Hollow poly(alpha-methylstyrene) (PAMS) shows application in inertial confinement fusion experiments as the degradable mandrels of glow plasma polymer shells. However, the molecular weight of PAMS has great influence on the quality of mandrels. In this work, this influence was systematically studied using several PAMS samples with different molecular weights. For PAMS shells with 900 μm inner diameter and different wall thickness, when the molecular weight of PAMS is in the range of 300-500 kg·mol^-1, perfect sphericity and good wall thickness uniformity can be obtained. In contrast, when increasing molecular weight to 800 kg·mol ^-1, the sphericity and the wall thickness uniformity become worse. Moreover, compared with the wall uniformity, the sphericity of PAMS shells was much less sensitive to the molecular weight. The results also showed that the stability of W1/O compound droplets of PAMS shells were less affected by the molecular weight. It was revealed that the wall uniformity and the sphericity of the PAMS shells were associated with the diffusion rates of fluorobenzene (FB).

Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion (ICF) experiments. Driven by the need to control the shape of water-in-oil (W1/O) compound droplets, the effects of the density matching level, the interfacial tension and the rotation speed of the continuing fluid field on the sphericity and wall thickness uniformity of the resulting polymer shells were investigated and the spherical and concentric mechanisms were also discussed. The centering of W1/O compound droplets, the location and movement of W1/O compound droplets in the external phase (W2) were significantly affected by the density matching level of the key stage and the rotation speed of the continuing fluid field. Therefore, by optimizing the density matching level and rotation speed, the batch yield of polystyrene (PS) shells with high sphericity and uniform wall thickness increased. Moreover, the sphericity also increased by raising the oil/water (O/W2) interfacial tension, which drove a droplet to be spherical. The experimental results show that the spherical driving force is from the interfacial tension affected by the two relative phases, while the concentric driving force, as a resultant force, is not only affected by the three phases, but also by the continuing fluid field. The understanding of spherical and concentric mechanism can provide some guidance for preparing polymer shells with high sphericity and uniform wall thickness.Physics for financial support (2014B0302052) and National Natural Science Foundation of China (U1530260).

为提高惯性约束聚变（ICF）点火靶尺度（约2 mm）聚苯乙烯（PS）空心微球的球形度,研究了油相与外水相界面张力、初始油相质量分数和固化旋转流场转速对PS微球球形度的影响。结果表明,将双重乳液体系外水相中的表面活性剂聚乙烯醇（PVA）替换为聚丙烯酸（PAA）后,油相与外水相之间的界面张力增大了约10倍,PS空心微球的球形度显著提高,球形偏离度小于1 μm的微球比例由5%增加至约50%；但是,在较宽范围内改变油相初始质量分数及旋转固化流场转速,对PS微球球形度的影响并不显著,球形偏离度值小于1 μm的PS微球比例介于40%~60%之间。

在乳液微封装技术制备聚苯乙烯空心微球的工艺中，固化过程是决定微球球形度及壁厚均匀性的关键阶段。基于乳粒发生器制备内径(850±10) μm、壁厚(250±25) μm的复合乳粒，以25 ℃,45 ℃和65 ℃作为固化温度，考察了固化温度对微球球形度和壁厚均匀性的影响。结果表明，固化温度越低，界面张力越高，乳液固化速率越慢，微球球形度和壁厚均匀性越好。当固化温度为25 ℃时，批次微球中球形偏离值优于2 μm的微球产率为90%，壁厚偏差值优于2 μm的微球产率为40%，明显优于固化温度为45 ℃和65 ℃时微球的质量。

采用射频(RF)感应等离子体对颗粒形状不规则的氧化铝粉作球化处理, 当氧化铝以极短暂时间快速穿越射频等离子体炬时, 颗粒因受热而熔化成液滴, 快速冷却, 形成球形固态颗粒。应用单因素法讨论射频等离子体制备球形氧化铝的工艺参数, 研究了制备过程中相关的中气流量、抽风负压、送粉速度和分散方式等主要工艺参数对球形氧化铝粉的影响。用电子扫描显微镜(SEM)观测评估球化效果, 测定松装密度和振实密度。

为建立高效简洁的厚壁空心微球球形度和壁厚均匀性的表征和测量方法, 以内径850 μm、壁厚25 μm的厚壁聚苯乙烯(PS)微球为测量对象, 分析球形度和壁厚均匀性的表征方法, 探讨测量过程中采样方式对表征微球球形度和壁厚均匀性的影响。研究表明: 对于批量微球球形度和壁厚均匀性的表征, 当抽样数目不小于30时, 测量结果之间的差异很小; 而对于单一微球的球形度和壁厚均匀性的表征, 至少3个不同投影面的测量结果的平均值才趋于稳定。不同投影面导致球形度或壁厚均匀性较差的批次样品的测量结果有一定差异, 多次投影测量可提高测量结果的可靠性。

基于VMR显微镜系统, 提出了一种小批量测量聚α-甲基苯乙烯(PAMS)芯轴直径和球形度的方法, 初选满足技术指标的微球。小批量测量1 mm标准球, 测量结果95%出现在(998.2±1.2)μm之间。测量值与标准值之间的偏差为标准值的0.06%, 扩展不确定度偏差为测量值的0.24%, 说明该批量测量结果准确度和稳定性较好。将此方法应用于PAMS芯轴初选, 与手动测量结果相比, 批量测量结果的偏差具有单向性, 且最大偏差约10 μm, 满足初选测量要求。

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