三聚氰胺尿素甲醛膠熱動力分析研究及其應用

Reaction Kinetics Behavior of Melamine-Urea-Formaldehyde Wood Adhesives by Differential Thermal Analysis and Its Application

鄒哲宗(Che-Tsung Tsou) ； 夏滄琪(Tsang-Chyi Shiah)

《台灣林業科學》 18卷4期 (2003/12) Pp. 339-348

https://doi.org/10.7075/TJFS.200312.0339

摘要

三聚氰胺尿素甲醛膠為家具工廠常用之膠料，瞭解其熱硬化動力學性質有其必要。本研究自行合成尿素三聚氰胺膠(MUF)，其U/M重量比為60:38，F/(U+M)為1:1.3，固體含量為47.8%，黏度為7cps(25℃)，pH值為7.7，而添加0.2%氯化銨硬化劑之沸水膠凝時間為45s。MUF膠採用示差掃瞄熱分析儀，以ASTM Method E698之方法分析得到其熱硬化動力學參數值。當添加0.1%之硬化劑時，其聚合反應活化能為69.4 kJ/mole，而壓板使板中心溫度達140℃時，須138s完全硬化；當添加0.2%之硬化劑時，其活化能則為73.4 kJ/mole，而完全硬化時間則減少至78s；當添加0.3%之硬化劑時，其活化能增為76.9 kJ/mole，而完全硬化時間則只須要50s。
將所合成之膠料與家具工廠之木材粒片混合，並以一次成型技術製造複合板。此複合板依ASTM D4065-95標準，由多頻率掃瞄方式，測定其彈性模量、粘性模量，與阻尼等粘彈特性。並以WLF方程式所研發之時間－溫度重疊軟體，繪圖得知角頻率與彈性模量、粘性模量、阻尼之對數關係，進而求出此複合板在長期經時使用之機械性能變化，並了解其處於不同低頻或極高頻刺激下之粘彈特性的變化。其結果為複合板之E'、E”及Tan δ與0.1~10 Hz頻率，由50~225℃之關係圖。獲知UMF複合板E'值隨溫度增加而下降，在超過180℃之後，由於熱劣化的緣故，使其軟化更加迅速，同時也觀察到E”及Tan δ急劇上升。

關鍵字

三聚氰胺尿素甲醛膠 ； 示差掃瞄熱分析 ； 活化能 ； 粘彈性

並列摘要

Melamine-urea-formaldehyde (MUF) resin is frequently used in the wood industry. It is important to understand the kinetics of its polymerization properties. A MUF resin was synthesized with a U/M weight ratio of 60:38 and a F/ (M+U) weight ratio of 1:1.3. This MUF resin had a solids content of 47.8%, a viscosity of 7 cps (at 25℃), pH 7.7, and a gel time of 45 second with 0.2% ammonium chloride. A differential scanning calorimeter was used to determine the thermal properties of the MUF resin with 0.1% hardener. The activation energy of polymerization was increased to 69.4 kJ/mole, and it was estimated that this resin would completely cure in 138 s at a press temperature of 140℃. The activation energy of polymerization with 0.2% hardener was 73.4 kJ/mole, and it required 78 s to completely harden. With 0.3% hardener, the activation energy was increased to 76.9 kJ/mole, and it required only 50 s to completely harden. The activity energy was 90 kJ/mole if the hardener was not added.
Molded particleboard with a veneer of Anisoptera spp. was made with the MUF resin, and the viscoelastic properties of this particleboard, such as E' (elastic modulus), E” (viscous modulus), and Tan δ (damping), were determined according to ASTM D4065-95 methods. Also, the technique of time-temperature-superposition based on the well-known WLF equation was employed to obtain the master curves of E', E” and Tan δ versus angular frequency (ω) in double logarithm plots. Therefore, the long-term mechanical properties of the composite boards could be predicted. The modulus decay of the board with time was estimated from the lower angular frequency side of E'. Similarly, the impact behavior of the composite board could be predicted reasonably well from the higher angular frequency side of Tan δ.

並列關鍵字

melamine-urea-formaldehyde resin ； differential scanning calorimeter ； activation energy ； viscoelasticity