Structure and Mechanical Properties of Multi-Walled Carbon Nanotubes-Filled Isotactic Polypropylene Composites Treated by Pressurization at Different Rates

Polymers

Changyu Shen¹  Wenxia Jia¹  Zhen Wang¹  Yaming Wang¹  Xiaoting Li¹  Beibei Dong¹  Huan Yuan¹  Chuntai Liu¹  Fengmei Su¹  Chunguang Shao¹ 

[1] Key Laboratory of Materials Processing and Mold (Zhengzhou University), Ministry of Education, National Engineering Research Center for Advanced Polymer Processing Technology, Zhengzhou University, Zhengzhou 450002, China;

关键词: isotactic polypropylene;    multi-walled carbon nanotubes;    pressurization rate;    crystalline behavior;    mechanical properties;   

DOI  :  10.3390/polym11081294

来源: DOAJ

【 摘 要 】

Isotactic polypropylene filled with 1 wt.% multi-walled carbon nanotubes (iPP/MWCNTs) were prepared, and their crystallization behavior induced by pressurizing to 2.0 GPa with adjustable rates from 2.5 to 1.3 × 10⁴ MPa/s was studied. The obtained samples were characterized by combining wide angle X-ray diffraction, small angle X-ray scattering, differential scanning calorimetry, transmission electron microscopy and atomic force microscopy techniques. It was found that pressurization is a simple way to prepare iPP/MWCNTs composites in mesophase, γ-phase, or their blends. Two threshold pressurization rates marked as R₁ and R₂ were identified, while R₁ corresponds to the onset of mesomorphic iPP formation. When the pressurization rate is lower than R₁ only γ-phase generates, with its increasing mesophase begins to generate and coexist with γ-phase, and if it exceeds R₂ only mesophase can generate. When iPP/MWCNTs crystallized in γ-phase, compared with the neat iPP, the existence of MWCNTs can promote the nucleation of γ-phase, leading to the formation of γ-crystal with thicker lamellae. If iPP/MWCNTs solidified in mesophase, MWCNTs can decrease the growth rate of the nodular structure, leading to the formation of mesophase with smaller nodular domains (about 9.4 nm). Mechanical tests reveal that, γ-iPP/MWCNTs composites prepared by slow pressurization display high Young’s modulus, high yield strength and high elongation at break, and meso-iPP/MWCNTs samples have excellent deformability because of the existence of nodular morphology. In this sense, the pressurization method is proved to be an efficient approach to regulate the crystalline structure and the properties of iPP/MWCNTs composites.

【 授权许可】

Unknown