How can cellulose nanocrystals be used for bio-based material modification?
At present, the biomass raw materials that can be directly extracted are mainly starch, cellulose, lignin, etc. Among them, cellulose is the most abundant organic polymer material in nature. Renewable resources. Cellulose nanocrystals (CNC) are a kind of nanocellulose. Cellulose is a macromolecule material with at least one dimension of nanoscale made by chemical, mechanical, biological and other processing methods. It is widely used in packaging. , coatings, biomedicine, wastewater treatment, energy and electronics.
As one of the widely used types of nanocellulose, cellulose nanocrystals (CNC) have the characteristics of high Young's modulus, high strength, high aspect ratio, huge specific surface area, low thermal expansion coefficient, high transparency, and good barrier properties. It is a good reinforcing agent for materials and shows great market potential in high-performance composite materials.
Some researchers have compounded cellulose nanocrystals with rubber. When they are compounded with other polymers as reinforcing fillers, hydrogen bonds between fillers and fillers and fillers and polymers can be formed, which changes the mechanical properties of the material. Compared with the previous ones, the mechanical properties of the prepared composites were greatly improved, the mechanical properties of the composites were significantly improved, and the water-responsive properties of the composites also changed significantly. In addition, some researchers mixed natural rubber (NR) and epoxidized rubber (ENR) with different contents of CNCs, and found that, and under the same content of CNCs, the modulus growth rate of ENR nanocomposites was higher than that of NR. The nanocomposites are more significant.
In addition to non-degradable natural rubber, cellulose nanocrystals, as natural bio-based materials, can also be used in polylactic acid PLA. PLA has good biodegradability, moderate mechanical strength, and good processing performance, and can be processed by traditional plastic processing equipment. However, the brittleness of PLA, low barrier properties, poor thermal stability, and insufficient strength in bone tissue engineering applications limit the application of PLA. Because of its large aspect ratio, high strength and elastic modulus, and complete degradability, nanocellulose has become an excellent reinforcing material for polylactic acid.
Some researchers used vinyl acetate and butyl acrylate to coat and modify CNC by free-radical polymerization, and composite the obtained modified cellulose nanocrystals (m-CNC) with PLA to manufacture bio-based composites. It was found that the tensile strength of m-CNC/PLA composites showed an upward trend with the increase of m-CNC content, and the tensile strength of the composites could be increased by up to 40% compared with pure PLA.
