College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University , Chengdu 610065, People's Republic of China.
Patent Examination Cooperation Center of the Patent Office, SIPO , Sichuan 610213, People's Republic of China.
ACS Appl Mater Interfaces. 2017 Aug 30;9(34):29071-29081. doi: 10.1021/acsami.7b07947. Epub 2017 Aug 21.
The low efficiency of thermal conductive filler is an unresolved issue in the area of thermal conductive polymer composites. Although it is known that minimizing phonon or electron interfacial scattering is the key for achieving high thermal conductivity, the enhancement is generally limited by preparation methods that can yield the ideal morphology and interfaces. Herein, low temperature expandable graphite (LTEG) is added into a commercial impact modifier (Elvaloy4170), which is then coated onto poly(butylene terephthalate) (PBT) particles with various sizes at millimeter scale between their melting temperatures. Thus, macroscopic segregated filler networks with several considerations are constructed: high LTEG loading leads to a short distance between fillers and a robust filler network; continuous Elvaloy-LTEG phase leads to a continuous filler network; and good interaction among filler and matrix leads to good interfacial interaction. More importantly, the rather large size of PBT particles provides the filler networks with low specific interfacial area, which minimizes the interfacial scattering of phonons or electrons. Relative to homogeneous composites with an identical composition, the thermal conductivity is enhanced from 6.2 to 17.8 W/mK. Such an enhancement span is the highest compared with results reported in the literature. Due to possible "shortcut" behavior, much higher effectiveness can be achieved for the current system than found in literature results when the Elvaloy-LTEG phase is considered as filler, with the effectiveness even exceeding the upper limit of theoretical calculation for highly loaded Elvaloy-LTEG phase with relatively large PBT particle sizes. This could provide some guidelines for the fabrication of highly thermal conductive polymer composites as well as multifunctional polymer composites.
导热填料效率低下是导热聚合物复合材料领域尚未解决的问题。虽然众所周知，最小化声子或电子界面散射是实现高热导率的关键，但增强通常受到可产生理想形态和界面的制备方法的限制。在此，低温可膨胀石墨（LTEG）被添加到商业冲击改性剂（Elvaloy4170）中，然后在其熔融温度之间的毫米尺度上将其涂覆到各种尺寸的聚对苯二甲酸丁二醇酯（PBT）颗粒上。因此，构建了具有以下几点考虑的宏观分离填充网络：高 LTEG 负载导致填料之间的距离较短且填料网络坚固；连续的 Elvaloy-LTEG 相导致连续的填料网络；以及填料与基体之间的良好相互作用导致良好的界面相互作用。更重要的是，较大的 PBT 颗粒尺寸为填料网络提供了低比表面积，从而最小化了声子或电子的界面散射。与具有相同组成的均相复合材料相比，热导率从 6.2 W/mK 提高到 17.8 W/mK。与文献中报道的结果相比，这种增强幅度是最高的。由于可能存在“捷径”行为，当前系统的有效性可能比文献中报道的 Elvaloy-LTEG 相作为填料时的结果高得多，即使在考虑具有较大 PBT 颗粒尺寸的高负载 Elvaloy-LTEG 相时，其有效性甚至超过理论计算的上限。这可为高热导率聚合物复合材料以及多功能聚合物复合材料的制备提供一些指导。
