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Isothermal crystallization kinetics and subsequent melting behavior of β ‐nucleated isotactic polypropylene/graphene oxide composites with different ordered structure
Author(s) -
Yu Yansong,
Zeng Fangxinyu,
Chen Jinyao,
Kang Jian,
Yang Feng,
Cao Ya,
Xiang Ming
Publication year - 2018
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.5625
Subject(s) - materials science , crystallization , crystallite , tacticity , differential scanning calorimetry , isothermal process , kinetics , oxide , nucleation , crystallography , composite material , thermodynamics , polymer , chemistry , polymerization , metallurgy , physics , quantum mechanics
The effects of ordered structure on isothermal crystallization kinetics and subsequent melting behavior of β ‐nucleated isotactic polypropylene/graphene oxide (iPP/GO) composites were studied using differential scanning calorimetry. The ordered structure status was controlled by tuning the fusion temperature ( T f ). The results showed that depending on the variation of crystallization rate, the whole T f range could be divided into three regions: Region I ( T f > 179 °C), Region II (170 °C ≤ T f ≤ 179 °C) and Region III ( T f < 170 °C). As T f decreased from Region I to Region III, the crystallization rate would increase substantially at two transition points, due to the variation of the ordered structure status. Calculation of Avrami exponent n indicated that the ordered structure induced the formation of two‐dimensional growing crystallites rather than three‐dimensional growing crystallites. Moreover, in the case of isothermal crystallization, the ordered structure effect (OSE) can also greatly increase the relative content of β ‐phase ( β c ). In Region II, OSE took place, resulting in evident increase of β c , achieving 92.4% at maximum. The variation of the isothermal crystallization temperature ( T iso ) had little influence on the T f range (Region II) of the OSE. The higher T f in Region II was more favorable for the formation of higher β c . The ordered structure was favorable for the improvement of the nucleating efficiency of β ‐nucleating agent ( β ‐NE), and was more effective for the improvement of lower β ‐NE. © 2018 Society of Chemical Industry