摘要
对聚乙烯醇缩丁醛(PVB)进行热氧老化试验,采用三种表征方法,从化学结构变化的角度对PVB的热氧老化机理进行研究。研究结果表明:PVB的抗热氧老化性能较差,其羟基、羰基、缩丁醛基均对热敏感。老化前期PVB主要发生降解,首先是在热的作用下,羟基氧化、酯基分解、缩醛环受热开环生成烷氧自由基,然后生成酮、醛,生成的自由基可以诱导分子链断裂并夺取PVB中活泼的氢原子进而又生成自由基。老化后期PVB老化反应以交联为主。热氧老化1d即生成醛,羟基、酯羰基开始减少,老化2d生成酮,缩醛环老化6d急剧减少,在长达30d的热氧老化过程中未产生烯烃。以羰基相对甲基伸缩振动峰的吸光度A1732/A1378来表征PVB的老化程度,建立了本实验条件下的热氧老化方程。
Thermo-oxidative(TO)aging test for polyvinyl butyral(PVB)was carried out.Chemical structure changes of PVB in the TO aging process were studied by means of three characterizations:1H-NMR,FT-IR and UV-Vis.TO aging mechanism of PVB was discussed.The results showed that PVB had poor anti-TO aging performance and the hydroxyl,carbonyl and butyral group of its three functional groups were sensitive to heat.In the early stage of aging,PVB was mainly degraded.Firstly,under the effect of heat,hydroxyls were oxidized and ester groups were decomposed.Then acetal rings were opened.The three reactions produced alkoxy radicals and then ketones and aldehydes in further aging process.Alkoxy radicals induced molecular chains rupture.They could also capture active hydrogen atoms in PVB and then produced radicals again.In the later stage of aging,aging reaction of PVB was mainly crosslinking.At 1 d after TO aging,aldehydes were produced.Hydroxyls and ester carbonyls began to decrease.At 2 d after TO aging,ketones were produced.At 6 d after TO aging,acetal rings sharply decreased.During 30 d after TO aging,no olefins were produced.The degree of aging was characterized by the ratio of the absorbance of the carbonyl to that of the methyl,A1732/A1378.The TO aging equation was established under the experimental conditions.
作者
钟建永
李志辉
丁玲
梁梨花
邹友思
ZHONG Jianyong;LI Zhihui;DING Ling;LIANG Lihua;ZOU Yousi(College of Materials,Xiamen University,Xiamen 361005,China)
出处
《材料科学与工程学报》
CAS
CSCD
北大核心
2019年第6期928-933,共6页
Journal of Materials Science and Engineering
