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Official Journal of the Japan Wood Research Society

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Na2O-SiO2 wood-inorganic composites prepared by the sol-gel process and their fire-resistant properties


For enhancing fire-resistant properties, a binary system to prepare wood-inorganic composites was studied by adding sodium methoxide (SM) or sodium acetate (SA) to a reaction system for SiO2 composites. Compared with the SiO2 composites, both the Na2O-SiO2 composites prepared could be greatly improved up to 600°C-700°C (glowing). From scanning electron microscopic observations, this enhanced fire resistance was assumed to be due to chemical and physicochemical effects, such as dehydration and carbonization of wood by Na2O gel. The glassy layer and intumescent structure formed over the cell walls were thought to prevent oxidation and heat transfer from proceeding into the inner portion of the wood cell walls. However, the reaction medium with SM to prepare Na2O-SiO2 composites was basic, whereas that with SA was rather neutral. In addition, in the latter composites, most of the inorganic gel was formed within the cell wall, retaining the porous structure characteristic of wood. Therefore, the Na2O-SiO2 composites prepared with SA can be concluded to be preferable for practical purposes.


  1. 1.

    Nishimoto K, Tsunoda K, Imamura Y (1988) New complex material, wood ceramic — their properties. In: Proceedings of S5. 03–04 Session IUFRO D5, Forest Products Conference, Sao Paulo, Brazil, pp 55–63

  2. 2.

    Furuno T, Kuriu T, Matsuoka S, Inoue T, Uehara T (1997) Wood-mineral composites using colloidal silica solution system and their properties (in Japanese). J Soc Mater Sci Jpn 46:401–407

    CAS  Article  Google Scholar 

  3. 3.

    Su W, Hata T, Imamura Y, Ishihara S (1995) Mechanism evaluation and development of suppression of wood combustion by boric compounds. 1. Oxygen index of filter paper and Douglas fir veneer treated with boric acid and mixture of boric acid-alkaline metal hydroxide (in Japanese). Wood Preserv 21:299–305

    Article  Google Scholar 

  4. 4.

    Saka S, Sasaki M, Tanahashi M (1992) Wood-inorganic composites prepared by sol-gel processing. I. Wood-inorganic composites with porous structure. Mokuzai Gakkaishi 38:1043–1049

    CAS  Google Scholar 

  5. 5.

    Ogiso K, Saka S (1993) Wood-inorganic composites prepared by sol-gel process. II. Effects of ultrasonic treatments on preparation of wood-inorganic composites. Mokuzai Gakkaishi 39:301–307

    CAS  Google Scholar 

  6. 6.

    Saka S, Yakake Y (1993) Wood-inorganic composites prepared by sol-gel process. III. Chemically-modified wood-inorganic composites. Mokuzai Gakkaishi 39:308–314

    CAS  Google Scholar 

  7. 7.

    Ogiso K, Saka S (1994) Wood-inorganic composites prepared by sol-gel process. IV. Effects of chemical bonds between wood and inorganic substances on property enhancement. Mokuzai Gakkaishi 40:1100–1106

    CAS  Google Scholar 

  8. 8.

    Saka S (1995) Topochemistry of wood-inorganic composites as prepared by sol-gel process (in Japanese). Mokuzai Kogyo 50:400–406

    CAS  Google Scholar 

  9. 9.

    Miyafuji H, Saka S (1996) Wood-inorganic composites prepared by the sol-gel process. V. Fire-resisting properties of the SiO2-P2O5-B2O3 wood-inorganic composites. Mokuzai Gakkaishi 42:74–80

    CAS  Google Scholar 

  10. 10.

    Saka S, Tanno F (1996) Wood-inorganic composites prepared by the sol-gel process. VI. Effects of a property-enhancer on fireresistance in SiO2-P2O5 and SiO2-B2O3 wood-inorganic composites. Mokuzai Gakkaishi 42:81–86

    CAS  Google Scholar 

  11. 11.

    Miyafuji H, Saka S (1998) SiO2-P2O5,-B2O3 wood-inorganic composites prepared by metal alkoxide oligomers and their fire-resisting properties. Holzforschung 52:410–416

    CAS  Article  Google Scholar 

  12. 12.

    Saka S, Ueno T (1997) Several SiO2 wood-inorganic composites and their fire-resisting properties. Wood Sci Technol 31: 457–466

    CAS  Google Scholar 

  13. 13.

    Tanno F, Saka S, Takabe K (1997) Antimicrobial TMSAC-added wood-inorganic composites prepared by the sol-gel process. Mater Sci Res Int 3:137–142

    CAS  Google Scholar 

  14. 14.

    Miyafuji H, Saka S (1997) Fire-resisting properties in several TiO2 wood-inorganic composites and their topochemistry. Wood Sci Technol 31:449–455

    CAS  Google Scholar 

  15. 15.

    Miyafuji H, Saka S (1999) Topochemistry of SiO2 wood-inorganic composites for enhancing water-repellency. Mater Sci Res Int 4:270–275

    Google Scholar 

  16. 16.

    Browne FL (1958) Theories of the combustion of wood and its control. In: U.S. Forest Service no. 2136. Forest Product Laboratory, Madison, WI, USA, pp 20–33

    Google Scholar 

  17. 17.

    Vandersall HL (1971) Intumescent coating system, their development and chemistry. J Fire Flamm 2:97–140

    CAS  Google Scholar 

  18. 18.

    Takenami K (1965) Studies on the discoloration of wood. IV. Alkaline strain (in Japanese). Mokuzai Gakkaishi 11:47–52

    Google Scholar 

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Correspondence to Hisashi Miyafuji.

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Miyafuji, H., Saka, S. Na2O-SiO2 wood-inorganic composites prepared by the sol-gel process and their fire-resistant properties. J Wood Sci 47, 483–489 (2001).

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Key words

  • Wood-inorganic composites
  • Sol-gel process
  • Na2O-SiO2
  • Thermal analysis
  • Fire resistance