| This paper studied the effects of monomer ratio, emulsifier amount on the conversion rate of copolymer emulsion, gel content, latex particle size, rheological properties of latex and latex film-forming properties; the effects of Substituents, monomer ratio, film-forming additives on the thermal properties of copolymers; and also detail discussed properties of emulsion copolymers of the same number of C atoms of different substituent and different amount of emulsifier, focusing on its film-forming properties after the film-forming additives added; thermal properties of copolymers.In this paper, we synthesized N-phenyl maleamide acid (NPMA), N-cyclohexyl maleamide acid (CHMA) from the reaction of certain percentage of maleic anhydride (MA) and aniline or cyclohexylamine in the presence of ethyl acetate, Then the maleamic acid reacted with acetic anhydride, triethylamine at60℃, Obtained N-phenylmaleimide (NPMI), N-cyclohexylmaleimide (CHMI). the melting point of the products were Measured, the structure of the products was charactized by FT-IR、1H-NMR. in the range of copolymerization ratio of the heat-resistant monomers(maleic anhydride、N-phenyl (cyclohexyl) maleic acid amide (imide))and styrene,(1) changed the ratio of heat-resistant monomer with styrene, obtained high stability, high solid content (40%), low viscosity of the copolymer emulsion by seed emulsion polymerization,(2)when nst/nNRMI=95/5,changed the amount of added emulsifier,obtained copolymer emulsion by this method.the properties of emulsions and their films, such as stabilities, rheology, particle size, surface tension were charactized by rotary viscosimeter, PCS, surface tension instrument.added film-forming additives into the copolymer emulsion and tested the film-forming properties on the paper, glass, and polyester sheet.The results show that:First, NPMA、CHMA、NPMI、CHMI were synthesized by Modified of acetic anhydride method. The yield of these were more than73%.the melting point of each monomer are similar with the related literature.Second, Five kinds of copolymers Emulsion(St/MA, St/NPMA, St/CHMA, St/NPMI, St/CHMI) were prepared by semi-continuous emulsion polymerization, which were high conversion rate, low gel ratio, low viscosity.(1) copolymerization ratio of St and NPMI was up to70/30,the color of copolymer emulsion was bule, copolymerization ratio increased, latex color deepened. The copolymerization ratio of St and CHMI was no more than80/20, milky, two systems latex were high yield78%, stable, and lower gel ratio. NRNI content in mixed monomers increased, latex surface tension changed little, particle size decreases, Diameter distribution is narrow, the particle size or distribution of St/CHMI system greater than these of St/NPMI. emulsifier content increased.the two systems monomer conversion significantly improved, gel ratio was smaller, lower surface tension, particle size Small, narrow distribution, a more stable emulsion, the viscosity increased.(2) the copolymerization ratio of nst/ncHMA, nst/nNPMA less than96/4,adding appropriate amount of ammonia can increase the monomer conversion rate, reduce the amount of gel, it was in favor of emulsion stability when adding ammonia adjusted pH in the time of the pre-emulsion. compared with the same copolymerization ratio without adding ammonia adjusted pH, adding a certain amount of ammonia would improve the conversion rate of monomer, apparent viscosity increased.(3) nst/nMA is greater than or equal to80/20, the content of MA increased in the content of mixed monomer, monomer conversion decreased, gel ratio increased, surface tension decreased, viscosity increased, latex diameter increased,a narrow particle size distributions. it was good stability. All of systems copolymer emulsions were pseudoplastic fluid.Third, Toluene is the best film-forming additives of such copolymer emulsion, and the way of adding film-forming additives, when polymerization reaction is completed, which was the best. When added toluene12g in20g latex, St/NPMI, St/CHMI copolymer emulsion were able to filming on the sheet of paper or polyester, as for the glass, its Phenomenon are chap and Powder precipitation, St/CHMI copolymer emulsion were suitable to film on paper and polyester, which performance is better than other systems, Amount of emulsifier increases, the two systems copolymer emulsion filmed on the polyester performance better. When added toluene less than16g, the swelling of the St/NPMA, St/CHMA copolymer emulsion, which had a good film-forming properties on paper, St/CHMA had the best performance film on the polyester film, while St/NPMA had best performance film on the paper, when the system copolymer film on the glass, the film easy to shrink, dry and easy chap, bubble serious, concentration ratio increases, there was powder precipitation. Toluene is unfit for St/MA copolymer emulsion film-forming additives, when toluene was added, St/MA copolymer emulsion stability were break.Fourth, when fixed the monomer ratio, the glass transition temperature of cyclohexyl substituted copolymer were higher than phenyl substituted copolymer, Heat resistance of amide acid coplymer were better than imide copolymer. When the monomer ratio increases,In the same system, the heat resistance of copolymers increased, after adding film-forming additives, the glass transition temperature of the polymer was lower,Ti、Tf、 Tmax changed little. |
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