Synthesis and characterization of high-molecular-weight syndiotactic amorphous polypropylene

被引:46
作者
De Rosa, C
Auriemma, F
de Ballesteros, OR
Resconi, L
Fait, A
Ciaccia, E
Camurati, I
机构
[1] Univ Naples Federico II, Dipartimento Chim, I-80126 Naples, Italy
[2] Basell Polyolefins, Ctr Ric G Natta, I-44100 Ferrara, Italy
关键词
D O I
10.1021/ja035911y
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Heterocycle-fused titanium indenyl silylamido dimethyl complexes produce very high molecular weight polypropylene having a prevailingly syndiotactic microstructure with syndiotactic pentad contents rrrr up to 40-55% (sam-PP). The samples are basically amorphous and may slowly develop a low level of crystallinity (16-20%) at room temperature. A structural characterization has shown that sam-PP samples crystallize in disordered modifications of the helical form I of syndiotactic polypropylene (s-PP). The stretching of compression-molded films of sam-PP samples produce oriented crystalline fibers in the trans-planar mesomorphic form of s-PP. The low stereoregularity prevents the formation of the ordered trans-planar form III of s-PP, which instead is obtained in stretched fibers of the highly stereoregular and crystalline s-PP. The trans-planar mesomorphic form, obtained in stretched fibers, in turn transforms into the helical form I upon releasing the tension. The analysis of the mechanical properties has shown that sam-PP samples show good elastic behavior in a large range of deformation with remarkable strength, due to the presence of crystallinity. A comparison with the mechanical properties of less syndiotactic and fully amorphous samples is reported. These fully amorphous samples present lower strength and experience rapid viscous flow of the chains at high deformations and/or by application of stresses for long times. The higher strength in the semicrystalline sam-PP samples makes these materials interesting thermoplastic elastomers showing high toughness and ductility.
引用
收藏
页码:10913 / 10920
页数:8
相关论文
共 51 条
[1]  
Auriemma F, 1998, J POLYM SCI POL PHYS, V36, P395, DOI 10.1002/(SICI)1099-0488(199802)36:3<395::AID-POLB1>3.0.CO
[2]  
2-R
[3]   Origin of the elastic behavior of syndiotactic polypropylene [J].
Auriemma, F ;
de Ballesteros, OR ;
De Rosa, C .
MACROMOLECULES, 2001, 34 (13) :4485-4491
[4]  
AURIEMMA F, IN PRESS J AM CHEM S
[5]   Microstructure of polypropylene [J].
Busico, V ;
Cipullo, R .
PROGRESS IN POLYMER SCIENCE, 2001, 26 (03) :443-533
[6]  
CANICH JA, 1991, Patent No. 5026798
[7]  
CANICH JAM, 1996, Patent No. 5504169
[8]   CRYSTAL-STRUCTURE OF THE PLANAR ZIGZAG FORM OF SYNDIOTACTIC POLYPROPYLENE [J].
CHATANI, Y ;
MARUYAMA, H ;
NOGUCHI, K ;
ASANUMA, T ;
SHIOMURA, T .
JOURNAL OF POLYMER SCIENCE PART C-POLYMER LETTERS, 1990, 28 (13) :393-398
[9]   STRUCTURE OF A NEW CRYSTALLINE PHASE OF SYNDIOTACTIC POLYPROPYLENE [J].
CHATANI, Y ;
MARUYAMA, H ;
ASANUMA, T ;
SHIOMURA, T .
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, 1991, 29 (13) :1649-1652
[10]  
CORRADINI P, 1967, J POLYM SCI C, V16, P2477