Multi-Fold Enhancement in Compressive Properties of Polystyrene Foam Using Pre-delaminated Stearate Functionalized Layer Double Hydroxides
Multi-Fold Enhancement in Compressive Properties of Polystyrene Foam Using Pre-delaminated Stearate Functionalized Layer Double Hydroxides
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DOI：
10.3390/polym12010008
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发表时间：
2019-12
期刊：
影响因子：
5
通讯作者：
Emmanuel O. Ogunsona;K. Dagnon;N. D'Souza
中科院分区：
文献类型：
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作者：
Emmanuel O. Ogunsona;K. Dagnon;N. D'Souza
开发环境友好的苯乙烯泡沫是一个关键的环境需求。超临界CO2在泡沫塑料中的应用已被证明是一条有价值的途径。同时还在研究添加填料以增加气泡成核。使用的主要填料是高表面积填料，例如近晶粘土。然而，迄今为止的所有研究表明，压缩模量的极限为152%，压缩应力的极限为260%。即使有这样的增益，这些值也限制了结构应用。Suh和Cotton在1987年的开创性工作证明了碳酸钙和CO2中的羰基键相互作用并影响超临界CO2泡沫的成核效率和性能。本文合成了一种高比表面积粘土（层状双氢氧化物），它以剥离状态开始，然后用长链烷基羧酸酯（硬脂酸）官能化。结果是与聚苯乙烯（PS）相比，压缩性能显著提高数倍;压缩模量和强度分别增加268%和512%。使用预分层方法，在粘土中实现了更高的表面积。硬脂酸盐的存在通过疏水-疏水相互作用改善了粘土层与PS之间的相互作用。观察到纳米复合材料的玻璃化转变温度在发泡后向更高的值偏移。结果指出了一条使用具有官能团的预分层粘土来提高环保泡沫性能的新途径。
Developing an environmentally benign styrene foam is a critical environmental need. Supercritical CO2 use in foams has proven to be a valuable path. Adding fillers to increase bubble nucleation has been pursued concurrently. A prominent filler used is high surface area fillers, such as smectic clays. However, all studies to date show a limit of 152% in compressive moduli and 260% in the compressive stress. The values, even with such gains, limit structural application. A seminal work in 1987 by Suh and Cotton proved that carbonyl linkages in calcium carbonates and CO2 interact and impact nucleation efficiency and performance in supercritical CO2 foams. In this paper, a high surface area clay (layer double hydroxides) which begins in an exfoliated state, then functionalized with a long chain alkyl carboxylate (stearic acid) is synthesized. The result is a remarkable multi-fold improvement to the compressive properties in comparison to polystyrene (PS); a 268% and 512% increase in compressive modulus and strength, respectively. Using a pre-delaminated approach, the higher surface area was achieved in the clays. The presence of the stearate improved the interactions between the clay galleries and PS through hydrophobic-hydrophobic interactions. The glass transition temperature of the nanocomposites was observed to shift to higher values after foaming. The results point to a new path to increase performance using a pre-delaminated clay with functional groups for environmentally benign foams.