Preparation And Properties Of Starch-based Porous And Membrane Materials

Starch is non-toxic, safe and biodegradable. Nature starch is sensitive to moisture,and exhibited low mechanical strength and freeze thaw stability. In order to overcomethe above-mentioned drawbacks, much effort has been focused on the functionaliza-tion of starch, which is generally called modified starch.Porous starch (PS) is a new type of modified starch, as the absorption material, itis non-toxic, safe and biodegradable, and focused on by domestic and foreign expertsand scholars. With the development of porous starch, it has been widely applicationon food, pharmaceuticals, agriculture, cosmetics, pulp, paper and other industries. Inthis study, potato starch was used to prepare controllable porous starch with differentstarch concentrations by the single or dual freezing process. The porous starch wascharacterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric(TG) analysis and scanning electron microscopy (SEM). In the single freezing process,with the increasing of the starch paste concentrations, pore size, moisture adsorption,oil adsorption capacity and methylene blue adsorption of PSs decreased greatly, whilethe apparent density increased. In the dual freezing process, the starch pasteconcentrations had few effects on the apparent density, pore size, moisture adsorption,oil adsorption capacity and methylene blue adsorption of CAPSs. In order to improveproperties of porous starch, preparation of succinic ester (SA) modified porous starch(SAPSs). With an increase of the SA/starch ratio, a linear increase in the degrees ofsubstitution (DS) of the SAPSs appeared. And the moisture adsorption, oil adsorptioncapacity and methylene blue adsorption of the SAPSs also apparent increased.Much effort has been made to devolop biodegradable materials because of theworldwife environment and resources problems resulted from petroleum-derivedplastics. Starch, a natural renewable polysaccharide obtained from a great variety ofcrops, is one of the promising raw materials for the production of biodegradableplastics. In this study, graphite and carbon black(CB) as raw material, the grapheneoxide(GO) and carbon black-oxide(CBO) were prepared by oxidizing graphite andcarbon black in a modified Hummer’s method, the GO were reduced by glucose toobtain reduced graphene oxide(RGO). The membrane materials were prepared by thecasting method. GO, RGO, CB and CBO were respectively dispersed into a solutionof distilled water, glycerol and potato starch were added into the obtained suspensions. And the mixture heated at95℃for0.5h with constant stirring. The mixture was castinto a film after being dried. The membrane materials were characterized by FT-IR,TG, SEM and ultraviolet-visible (UV-vis). Compared with starch film, improved themechanical strength, thermal stability, moisture barrier and qualify the functionalproperties such as ultraviolet-visible absorbance and electrical conductivity of thecomposites. The composites with desirable mechanical properties are one ofpromising candidates for advanced UV shielding, biochemical or electrochemicalmaterials.