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The university of science and technology of China (ustc) has developed the biomimetic structure material of light, high strength and strong nano cellulose

Time : 2020-05-26 Hits : 17

Since the birth of human civilization, material has been the material basis of social development and progress. Structural materials such as metals, ceramics and polymers are the most widely used of all existing materials. In recent years, the development of high-performance materials with mutual exclusion (such as strength and toughness), especially building materials based on the nanometer scale, has attracted more and more attention.

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Recently, the team of academician yu shuhong from the university of science and technology of China has successfully developed a nano-cellulose high-performance biomimetic structure material (CNFP). This material has excellent comprehensive properties, its density is only one-sixth of that of steel, specific strength, specific toughness are more than traditional alloy materials, ceramics and engineering plastics.

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Cellulose is one of the most abundant natural organic matter in the world. Cotton, hemp, straw, straw, bagasse, etc., can all provide cellulose. Therefore, the extensive biological sources lay a sustainable foundation for this material.

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The results were published May 1 in the journal Science Advances (Science Advances 2020) as "Lightweight, tough, and sustainable cellulose nanofiber-derived bulk structural materials with low thermal expansion coefficient." 6, eaaz1114).

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It was found that the lightweight, high strength and toughness properties of CNFP mainly come from the design of micron-scale layered structure and nanometer three-dimensional network structure. Internal highly crystalline cellulose nanofibers can provide extremely high intensity, through a large number of hydrogen bonding between the fibers such as reversible interaction networks, under external force in the high density of reversible interaction network can quickly dissociation and refactoring, absorb a lot of energy, make material with high strength and high toughness, overcomes the traditional structural materials with both high strength and high toughness of hard problem.

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Its scale stability and thermal impact resistance are shown as follows: in the temperature range from -120°C to 150°C, the coefficient of thermal expansion is as low as 5 × 10-6 k-1. That is to say, even if the temperature fluctuation reaches 100℃, its size change is also in the 10,000 within five, only a fifth of aviation aluminum alloy, engineering plastic dozens of a, close to ceramics. Moreover, its mechanical properties and dimensions are still highly stable under repeated severe thermal shock cycle tests between 120℃ and -196℃.

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At the same time, CNFP also has high impact resistance, high damage tolerance and high energy absorption performance, which is expected to make it can be used as a substitute for alloy. The ultra-high speed impact test results of the separated hopkinson pressure bar show that under the high-speed impact of 28 m · s-1 (the speed is equivalent to that of a high-speed car), it shows the ultra-high compressive strength of 1600MPa and can absorb the impact energy of up to 387.5mj · m-3 within 0.07 ms. This is mainly because its internal three-dimensional nanofiber network slips when subjected to high-speed impact, and a large number of hydrogen bonds between the nanofibers undergo rapid dissociation and reconstruction, which can absorb and convert the impact kinetic energy into heat.

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Thus, the sustainable new natural nanofibers bionic structure material, integrates include lightweight Gao Qiangren, high dimensional stability and thermal shock, resistance to impact, the excellent properties such as high damage tolerance, it is expected to lightweight shock protection and cushioning material, space materials, precision instrument parts, and other fields will have broad application prospects.

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