Effect of the ethylene/vinyl acetate ratio of ethylene-vinyl acetate emulsion on the curing behavior of an emulsion polymer isocyanate adhesive for wood
Effect of the ethylene/vinyl acetate ratio of ethylene-vinyl acetate emulsion on the curing behavior of an emulsion polymer isocyanate adhesive for wood
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DOI：
10.1007/s10086-008-0951-y
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发表时间：
2008-05
影响因子：
2.9
通讯作者：
Naruhito Hori;K. Asai;Akio Takemura
中科院分区：
文献类型：
--
作者：
Naruhito Hori;K. Asai;Akio Takemura
研究了不同乙烯-醋酸乙烯酯（伊娃）乳液对乳液型异氰酸酯木材胶粘剂固化行为的影响，发现伊娃的乙烯/醋酸乙烯酯重量比（E/VA）可以控制胶粘剂的发气量。VA含量较高的伊娃降低了初始阶段的气体排放量，这是由于NCO基团与水之间的反应程度造成的。由于CaCO_3和水的宽红外吸收掩盖了NCO产物在红外光谱中的信息，因此不能确定NCO的反应方案。溶胀度的检查表明，尽管伊娃的变化，但储存3周的粘合剂膜具有相同程度的交联结构。IR光谱支持了这一结果，其显示在这些膜中保留了相同量的NCO。所制备的胶粘剂具有良好的粘接性能。研究结果表明，E/VA比对胶粘剂固化初期的固化行为有影响，而贮存3周后的交联结构和粘接性能与E/VA无关。
We investigated the curing behavior of an emulsion polymer isocyanate adhesive for wood with different ethylene-vinyl acetate (EVA) emulsions, because it was found that the ethylene/vinyl acetate weight composition (E/VA ratio) of EVA could control the volume of gas emitted from the adhesive. EVA with higher VA content reduced the volume of gas emitted at the initial stage, which was caused by the extent of the reaction between the NCO groups and water. The reaction scheme of NCO could not be determined because the broad infrared (IR) absorptions due to CaCO3 and water masked the information of the NCO products in IR spectra. Examination of the degree of swelling suggested that the adhesive films stored for 3 weeks had the same degree of cross-linking structure in spite of the variation of EVA. This result was supported by IR spectroscopy, which showed the same amounts of NCO remained in these films. All the adhesives prepared in this study had satisfactory bond performance. The findings indicate that the E/VA ratio affects the curing behavior of the adhesive in the initial curing stage, whereas the cross-linking structure and the bond performance were independent of the E/VA ratio after storage for 3 weeks.