| In this paper,thezinc chloride solution was used as the plasticizer to prepare starch/cellulose blended materials.The molecular structure,the preparation methods of blended materials,and the factors that could affect the properties of blend materials were explored.The conclusions were as follows:1.The rheological properties of starch-cellulose-zinc chloride solutions were studied.Firstly,the effects of cellulose on the viscosity and viscosity stability of the solutions were much more obviously.Besides,there was no strong interaction between starch molecules and cellulose molecules in solutions.In addition,based on the rheological data of 40 samples,an empirical formula for the index n in rheological equation was obtained by regression method.And this empirical formula could calculate the index n of the mixed solution under any temperature,starch concentration,and cellulose concentration.2.Using the casting method,the starch/cellulose blended materials with the starch contentless than 50% were prepared.For the preparation,the ethanol/water mixture solutions were used as the coagulation baths.Under these coagulation baths,the surfaces of blended materials were smooth,the internal structures were uniform,and the zinc content of blended materials was 3 to 6%.What is more,with the increase of cellulose content in the blended materials,the tensile strength increased,the elongation at break decreased,the water absorption decreased,and the degradation rate decreased.The pure cellulose material had a tensile strength of 42.7±1.9 MPa,the elongation at break was 10.1±1.4%,the water absorption was 51.5±0.9%,and the 50-day degradation rate was 41.8±2.3%.When the cellulose content was reduced to 50%,the tensile strength of the blended material was 4.7±0.4 MPa,the elongation at break was 16.8±0.7%,the water absorption was 72.3±1.7%,and the 50-day degradation rate reached 70.6±1.9.%.The degradation rates of the blended material were not affected by the zinc content.3.Using the hot-pressing method,the starch/cellulose blend materials with the cellulose content less than 15% were prepared.The long straight cellulose molecules had a significant reinforcement effect on the starch-based material.Therefore,the thermo-degradation temperature and the mechanical properties of the blended materials were improved.However,if the amount of cellulose was too high,the phase separation occurred,and the mechanical properties became poor.When the content of cellulose was 7%,the tensile strength and elongation of blended materials were the highest,namely 4.0±0.3 MPa and 2.1±1.1%.Secondly,with the increase of zinc chloride solution(the plasticizer),thephase transitions of starch and cellulose were promoted,and the mechanical properties of the materials were improved.However,excessive zinc chloride solution caused the degradation of starch molecules,resulting in the deterioration of mechanical properties.Besides,when the hot pressing temperature was high,the phase transition of starch and cellulose was promoted,and the mechanical properties were improved correspondingly.However,if the temperature was too high,which made the moisture of zinc chloride solution vaporized,the structure of the blended materials becameloose,which resulted in the poor mechanical properties.4.The starch-cellulose-polyurethane acrylate composites were prepared by using PUA resin impregnation and curing method.When the resin concentration was 30%and the photocuring time was 120 s,the properties of the composites were best.The PUA resin could enter into the mesh of the starch/cellulose blended materials,so the surface of the material was smooth,flat and tight.Besides,the thermo-stability and the hydrophobicity of composites were obviously improved.When the photocuring time was 120 s and the resin elongation was 30%,the elongation at break and tensile strength reached the maximum were 99.3±6.1% and 11.3±1.4 MPa,respectively.The water absorption of the composite was 53.6%,which was lower than that of starch/cellulose blends,which was 32.7±1.5%. |
PDF Full Text Request