Bonding Properties And Research On Modification Of Fast-growing Poplar

Glue fast-growing Poplar material by double ingredients, tannin-formaldehyde resin, and compression shear strength was tested and evaluated in this research, and PUR adhesive as well. The Poplar substrate was impregnated with low molecule phenole-formaldehyde resin (PF), melamin-formaldehyde resin (MF) and tannin-formaldehyde resin (TF) made in laboratory separately to manufacture strength-highly wood material. The untidecay ability of treated wood was evaluated clearly. The data and conclusions in this paper can be functioned as reference for manufactuing structural GLULAM by fast-growing Poplar . The results were listed as following: The weight of dry tannin powder was looked on as cardinal number. Compression shear strength of samples by TF adhesive, could reach peak, when the number of acetic zinc was 5%, sodium hydroxide whose concentration was 30% was 4.2%, formaldehyde was 8% and resorcin was 10%, and the dry compression shear strength values of samples by TF adhesive fluctuated between 8.08MPa and 8.92MPa. However, reduplicate cooked wet strength of samples by TF adhesive was not strongth, could be neglectable, and wood failure ratio was much little. That is to say, the wet strength of TF adhesive was poor. Ones by PUR was better much than that, the dry values were more than 9.8MPa, wood failure ratio was over 75%, could meet Japanese Glulam Standard Jas, and their reduplicate cooked wet strength keeped 22%～46% of dry strength. After impregnated with PF resin, the treated samples became more weighter. The weight percent gains (WPG) of samples increased as impregnating time prolonged, and the relationship between WPG of samples and resins'concentration as well. The mechanical performance was improved more or less as long as samples was impregnated, and the strength values was proportionable to WPG.. WPG was more bigger if samples were impregnated after being cold-compressed, but the final effect was not obvious. Having been impregnated with thermosetting resin, even bending strength was 11%～36% more than those untreated samples, and even modulus of elasticity was 11%～22% more than those untreated samples. However, WPG of thickness-smaller samples would be bigger, but the strength-proving effect was not satisfactory. In addition, PF and TF resin was adopted in this experiment, and the results resembled with PF resin. If much more mechanical performance material was wanted by means of impregnating resin into compressed wood, it is necessary to assure the integrality of wood during being cold-compressed. In a word, the Poplar-strengthening method by cold-compression and impregnation was not too good. The natural untidecay ability of untreated Poplar wood was poor, while the performance of ones modified with PF could be enhanced distinctly. The weight percent losses (WPL) of untreated samples reached 9.52% when decaying time was 8 weeks. WPL of treated samples all was lower than 2%, and could be samllest if WPG was 14.2%. The results showed, the untidecay ability of treated fast-growing with PF resin, could be improved clearly.