Premium
Nonisothermal orientation‐induced crystallization in melt spinning of polypropylene
Author(s) -
Jinan Cao,
Kikutani Takeshi,
Takaku Akira,
Shimizu Jiro
Publication year - 1989
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1989.070370919
Subject(s) - crystallization , monoclinic crystal system , spinning , crystallinity , materials science , melt spinning , crystal (programming language) , polypropylene , crystallography , composite material , chemical engineering , thermodynamics , crystal structure , chemistry , physics , computer science , programming language , engineering
Two kinds of polypropylene with different molecular weight (MI = 15 and 30) were melt‐spun at the spinning temperatures of 210–290°C and take‐up velocities of 0.15–3 km/min. In the cases of the spinning temperatures of 270 and 290°C for MI15 and 250 and 290°C for MI30, the density showed a minimum with increasing take‐up velocity at around 0.5–1 km/min. This result suggests that crystallization behavior is influenced by two competitive effects, i.e., cooling rate and crystallization rate both of which are enhanced by the increase in take‐up velocity. Crystal structures of slightly oriented monoclinic, slightly oriented pseudohexagonal, highly oriented pseudohexagonal, and highly oriented monoclinic were successively observed with increasing take‐up velocity. The change of crystallization temperature may result in the different kinds of crystal modifications. Numerical calculations on nonisothermal orientation‐induced crystallization in the melt spinning process and experimental results showed qualitative agreement in the change of crystallinity with take‐up velocity, spinning temperature, and molecular weight.