Zimnyakov Dmitry, Alonova Marina, Ushakova Ekaterina
Physics Department, Yury Gagarin State Technical University of Saratov, 410054 Saratov, Russia.
Precision Mechanics and Control Institute of Russian Academy of Sciences, 24 Rabochaya st., 410024 Saratov, Russia.
Polymers (Basel). 2021 Apr 1;13(7):1115. doi: 10.3390/polym13071115.
Self-similar expansion of bubble embryos in a plasticized polymer under quasi-isothermal depressurization is examined using the experimental data on expansion rates of embryos in the CO-plasticized d,l-polylactide and modeling the results. The CO initial pressure varied from 5 to 14 MPa, and the depressurization rate was 5 × 10 MPa/s. The constant temperature in experiments was in a range from 310 to 338 K. The initial rate of embryos expansion varied from ≈0.1 to ≈10 µm/s, with a decrease in the current external pressure. While modeling, a non-linear behavior of CO isotherms near the critical point was taken into account. The modeled data agree satisfactorily with the experimental results. The effect of a remarkable increase in the expansion rate at a decreasing external pressure is interpreted in terms of competing effects, including a decrease in the internal pressure, an increase in the polymer viscosity, and an increase in the embryo radius at the time of embryo formation. The vanishing probability of finding the steadily expanding embryos for external pressures around the CO critical pressure is interpreted in terms of a joint influence of the quasi-adiabatic cooling and high compressibility of CO in the embryos.
利用在CO增塑的d，l-聚丙交酯中胚胎膨胀速率的实验数据并对结果进行建模，研究了准等温降压下泡状胚胎在增塑聚合物中的自相似膨胀。CO初始压力在5至14MPa之间变化，降压速率为5×10MPa/s。实验中的恒定温度在310至338K范围内。随着当前外部压力的降低，胚胎的初始膨胀速率从约0.1μm/s变化到约10μm/s。在建模时，考虑了临界点附近CO等温线的非线性行为。建模数据与实验结果令人满意地吻合。外部压力降低时膨胀速率显著增加的效应是根据竞争效应来解释的，这些效应包括内部压力的降低、聚合物粘度的增加以及胚胎形成时胚胎半径的增加。对于围绕CO临界压力的外部压力，找到稳定膨胀胚胎的消失概率是根据胚胎中CO的准绝热冷却和高压缩性的联合影响来解释 的。
