This study investigates the dispersion and compatibility of low-entangled “dis-entangled” UHMWPE (dis-UH) in a high-density polyethylene (HDPE) matrix using solvent-free melt-blending conditions and compares it with entangled UHMWPE (eUH) in the same matrix. The findings reveal that dis-UH/HDPE exhibits a significantly lower viscosity ratio than eUH/HDPE (1 and 4, respectively), indicating a lower critical capillary number (Cacritical), thus enhanced dispersion and compatibility. Blends with varying dis-UH content up to 20 wt% show homogeneity, evidenced by DSC and SEM analysis, and demonstrate improved mechanical properties by 36 % in the maximum stress (σmax) and 39 % in Young's modulus (E). Linear viscoelasticity assessments reveal that higher dis-UH content slow the dynamics and increase the apparent weight average molecular weight (Mw), consistent with previous reports for linear entangled PE. The zero-shear viscosity (η0) scaling with Mw (η0∝Mn) is adjusted for high polydispersity, yielding a transitional point in the scaling exponent (n) from 3.6 to 3 at a reptation number of entanglement segments (Mr/Me) of ∼287, in line with theoretical predictions. To rationalize the success of the homogenization process, we propose a qualitative molecular picture inspired from the constraint release Rouse mechanism involved in the disorientation process of bi-disperse linear polymers. In the case of dis-UH/HDPE blends, with initially lower density of long-long entanglements within dis-UH, and the highest density of short-short entanglements within HDPE matrix, the formation of long-short entanglements between dis-UH and HDPE is facilitated, which results in successful homogenization process. In the contrary, the establishment of long-short entanglements in eUH/HDPE blends will require unwinding of the long-long entanglements, which holds a higher kinetic barrier compared to dis-UH/HDPE blends, leading to unsuccessful homogenization.

中文翻译：

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商用线性聚乙烯与低缠结超高分子量聚乙烯的熔融共混：从分散相容性到粘弹性缩放定律


本研究使用无溶剂熔融共混条件研究了低缠结“解缠结”UHMWPE (dis-UH) 在高密度聚乙烯 (HDPE) 基质中的分散性和相容性，并将其与缠结 UHMWPE (eUH) 进行了比较相同的矩阵。研究结果表明，dis-UH/HDPE 的粘度比明显低于 eUH/HDPE（分别为 1 和 4），表明临界毛细管数 (Caritic) 较低，从而增强了分散性和相容性。 DSC 和 SEM 分析证明，不同 dis-UH 含量高达 20 wt% 的共混物显示出均质性，并且最大应力 (σmax) 机械性能提高了 36%，杨氏模量 (E) 提高了 39%。线性粘弹性评估表明，较高的 dis-UH 含量会减慢动力学并增加表观重均分子量 (Mw)，这与线性缠结 PE 的先前报告一致。零剪切粘度 (η0) 与 Mw (η0∝Mn) 的比例调整为高多分散性，在缠结段的重复数 (Mr/Me) 处产生比例指数 (n) 从 3.6 到 3 的过渡点∼287，符合理论预测。为了合理化均质化过程的成功，我们提出了一种定性分子图，其灵感来自于双分散线性聚合物定向过程中涉及的约束释放劳斯机制。对于 dis-UH/HDPE 共混物，最初 dis-UH 内的长-长缠结密度较低，而 HDPE 基质内的短-短缠结密度最高，在 dis-UH 和 HDPE 之间形成长-短缠结。 HDPE 得到促进，从而实现成功的均质化过程。 相反，eUH/HDPE 共混物中长短缠结的建立需要解开长长缠结，与 dis-UH/HDPE 共混物相比，其具有更高的动势垒，导致均化不成功。