Embabi Mahmoud, Kweon Mu Sung, Chen Zuolong, Lee Patrick C
Multifunctional Composites Manufacturing Laboratory (MCML), Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada.
Polymers (Basel). 2020 Nov 4;12(11):2585. doi: 10.3390/polym12112585.
Fiber-reinforcement is a well-established technique to enhance the tensile properties of polymer composites, which is achieved via changing the reinforcing material concentration and orientation. However, the conventional method can be costly and may lead to poor compatibility issues. To overcome these challenges, we demonstrate the use of micro-/nanolayer (MNL) extrusion technology to tune the mechanical properties of polypropylene (PP)/polyethylene terephthalate (PET) fibrillar blends. PET nanofibers-in-PP microfiber composites, with 3, 7, and 15 wt.% PET, are first prepared using a spunbond system to induce high aspect-ratio PET nanofibers. The PP/PET fibers are then reprocessed in an MNL extrusion system and subjected to shear and extensional flow fields in the channels of the uniquely designed layer multipliers. Increasing the mass flow rate and number of multipliers is shown to orient the PET nanofibers along the machine direction (MD), as confirmed via scanning electron microscopy. Tensile tests reveal that up to a 45% and 46% enhancement in elastic modulus and yield strength are achieved owing to the highly aligned PET nanofibers along the MD under strongest processing conditions. Overall, the range of tensile properties obtained using MNL extrusion implies that the properties of fiber-reinforced composites can be further tuned by employing this processing technique.
纤维增强是一种成熟的提高聚合物复合材料拉伸性能的技术，它是通过改变增强材料的浓度和取向来实现的。然而，传统方法成本高昂，且可能导致相容性差的问题。为了克服这些挑战，我们展示了使用微/纳米层（MNL）挤出技术来调节聚丙烯（PP）/聚对苯二甲酸乙二酯（PET）纤维共混物的机械性能。首先使用纺粘系统制备含3 wt.%、7 wt.%和15 wt.% PET的PET纳米纤维增强PP微纤维复合材料，以诱导出高长径比的PET纳米纤维。然后将PP/PET纤维在MNL挤出系统中进行再加工，并在独特设计的层倍增器通道中经受剪切和拉伸流场。通过扫描电子显微镜证实，增加质量流速和倍增器数量可使PET纳米纤维沿机器方向（MD）取向。拉伸试验表明，在最强加工条件下，由于PET纳米纤维沿MD高度取向，弹性模量和屈服强度分别提高了45%和46%。总体而言，使用MNL挤出获得的拉伸性能范围表明，采用这种加工技术可以进一步调节纤维增强复合材料的性能。
