水性异氰酸酯木材胶黏剂耐久性研究

Durability of Aqueous Polymer Isocyanate Wood Adhesive

通过红外、热重和压剪强度分析,对水性异氰酸酯（API）木材胶黏剂在加速老化处理1~7个周期（A1~A7）和湿热老化处理1~7个周期（H1~H7）的耐久性进行了研究。红外分析表明：未处理的API胶膜（S）含有大量的异氰酸酯基团,A1~A7的API胶膜中异氰酸酯基团全部消失,H1~H3的API胶膜中仍有异氰酸酯吸收峰存在,但强度减弱,H4~H7的异氰酸酯基团消失。热重分析结果表明：A1~A4胶膜的初期热稳定性优于H1~H4,5~7个周期热稳定性几乎相同。在相同质量损失下,加速老化处理API胶膜更稳定,A1~A7降解活化能不完全相同,即降解速度不同;而H1~H7胶膜的活化能几乎相同。2种处理方法胶合制品的压剪强度随时间延长逐渐降低,加速老化处理到第3个周期压剪强度仅为5.32MPa,湿热老化处理到第5个周期压剪强度降为6.92 MPa,均达不到国家标准。

The durability of aqueous polymer isocyanate （API） wood adhesive was studied under accelerated aging process for 1 - 7 cycles （ A1 - A7 ） and hydrothermal aging for 1 - 7 cycles （ H1 - H7 ） by using Fourier transform infrared spectroscopy （FT-IR） , thermogravimetric analysis （TGA）, and compressive shear strength analysis. FT-IR analysis showed that the untreated API film（S） contained a considerable amount of isocyanate group, whereas the isocyanate groups of API films for A1 -A7 disappeared. Absorption peaks of isoeyanate group of API films for H1 - H3 still existed, but the intensity weakened. The isocyanate groups of API films for H4 - H7 also disappeared. TGA analysis showed that thermal stabilities of A1 - A4 in the initial stage were superior to those of H1 - I-I4, but they were almost the same in the 5 - 7 cycles. Under the same weight loss, the API films with accelerated aging process were more stable, and the degradation activation energies of A1 - A7 were not exactly the same, namely, the degradation rates were different. However, the activation energies of H1 - H7 were almost the same. The compressive shear strengths of glued products treated in the two methods were gradually decreased. The compressive shear strengths of the API films with accelerated aging process for the third cycle was 5.32 MPa and that of sample with hydrothermal aging for the fifth cycle was 6.92MPa. They did not meet the national standards.