Preparation And Application Of Hydroxyl-terminated Polystrene

As the country 's emphasis on environmental protection and the demand of quality life becomes higher and higher,waterborne polyurethane coatings develop rapidly.However,traditional aqueous polyurethane coating is soft and heat resistance is not good.Aimed at this drawback,this thesis mainly study synthesis of hydroxyl-terminated polystyrene(HTPS)with anionic active polymerization and then apply into polyurethane to improve the performance.In this thesis,hydroxyl-terminated polystyrene was synthesized using sodium naphthalene as initiator,tetrahydrofuran as solvent,styrene as monomer.Synthesis process was adding sodium naphthalene and styrene into the tetrahydrofuran,after the reaction system changing into red add epoxy propane,finally acidize and add anhydrous ethanol.With the orthogonal design method and single-factor-experiment,the technics of synthesizing Hydroxyl-terminated Polystyrene had been studied in this paper.Optimizational process was polymerization temperature was 0?,polymerization time was 60 minutes,the molecular mole ratio of monomer and initiator controlled molecular weight of polymer.The chemical structure of samples were characterized by IR and 1H NMR,the result shows the synthesized product is the target product;Its molecular weight was measured by GPC,the theory molecular weight was near to the measured molecular weight;Phthalic anhydride method was used to measure hydroxyl value of sample,and then calculate molecular weight of polymer.The result shows that using this method,the molecular weight of HTPS can be controlled accurately.The UV-curable waterborne polyurethane was synthesized by using isophorone diisocyanate(IPDI)?polytetrahydrofuran(PTMEG,Mn=2000)?hydroxyl-terminated polystyrene and dimethylol propionic acid(DMPA).The rigid phenyl group was introduced into the UVWPU structure to improve heat resistance and hardness of the coating film,the product was confirmed by IR.The effect of curing parameter?amount of DMPA and hydroxyl-terminated polystyrene on the properties of coating and emulsion stability were investigated.The result shows that the storage stability of the emulsion is over 6 months when the amount of DMPA is above 6%.DMPA amount from 6%to 9%.The average particle diameter of emulsion decreases from 84.64 nm to 55.28 nm;The coating film exhibit excellent appearance and good properties when the curing parameter is above 1.35;The pencil hardness is H and adhesion of modified coating film is 1;5%and 10%of weight-loss temperature is at 245? and 282?.The temperature of 5%and 10%weight-loss is 32? and 27? higher than the UVWPU without modified,the adhesion and pencil hardness are also improved.