丁苯胶乳接枝醋酸乙烯酯共聚改性的研究

GRAFTING COPOLYMERIZATION OF VAc ON BUTADIENE-STYRENE LATEX

为了改善丁苯胶乳(SB)与水泥的相容性,采用醋酸乙烯酯(VAc)单体与SB进行乳液接枝共聚。研究了单体浓度、引发剂和乳化剂的用量、反应温度、反应时间等对接枝率的影响,确定了最佳的接枝反应条件为:[VAc]=5.0mol/L;[(NH4)2SO3]=9.4×10-3mol/L;乳化剂C12H25SO3Na含量为4%(按单体质量计),温度80℃,时间3h。以IR测定了未接枝的的SB和接枝物的结构,比较二者的IR谱图,在1815.44cm-1、1753.91cm-1处有强吸收峰,表明接枝物含有羰基,从而证明VAc接枝到SB上。以SEM观察了胶乳的成膜性,接枝聚合物的成膜性远优于未接枝的SB膜;其拉伸强度显著提高。

In order that the compatibilities between butadiene-styrene(SB) latex and cement were modified, the (NH_4)_2SO_3-induced grafting copolymerization of vinyl acetate (VAc) to SB latex was studied. The effects of [VAc], [(NH_4)_2SO_3], [C_(12)H_(25)SO_3Na], reacting temperature and time on the degree of grafting were investigated. It shows that the optimum grafting conditions were [VAc]=(5.0) mol/L; [(NH_4)_2SO_3]=(9.4)×10^(-3) mol/L; [C_(12)H_(25)SO_3Na]:4 %(according to m(VAc)), t=80 ℃; t=3 h. When the IR spectra of ungrafted SB latex and SBR-g-VAc are compared, it is seen that in the specteum of SBR-g-VAc new absortion appeared, at about (1815.44) cm^(-1), (1753.91) cm^(-1)(ester carboxyl group), this proved that VAc is grafted onto the SBR. Compared the membrane-forming behaviour by SEM, SBR-g-VAc membrane is better than ungrafted SB latex membrane. The tensile strength of SBR-g-VAc membrane is increased notabily and its elongation of break is decreased.