Method of forming a cellulose nanocrystalline film

Patent metadata

Field	Value
Publication number	US-9296131-B2
Application number	US-201313855119-A
Country	US
Kind code	B2
Filing date	Apr 2, 2013
Priority date	Oct 13, 2010
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

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, the method comprising:
providing a suspension of cellulose nanocrystals extracted from plant biomass;
altering the pH of the suspension to a substantially neutral pH;
shearing the neutralized suspension at a defined shearing rate using a doctor blade;
orienting cellulose nanocrystals of the neutralized suspension in a substantially axial direction;
removing water from the sheared cellulose nanocrystal suspension; and
forming a cellulose nanocrystal film having a substantially uniaxial orientation in the axial direction.

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

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

4. The method of claim 1 , wherein the altering step comprises:
adding a base material to the suspension; and
increasing the pH of the suspension until the pH is substantially neutral.

5. The method of claim 4 , wherein the base material comprises sodium hydroxide, potassium hydroxide, or ammonium hydroxide.

6. The method of claim 4 , wherein after the increasing step, the pH of the cellulose nanocrystal suspension is between about 4-10.

7. The method of claim 4 , further comprising dialyzing the suspension to remove the base from the suspension.

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

9. The method of claim 1 , wherein the suspension further comprises a hydrophobic agent.

10. The method of claim 9 , wherein the hydrophobic agent comprises an epoxydyzed soybean oil or an elastomer material.

11. The method of claim 1 , wherein a concentration of the cellulose nanocrystals in the suspension is above the lyotropic limit.

12. The method of claim 11 , further comprising controlling viscosity of the suspension by providing the suspension with a concentration of the cellulose nanocrystals between about 3 wt. % and 15 wt. %.

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

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

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

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

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

Assignees

• Purdue Research Foundation

Inventors

• Youngblood Jeffrey P
• Moon Robert J
• Reising Alex

Classifications

• B29C41/24 Primary

  for making articles of indefinite length · CPC title

• B29K2001/00

  Use of cellulose, modified cellulose or cellulose derivatives, e.g. viscose, as moulding material · CPC title

• C08J2301/12

  Cellulose acetate · CPC title

• C08B15/08

  Fractionation of cellulose, e.g. separation of cellulose crystallites · CPC title

• C08L1/02

  Cellulose; Modified cellulose · CPC title