PM Development Team, Lotte Chemical Corporation, Daejeon, Republic of Korea.
Department of Polymer Science and Engineering, Chungnam National University, Daejeon, Republic of Korea.
J Microencapsul. 2020 May;37(3):183-192. doi: 10.1080/02652048.2020.1714763. Epub 2020 Jan 31.
Microcapsules containing initiator of cumene hydroperoxide or -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 th-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.
采用油包水乳液缩聚法制备了以过氧化二异丙苯或过氧化叔丁基-2-乙基己酸酯为芯材、聚脲为壳材的微胶囊引发剂，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。与未封装的引发剂相比，使用封装的引发剂显著延迟了反应，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。此外，随着反应温度的升高，包封引发剂缩短了时滞，增加了最高点的热流，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。通过改进的 Kamal 模型计算的理论值，包括 th 级反应公式和自动加速反应，与我们的实验数据吻合较好。我们在更高的转化率下观察到更明显的自动加速反应。
