Study On Preparations And Performances Of Functionalized Zein Films

Zein,a major by-product of the starch processing and bioethanol industries,could be converted into films through self-assembly.Due to its water-insolubility,biodegradability and biocompatibility,zein has the potential to become a functionalized material.However,zein films have limited application in chemical engineering and environmental protection because of some inherent drawbacks,such as brittleness,poor processability and low adsorption capacity for ions.In this thesis,to enhance the mechanical properties and adsorption for heavy metal ions,the preparations and modifications of zein films were studied in depth as follows.?1?To obtain high-elongation zein films,glycerol and a series of polyethers,i.e.poly?ethylene glycol?,poly?propylene glycol?or poly?tetramethylene glycol?,were chosen as mixed plasticizers.The synergistic plasticized zein films showed excellent elongation at break of 530%with lower glass transition temperature.This result was attributed to the structural change of zein molecules,i.e.the disruption of inter-?-helix packing and the increase of?-sheet content,then the plasticization mechanism was proposed.Due to the hydrophilic/hydrophobic nature of plasticizers and the structure of films,plasticized zein films had different water vapor permeabilities.All zein films exhibited excellent UV barrier properties.?2?The coaxial electrospinning was utilized to embed sodium lignosulfonate?SLS?in electrospun zein films to enhance adsorption capacity for heavy metal ions.The optimal main process parameters were determined,i.e.,the electrospinning voltage 14 kV,core-to-sheath flow rate ratio 1:1.TEM result indicated that SLS was embedded successfully in electrospun zein films,but its loading capacity and encapsulation efficiency were influenced by the pH of solution.The results indicated that SLS enhanced adsorption capacity of Ni²⁺,Zn²⁺and Cd²⁺,and the pseudo-second-order model was more suitable to describe the adsorption.Furthermore,the adsorption capacity increased with increasing the pH of solution.These results are valuable for the modifications and functionalizations of zein films.