微波辐照实现PVC-PS之间的Friedel-Crafts接枝反应

在四氢呋喃、环己酮等溶液中实现了聚氯乙烯(PVC)与聚苯乙烯(PS)的Friedel-Crafts接枝反应,考察了加热方式、反应温度、催化剂种类、催化剂用量对接枝反应的影响,通过FTIR表征了PVC-g-PS接枝物的结构,探讨了反应的机理和特点.研究发现,油浴加热和微波辐照都能使PVC和PS发生接枝反应,但微波辐照效果更好,油浴加热,接枝率仅0.27%,而微波辐照接枝率高达23%;油浴加热时产物少且多为间位,微波辐照时产物多且多为对位和邻位.无水AlCl3、无水FeCl3、无水SnCl4皆对PVC与PS之间的Friedel-Crafts反应具有催化活性,其中无水AlCl3的催化活性最高,其最佳用量为质量分数3%,此时,接枝率达到29%.当无水AlCl3过高时,PVC降解,产生双键,接枝率下降.表明微波辐照是实现PVC与PS之间Friedel-Crafts接枝反应的有效途径.

FRIEDEL-CRAFTS REACTION GRAFTING OF PVC AND PS THROUGH MICROWAVE IRRADIATION

With tetrahydrofuran or cyclohexanone as dissolvent,Friedel-Crafts reaction grafting of polyvinyl chloride and polystyrene was realized through microwave irradiation.Graft of PVC-g-PS was successfully prepared.Influence of heating method,reaction temperature,type and mass fraction of catalyst on grafting reaction and grafting ratio was investigated.Graft structure of PVC-g-PS was characterized through FTIR,the mechanism and features were discussed.Results showed that Friedel-Crafts reaction grafting of polyvinyl chloride and polystyrene can carry out through heating by oil bath or microwave irradiation.Under heating with oil bath the graft of PVC-g-PS occurs at the meta position of the benzene ring,and the graft ratio is only 0.27%;while in the case of microwave irradiation,the graft of PVC-g-PS occurs at ortho-para positions of the benzene ring,and the graft ratio reaches up to 23%.Anhydrous AlCl3,FeCl3 or SnCl4 can all catalyze Friedel-Crafts reaction grafting of polyvinyl chloride and polystyrene,but the best catalytic activity is observed for anhydrous AlCl3.When the mass fraction of anhydrous AlCl3 is 3%,the highest graft ratio reaches up to 29%,but when mass fraction of anhydrous AlCl3 is over 3%,the graft ratio declines,PVC begins degradation and produces olefinic bonds.Research results demonstrate that microwave irradiation is an effective way of realizing Friedel-Crafts reaction grafting of polyvinyl chloride and polystyrene.