Controllable cell structures of poly(ether-block-amide) foams via isothermal melt crystallization-foaming in supercritical CO2

IF 3.4 3区工程技术 Q2 CHEMISTRY, PHYSICAL Journal of Supercritical Fluids Pub Date : 2023-10-01 DOI:10.1016/j.supflu.2023.106030

Chenguang Wang, Menglong Xu, Yichong Chen, Zhimei Xu, Ling Zhao, Dongdong Hu

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Abstract

A simple isothermal melt crystallization-foaming method was proposed to regulate the crystallinity (X_c) of PEBA to prepare poly(ether-block-amide) (PEBA) foams with uniform or bimodal cell structures by supercritical CO₂. PEBA with different X_c values was obtained by controlling the isothermal crystallization temperature (T_iso) and time (t_iso). The rheological and DSC results showed that the viscoelasticity and X_c of the samples increased with decreasing T_iso and increasing t_iso. PEBA foams with X_c above 1.1% exhibited a distinct bimodal cell structure. The increased crystals acted as heterogeneous nucleation sites to increase the cell density from 6.8 × 10⁶ cells/cm³ to 3.58 × 10¹⁰ cells/cm³. The size of large cells decreased from 206.4 µm to 48.0 µm, and the number ratio of small to large cells increased from 2.34 to 65 times. Finally, a mechanism to explain the cell structure variation in PEBA foams was proposed, providing a new strategy for regulating the cell structure of polymeric foams.

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超临界CO2等温熔融结晶发泡聚醚块酰胺泡沫的可控制胞体结构

提出了一种简单的等温熔融结晶发泡方法来调节PEBA的结晶度（Xc），通过超临界CO2制备具有均匀或双峰胞结构的聚醚嵌段酰胺（PEBA）泡沫。通过控制等温结晶温度（Tiso）和时间（Tiso）获得具有不同Xc值的PEBA。流变学和DSC结果表明，样品的粘弹性和Xc随着Tiso的减少和Tiso的增加而增加。Xc高于1.1%的PEBA泡沫表现出明显的双峰胞结构。增加的晶体作为非均匀成核位点，使细胞密度从6.8×106个细胞/cm3增加到3.58×1010个细胞/cm3。大细胞的大小从206.4µm减少到48.0µm，小细胞与大细胞的数量比从2.34倍增加到65倍。最后，提出了解释PEBA泡沫中细胞结构变化的机制，为调节聚合物泡沫的细胞结构提供了新的策略。

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来源期刊

Journal of Supercritical Fluids 工程技术-工程：化工

CiteScore

7.60

自引率

10.30%

发文量

236

审稿时长

56 days

期刊介绍： The Journal of Supercritical Fluids is an international journal devoted to the fundamental and applied aspects of supercritical fluids and processes. Its aim is to provide a focused platform for academic and industrial researchers to report their findings and to have ready access to the advances in this rapidly growing field. Its coverage is multidisciplinary and includes both basic and applied topics. Thermodynamics and phase equilibria, reaction kinetics and rate processes, thermal and transport properties, and all topics related to processing such as separations (extraction, fractionation, purification, chromatography) nucleation and impregnation are within the scope. Accounts of specific engineering applications such as those encountered in food, fuel, natural products, minerals, pharmaceuticals and polymer industries are included. Topics related to high pressure equipment design, analytical techniques, sensors, and process control methodologies are also within the scope of the journal.