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Chin J Mater Res  2009, Vol. 23 Issue (3): 242-250    DOI:
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Cr-catalyzed ethylene copolymers studied by solid-state 1H NMR techniques: the influence of hexene content and different duration grades polyethylene pipe
LI Wei 1;  YAN Xiaowei 1;  WANG Jingdai 1;  YANG Yongrong 1; Alina BUDA 2; Blumich BERNHARD 2
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LI Wei YAN Xiaowei WANG Jingdai YANG Yongrong Alina BUDA . Cr-catalyzed ethylene copolymers studied by solid-state 1H NMR techniques: the influence of hexene content and different duration grades polyethylene pipe. Chin J Mater Res, 2009, 23(3): 242-250.

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Abstract  

Using different  1H solid--state NMR techniques, the Cr--catalyzed ethylene--hexene copolymer with different hexene content was investigated, and the effects of comonomer content on the phase composition, molecular
mobility and domain size of the copolymer were studied. The results showed that the mass fraction of crystalline phase was decreased with the hexene content increasing, while the fractions of the other two components were
increased. Meanwhile, the fraction of the interface and amorphous component was increased in the NMR long period. Furthermore, we choose the variance of MI/MA , the ratio of mass fraction of interface component to the fraction of amorphous component, with temperature as the qualitative determination of the confined degree of the segment in non--crystalline  region. Cr--catalyzed PE copolymer for pipe application with different duration grade was investigated. It was found that the mass fraction of rigid component decreased with the duration-grade increasing, while the fractions of the other two components increased. The same trend of the fraction in NMR long period was illustrated by the 1H spin diffusion result. The variance of  MI/MA showed great correspondence to the duration grade of the materials.

Key words:  measurement and analysis for materials      1H solid-state NMR      ethylene--hexene copolymer      phase structure     
hexene content
     
Received:  11 November 2008     
ZTFLH: 

TG111

 
Fund: 

Supported by National Natural Science Foundation of China Nos.20676114 and 20490205, National High--Tech Research and Development Program of China No.2007AA030208, CSC--DAAD(PPP, 2004) Cooperative Program, and Natural Science Foundation of Zhejiang Province No.Y406293.

URL: 

https://www.cjmr.org/EN/     OR     https://www.cjmr.org/EN/Y2009/V23/I3/242

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