A solvent-free route to high performance ultra-high molecular weight polyethylene (UHMWPE) film threads is currently under intensive development. It involves compaction/sintering of UHMWPE reactor powder at T < T_m followed by orientation hardening of the sintered film cut into narrow strips. However, not any kind of reactor powder can be transformed into the desired high-performance material. The presence of a monoclinic crystalline phase (MP) in the powder is considered as one of the key parameters indicating its applicability for solvent-free processing. Since the MP is stable only under stress, the assumption has been made that the observed MP is generated during tableting for X-ray analyses rather than during synthesis of the nascent powder. We show that comparative X-ray analysis of a tablet and a single “virgin” particle using synchrotron radiation indicates that the MP content in the virgin particle was far less than that in the compressed tablet. Only the (001) MP peak was resolved while the others were severely overlapped with the normal, orthorhombic reflections. Thus, it supports our idea that the widely observed MP phase is, for the most part, generated during the sample preparation for the X-ray analyses.

目前正在大力开发无溶剂的高性能超高分子量聚乙烯（UHMWPE）薄膜线。它涉及在U <T _m时压实/烧结UHMWPE反应器粉末然后将烧结膜定向硬化，切成窄条。但是，没有任何一种反应堆粉末都可以转化为所需的高性能材料。粉末中单斜晶相（MP）的存在被认为是指示其在无溶剂加工中的适用性的关键参数之一。由于MP仅在应力下稳定，因此可以假设观察到的MP是在压片过程中产生的，用于X射线分析，而不是在合成新生粉末时产生。我们显示，使用同步加速器辐射对片剂和单个“原始”颗粒进行的X射线比较分析表明，原始颗粒中的MP含量远小于压片中的MP含量。只有（001）MP峰被解析，而其他峰与正常峰严重重叠，斜方晶状体的反射。因此，它支持了我们的观点，即广泛观察到的MP相主要是在X射线分析的样品制备过程中产生的。