Renewable content carbohydrate-based polymeric materials with high density and increased strength

Abstract

Described herein are methods for increasing strength of blown films, by forming the films using a film blowing apparatus where the film is formed from a blend of a first polymeric material and a renewable carbohydrate-based polymeric material having particular characteristics. By using such a blend, and ensuring that the film blowing apparatus is operated at a high blow up ratio of at least 2.0, and/or using a narrow die gap of no more than 500 microns, Applicant has discovered that increased strength in the film can be obtained, as compared to where (i) the renewable carbohydrate-based polymeric material is not included or (ii) where the film is blown at lower blow up ratios and/or wider die gaps.

1 . A blown plastic film comprising:
 a blend including a first polymeric material and a renewable starch-based polymeric material, wherein the renewable starch-based polymeric material is (i) substantially amorphous, having a crystallinity of no more than 20%, (ii) has a Young's modulus of at least 1.0 GPa, and/or (iii) has a glass transition temperature of 70° C. to 100° C.;   wherein:
 the blown plastic film exhibits increased strength; 
 wherein the renewable starch-based polymeric material has a density greater than 1.25 g/cm 3 . 
   
     
     
         2 . The plastic film of  claim 1 , wherein the first polymeric material comprises a polyolefin. 
     
     
         3 . The plastic film of  claim 1 , wherein the first polymeric material comprises one or more of polyethylene, polypropylene, polyethylene terephthalate, or a polyester. 
     
     
         4 . The plastic film of  claim 1 , wherein the first polymeric material comprises one or more of polystyrene, ABS, nylon, polyvinyl chloride, or polycarbonate. 
     
     
         5 . The plastic film of  claim 1 , wherein the first polymeric material comprises at least one of polyethylene or polypropylene. 
     
     
         6 . The plastic film of  claim 1 , wherein the first polymeric material comprises LLDPE. 
     
     
         7 . The plastic film of  claim 1 , wherein the blown plastic film has a thickness of from 0.1 mil to 10 mils. 
     
     
         8 . The plastic film of  claim 1 , wherein the renewable starch-based polymeric material is formed from a blend of at least two different starches. 
     
     
         9 . The plastic film of  claim 1 , wherein the strength is increased by at least 10% as compared to strength of a comparative film formed from only the first polymeric material. 
     
     
         10 . The plastic film of  claim 1 , wherein the renewable starch-based polymeric material is (i) substantially amorphous, having a crystallinity of no more than 20%, (ii) has a Young's modulus of at least 1.0 GPa, and (iii) has a glass transition temperature of 70° C. to 100° C. 
     
     
         11 . The plastic film of  claim 1 , wherein the renewable starch-based polymeric material is substantially amorphous, having a crystallinity of no more than 20%. 
     
     
         12 . The plastic film of  claim 1 , wherein the renewable starch-based polymeric material has a Young's modulus of at least 1.0 GPa. 
     
     
         13 . The plastic film of  claim 1 , wherein the renewable starch-based polymeric material has a glass transition temperature of 70° C. to 100° C.