Li Zhengkun, Jia Yingbin, Bai Shibing
State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University Chengdu 610065 China
RSC Adv. 2018 Jan 12;8(6):2880-2886. doi: 10.1039/c7ra11760d.
Polysulfone (PSU) is considered as an important candidate for the fabrication of high-performance microcellular polymers, but the preparation of PSU foam with a high expansion ratio still remains a big challenge worldwide. In this study, high expansion ratio PSU foam was successfully prepared by a supercritical carbon dioxide (CO) assisted molding foaming method. The foaming behavior of PSU under supercritical CO was systematically studied in various process conditions and different microcellular structures were created in PSU foams. The results showed that foaming temperature and CO concentration were the key factors to obtain microcellular foams with tailored microstructures. The cellular structure and expansion ratio of PSU foam obviously changed with different foaming temperatures. The expansion ratio and average cell size firstly increased and then decreased as foaming temperature increased. However, the cell density decreased and then remained stable as foaming temperature increased. The maximum expansion ratio of 11.0 was reached at the optimum foaming temperature of 200 °C. Cellular structure and morphologies of the foam changed obviously at CO concentrations below 5% and remained stable at CO concentrations above 5%. Finally, the prepared PSU foams exhibit excellent mechanical strength, good thermal conductivity, and superb heat retardancy, thus may have great potential application as a kind of substitute material in the electrical wire and cable industry, railway and steamer transportation, oil and gas platforms, military use and in other fields.
聚砜（PSU）被认为是制造高性能微孔聚合物的重要候选材料，但制备具有高膨胀率的聚砜泡沫在全球范围内仍然是一个巨大的挑战。在本研究中，通过超临界二氧化碳（CO₂）辅助模塑发泡法成功制备了高膨胀率的聚砜泡沫。系统研究了聚砜在超临界CO₂下在各种工艺条件下的发泡行为，并在聚砜泡沫中形成了不同的微孔结构。结果表明，发泡温度和CO₂浓度是获得具有定制微观结构的微孔泡沫的关键因素。聚砜泡沫的泡孔结构和膨胀率随不同的发泡温度而明显变化。随着发泡温度的升高，膨胀率和平均泡孔尺寸先增大后减小。然而，泡孔密度随着发泡温度的升高而降低，然后保持稳定。在200℃的最佳发泡温度下达到了最大膨胀率11.0。当CO₂浓度低于5%时，泡沫的泡孔结构和形态明显变化，而当CO₂浓度高于5%时则保持稳定。最后，制备的聚砜泡沫表现出优异的机械强度、良好的导热性和卓越的阻燃性，因此作为一种替代材料在电线电缆行业、铁路和轮船运输、油气平台、军事用途及其他领域可能具有巨大的潜在应用价值。
