甲醛用量对苯并噁嗪树脂合成反应的影响

Influence of Formaldehyde Dosage on Synthesis of Benzoxazine Resin

以甲醛、苯酚和4,4′-二氨基二苯基甲烷(MDA)为原料,固定其他反应条件,只改变甲醛用量(n(甲醛)∶n(MDA)),合成了一系列MDA/苯酚型苯并噁嗪树脂(简称苯并噁嗪树脂);采用傅里叶变换红外光谱和核磁共振氢谱对苯并噁嗪树脂的结构进行表征,通过凝胶渗透色谱测定了苯并噁嗪树脂的相对分子质量及其分布,并通过测定凝胶化时间和示差扫描量热方法对苯并噁嗪树脂的热固化行为进行分析,研究了甲醛用量对苯并噁嗪树脂合成反应的影响。实验结果表明,当n(甲醛)∶n(MDA)=4.2～4.8时,苯并噁嗪的成环率较高,副产物较少,苯并噁嗪树脂的凝胶化时间相对较长,固化放热峰值温度较高;当n(甲醛)∶n(MDA)=4.4时,苯并噁嗪单体的成环率最高。

To investigate the influence of initial mole ratio of formaldehyde to 4,4′-diaminodiphenyl methane （MDA） on synthesis of benzoxazine resin, when other reaction conditions were fixed, a series of benzoxazine resins with different mole ratios of formaldehyde to MDA were synthesized. The structures of obtained benzoxazine resins were characterized by means of FTIR and 1H NMR. Relative molecular mass and its distribution were determined by GPC. The thermal curing behaviors of benzoxazine resins were analyzed by means of gel time and DSC. When mole ratios of formaldehyde to MDA are in the range of 4.2 to 4.8, oxazine-ring contents are relatively higher, the amounts of by- products are less, the gel time gets longer and peak temperature of curing rises. Specifically, the oxazine-ring content is maximum when mole ratio of formaldehyde to MDA is 4.4.