Cellulose nanofiber and preparation method thereof

Abstract

The invention provides a preparation method of cellulose nanofiber. The preparation method comprises the following steps of 1) dispersing cellulose in a first organic solvent to prepare a cellulose dispersion liquid; 2) adding lithium hydroxide into the cellulose dispersion liquid obtained in the step (1) to fully swell the cellulose; 3) reacting the fully swollen cellulose obtained in the step (2) with anhydride, and washing reaction liquid to obtain a cellulose reaction product; and 4) dispersing the cellulose reaction product obtained in the step 3) in an alkaline aqueous solution, performing centrifuging, and dialyzing a supernate to obtain a suspension containing the cellulose nanofiber. According to the preparation method, the raw materials are wide and easy to obtain, only simple and mild magnetic stirring is needed, the whole process can be carried out at room temperature, the reaction condition is mild, and the cost is low. The length-diameter ratio of the prepared cellulose nanofiber is greater than 800, and the cellulose nanofiber has higher modifiability and excellent mechanical properties.

Description

technical field [0001] The patent of the present invention relates to the fields of chemical engineering and polymer functional materials, especially cellulose nanofibers and their preparation methods. Background technique [0002] Cellulose is a kind of natural linear polymer with abundant reserves and the widest distribution in the world, and it is environmentally friendly, green and degradable. In recent years, it has been found that cellulose can obtain nanoscale-sized one-dimensional or two-dimensional cellulose materials after chemical or mechanical treatment under suitable conditions. This discovery is expected to further expand the application range of cellulose. Among them, microfibrillated cellulose nanofibers have been proposed to have ultra-high aspect ratio and excellent mechanical properties, so they are widely used as reinforcement materials for nanofillers and polymers. At the same time, the reduction of size particles makes cellulose nanofibers have larger ...

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Problems solved by technology

For example, at the earliest, people used a high-pressure homogenizer to vibrate fibers in water to obtain cellulose nanofibers, and later derived ultrasonic methods, ball milling methods, etc. can produce cellulose nanofibers, but these methods need to consume a lot of energy, and The requirements for machinery and equipment are high; in addition, the method of using chemical pretreatment to destroy some hydrogen bonds in cellulose and to charge cellulose can reduce the energy consumption of subsequent mechanical treatment to a certain extent, but the toxicity of chemical reagents cannot be avoided , Decreased structural stability of cellulose and other issues; biological enzyme method can obtain cellulose nanofibers with complete structure relatively mildly, but the yield is low, requiring a long period and strict environmental conditions

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