Abstract
Herein, we investigate the low-velocity impact behavior of polypropylene random copolymer (PPR)/multi-wall carbon nanotube (MWCNT) and high-density polyethylene (HDPE)/MWCNT plate-lattices processed via fused filament fabrication additive manufacturing, utilizing in-house nanoengineered filament feedstocks. We examine the dynamic crushing and energy absorption characteristics of three typical elementary plate-lattices, namely, simple cubic (SC), body-centered cubic (BCC) and face-centered cubic (FCC) as well as three hybrid plate-lattices (SC-BCC, SC-FCC and SC-BCC-FCC) comprising different weight fractions of MWCNTs at different impact energy levels. The results reveal that the SC-BCC-FCC nanocomposite plate-lattice offers the most favorable impact response as each constituent plate in the lattice contributes to the load carrying capacity for all direction vectors included in the plane of the plate. Furthermore, the results show that impregnating MWCNTs into the PPR and HDPE plate-lattices significantly influences their impact energy attenuation characteristics. Compared with the respective unreinforced plate-lattices, PPR/6 wt% MWCNT SC-BCC-FCC plate-lattices evince higher energy absorption (70%) than HDPE/6 wt% MWCNT SC-BCC-FCC plate-lattices (47%) due to uniform MWCNT dispersion and effective interfacial interaction of MWCNTs in PPR matrix. Our hybrid 3D plate-lattices exhibit a specific energy absorption (SEA) capacity as high as 19.9 J/g, demonstrating their superior impact performance over aluminum and other conventional lattices.
Highlights
The scope of employing architected materials processed at different length scales is constantly growing in aerospace, marine, automotive, biomedical, and civil sectors [1,2,3,4]
In order to explicitly report the effect of polymer/Multi-walled carbon nanotube (MWCNT) interaction on the energy absorption characteristics, the normalized absorbed energy of high-density polyethylene (HDPE)/MWCNT and PPR/MWCNT simple cubic (SC)-body-centered cubic (BCC)-face-centered cubic (FCC) plate-lattices were evaluated as the ratio of the absorbed energy of the MWCNT loaded specimen to the absorbed energy of the corresponding neat specimen
Subjecting the MWCNT reinforced HDPE and PPR specimens to higher impact energies did not result in complete compaction/densification, but in stable and continuous crushing of different plate-lattices, evident from the continuous increase in duration of the oscillating plateau region with increasing impact energy level
Summary
The scope of employing architected materials processed at different length scales (such as nano-, micro-, meso- and macro-architected lattices) is constantly growing in aerospace, marine, automotive, biomedical, and civil sectors [1,2,3,4]. Polypropylene (PP) and highdensity polyethylene (HDPE) are the most widely used commodity plastics for several industrial applications, mainly owing to their low cost, abundant availability, and ease of processing [21,22] They exhibit relatively high performance/cost ratio, and can be re-used many times devoid of considerable loss of their properties [23,24]. Different nano or micro fillers and other thermoplastics or elastomers were employed as modifiers to enhance the dynamic energy absorption characteristics of PP/HDPE [29,30] Factors such as the matrix property, the polymer blend structure, the matrixfiller compatibility and the interfacial adhesion affect the toughening [31,32]. The present investigation focuses on the low-velocity behavior of PPR/MWCNT and HDPE/MWCNT plate-lattices comprising different concentrations of MWCNTs at different impact energy levels
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