The invention aims to use
acetic anhydride and
benzoic anhydride to perform esterification modification on cassava
starch to prepare double esterified
starch (DES) so as to improve the compatibility of
polylactic acid (PLA) and esterified
starch. The biodegradable double esterified starch / PLA film is prepared by adopting a solution
casting method, and the structure, morphology, air permeability, mechanical properties and biodegradability of the biodegradable double esterified starch / PLA film are researched. Compared with a pure PLA film, the 50 / 50
composite film has the advantages that the
water vapor transmission rate is reduced by 50%, the tensile strength is 3.8 MPa, the elongation at break is improved by 74%, and the
composite film has a better
composite effect, however, when the addition amount of the double esterified starch is 75%, the
composite film still has better mechanical properties (the tensile strength is 2.1 MPa, and the elongation at break is 125%). The composite film also has good transparency and degradation performance, and the degradation rate is 28% after the composite film is buried in soil for one week. The research provides an
effective method for preparing the starch /
polylactic acid composite film, the
raw material cost of a single PLA film is reduced, and the starch /
polylactic acid composite film is a promising biological
composite material.