Starch-based biodegradable material composition

1. A starch-based biodegradable material composition comprising:

an enzyme-hydrolyzed starch; and a biodegradable polyester selected from at least one of polybutylene succinate and polybutylene adipate/terephthalate, wherein said starch-based biodegradable material composition is made by a method comprising the steps of:

(a) mixing a native starch with a biodegradable polyester selected from at least one of polybutylene succinate and polybutylene adipate/terephthalate so as to form a solid mixture;

(b) mixing a starch-hydrolyzing enzyme with a liquid additive so as to form a liquid mixture; and

(c) blending the solid mixture and the liquid mixture so as to induce hydrolysis of the native starch to form the enzyme-hydrolyzed starch; and

(d) chemically blending the enzyme-hydrolyzed starch and the biodegradable polymer to form the starch-based biodegradable material;

wherein the starch-hydrolyzing enzyme has an activity ranging from 15000 U to 40000 U and wherein said native starch has a weight ratio to said starch enzyme not greater than 190.

2. The starch-based biodegradable material composition of claim 1 , further comprising a plasticizer selected from the group consisting of glycerol, lecithin, and a combination thereof.

3. The starch-based biodegradable material composition of claim 2 , further comprising a strength-improving agent selected from the group consisting of TiO 2 , CaO, CaCO 3 , silica, and combinations thereof.

4. The starch-based biodegradable material composition of claim 2 , wherein said enzyme-hydrolyzed starch has a weight ratio to said biodegradable polyester ranging from 0.6 to 2.6.

5. The starch-based biodegradable material composition of claim 4 , wherein said enzyme-hydrolyzed starch has a weight ratio to said biodegradable polyester ranging from 1.1 to 2.6.

6. The starch-based biodegradable material composition of claim 5 , wherein said enzyme-hydrolyzed starch has a weight ratio to said plasticizer ranging from 0.014 to 0.4.

7. The starch-based biodegradable material composition of claim 6 , wherein said enzyme-hydrolyzed starch has a weight ratio to said plasticizer ranging from 0.17 to 0.36.

8. The starch-based biodegradable material composition of claim 1 , wherein said native starch has a weight ratio to said starch-hydrolyzing enzyme not greater than 100.

9. The starch-based biodegradable material composition of claim 8 , wherein said native starch is selected from the group consisting of tapioca starch, corn starch, wheat starch, potato starch, gramineae starch, legume starch, and combinations thereof.

10. The starch-based biodegradable material composition of claim 1 , wherein said starch-hydrolyzing enzyme is selected from the group consisting of α-amylase, β-amylase, isoamylase, glucoamylase, pullulanase, cyclodextrin glucano-transferase, β-fructofuranosidase, and combinations thereof.

11. A method for making a starch-based biodegradable material composition comprising:

(a) mixing a native starch with a biodegradable polyester selected from at least one of polybutylene adipate/terephthalate and polybutylene succinate so as to form a solid mixture;

(b) mixing a starch-hydrolyzing enzyme with a liquid additive so as to form a liquid mixture;

(c) blending the solid mixture and the liquid mixture so as to induce hydrolysis of the native starch to form the enzyme-hydrolyzed starch; and

(d) chemically blending of the enzyme-hydrolyzed starch and the biodegradable polyester to form the starch-based biodegradable material composition, wherein the starch-hydrolyzing enzyme has an activity ranging from 15000 U to 40000 U and wherein said native starch has a weight ratio to said starch enzyme not greater than 190.

12. The method of claim 11 , wherein the starch-hydrolyzing enzyme is active within a temperature ranging from 25° C. to 110° C.

13. The method of claim 11 , wherein the liquid additive is selected from water, a plasticizer, and a combination thereof.

14. The method of claim 13 , wherein the liquid additive contains water and the plasticizer at a weight ratio ranging from 1:1 to 1:3.

15. The method of claim 11 , wherein the solid mixture includes a strength-improving agent selected from the group consisting of TiO 2 , CaO, CaCO 3 , silica, and combinations thereof.

16. The method of claim 11 , wherein the native starch, the biodegradable polyester and the liquid additive have a weight ratio ranging from 1:0.6:0.3 to 1:2.6:0.5.

17. The method of claim 16 , wherein the native starch, the biodegradable polyester and the liquid additive have a weight ratio ranging from 1:1.1:0.3 to 1:2.6:0.5.

18. A starch-based biodegradable film that comprises:

an enzyme-hydrolyzed starch; and a biodegradable polyester selected from at least one of polybutylene succinate and polybutylene adipate/terephthalate, wherein said starch-based biodegradable film composition is made by a method comprising the steps of:

(a) mixing a native starch with a biodegradable polyester selected from at least one of polybutylene succinate and polybutylene adipate/terephthalate so as to form a solid mixture;

(b) mixing a starch-hydrolyzing enzyme with a liquid additive so as to form a liquid mixture;

(c) mixing the solid mixture and liquid mixture together; and

(d) extruding the resultant mixture from step (c) so as to induce hydrolysis of the native starch and chemical blending of the resultant enzyme-hydrolyzed starch and the biodegradable polyester to form the starch-based biodegradable film wherein the starch-hydrolyzing enzyme has an activity ranging from 15000 U to 40000 U and wherein said native starch has a weight ratio to said starch enzyme not greater than 190.

19. A method of making a starch-based biodegradable film comprising:

(a) mixing a native starch with a biodegradable polyester selected from at least one of polybutylene succinate and polybutylene adipate/terephthalate so as to form a solid mixture;

(b) mixing a starch-hydrolyzing enzyme with a liquid additive so as to form a liquid mixture;

(c) mixing the solid mixture and liquid mixture together; and

(d) extruding the resultant mixture from step (c) so as to induce hydrolysis of the native starch and chemical blending of the resultant enzyme-hydrolyzed starch and the biodegradable polyester to form the starch-based biodegradable film wherein the starch-hydrolyzing enzyme has an activity ranging from 15000 U to 40000 U and wherein said native starch has a weight ratio to said starch enzyme not greater than 190.

20. The method of claim 19 , wherein the extruding in step (d) is conducted through a twin extruder.