Abstract Structure of polycaprolactone (PCL) crystallized in a wide concentration range was investigated to correlate entanglement content with the formed structure. Mixed solvent constituted by good solvent chloroform and nonslovent ethanol was used to control the concentration crystallization started (conset, weight fraction), which varied from 0.13 to 0.53. Crystallization at higher conset was achieved by electrospinning and melt crystallization. The concentration correlates with entanglement number (N) by the scaling law N/N0 = ϕ1.3 with ϕ the volume fraction of polymer in solution. In this work, the scaling law was modified as N/N0 ≈ conset1.3 as an approximation. Thickness of amorphous region (la) and fusion enthalpy (ΔH) were obtained through small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC). It is found that la increases monotonically with conset1.3 from 4.5 nm to 10.2 nm, and ΔH decreases monotonically from 92 J/g to 50 J/g. The smooth change of la and ΔH with conset1.3 indicates increased entanglement leads to thicker amorphous region and lower crystallinity, which is valid even when the entanglement number is as low as one-tenth of that in melt. Moreover, changes in lamellae thickness (lc) is also discussed.

中文翻译：

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减少缠结的聚己内酯结晶

摘要 研究了在宽浓度范围内结晶的聚己内酯 (PCL) 的结构，以将缠结含量与形成的结构相关联。由良溶剂氯仿和无溶剂乙醇构成的混合溶剂用于控制开始结晶的浓度（浓度，重量分数），其在0.13至0.53之间变化。通过静电纺丝和熔融结晶实现更高浓度的结晶。浓度与纠缠数 (N) 相关，按比例定律 N/N0 = ϕ1.3，其中 ϕ 是溶液中聚合物的体积分数。在这项工作中，缩放定律被修改为 N/N0 ≈ conset1.3 作为近似值。通过小角 X 射线散射 (SAXS) 和差示扫描量热法 (DSC) 获得非晶区的厚度 (la) 和熔化焓 (ΔH)。发现la随着conset1.3从4.5nm单调增加到10.2nm，并且ΔH从92J/g单调减少到50J/g。la 和 ΔH 随 conset1.3 的平滑变化表明缠结增加导致非晶区变厚和结晶度降低，即使缠结数低至熔体中的十分之一，这也是有效的。此外，还讨论了薄片厚度 (lc) 的变化。