The Research And Application Of Starch Adhesive Modified By Vinyl Monomers

In recent years, natural polymers and modified natural polymer have beengaining increasing importance in the industry, which promote in-depth study ofstarch modification technology. Some main chemical raw material such as starchis relatively inexpensive, abundant, renewable and biodegradable. After beingmodified, it can possess the properties of both starch and modifier, and thesis thisresearch have being focused on. In this paper, use maize starch as main material,ammoniaum persulfate as oxidant. Based on oxidized maize starch which was notpasted, ammoniaum persulfate-sodium bisulfite redox system was chose as theinitiator of copolymerization in this paper, using styrene, ethyl acrylate, butylacrylate and acrylic acid, with the graft of maize starch, and then starch graftcopolymers was prepared. The applied research such as water-resistance andflowability of starch adhesives used in paper adhesives was mainly studied.The single-factor experiments were used to study the effect of reaction time,reaction temperature, the dosage of initiator and monomer on applicationperformance of starch adhesive. On the basis of the single-factor experiments, thefour factors and five levels orthogonal experiment was used to decide theoptimum reaction conditions. Through the single factor experiment, the factorsthat had importantly influenced on viscosity and water absorption were mainlyinvestigated, including the dosage of oxidant, the dosage of initiator andmonomer, reaction time, reaction temperature. The optimum conditions were: thedosage of oxidant (ammoniaum persulfate)1.2%(mass ratio, based on native cornstarch, the same blow), the dosage of initiator0.6%, the amount of monomer15%,reaction time2h, reaction temperature50℃.In addition, to research the effect of additives on application performance ofproduct, the single-factor experiments were used too. These factors werecomposed of the dosage of fillers, preservatives, plasticizers and defoamers, Onthe basis of the experiments, the four factors and three levels orthogonalexperiment was used to decide the optimum reaction conditions. Through thesingle factor experiment, the factors that had importantly influenced on viscosityand water absorption were mainly investigated, including the dosage of fillers,preservatives, plasticizers and defoamers. The optimum conditions were: the dosage of fillers (bentonite)5%(mass ratio, based on native corn starch), thedosage of plasticizers (glycerine)3%(mass ratio, based on native corn starch)amount of preservatives (sodium benzoate)3‰, the dosage of defoamers (tributylphosphate)5‰.On this condition, the viscosity of starch adhesives was about850mPa.s, the water-resistant time increased to21d, storage time was above30dand water absorption was46%.Native starch, oxidized maize starch and starch graft copolymers wereinvestigated by Fourier Transform Infrared (FTIR) spectroscopy, ScanningElectron Microscope (SEM) and Thermogravimetric analysis (TG).The resultsindicated that starch graft copolymers not only in the molecular, but also in themorphological appearance all have apparent changes. These changes can play adecisive role in improving application performance of starch and expanding theapplication of starch.In a word, starch adhesive modified by oxidant and vinyl monomers, afterdetermining, can meet the need of industry and application. However, from thepoint of all the experiment, not all the use have gained the best performance,further study will still be needed.