A method for preparing cellulose nano-whiskers from microcrystalline cellulose in combination with alkali treatment and high-intensity ultrasound

Abstract

The invention provides a method for preparing cellulose nano-whiskers from microcrystalline cellulose in combination with alkali treatment and high-intensity ultrasound, comprising: soaking, alkali treatment, acid treatment, high-intensity ultrasonic treatment, and freeze-drying. On the premise of ensuring that the cellulose nano-whiskers remain Type I, the present invention creatively uses alkali treatment and low-concentration acid treatment for the first time to prepare cellulose nano-whiskers in combination with high-intensity ultrasound, avoiding the traditional use of high-concentration strong acid treatment. environmental pollution, waste of resources and time. The cellulose nano-whiskers prepared by the invention have better dispersibility and stability, are convenient to operate, do not need to consume a large amount of concentrated acid, and do not cause secondary pollution to the environment. The crystallinity of the finally prepared cellulose nano whiskers is more than 70%, the diameter is about 3-20nm, and the length is 200-400nm.

Description

technical field

[0001] The present invention relates to a method for preparing cellulose nano-whiskers from microcrystalline cellulose, more specifically to a method for preparing cellulose nano-whiskers from microcrystalline cellulose in combination with alkali treatment and high-intensity ultrasound, which belongs to nanomaterial preparation technology field. Background technique

[0002] At least one dimension is in the range of nanoscale (1 ~ 100nm), or the materials composed of them as basic units are called nanomaterials. Cellulose nanowhiskers belong to ultrafine fibers with a diameter of less than 100nm, which have unique mechanical, thermodynamic and hydrodynamic properties, and can be widely used in the field of composite materials. Its blending with polymer materials can significantly change the mechanical, optical, thermal and electrical properties of polymer materials. In addition, cellulose nanowhiskers have very broad application prospects in cosmetics, food...

Examples

Embodiment 1

[0039] 1) Soaking: add microcrystalline cellulose to water and soak for 12-24 hours to obtain water-soaked microcrystalline cellulose.

[0040] 2) Alkali treatment:

[0041] According to the mass ratio of 1:10~30, add the soaked microcrystalline cellulose into the aqueous sodium hydroxide solution, keep the temperature at 70°C, and react for 1~2h at the stirring speed of 200~2000rpm (rev / min) to obtain alkali-treated microcrystalline cellulose. Crystalline cellulose, the concentration of sodium hydroxide aqueous solution is 3% to 5%.

[0042] 3) Acid treatment:

[0043] According to the mass ratio of 1:10-30, add the alkali-treated microcrystalline cellulose to the hydrochloric acid aqueous solution, keep the temperature at 90°C, and react for 1-4 hours under the condition of stirring speed of 200-2000rpm to obtain the acid-treated microcrystalline cellulose, the concentration of the hydrochloric acid aqueous solution 1% to 2%. The SEM photo of microcrystalline cellulose af...

Embodiment 2

[0049] The difference between this embodiment and the first embodiment is:

[0050] In step 2), the reaction temperature is 80°C, and the concentration of the aqueous sodium hydroxide solution is 5% to 7%;

[0051] In step 3), the reaction temperature is 85°C, and the concentration of the aqueous hydrochloric acid solution is 2% to 4%;

[0052] In step 4), the output power of the ultrasound is 1000-1200W, and the ultrasound time is 25-35 minutes.

[0053] The TEM picture of gained cellulose nano whiskers is shown in Figure II .

Embodiment 3

[0055] The difference between this embodiment and the specific embodiment one and two is:

[0056] In step 2), the reaction temperature is 90°C, and the concentration of the aqueous sodium hydroxide solution is 7% to 9%;

[0057] In step 3), the reaction temperature is 80°C, and the concentration of the aqueous hydrochloric acid solution is 4% to 6%;

[0058] In step 4), the output power of the ultrasound is 1200-1500W, and the ultrasound time is 20-30 minutes.

technical field

[0001] The present invention relates to a method for preparing cellulose nano-whiskers from microcrystalline cellulose, more specifically to a method for preparing cellulose nano-whiskers from microcrystalline cellulose in combination with alkali treatment and high-intensity ultrasound, which belongs to nanomaterial preparation technology field. Background technique

[0002] At least one dimension is in the range of nanoscale (1 ~ 100nm), or the materials composed of them as basic units are called nanomaterials. Cellulose nanowhiskers belong to ultrafine fibers with a diameter of less than 100nm, which have unique mechanical, thermodynamic and hydrodynamic properties, and can be widely used in the field of composite materials. Its blending with polymer materials can significantly change the mechanical, optical, thermal and electrical properties of polymer materials. In addition, cellulose nanowhiskers have very broad application prospects in cosmetics, food...

Examples

Embodiment 1

[0039] 1) Soaking: add microcrystalline cellulose to water and soak for 12-24 hours to obtain water-soaked microcrystalline cellulose.

[0040] 2) Alkali treatment:

[0041] According to the mass ratio of 1:10~30, add the soaked microcrystalline cellulose into the aqueous sodium hydroxide solution, keep the temperature at 70°C, and react for 1~2h at the stirring speed of 200~2000rpm (rev / min) to obtain alkali-treated microcrystalline cellulose. Crystalline cellulose, the concentration of sodium hydroxide aqueous solution is 3% to 5%.

[0042] 3) Acid treatment:

[0043] According to the mass ratio of 1:10-30, add the alkali-treated microcrystalline cellulose to the hydrochloric acid aqueous solution, keep the temperature at 90°C, and react for 1-4 hours under the condition of stirring speed of 200-2000rpm to obtain the acid-treated microcrystalline cellulose, the concentration of the hydrochloric acid aqueous solution 1% to 2%. The SEM photo of microcrystalline cellulose af...

Embodiment 2

[0049] The difference between this embodiment and the first embodiment is:

[0050] In step 2), the reaction temperature is 80°C, and the concentration of the aqueous sodium hydroxide solution is 5% to 7%;

[0051] In step 3), the reaction temperature is 85°C, and the concentration of the aqueous hydrochloric acid solution is 2% to 4%;

[0052] In step 4), the output power of the ultrasound is 1000-1200W, and the ultrasound time is 25-35 minutes.

[0053] The TEM picture of gained cellulose nano whiskers is shown in Figure II .

Embodiment 3

[0055] The difference between this embodiment and the specific embodiment one and two is:

[0056] In step 2), the reaction temperature is 90°C, and the concentration of the aqueous sodium hydroxide solution is 7% to 9%;

[0057] In step 3), the reaction temperature is 80°C, and the concentration of the aqueous hydrochloric acid solution is 4% to 6%;

[0058] In step 4), the output power of the ultrasound is 1200-1500W, and the ultrasound time is 20-30 minutes.

Images