| Due to the shortage of petrochemical resources and environmental pollution caused by the extensive use of traditional polymers,it is great significance to develop a wide range of renewable starch resources and prepare biodegradable bio-based materials to replace the petrochemical based polymers.But starch itself has the defects of easy swelling and poor water resistance,which limits its application scope.In this thesis,starch was modified by esterification in solid phase reaction to improve its hydrophilic properties,and a series of starch carbamate（Sc）based composite films were prepared by combining the prepared Sc with other natural or synthetic polymers.We explored the application potential of starch carbamate based composite materials in degradable film materials,paper coated packaging materials and battery separator energy storage,hoping to broaden the application range of starch based biomass materials.（1）A biomass based composite film was prepared by a simple solution casting method by mixing Sc with cellulose nanofibers（CNF）and calcium lignosulfonate（CL）in proportion.We investigated the effects of the degree of substitution of Sc,the content of calcium lignosulfonate and CNF on the structure and properties of the composite films.The microstructure evolution of the composite films was tracked by SEM,FT-IR,XRD,TG and other characterization methods.The results showed that with the increase of urea concentration,the degree of substitution of Sc increased,then the mechanical properties,UV resistance,water resistance and thermal stability of the S c-CL-CNF composite films were significantly improved.When the degree of substitution of Sc was 0.14 and the amount of CL and CNF was 0.75 g and 6.5%,respectively,Sc-CL-CNF composite films had best mechanical properties（elongation at break is 118%）,UV blocking ability,water vapor blocking ability and thermal stability.Starch carbamate based composite film provided a new way for the design of degradable film packaging materials.（2）Sc-CL-CNF mixed film liquid prepared by the above method was used as coating and coated on the surface of paper.We investigated the effects of the degree substitution of starch carbamate,the content of CL and CNF on mechanical properties and barrier properties of paper.The results showed that when the degree of substitution of Sc was 0.1,the amount of CL and CNF was 1 g and 6.5%,respectively,the tensile index of composite coating paper was increased by 13.60%,the air blocking ability was increased by 89.08%,and the UV blocking ability was also greatly improving.Furthermore,nano-silver（Ag NP）solution was added into the coating solution to give antibacterial ability to coated paper,which was applied to cherry tomatoes packaging with obvious fresh-keeping effect.Sc-CL-CNF-Ag NP coated paper has great application potential in the field of food packaging.（3）The felt-like nanonetwork composite films with Sc and polyvinylidene fluoride（PVDF）were prepared by electrospinning and applied in the field of lithium ion battery separator.We investigated the effects of the degree of substation of Sc,Sc to PVDF ratio,spinning solution concentration and spinning voltage on mechanical properties and ionic conductivity of the composite films.The best electrospinning process was that the spinning voltage was 23 k V,the accepting distance was 14.5 cm,the advancing distance was 2 m L/h,the drum speed was 1000 rpm/min,the spinning solution concentration was 18%,the ratio of Sc to PVDF was 1:2,and th e degree of substation of Sc was 0.14.The Sc-PVDF composite film had excellent ionic conductivity(1.38×10-3 S cm-1)and mechanical properties（45 MPa,155%）.Sc-PVDF composite separator had specific capacity retention rate（95.63%）at 1 C cycles 100 times.Compared with commercial diaphragm PP,Sc-PVDF composite separator shows more outstanding cycle stability,and has good application potential in the field of battery separator. |
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