Microcapsules containing initiator of cumene hydroperoxide or tert-butyl peroxy-2-ethylhexanoate as core material and polyurea as shell material were prepared by condensation polymerisation in oil-in-water emulsion at different agitation speeds. And their effects on the polymerisation of methyl methacrylate were investigated by isothermal differential scanning calorimetry. In comparison to unencapsulated initiators, the use of encapsulated initiators significantly delayed the reaction, reduced the maximum heat flow, relatively reduced the maximum reaction rate, and made the conversion smaller. In addition, the encapsulated initiator shortened the time lag, increased the heat flow at the maximum point as the reaction temperature increased, and further delayed the appearance time of the maximum reaction point as the agitation speed decreased. The theoretical values calculated by the modified Kamal model, including the nth-order reaction formula and the autoacceleration reaction, were in good agreement with our experimental data. We observed the more prominent autoacceleration reaction at a higher conversion.

中文翻译：

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等温差示扫描量热法研究引发剂封装对甲基丙烯酸甲酯聚合的影响。

通过在水包油型乳液中以不同的搅拌速度进行缩聚反应，制备了以氢过氧化枯烯或过氧-2-乙基己酸叔丁酯为引发剂，聚脲为壳材料的微胶囊。通过等温差示扫描量热法研究了它们对甲基丙烯酸甲酯聚合的影响。与未包封的引发剂相比，使用包封的引发剂显着延迟了反应，降低了最大热流，相对降低了最大反应速率，并使转化率降低。另外，包封的引发剂缩短了时间滞后，随着反应温度升高，在最大点增加了热流，并且随着搅拌速度的降低进一步延迟了最大反应点的出现时间。由改进的Kamal模型计算得到的理论值，包括n阶反应公式和自加速反应，与我们的实验数据非常吻合。我们观察到在更高的转化率下更显着的自加速反应。