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使用了一种有特殊形态结构的均相化非均相催化剂——杨梅型聚羧酸氧钒(Ⅳ)(PV)与硫脲(TU)组成的氧化还原体系,引发硝酸溶液中丙烯腈(AN)的聚合反应。在实验条件下,得到表现聚合速度的关系式如式(1)。PV(Ⅳ)-TU体系引发丙烯腈和丙烯酸甲酯(MA)共聚合的结果,表明反应按自由基机理进行。 硫酸氧钒(Ⅳ)与硫脲的组合不能引发丙烯腈聚合,但杨梅型聚羧酸氧钒(Ⅳ)在羧基配位体的协同作用下,极容易通过络合物内部的电子转移被氧化成五价钒而有较高的引发活性。这一氧化过程被大分子链效应所促进。大分子链的空间阻碍使链终止反应遵循双分子历程而不是通过向钒(Ⅴ)转移的方式进行。这些异常的行为从硫酸氧钒(Ⅳ)、异丁酸氧钒(Ⅳ)和聚甲基丙烯酸氧钒(Ⅳ)的模拟试验,以及VO_2~+-TU氧化还原体系引发硝酸溶液中丙烯腈聚合动力学的研究结果所证实。
A redox system consisting of a homogeneous heterogenous heterogeneous catalyst with special morphological structure, ie, bayberry-type poly (vinylene carbonate) (PV) and thiourea (TU), was used to initiate the nitrile acid solution of acrylonitrile AN) polymerization reaction. Under the experimental conditions, the relationship between the polymerization rate and the polymerization rate is obtained as shown in equation (1). The PV (IV) -TU system initiated the copolymerization of acrylonitrile and methyl acrylate (MA), indicating that the reaction proceeds according to the free radical mechanism. The combination of vanadyl sulfate (IV) with thiourea does not initiate the polymerization of acrylonitrile, but vanadium (IV) vanillin polycarboxylate is very easily oxidized by electron transfer within the complex under the synergistic effect of the carboxy ligands Vanadium pentavalent and have a higher activity. This oxidation process is promoted by the macromolecular chain effect. The steric hindrance of the macromolecular chains allows the chain termination reaction to follow a bimolecular process rather than by transferring to vanadium (V). These abnormal behaviors were simulated from the simulation of vanadyl sulfate (IV), vanadyl isobutyrate (IV) and vanadyl poly (valerate) (IV), and the polymerization of acrylonitrile in nitric acid solution initiated by VO_2 ~ + -TU redox system Kinetic findings confirmed.