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Effects of melt structure on non‐isothermal crystallization behavior of isotactic polypropylene nucleated with α/β compounded nucleating agents
Author(s) -
Zhang Qiyan,
Peng Hongmei,
Kang Jian,
Cao Ya,
Xiang Ming
Publication year - 2017
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.24476
Subject(s) - tacticity , materials science , crystallization , nucleation , isothermal process , phase (matter) , recrystallization (geology) , thermal stability , chemical engineering , thermodynamics , atmospheric temperature range , crystal structure , melting point , crystallography , composite material , polymerization , polymer , organic chemistry , chemistry , physics , engineering , paleontology , biology
In this study, the effects of melt structure (tuned by controlling the fusion temperature T f ) on non‐isothermal crystallization and subsequent melting behaviors of isotactic polypropylene (iPP) nucleated with α/β compounded nucleating agents (α/β‐CNAs) have been further investigated. The results show that under all cooling rates studied (2–40°C/min), the crystallization temperature on cooling curves increased gradually with decrease of T f , meanwhile, when T f was in temperature range of 166°C–179°C where ordered structures survived in the melt (defined as Region II), crystallization activation energy ΔE was found to be evidently lower compared with that when T f > 179°C or T f < 166°C. The results of subsequent heating showed that occurrence of Ordered Structure Effect can be observed at all the cooling rates studied; the location of the Region II was constant when cooling rate varied; Low cooling rate encouraged formation of more β‐phase triggered by ordered structure. Moreover, the role of ordered structure on β‐α recrystallization was comparatively studied by tuning the end temperature of recooling ( T end ) after held at T f , and it was found that ordered structure encouraged the formation of β‐phase with high thermal stability at low temperature part of Region II, while enhanced the β‐crystal with relatively low thermal stability at high temperature part of Region II. POLYM. ENG. SCI., 57:989–997, 2017. © 2016 Society of Plastics Engineers