MDI与HDI封端共聚甲醛研究.pdf

第42卷第6期
塑料工业
2014年6月
CHINA PLASTICS INDUSTRY
树脂改性
MDI与HD封端共聚甲醛硏究
与合金
杨锐,向明,蔡燎原,曹亚,蓝方,杨锋
(高分子材料工程国家重点实验室,四川大学高分子研究所,四川成都610065)
摘要:采用反应性熔融挤出法对共聚甲醛进行封端处理,研究两种不同异氰酸酯4,4'-二苯基甲烷二异氰酸酯
(MDI)与六亚甲基二异氰酸酯(HDI)与共聚甲醛反应性挤出后的稳定化效果。通过测定熔体质量流动速率
(MFR)、红外分析、热重分析(TGA)和黄色指数,评价共聚甲醛封端效果。结果表明,两种异氰酸酯均能对共聚
甲醛进行封端,提高其热稳定性,MD川较HDI对共聚甲醛热稳定性的提高稍显著一些。随着异氰酸酯添加量增加,采
用MDI反应性挤出样的MFR剧烈下降,而采用HDI反应性挤出样则下降一些后便保持平稳。MDI与共聚甲醛反应性
挤出样较HD与共聚甲醛反应性挤出样老化过程中颜色变黄更明显。
关键词:共聚甲醛;稳定化;黄色指数
DOI:10.3969/ l. Issn.1005-5770.2014.06.006
中图分类号:TQ326.5
文献标识码:A
文章编号:1005-5770(2014)06-0021-04
Study on CO-POM Terminated with MDI and HDI
YANG Rui, XIANG Ming, CAI Liao-yuan, CAO Ya, LAN Fang, YANG Feng
(The State Key Lab of Polymer Materials Engineering, Polymer Research Institute of Sichuan University
Chengdu 610065, China)
Abstract The polyoxymethylene copolymer was terminated during melting extrusion with isocyanates
The stability of reaction products with two different isocyanates"4, 4-diphenylmethane diisocyanate and
hexamethylene diisocyanate was investigated. The effects of eliminating the terminal hydroxyl were evaluated
by melt flow rate(MFR), Fourier transform infrared spectroscopy(FTTR ), thermal gravimetric analysis
(TGA )and yellow index(Y). The results showed that the two isocyanates both can make the unstable
terminals end-capped and improve the thermal stability of CO-POM. The MDIS effect on improving the
thermal stability was slightly better than HDIS. The MFR values of reaction product with the MDI decreased
fiercely while the reaction product with the HDI dropped some and then remained stable. Moreover, it was
found that during aging, the yellowing degree of reaction products with the MDI were evidently higher than
that with HDI
Keywords: Polyoxymethylene Copolymer; Stabilization; Yellow Inde
共聚甲醛一般是以三聚甲醛为单体,以环氧乙烷共聚甲醛的热稳定性降低。因此,对共聚甲醛树
或1
氧戊环为共聚单体通过阴离子聚合制得脂进行端基稳定化处理就十分必要,熔融后处理法是
的一种热塑性工程塑料。共聚甲醛力学性能优异,尺一种传统的共聚甲醛端基稳定化处理方法“,在其
寸稳定性好,耐水、耐油、耐疲劳性好,在机械、汽基础上,本文采用反应性熔融挤出封端法对共聚甲醛
车、电子电器和日用消费品等领域均有广泛应进行端基稳定化处理,采用两种异氰酸酯MDI与
用
然而,在聚合过程中,体系中微量的水、HDI作为封端剂,与共聚甲醛混合均匀后在排气式双
甲醇、甲酸等杂质会引发链转移反应,从而在分子链螺杆挤出机中挤出,使异氰酸酯与共聚甲醛中的端羟
末端形成半缩醛端基(-CH2OH)。该端基的热稳定基在熔融挤出过程中充分反应封端,消除不稳定端
性极差,受热极易分解,导致脱甲醛反应连续发生,基,研究反应性挤出产物的熔体质量流动速率、热稳
青年科学基金项目(5
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作者简介:杨锐,男,1989年生,硕土研究生,主要从事高分子材料加工与改性研究。