Thermal properties of spray-dried cellulose nanofibril-reinforced polypropylene composites from extrusion-based additive manufacturing
Thermal properties of spray-dried cellulose nanofibril-reinforced polypropylene composites from extrusion-based additive manufacturing
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DOI：
10.1007/s10973-018-7759-9
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发表时间：
2018-10
影响因子：
4.4
通讯作者：
Lu Wang;J. Palmer;M. Tajvidi;D. Gardner;Yousoo Han
中科院分区：
文献类型：
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作者：
Lu Wang;J. Palmer;M. Tajvidi;D. Gardner;Yousoo Han
与全同立构PP均聚物相比，聚丙烯嵌段共聚物（PPco）在基于挤出的增材制造中更容易加工，因为它在打印期间收缩和翘曲更少。本研究调查了PPco和喷雾干燥CNF（SDCNF）-PPco复合颗粒制剂的热性能。热重分析数据表明，SDCNF的加入降低了PPco粒料的热降解起始温度，并增加了PPco粒料的残余质量含量（450 °C）。SDCNF和PPco的峰值降解温度保持相同。SDCNF和MAPP的加入提高了PPco的峰值结晶温度和相对结晶度。PPco的峰值熔融温度没有显著变化。印刷样品显示出三个熔融峰（β、β′和α晶体），而注塑PPco仅显示出一个熔融峰（α晶体）。动态力学分析结果表明，印刷SDCNF-PPco复合材料的热变形温度高于注塑PPco。SEM显微照片显示，添加SDCNF增加了印刷部件内部的空隙数量。
Polypropylene block copolymer (PPco) is easier to process in extrusion-based additive manufacturing compared to isotactic PP homopolymer because it shrinks and warps less during printing. This study investigated the thermal properties of PPco and spray-dried CNF (SDCNF)-PPco composite pellet formulations. Thermogravimetric analysis data showed that the addition of SDCNF lowered the thermal degradation onset temperature and increased the residual mass content (at 450 °C) of PPco pellets. The peak degradation temperatures of SDCNF and PPco remained the same. The peak crystallization temperature and relative crystallinity of PPco were increased by the addition of SDCNF and MAPP. The peak melting temperature of PPco was not significantly changed. Printed specimens showed three melting peaks (β,β′ andαcrystals) while injection molded PPco only showed one (αcrystal) melting peak. Dynamic mechanical analysis results showed that the heat deflection temperatures of printed SDCNF-PPco composites were higher than injection molded PPco. SEM micrographs showed that the addition of SDCNF increased the number of voids inside the printed parts.