Crystallinity (X_c) is a crucial crystallographic factor that related closely to mechanical properties in linear polyethylene or high density polyethylene (HDPE), whose molecular weight (MW) is at a 10⁵ level. However, as a typically intractable-processing polymer, the structure-property relationship concerned X_c is still ambiguous for ultrahigh molecular weight polyethylene (UHMWPE) with MW﹥1.5 × 10⁶. The reason is that high entanglement density hinders chain mobility in the course of UHMWPE crystallization, thus crystalline degree in UHMWPE molding parts is difficult to be artificially modulated within a wide scope. In this study, low chain-entanglement status of UHMWPE melt was achieved by (1) utilizing lowly entangled nascent UHMWPE synthesized via the single-site Ziegler-Natta catalyst, and (2) decreasing the sintered temperature. It is impressive that partial disentanglement reserved in the melt is favorable for obtaining higher crystallinity. Meanwhile, an isothermal crystallization treatment was additionally adopted to further improve the capacity of regulating crystallization after the traditional two-step sintering procedure. By a combination of varying the initial entanglement in nascent powders, sintering temperature, isothermal crystallization duration, and molecular weight of UHMWPE, the X_c of the compression-sintered products has been successfully adjusted in the relatively broad range of 29%≦ X_c ≦ 65%, which offered an opportunity to validly survey the correlation between mechanical property and crystallinity. Particular attention was paid to the yield strength. A linear master straight-line can be plotted as yield strength vs. X_c for all of the samples inspected, indicating crystallinity also plays a dominant role on mechanical performances of UHMWPE sintering parts, as same in the case of HDPE. However, the mechanical reinforcement induced by increment of X_c in UHMWPE is more efficient than in HDPE. The yield strength of UHMWPE is much higher than that of HDPE at the same X_c, indicating the amorphous phase or entanglements in UHMWPE is crucial to determine the mechanical property. These findings are of significance for guiding the manufacturing of high-performance UHMWPE materials via crystallization manipulation.

结晶度（X _c）是一个至关重要的晶体学因子，与线性聚乙烯或高分子量聚乙烯（HDPE）的机械性能密切相关，后者的分子量（MW）为10 ⁵。然而，作为一种典型的难加工聚合物，对于M W﹥ 1.5×10 ^6的超高分子量聚乙烯（UHMWPE），其结构性质关系X _c仍然是模棱两可的。。原因是高的缠结密度阻碍了UHMWPE结晶过程中的链迁移，因此难以在大范围内人为地调节UHMWPE成型部件的结晶度。在这项研究中，UHMWPE熔体的低链缠结状态是通过（1）利用通过单中心Ziegler-Natta催化剂合成的低缠结新生UHMWPE以及（2）降低烧结温度来实现的。令人印象深刻的是，保留在熔体中的部分解缠有助于获得更高的结晶度。同时，在传统的两步烧结工艺之后，额外采用了等温结晶处理以进一步提高调节结晶的能力。结合改变初生粉末的初始缠结，烧结温度，X _Ç压缩烧结产品已经在相对宽的范围的29％≦被成功地调整X _Ç  ≦65％，这提供了一个机会，以有效地调查机械性能和结晶性之间的相关性。特别注意屈服强度。可以将线性主直线绘制为所有检查样品的屈服强度与X _c的关系，这表明与HDPE一样，结晶度在UHMWPE烧结零件的机械性能中也起着主导作用。但是，UHMWPE中X _c的增加引起的机械增强比HDPE中更有效。在相同的条件下，UHMWPE的屈服强度远高于HDPEX _c表示UHMWPE中的非晶相或缠结对于确定机械性能至关重要。这些发现对于通过结晶操作指导高性能UHMWPE材料的制造具有重要意义。