Simultaneous synchrotron small- and wide-angle X-ray scattering (SAXS/WAXS) was used to follow the crystalline morphology evolution of poly-L- lactic acid (PLLA) during uniaxial deformation at various draw temperatures (T_d). The mechanical behaviour of PLLA, was found to be strongly dependent on T_d. 2D SAXS/WAXS data taken during the draw showed that at low T_ds cavitation and voiding occurred and the initial crystallites underwent ‘overdrawing’ where they slip and are partially destroyed. SEM confirmed that surface voiding and cavitation had occurred at T_d = 60 and 65 °C but was absent at higher T_ds. During the draw, no long-range macromolecular lamellar structure was seen in the SAXS, but small crystallites of the disordered α′ crystal form of PLLA were observed in the WAXS at all T_ds. The PLLA samples were then step annealed in a second processing stage (post-draw) to develop the oriented crystalline lamellar structure and increase the amount of the stable α crystalline form. SAXS/WAXS data showed that a highly oriented lamellar stack macrostructure developed on annealing, with increased crystallite size and crystallinity at all T_ds. Furthermore, step annealing drove the crystalline transition in all samples from the disordered α′ crystal form to the stable α crystal form. Therefore, varying pre- and post-processing parameters can significantly influence the mechanical properties, orientation, crystalline morphology and crystal phase transition of the final PLLA material.

同步同步加速器小角度和广角X射线散射（SAXS / WAXS）用于跟踪在不同拉伸温度（T _d）下单轴变形过程中聚L-乳酸（PLLA）的晶体形态演变。发现PLLA的机械性能强烈依赖于T _d。在拉伸过程中获得的2D SAXS / WAXS数据表明，在低T _d时会发生空化和空洞现象，并且最初的微晶经历了“过度拉伸”，它们在此处滑动并被部分破坏。SEM证实在T _d  = 60和65°C时发生了表面空洞和空化，但在更高的T _d处则没有s。在拉伸过程中，在SAXS中未观察到大范围的大分子层状结构，但在所有T _d的WAXS中均观察到了PLLA无序α'晶型的小晶粒。然后在第二个加工阶段（拉伸后）对PLLA样品进行逐步退火，以形成取向的晶体层状结构并增加稳定的α晶型的数量。SAXS / WAXS数据显示，退火时形成了高度取向的层状叠层宏观结构，在所有T _d处晶粒尺寸和结晶度均增加s。此外，逐步退火驱动所有样品中的晶体转变，从无序的α'晶型到稳定的α晶型。因此，变化的预处理和后处理参数会显着影响最终PLLA材料的机械性能，取向，晶体形态和晶体相变。