采用对样品进行液氮淬火及溴化处理的制样方法,以期达到消除分子晶体场及分子链烯类端基对分析谱带的影响和干扰,结果表明:(1) 1 378 cm-1甲基对称变形振动谱带强而尖锐,和1 368 cm-1亚甲基面外摇摆振动谱带清晰分开,表明分子链上只存在一种单一的支链;(2) 890 cm-1附近不存在表征长支链的甲基面内摇摆振动峰,只有772 cm-1附近存在表征乙基支链的亚甲基面内摇摆振动峰.成功地鉴定了以1-丁烯为共聚单体的线型低密度聚乙烯,方法简便、快速,为鉴定其他类的以α-烯烃为共聚单体的线型低密度聚乙烯(LLDPE)提供了重要思路.

Quenching and bromination were applied to the pretreatment of LLDPE samples to eliminate the interferences due to crystal field and terminal -C=C- group in the carbon chain in FTIR spectrometry.As shown by the result of this modification,(1) strong and sharp symmetrical transform vibration spectral band of methyl group [δs(CH3)] at 1 378 cm-1 was obtained and separated clearly from the external-facing swinging vibration spectral band of methylene group at 1 368 cm-1,indicating the existence of only one single branch chain in the molecular chain;(2) internal-facing swinging vibration spectral band near 890 cm-1,characterizing the presence of long branch chain,was not observed,and only the internal-facing swinging vibration spectral band of methylene group at 772 cm-1 was found,indicating the existence of ethyl branch chain.The proposed method was used successfully as a rapid and simple method for the identification of LLDPE with 1-butene as monomer in the copolymerization.It also gave an important idea for the identification of LLDPE with other α-olefin as monomer.