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Influence of molecular weight and spinning conditions on the crystalline morphology of polypropylene fibres
Author(s) -
Prost C.,
Nemoz G.,
Hagege R.,
Souffache E.,
Michel A.
Publication year - 1989
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19890230114
Subject(s) - polypropylene , monoclinic crystal system , materials science , spinning , elongation , phase (matter) , morphology (biology) , composite material , relaxation (psychology) , melt spinning , polymer chemistry , crystallography , chemistry , crystal structure , organic chemistry , ultimate tensile strength , psychology , social psychology , genetics , biology
In the spinning of polypropylene the “smectic” phase generally appears in the as spun fibres obtained from high fluidity polypropylene (for example M̄ w = 118000) at 200°C and more. The amount of the “smectic” form decreases as the draw down ratio increases. At 200°C and for a draw ratio of 40 the “smectic” form is about 70% of the crystalline phase. At 200°C and for a draw ratio of to 130 or higher, only the monoclinic form is observed. At 180°C, and whatever is the draw ratio, only the monoclinic form is observed. For high‐molecular ‐ weight polypropylene (for example M̄ w = 320000) the “smectic” form has never been observed whatever is the spinning temperature within the range 220–260°C. The fibres with high amount of smectic phase show low orientation factors, whereas the fibres having only monoclinic form show the highest orientation factors. These results, compared with elongational behaviour of the polypropylene, suggest that the smectic form appears in the fibres as the elongation rate on the spinning line is lower than the relaxation rate of polypropylene chains.