Method of producing a softwood lignin derivative
The present invention relates to softwood lignin derivatives having an aliphatic hydroxyl content of from about 2.5 mmol/g to about 7 mmol/g lignin, and the preparation method thereof. The preparation method comprises: pulping a fibrous biomass, heating the biomass, maintaining the elevated temperature for 1 minute or longer, separating the cellulosic pulp to form a lignin-rich material, and recovering derivatives of native lignin. The lignin derivatives have a desired antioxidant activity characterized by radical scavenging index (RSI). Another aspect of the invention relates to compositions comprising the softwood lignin derivative. Another aspect of the invention relates to a use of the softwood lignin derivatives comprising incorporating the softwood lignin derivatives into polymer compositions.
1. A method of producing a softwood lignin derivative, comprising:
a. pulping a fibrous biomass;
b. heating the biomass;
c. maintaining the elevated temperature for 1 minute or longer;
d. separating the cellulosic pulp to form a lignin-rich material; and
e. recovering derivatives of native lignin, wherein the derivatives have an aliphatic hydroxyl content of from 2.5 mmol/g to about 7 mmol/g, phenolic hydroxyl content of from about 2 mmol/g to about 8 mmol/g, and a normalized RSI of 10 or greater;
wherein the pulping process is selected from the group consisting of: steam explosion, dilute acid hydrolysis, ammonia fiber expansion, autohydrolysis, soda pulping or modifications thereof, and organosolv process.
2. The method according to claim 1 , wherein the derivative has an aliphatic hydroxyl content of from about 2.75 mmol/g to about 5 mmol/g.
3. The method according to claim 1 , wherein the fibrous biomass comprises pine, spruce, or combinations/hybrids thereof.
4. The method according to claim 1 , wherein the fibrous biomass comprises Pinus radiata, Pinus taeda , spruce, or combinations/hybrids thereof.
5. The method according to claim 1 , wherein the derivative has an alkoxy content of 1.4 mmol/g or less.
6. The method according to claim 1 , wherein the derivative has an alkoxy content of 0.1 mmol/g or greater.
7. The method according to claim 1 , wherein the derivative has a normalized RSI of 15 or greater.
8. The method according to claim 1 , wherein the derivative has a normalized RSI of 40 or less.
9. The method according to claim 1 , wherein the lignin derivative has a normalized RSI of about 15 to about 35.
10. The method according to claim 1 , wherein the derivative has a polydispersity from about 1 to about 5.
11. The method according to claim 1 , wherein the pulping process is steam explosion.
12. The method according to claim 1 , wherein the pulping process is dilute acid hydrolysis.
13. The method according to claim 1 , wherein the pulping process is ammonia fiber expansion.
14. The method according to claim 1 , wherein the pulping process is autohydrolysis.
15. The method according to claim 1 , wherein the pulping process is soda pulping or modifications thereof.
16. The method according to claim 1 , wherein the pulping process is organosolv process.