In-situ cooling of adsorbed water to control cellular structure of polypropylene composite foam during CO2 batch foaming process
In-situ cooling of adsorbed water to control cellular structure of polypropylene composite foam during CO2 batch foaming process
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CO2间歇发泡过程中吸附水的原位冷却控制聚丙烯复合泡沫的泡孔结构
DOI：
10.1016/j.polymer.2018.09.034
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发表时间：
2018-10-24
期刊：
影响因子：
4.6
通讯作者：
Tang, Tao
中科院分区：
文献类型：
--
作者：
Li, Minggang;Qiu, Jian;Tang, Tao
聚合物发泡过程中，特别是对于结晶聚合物如聚丙烯（PP），由于难以去除内部热量，泡孔结构的固定阶段难以控制。为了在固定阶段控制泡孔结构，我们建立了一种通用的方法，即在PP发泡过程中引入水作为原位内冷却剂。特别地，在发泡能力较差的高熔体流动指数聚丙烯（HMI-PP）中加入亲水性填料，研究吸附水对PP/填料复合材料在sc-CO2间歇发泡过程中发泡过程的影响。与纯HMI-PP相比，HMI-PP/亲水性填料复合材料表现出对水的吸附量和熔体粘度的增加。复合材料中的水在发泡过程中起着关键作用，不仅起到了物理发泡剂的作用，提高了PP复合泡沫的体积膨胀率，而且通过热成像技术证明了其具有快速冷却发泡的功能。结果表明，HMI-PP基体中亲水性填料的存在显著改善了HMI-PP的发泡性能，包括防止内部气泡破裂和显著提高泡沫体的体积膨胀率。用高分子量聚丙烯（HMW-PP）、高熔体强度聚丙烯（HMS-PP）等聚丙烯材料验证了该方法的适用性。
The fixation stage of cellular structure during polymer foaming process is difficult to control due to difficult removing of internal heat, especially for crystalline polymers such as polypropylene (PP). In order to control cellular structure in the fixation stage, we established an universal method by introducing water as an in-situ internal cooling agent during the foaming process of PP. Particularly, hydrophilic fillers were added into the high melt flow index polypropylene (HMI-PP) with poor foaming ability to study the effect of adsorbed water on the foaming process of PP/filler composites during sc-CO2 batch foaming process. Compared to pure HMI-PP, HMI-PP/hydrophilic filler composites showed increased adsorption amount for water and melt viscosity. The water within the composites played a key role in the foaming process, which not only served as a physical foaming agent to increase the volume expansion ratio of PP composite foam, but also showed the function of rapid cooling foam proved by thermal imaging technology. As a result, the presence of some hydrophilic fillers within HMI-PP matrix significantly improved the foaming properties of HMI-PP, including preventing internal bubble collapse and significantly increasing the volume expansion ratio of the foam. The applicability of this method was validated using other PP materials besides HMI-PP, including high molecular weight PP (HMW-PP), high melt strength PP (HMS-PP).