Method of forming a cellulose nanocrystalline film

Patent metadata

Field	Value
Publication number	US-9969108-B2
Application number	US-201615045802-A
Country	US
Kind code	B2
Filing date	Feb 17, 2016
Priority date	Oct 13, 2010
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

A method is provided for forming a substantially uniaxially-oriented, high content cellulose nanocrystal film. The method includes providing a plant-biomass-based suspension of cellulose nanocrystals and altering the pH of the cellulose nanocrystals to a substantially neutral pH. The suspension is sheared at a shearing rate. The method further includes orienting the cellulose nanocrystals in a substantially axial direction and removing water from the sheared cellulose nanocrystal suspension. As a result, a substantially uniaxially-oriented cellulose nanocrystal film is formed.

First claim

The invention claimed is:

1. A method of forming a substantially uniaxially-oriented, high content cellulose nanocrystal film for a commercial application, the method comprising:
providing a cellulose nanocrystal suspension derived from plant-biomass-based material, where a concentration of the cellulose nanocrystals in the suspension is above a lyotropic limit;
adjusting the pH of the suspension to a substantially neutral pH;
shearing the neutralized suspension at a defined shearing rate using a doctor blade so as to substantially uniaxially orient the nanocrystals;
removing water from the sheared cellulose nanocrystal suspension; and
forming a cellulose nanocrystal film having the substantially uniaxial orientation.

2. The method of claim 1 , further comprising adding a hydrophobic agent to the suspension.

3. The method of claim 2 , wherein the hydrophobic agent comprises an epoxydyzed soybean oil or elastomer material.

4. The method of claim 1 , further comprising controlling the viscosity of the suspension by providing the suspension with a concentration of the cellulose nanocrystals between about 3 wt. % and 15 wt. %.

5. The method of claim 1 , wherein the adjusting step comprises adding a base material to the suspension.

6. The method of claim 5 , wherein the base material comprises sodium hydroxide, potassium hydroxide, or ammonium hydroxide.

7. The method of claim 1 , wherein the removing step comprises:
cooling the sheared cellulose nanocrystal suspension to a temperature at or above its freezing point; and
applying a vacuum to the cooled suspension for a period of time,
wherein the period of time is minimized to maintain the orientation of the cellulose nanocrystals in the formed film.

8. The method of claim 1 , wherein the shearing rate is between about 100·s −1 and 10·s −1 .

9. The method of claim 1 , wherein the Herman's order parameter of the formed cellulose nanocrystal film is about 0.5 or greater.

10. The method of claim 1 , wherein the formed cellulose nanocrystal film comprises a tensile strength between about 250-350 MPa.

11. The method of claim 1 , wherein the formed cellulose nanocrystal film comprises an elastic modulus between about 30-60 GPa.

12. The method of claim 1 , the formed cellulose nanocrystal film comprises a strain-to-failure yield of approximately 10 times greater than that of glass.

13. The method of claim 1 , wherein the suspension is provided in a liquid crystalline form.

14. The method of claim 1 , wherein the forming step comprises forming a substantially flat and continuous film.

Assignees

• Purdue Research Foundation
• Us Agriculture

Inventors

• Youngblood Jeffrey P
• Moon Robert J
• Reising Alex

Classifications

• C08J2301/12

  Cellulose acetate · CPC title

• B29C70/14

  oriented · CPC title

• C08J2301/02

  Cellulose; Modified cellulose · CPC title

• C08J5/18

  Manufacture of films or sheets · CPC title

• B29K2105/162

  Nanoparticles · CPC title