Cellulose nanofibers and preparation method thereof

Abstract

The present invention provides a method for preparing cellulose nanofibers, comprising the following steps: Step 1): dispersing cellulose in a first organic solvent to prepare a cellulose dispersion; Step 2): adding the fibers obtained in step 1) to Lithium hydroxide is added to the cellulose dispersion to fully swell the cellulose; step 3): react the fully swollen cellulose obtained in step 2) with an acid anhydride, wash the reaction solution, and obtain a cellulose reaction product; step 4): the step 3) The obtained cellulose reaction product is dispersed in an alkaline aqueous solution, centrifuged, and the supernatant is dialyzed to obtain a suspension containing cellulose nanofibers. The preparation method provided by the invention has wide and readily available raw materials, only needs simple and mild magnetic stirring, the whole process can be carried out at room temperature, the reaction conditions are mild, and the cost is low. The prepared cellulose nanofibers have an aspect ratio of >800, 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 class of natural linear polymers with abundant reserves and the most widely distributed in the world. It is environmentally friendly, green and degradable. In recent years, it has been found that cellulose one-dimensional or two-dimensional materials can be obtained 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 ratios and excellent mechanical properties, so they are widely used as reinforcements for nanofillers and polymers. At the same time, the reduction of particle size enables cellulose nanofibers to have larger specific surface area a...

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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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