Thermal characterisation of high density polyethylene with multi-walled carbon nanotube

2018 ◽  
Vol 15 (8/9/10) ◽  
pp. 747
Author(s):  
Dong Wook Oh
Author(s):  
Felicia Stan ◽  
Nicoleta-Violeta Stanciu ◽  
Catalin Fetecau

Abstract This study focuses on 3D printing of multi-walled carbon nanotube/high density polyethylene (MWCNT/HDPE) composites. First, rheological properties of 0.1, 1, and 5 wt.% MWCNT/HDPE composites were investigated to estimate the 3D printability window. Second, filaments with 1.75 mm diameter were fabricated and subsequently extruded by a commercial 3D printer. Finally, the filaments and 3D printed parts were tested to correlate the rheological, mechanical, and electrical properties with processing parameters. Experimental results show that flow behavior of MWCNT/HDPE composites is a critical factor affecting the 3D printability. The shear viscosity exhibits good shear thinning behavior at high shear rates and significantly increases with increasing nanotube loading from 0.1 to 5 wt.%, at low shear rates. Reliable MWCNT/HDPE filaments were obtained with smooth surface finish and good mechanical and electrical properties. The 0.1 and 1 wt.% MWCNT/HDPE filaments exhibit very good printing characteristics. However, under the flow conditions of a standard 0.4-mm nozzle, 3D printing of 5 wt.% MWCNT/HDPE filament can be rather difficult primarily due to high shear viscosity and nozzle clogging. Thus, further investigation is needed to fully optimize the 3D printing of MWCNT/HDPE composites.


2010 ◽  
Vol 123-125 ◽  
pp. 59-62 ◽  
Author(s):  
T. Jeevananda ◽  
O.G. Palanna ◽  
Joong Hee Lee ◽  
Siddaramaiah ◽  
C. Ranganathaiah

The present study investigates the effect of the carboxylated multi-walled carbon nanotube (0~3 wt %) content on the electrical and thermal properties of high density polyethylene/carbon black/carboxylated multi-walled carbon nanotube (HDPE/CB/c-MWNT) hybrid nanocomposites. The room temperature electrical resistivity and positive temperature coefficient (PTC) intensity of the nanocomposites significantly improved with the addition of c-MWNT. However, the heat of fusion decreases as the amount of c-MWNT increases. Further, the microstructural parameters such as the fractional free volume (Fv) and free volume hole size (Vf) of the nanocomposites shows appreciable changes around the percolation threshold. Secondly, the PALS results seem to correlate well with the electrical and thermal properties of the composites.


Author(s):  
Felicia Stan ◽  
Nicoleta V. Stanciu ◽  
Catalin Fetecau ◽  
Laurentiu I. Sandu

In this work, friction spot stir welding (FSSW) is applied to join high-density polyethylene/multi-walled carbon nanotube (HDPE/MWCNTs) composites. Injection-molded coupons were welded with a single lap-shear configuration under different welding conditions (tool rotational speed, plunge depth, and dwell time). By analyzing the lap-shear tensile load and the fracture surface of the welded joints, it is found that the weld attributes (e.g. weld area and maximum lap-shear tensile load) increase with increasing dwell time, tool rotational speed, and plunging depth. The maximum lap-shear tensile load increases with nanotube loading up to a threshold, followed by a decreasing trend at nanotube loading higher than 1.0 wt.%. It is hypothesized that the bonding mechanism for FSSW of HDPE/MWCNT composites is mainly through the co-crystallization across the interface. When more nanotubes are involved in the welding zone (>1.0 wt.%), saturation of nucleation is reached, the positive effect on the crystallization is vanished, and consequently the overall mechanical properties decrease. Interface failure of the welded joints and bulk fracture originated from the upper coupon within the weld nugget perimeter were identified as the two main failure mechanisms.


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