Exothermic Supercooled Liquid-Liquid Transition in Amorphous Sulfur

Amorphous sulfur （a-S） is prepared by rapidly compressing molten sulfur to high pressure. From differential scanning calorimeter measurements, a large exothermic peak has been observed around 396K. Online wide-angled x-ray scattering spectra indicate that no crystallization occurs in the temperature range 295-453K, suggesting that the exothermal process corresponds to an amorphous-to-amorphous transition. The transition from amor- phous sulfur to liquid sulfur is further verified by the direct observation of sulfur melt at the temperature of the associated transition. This is the first time of reporting that a-S transforms to liquid sulfur directly, which has avoided a crystallization process. What is more, the transition is an exothermic and a volume expansion process.     

新型显示偏光片光学膜的加工-结构-性能关系

偏光片是薄膜晶体管液晶显示器(TFT-LCD)和有机发光二极管显示(OLED)中最重要的组成部分之一,是一种是由偏光膜、支撑膜、相位差膜等光学膜组合成的多层高分子复合膜.每个组成膜所用材料不同,在偏光片中也发挥不同的作用.随着新型显示的发展,偏振片的产业规模和需求呈井喷之势.然而,目前国内偏光片主要依赖进口,其原因是对偏光片中的各层高分子薄膜加工机制并不明晰,基础研究较为薄弱.本文介绍了本课题组在聚乙烯醇(PVA)偏光膜、三醋酸纤维素(CTA)相位差膜、聚对苯二甲酸乙二醇酯(PET)支撑膜的相关研究进展.通过高时间分辨同步辐射X射线散射与多种原位拉伸装置联用的实验手段,模拟真实复杂的工业生产环境,在线采集偏光片三张光学膜的结构演化规律,并建立其与光学等性能的关系,为光学膜高端制造提供基础原理指导.最后,我们展望了新型显示偏光片光学膜今后的发展方向.