Abstract:

Bonding strength for larch(Larix gmelinii)on radial and tangential surfaces were studied in this paper. The results showed that there was significant difference in bonding strength between radial and tangential surfaces. Dry compressing shear strength of quarter-sawn board of larch was 1.41 times of flat-sawn board of larch in normal conditions, but quarter-sawn board of larch had smaller wet compressing shear strength than flat-sawn board for repeatedly boiling samples. The results of shear strength to the grain and shear strength ratio of larch showed that the difference between radial and tangential bonding strength specimens lied in wood structure of larch. That is to say, there was difference in wood strength between radial and tangential surfaces of larch, wood strength of radial surface of larch was bigger than tangential surfaces. The reasons for which quarter-sawn board of larch had smaller wet compressing shear strength than flat-sawn board of larch for repeatedly boiling samples were also analyzed.

Key words: Larix gmelinii, Aqueous polymer isocyanate(API)adhesive, Bonding strength, Quarter-sawn board, Flat-sawn board, Compressing shear strength