High pressure crystallization of random propylene-ethylene copolymers:: α-γ Phase diagram

被引:47
作者
Dimeska, Anita
Phillips, Paul J. [1 ]
机构
[1] Univ Cincinnati, Dept Chem & Mat Engn, Cincinnati, OH 45221 USA
[2] Univ Tennessee, Dept Mat Sci & Engn, Knoxville, TN USA
基金
美国国家科学基金会;
关键词
alpha-phase; gamma-phase; phase diagram; WEIGHT ISOTACTIC POLYPROPYLENE; CRYSTAL-STRUCTURE; FORM; MORPHOLOGY; POLYMORPHISM; FRACTIONS; COMONOMER; CATALYSTS;
D O I
10.1016/j.polymer.2005.11.097
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
Two random propylene copolymers with low ethylene content synthesized by Ziegler-Natta catalysts were used is this study to investigate the formation of gamma-crystal phase during isothermal crystallization at high pressures. At atmospheric pressure these copolymers crystallize in a mixture of alpha- and gamma-crystals. The content of the gamma-phase in the copolymer crystals increased with increasing defect content, crystallization temperature and pressure. Wide-angle X-ray diffraction studies showed that crystallization of these copolymers at pressures above 88 MPa and temperature above 142 degrees C leads to formation of pure gamma-phase. The equilibrium melting temperature of the gamma-phase has been determined as a function of defect content and crystallization pressure. Temperature-pressure-composition alpha-gamma phase diagram of isotactic polypropylene was constructed based on the Gibbs free energy approach. This diagram enabled the extrapolation of the equilibrium melting temperatures of both phases for defect free isotactic polypropylene. They were found to be 186.9 degrees C for the alpha-phase and 189.9 degrees C for the gamma-phase. (c) 2006 Elsevier Ltd. All rights reserved.
引用
收藏
页码:5445 / 5456
页数:12
相关论文
共 33 条
[1]   POLYMORPHISM OF CRYSTALLINE POLYPROPYLENE [J].
ADDINK, EJ ;
BEINTEMA, J .
POLYMER, 1961, 2 (02) :185-193
[2]   Structural and kinetic factors governing the formation of the γ polymorph of isotactic polypropylene [J].
Alamo, RG ;
Kim, MH ;
Galante, MJ ;
Isasi, JR ;
Mandelkern, L .
MACROMOLECULES, 1999, 32 (12) :4050-4064
[3]   Crystallization of metallocene-made isotactic polypropylene:: Disordered modifications intermediate between the α and γ forms [J].
Auriemma, F ;
De Rosa, C .
MACROMOLECULES, 2002, 35 (24) :9057-9068
[4]  
AVELLA M, 1986, MAKROMOL CHEM, V187, P1927
[5]  
BRUCKNER S, 1989, NATURE, V340, P455, DOI 10.1038/340455a0
[6]   POLYMORPHISM IN ISOTACTIC POLYPROPYLENE [J].
BRUCKNER, S ;
MEILLE, SV ;
PETRACCONE, V ;
PIROZZI, B .
PROGRESS IN POLYMER SCIENCE, 1991, 16 (2-3) :361-404
[7]   PHYSICOCHEMICAL AND STRUCTURAL CHARACTERIZATION OF ETHYLENE PROPENE COPOLYMERS WITH LOW ETHYLENE CONTENT FROM ISOTACTIC-SPECIFIC ZIEGLER-NATTA CATALYSTS [J].
BUSICO, V ;
CORRADINI, P ;
DEROSA, C ;
DIBENEDETTO, E .
EUROPEAN POLYMER JOURNAL, 1985, 21 (03) :239-244
[8]   THE GAMMA-PHASE OF HIGH-MOLECULAR-WEIGHT POLYPROPYLENE .1. MORPHOLOGICAL ASPECTS [J].
CAMPBELL, RA ;
PHILLIPS, PJ ;
LIN, JS .
POLYMER, 1993, 34 (23) :4809-4816
[9]  
DIMESKA A, 2005, THESIS U TENNESSEE
[10]   Formation of the α and γ polymorphs in random metallocene-propylene copolymers.: Effect of concentration and type of comonomer [J].
Hosier, IL ;
Alamo, RG ;
Esteso, P ;
Isasi, JR ;
Mandelkern, L .
MACROMOLECULES, 2003, 36 (15) :5623-5636