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首页> 外文期刊>Polymers >Morphology, Nucleation, and Isothermal Crystallization Kinetics of Poly(???μ-caprolactone) Mixed with a Polycarbonate/MWCNTs Masterbatch
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Morphology, Nucleation, and Isothermal Crystallization Kinetics of Poly(???μ-caprolactone) Mixed with a Polycarbonate/MWCNTs Masterbatch

机译：聚（ε-己内酯）与聚碳酸酯/ MWCNTs母料混合的形貌，成核及等温结晶动力学

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In this study, nanocomposites were prepared by melt blending poly (???μ-caprolactone) (PCL) with a (polycarbonate (PC)/multi-wall carbon nanotubes (MWCNTs)) masterbatch in a twin-screw extruder. The nanocomposites contained 0.5, 1.0, 2.0, and 4.0 wt % MWCNTs. Even though PCL and PC have been reported to be miscible, our DSC (Differential Scanning Calorimetry), SAXS (Small Angle X-ray Scattering), and WAXS (Wide Angle X-ray Scattering) results showed partial miscibility, where two phases were formed (PC-rich and PCL-rich phases). In the PC-rich phase, the small amount of PCL chains included within this phase plasticized the PC component and the PC-rich phase was therefore able to crystallize. In contrast, in the PCL-rich phase the amount of PC chains present generates changes in the glass transition temperature of the PCL phase that were much smaller than those predicted by the Fox equation. The presence of two phases was corroborated by SEM, TEM, and AFM observations where a fair number of MWCNTs diffused from the PC-rich phase to the PCL-rich phase, even though there were some MWCNTs agglomerates confined to PC-rich droplets. Standard DSC measurements demonstrated that the MWCNTs nucleation effects are saturated at a 1 wt % MWCNT concentration on the PCL-rich phase. This is consistent with the dielectric percolation threshold, which was found to be between 0.5 and 1 wt % MWCNTs. However, the nucleating efficiency was lower than literature reports for PCL/MWCNTs, due to limited phase mixing between the PC-rich and the PCL-rich phases. Isothermal crystallization experiments performed by DSC showed an increase in the overall crystallization kinetics of PCL with increases in MWCNTs as a result of their nucleating effect. Nevertheless, the crystallinity degree of the nanocomposite containing 4 wt % MWCNTs decreased by about 15% in comparison to neat PCL. This was attributed to the presence of the PC-rich phase, which was able to crystallize in view of the plasticization effect of the PCL component, since as the MWCNT content increases, the PC content in the blend also increases. The thermal conductivities (i.e., 4 wt % MWCNTs) were enhanced by 20% in comparison to the neat material. The nanocomposites prepared in this work could be employed in applications were electrical conductivity is required, as well as lightweight and tailored mechanical properties.
机译：在这项研究中，通过在双螺杆挤出机中将聚（μ-己内酯）（PCL）与（聚碳酸酯（PC）/多壁碳纳米管（MWCNT））母料熔融共混来制备纳米复合材料。纳米复合材料包含0.5、1.0、2.0和4.0重量％的MWCNT。尽管据报道PCL和PC可以混溶，但我们的DSC（差示扫描量热法），SAXS（小角度X射线散射）和WAXS（广角X射线散射）结果显示出部分混溶性，形成了两相（富含PC和富含PCL的阶段）。在富含PC的相中，该相中包含的少量PCL链使PC组分塑化，因此富含PC的相能够结晶。相反，在富含PCL的相中，存在的PC链数量导致PCL相的玻璃化转变温度变化远小于Fox方程预测的变化。 SEM，TEM和AFM观察证实了两相的存在，即使有一些MWCNT团聚体局限于富含PC的液滴，仍有相当数量的MWCNT从富含PC的相扩散到富含PCL的相。标准DSC测量表明，在富含PCL的相上，MWCNT的成核作用在MWCNT浓度为1 wt％时达到了饱和。这与介电渗透阈值一致，该介电渗透阈值被发现在0.5至1wt％的MWCNT之间。然而，由于富含PC的相和富含PCL的相之间有限的相混合，成核效率低于PCL / MWCNT的文献报道。 DSC进行的等温结晶实验表明，由于成核作用，随着MWCNT的增加，PCL的整体结晶动力学增加。然而，与纯PCL相比，含有4wt％MWCNT的纳米复合材料的结晶度降低了约15％。这归因于富含PC的相的存在，鉴于PCL组分的增塑作用，该相能够结晶，因为随着MWCNT含量的增加，共混物中PC的含量也会增加。与纯材料相比，热导率（即4wt％的MWCNT）提高了20％。这项工作中制备的纳米复合材料可用于需要导电性以及轻量和量身定制的机械性能的应用中。

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