Method for production of cellulose nanocrystals from Miscathus giganteus and composites therefrom

• US 10,000,578 B2
• Filed: 12/19/2014
• Issued: 06/19/2018
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• Current Assignee: Case Western Reserve University
• Original Assignee: Case Western Reserve University
• Inventors: Rowan, Stuart, Hunsen, Mo, Way, Amanda
• Primary Examiner(s): Cai, Wenwen
• Application Number:
  US15/105,851
• Publication Number:
  US 20160319043A1
• Time in Patent Office: 1,278 Days
• CPC Class Codes: C08B 15/02 Oxycellulose; Hydrocellulose; Cellulosehydrate, e.g. microcrystalline cellulose
• CPC Class Codes: C08B 15/08 Fractionation of cellulose, e.g. separation of cellulose crystallites
• CPC Class Codes: C08B 5/14 Cellulose sulfate
• CPC Class Codes: C08L 1/04 Oxycellulose; Hydrocellulose , e.g. microcrystalline cellulose
• CPC Class Codes: C08L 47/00 Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds; Compositions of derivatives of such polymers C08L45/00 takes precedence; of conjugated diene rubbers C08L9/00 - C08L21/00
• CPC Class Codes: C08L 67/00 Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain of polyester-amides C08L77/12; of polyester-imides C08L79/08; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 71/02 Polyalkylene oxides
• CPC Class Codes: C08L 77/00 Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain of polyhydrazides C08L79/06; of polyamideimides or polyamide acids C08L79/08; Compositions of derivatives of such polymers
• CPC Class Codes: D21C 1/04 with acid reacting compounds
• CPC Class Codes: D21C 1/06 with alkaline reacting compounds
• CPC Class Codes: D21C 9/142 with ClO2/Cl2 in a multistage process involving ClO2/Cl2 exclusively
• CPC Class Codes: D21H 11/18 Highly hydrated, swollen or fibrillatable fibres

Abstract

Methods for isolating cellulose nanocrystals (CNCs) from the plant Miscanthus Giganteus (MxG). Impressive yields are obtained through a combination of processing steps including base hydrolysis, bleaching and acid hydrolysis. MxG-CNCs are produced having high aspect ratios, are biorenewable and can be used for a wide range of applications such as nanofillers in composites. MxG-CNC-containing composites are also disclosed.

Claims

1. A process for isolating cellulose nanocrystals from Miscanthus Giganteus, comprising the steps of:

performing a base hydrolysis step on a quantity of Miscanthus Giganteus;

performing a bleaching step on a solid material recovered from the base hydrolysis step;

performing an acid hydrolysis step on a solid material recovered from the bleaching step; and

recovering cellulose nanocrystals from Miscanthus Giganteus after performing the acid hydrolysis step.

2. The process according to claim 1, wherein prior to performing the base hydrolysis step a quantity of Miscanthus Giganteus is obtained and comminuted to a smaller average particle size.

3. The process according to claim 1, wherein the base hydrolysis step includes contacting the Miscanthus Giganteus with a basic solution having a pH of about 13 to about 14, and wherein the base utilized has a formula of MOH, wherein M is a cationic counter ion.

4. The process according to claim 3, wherein the bleaching step comprises contacting acetic acid and one or more of sodium chlorite or sodium hypochlorite with the solid material recovered from the base hydrolysis step, wherein the one or more of the sodium chlorite or sodium hypochlorite are present in a concentration between about 0.5 and about 4 weight percent and the concentration of acetic acid is between about 0.2 and about 9 weight percent.

5. The process according to claim 4, wherein the bleaching step is performed for about 1 to about 3 hours at a temperature of about 50°

C. to about 80°

C., wherein mixing is performed during at least part of the time period.

6. The process according to claim 4, wherein the acid hydrolysis step comprises contacting the solid material recovered from the bleaching step with an acid having a concentration ranging from 0.5 molar to about 18 molar.

7. The process according to claim 6, wherein the acid is one or more of hydrobromic acid, phosphoric acid, sulfuric acid or hydrochloric acid.

8. The process according to claim 7, wherein the acid hydrolysis step is performed for about 0.5 to about 24 hours.

9. The process according to claim 1, further including the step of adding carboxyl functionality to the recovered cellulose nanocrystals.