of the peaks at 1730 and 1240 cm⁻<fnref n="1" /> assigned to acetyl functional groups was a result of hemicellulose removal [2]. Organosolv & NaClO₂ treatment led to the disappearance of the peaks at 1508, 1465, and 1264 cm⁻<fnref n="1" />, indicating the absence of lignin.

* A higher treatment temperature, treatment duration or delignifying solution concentration may be required for NaOH and alkaline sulfite & H₂O₂ modification.

* The high glucose content was maintained in all modified wood, suggesting that cellulose was not much affected by the treatments, only lignin and hemicellulose were preferentially altered.

<figure><img src="image_11.png" /><figcaption>Fig. 1: FTIR spectra of poplar wood under different modification treatments.</figcaption></figure>

<figure><img src="image_12.png" /><figcaption>Fig. 2: Ratio of chemical components in poplar wood before and after modification treatments.</figcaption></figure>

### ❖ Drying kinetics

* For all drying methods, the drying rate decreases as the moisture content of samples reduces.

* Dielectric heating (microwave and radio frequency) is the fastest drying technique, yet it causes great dimensional shrinkage despite organic solvent exchange.

<figure><img src="image_13.png" /><figcaption>Fig. 3: Moisture content evolution of NaOH modified wood by different drying techniques.</figcaption></figure>

<figure><img src="image_14.png" /><figcaption>Fig. 4: Drying rate at logarithmic scale of different moisture contents for each drying technique.</figcaption></figure>

## Conclusions & Perspectives

* Organosolv & NaClO₂ modification, alkaline sulfite & H₂O₂ modification and NaOH modification appear to be the most to the least lignin removal efficiency respectively.

* Dielectric heating has the highest drying rate across all moisture contents whereas convective blow drying exhibits the lowest sectional shrinkage.

* The information reported allows a better understanding of wood modification and drying mechanisms for the design of appropriate manufacturing procedures.

* Future investigations should focus on the effects of delignification on the thermal, mechanical, and hygric properties of the French poplar wood.

## Acknowledgments

This work is supported by the French National Research Agency (ANR) and the company Dagard, under the « France Relance » plan. The research visit to Japan was co-funded by the I-Site project CAP 20-25 and the Tokyo University of Agri-culture and Technology.

## References

[1] Li T, Song J, Zhao X, et al (2018) Anisotropic, lightweight, strong, and super thermally insulating nanowood with naturally aligned nanocellulose. Sci Adv 4:eaar3724.

[2] Horikawa Y, Hirano S, Mihashi A, et al (2019) Prediction of Lignin Contents from In-frared Spectroscopy: Chemical Digestion and Lignin/Biomass Ratios of Cryptomeria japonica. Appl Biochem Biotechnol 188:1066-1076.

<footnote n="1">¹Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut Pascal, F-63000 Clermont-Ferrand, France.</footnote>

<footnote n="2">²Dagard Company, F-23600 Boussac, France.</footnote>

<footnote n="3">³Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchū, Tokyo 183-8509, Japan.</footnote>

<footnote n="4">⁴MINES Paris, PSL Research University, PERSEE - Center for Processes, Renewable Energies and Energy Systems, France.</footnote>

<footnote n="5">⁵Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France.</footnote>

<footnote n="6">⁶CENAREST, IRT, BP 14070, Libreville, Gabon.</footnote>

<footnote>yi_hien.chin@uca.fr</footnote>