Xu Jin-Ke, Zhang Li, Li De-Long, Bao Jin-Biao, Wang Zong-Bao
Ningbo Key Laboratory of Specialty Polymers, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, China.
ACS Omega. 2020 Apr 22;5(17):9839-9845. doi: 10.1021/acsomega.9b04501. eCollection 2020 May 5.
Poly(3-hydroxybutyrate--3-hydroxyvalerate) (PHBV) samples were successfully foamed using supercritical carbon dioxide as a physical foaming agent. PHBV sheets were first saturated at 175 °C followed by a foaming process at different temperatures (145 to 165 °C) and different CO pressures (10 to 29 MPa). It was found that microcellular structures with average cell sizes ranging from 6 to 22 μm and cell densities ranging from 10 to 1.2 × 10 cells/cm could be controllably prepared by selecting suitable foaming conditions. To investigate crystallization behavior during the foaming process and explore the corresponding foaming mechanism, differential scanning calorimetry, wide angle X-ray diffraction, and small-angle X-ray scattering characterizations were carried out. Stretching behavior during the cell growth stage may increase the crystal nucleation rate, and the generated crystal nucleus accelerates the crystallization rate as well as thickens PHBV crystal lamellae.
聚（3-羟基丁酸酯-3-羟基戊酸酯）（PHBV）样品成功地使用超临界二氧化碳作为物理发泡剂进行了发泡。PHBV片材首先在175°C下饱和，然后在不同温度（145至165°C）和不同CO压力（10至29MPa）下进行发泡过程。发现通过选择合适的发泡条件，可以可控地制备平均泡孔尺寸为6至22μm且泡孔密度为10至1.2×10个泡孔/cm的微孔结构。为了研究发泡过程中的结晶行为并探索相应的发泡机理，进行了差示扫描量热法、广角X射线衍射和小角X射线散射表征。泡孔生长阶段的拉伸行为可能会增加晶核形成速率，而生成的晶核会加速结晶速率并使PHBV晶体片层增厚。
