在位红外光谱法研究丙烯腈、二丙酮丙烯酰胺和丙烯酸甲酯三元共聚物的低温热解

本文用傅里叶变换红外光谱法在位连续测定了丙烯腈(AN)、二丙酮丙烯酰胺(DAA)和丙烯酸甲酯(MA)三元共聚物在不同气氛中低温热解时化学结构的变化。据光谱峰的变化规律,发现共聚物在空气中热解时脱氢和氧化主要在环化反应发生之后;在氧气中热解时脱氢和氧化主要发生在环化反应之前;在氮气中热解时仅有环化和脱氢反应。在比较各气氛中的成环序列长度时,在氮气中热解环序列在275℃以下稍短;275℃以上稍长。共聚物羰基增加的相对含量与热解时间的平方根成正比。

STUDY ON LOW TEMPERATURE PYROLYSIS OF AN/DAA/ MA COPOLYMERS USING ON-LINE IR METHOD

By on-line infrared spectroscopic method, the changes of chemical constitution of acy-lonitrile (AN)/diacetone acylamide (DAA)/methyl acylate (MA) copolymers have been measured continuously during its low temperature pyrolysis under different atmospheres. From the results it was found that during the pyrolysis dehydrogenation and oxidation reactions proceeded mainly after cyclization reaction under atmospheric environment, but proceeded before cyclization in pure oxygen. In nitrogen atmosphere, only cyclization and dehydrogenation occurred. It was shown that the length of cycloforming sequence of copolym-ers pyrolyzed in nitrogen before 275℃ was slightly shorter, and after 275℃ was slightly longer than that in other atmosphere. Based on the variation of intensities of characteristic peaks with heating time, it is obvious that the increment of relative content of carbonyl group in the samples is proportional to the square root of pyrolytic time.