Lightweight and tough nanocellular PP/PTFE nanocomposite foams with defect-free surfaces obtained using in situ nanofibrillation and nanocellular injection molding
Lightweight and tough nanocellular PP/PTFE nanocomposite foams with defect-free surfaces obtained using in situ nanofibrillation and nanocellular injection molding
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采用原位纳米纤化和纳米多孔注射成型获得轻质、坚韧的纳米多孔 PP/PTFE 纳米复合泡沫，表面无缺陷
DOI：
10.1016/j.cej.2018.05.161
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发表时间：
2018-10-15
影响因子：
15.1
通讯作者：
Park, Chul B.
中科院分区：
文献类型：
--
作者：
Wang, Guilong;Zhao, Guoqun;Park, Chul B.
轻质塑料材料对节约资源能源、减少环境污染、实现可持续发展具有重要意义。泡沫塑料注射成型是一种很有前途的轻质塑料部件制造技术。然而，这些塑料部件具有较差的机械性能和不完美的表面外观。为此，我们报道了一种将原位原纤化和纳米注射成型技术相结合的方法来制备表面无缺陷的轻韧聚丙烯(PP)/聚四氟乙烯(PTFE)纳米复合材料零件的新方法。首次采用基于双螺杆共混的原位法制备了纳米纤维PP/PTFE纳米复合材料。扫描电子显微镜(SEM)、流变学和差示扫描量热(DSC)分析，结合在线光学显微镜观察，证明了聚四氟乙烯纳米纤维的网络结构及其对熔体强度和促进结晶的积极作用。利用纳米纤维纳米复合材料，我们首次使用泡沫注射成型工艺实现了纳米细胞发泡。与普通PP相比，纳米PP/PTFE纳米复合泡沫塑料的力学性能显著提高，甚至比未发泡的PP具有更好的强度和延展性。其中，纳米泡沫的冲击强度比普通泡沫提高了700%，比非发泡产品提高了200%。此外，与普通泡沫塑料不同，纳米PP/PTFE纳米复合泡沫塑料具有优异的表面形貌，没有任何银色或漩涡痕迹。更重要的是，整个过程简单、灵活、高效、易于放大，并且可以很容易地扩展到其他材料。卓越的机械性能和表面外观，再加上灵活和可扩展的工艺，使纳米PP/PTFE纳米复合泡沫塑料在许多对重量和机械完整性都有要求的先进应用中具有广阔的前景。
Lightweight plastic materials are important for saving resources and energy, reducing environmental pollution, and achieving sustainable development. Foam injection molding is a promising technology for manufacturing lightweight plastic components. However, these plastic components present poor mechanical properties and imperfect surface appearances. Herein, we reported a novel strategy to prepare lightweight and tough polypropylene (PP)/polytetrafluoroethylene (PTFE) nanocomposite parts with defect-free surfaces by combining in situ fibrillation and nanocellular injection molding technologies. The nano-fibrillary PP/PTFE nanocomposite was firstly prepared using an in situ method based on twin-screw compounding. Scanning electron microscopy (SEM), rheological and differential scanning calorimetry (DSC) analysis, combined with online optical microscopy observation, demonstrated the network structure of PTFE nanofibrils and its positive effects on melt strength and promoting crystallization. Using nanofibrillary nanocomposites, we achieved nanocellular foaming, for the first time, using the foam injection molding process. The nanocellular PP/PTFE nanocomposite foam thus obtained significantly enhanced mechanical properties compared to the regular PP foam, and even superior strength and ductility compared to unfoamed PP. In particular, the impact strength of the nanocellular foam was 700% higher than that of the regular foam and 200% higher than that of the unfoamed product. Moreover, unlike regular foam, the nanocellular PP/PTFE nanocomposite foam showed outstanding surface appearance without any silver or swirl marks. More importantly, the whole process was facile, flexible, efficient, and easy to scale-up, and could be easily extended to other materials. The remarkable mechanical performance and surface appearance, combined with the flexible and extendable process, confers nanocellular PP/PTFE nanocomposite foams a promising future in many advanced applications where both lightweight and mechanical integrity are required.