Study On Synthesis And Application Of Starch Graft Copolymers

With the development of modern science and technology, the application of starch and its products are more widely, promote the development of the starch industry and in-depth study of starch technology. Starch is a wide variety of sources, low-cost natural macromolecular polymer, which are not only biodegradable but also renewable. Modified starch is the main way to expand the application of starch. After deformation of the starch, the chemical structure of starch has changed, so it has the performance which raw starch does not have. There are many ways of denatured starch, including the acid denaturation, oxidation, crosslinking, esterification, etherification, graft and so on.In this paper, the grafted method of modified starch was studied. With the graft skeleton of corn starch and under starch which were not pasting conditions, it was studied the graft copolymerization reaction of starch with the mixed monomers, which were formed by butyl acrylate (BA) and vinyl acetate (VAC), and the applied research of the starch graft copolymers was used in wood adhesives and interior wall paints.First, Screening study in the initiator or initiator system of the starch graft copolymer-rization reaction, compared and analyzed trigger effect of the three initiator system. These three initiator or initiator system were potassium permanganate, potassium persulfate-sodium thiosulfate and potassium persulfate. Final potassium persulfate was choiced as the initiator of graft copolymerization in this experiment.Next, the single-factor experiments were used to determine the optimum reaction conditions of the graft copolymerization of starch and the mixed monomers, which were formed by butyl acrylate (BA) and vinyl acetate (VAC). That the optimum conditions was the reaction time of 3h, the reaction temperature of 60℃,the monomer concentration of 3.0mol/L, the mixed-monomer mole ratio VAC:BA of 6:4,the initiator concentration of 2.0×10-2mol/L, the emulsifier concentration of 2.5 x 10-2mol/L. In these conditions,the graft rate and the graft efficiency were higher. Then in the base of single-factor experiment, four factors were selected, which were greater impact of the graft rate and the graft efficiency. By using orthogonal experiment analysis and the range analysis, the effect order of the graft rate in the four factors were:reaction time>monomer concentration>monomer ratio>initiator concentration.Using infrared spectroscopy, X-ray diffraction, thermal analysis and scanning electron microscopy testing methods analyze starch and starch graft copolymers, which found graft copolymer not only in the morphological appearance, but also in the molecular structure were all have great changes compared to native starch. These changes played a decisive role in improve various performance of starch and expanded the application of starch.The starch graft copolymer was used in wood adhesives and interior wall coating. The test results of study from morphology, pH, solid content, viscosity, shear strength, water resistance, stability, storage period, low temperature stability, drying time, coating appearance, abrasion resistance, alkali resistance and so on, founded that it could apply to these two aspects, but overall the use has not achieved the best performance, still need further study.