Isothermal crystallization kinetics and subsequent melting behavior of β‐nucleated isotactic polypropylene/graphene oxide composites with different ordered structure

• Published in: Polymer international Vol. 67; no. 9; pp. 1212 - 1220
• Main Authors: Yu, Yansong, Zeng, Fangxinyu, Chen, Jinyao, Kang, Jian, Yang, Feng, Cao, Ya, Xiang, Ming
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.09.2018; Wiley Subscription Services, Inc
• Subjects: Crystallites; Crystallization; Crystals; Differential scanning calorimetry; Fusion temperature; Graphene; graphene oxide; isotactic polypropylene; Isotacticity; isothermal crystallization kinetics; Melting; ordered structure; Organic chemistry; Polymer matrix composites; Polypropylene; Transition points; Variation; β‐nucleating agent
• ISSN: 0959-8103; 1097-0126
• DOI: 10.1002/pi.5625

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 (Tf). The results showed that depending on the variation of crystallization rate, the whole Tf range could be divided into three regions: Region I (Tf > 179 °C), Region II (170 °C ≤ Tf ≤ 179 °C) and Region III (Tf < 170 °C). As Tf 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 (βc). In Region II, OSE took place, resulting in evident increase of βc, achieving 92.4% at maximum. The variation of the isothermal crystallization temperature (Tiso) had little influence on the Tf range (Region II) of the OSE. The higher Tf in Region II was more favorable for the formation of higher βc. 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 In the case of isothermal crystallization of iPP/GO/WBG‐II composites, the ordered structure effect can also greatly increase the crystallization rate and the relative content of β‐phase.