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Strain-induced 3D-oriented crystallites in natural rubber/chitin nanofiber composites
Jinghua Wu1, Jin Yin1, Jian Hu1
1Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science & Technology, Qingdao City 266042, P. R. China. HuJian@qust.edu.cn.
Soft Matter
|April 4, 2023
Summary
Natural rubber composites with chitin nanofibers exhibit enhanced mechanical properties. These composites form 3D-oriented crystallites, suggesting potential for novel materials with shape memory ability.
Area of Science:
- Materials Science
- Polymer Science
- Nanotechnology
Background:
- Natural rubber (NR) composites can be engineered to achieve a spectrum of mechanical properties, ranging from rubbery to plastic behaviors, by varying filler content.
- Chitin nanofibers (ChNFs), derived from bio-based sources, offer unique properties for composite reinforcement.
- A constrained 3D network can be formed by combining natural rubber latex with modified chitin.
Purpose of the Study:
- To investigate the formation of 3-dimensionally oriented crystallites in natural rubber/chitin nanofiber (NR/ChNF) composites.
- To explore the impact of chitin nanofiber content on the strain-induced crystallization of natural rubber.
- To assess the potential for developing novel multifunctional NR/ChNF composites with enhanced mechanical properties and shape memory ability.
Main Methods:
- Fabrication of natural rubber composites with varying weight percentages of chitin nanofibers.
- Mechanical testing to evaluate the range of mechanical properties.
- Two-dimensional wide-angle X-ray diffraction (2D-WAXD) to analyze crystallite orientation under strain.
- Microstructural analysis to investigate 3D structure and morphology after crystallization.
Main Results:
- Inclusion of 30 wt% chitin nanofibers significantly lowers the strain required for strain-induced crystallization of natural rubber to 50%.
- NR/ChNF composites with over 5 wt% ChNFs exhibit 3D-oriented crystallite formation, resembling '3D-single crystal orientation' under strain.
- The study observed specific orientation of NR chain axes (c-axis along stretching, a- and b-axes along normal and transverse directions).
Conclusions:
- Chitin nanofibers act as effective reinforcing agents in natural rubber, promoting unique crystallite orientations.
- The formation of 3D-oriented crystallites in NR/ChNF composites offers a novel strategy for enhancing mechanical properties.
- These findings pave the way for developing advanced multifunctional composites with potential shape memory applications.
