scholarly journals Disassembly Study of Ultrasonically Welded Thermoplastic Composite Joints via Resistance Heating

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2521
Author(s):  
Harry Frederick ◽  
Wencai Li ◽  
Genevieve Palardy
Keyword(s):  
Tensile Load ◽  
Thermoplastic Composite ◽  
Nanocomposite Films ◽  
Slow Heating ◽  
Maximum Temperature ◽  
Composite Joints ◽  
Resistance Heating ◽  
Heating Rates ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

This manuscript explores the disassembly potential of ultrasonically welded thermoplastic composite joints for reuse or recycling through resistance heating via a nanocomposite film located at the welded interface. Nanocomposite films containing multi-walled carbon nanotubes (MWCNTs) were characterized for thermo-electrical behavior to assess self-heating. It was generally observed that maximum temperature increased with MWCNT and film thickness. To demonstrate potential for disassembly, glass fiber/polypropylene adherends were welded with nanocomposite films. Shear stress during disassembly was measured for three initial adherend’s surface temperatures. It was found that the required tensile load decreased by over 90% at the highest temperatures, effectively demonstrating the potential for disassembly via electrically conductive films. Fracture surfaces suggested that disassembly was facilitated through a combination of nanocomposite and matrix melting and weakened fiber–matrix interface. Limitations, such as slow heating rates and the loss of contact at the interface, imply that the method could be more suited for recycling, instead of repair and reuse, as the heat-affected zone extended through the adherends’ thickness at the overlap during heating.

Experimental Investigation of Morphological and Electrical Characteristics of PS/MWCNT Nanocomposite Films

2018 ◽  
Vol 915 ◽  
pp. 104-109
Author(s):  
Barış Demirbay ◽  
Şaziye Uğur
Keyword(s):  
Annealed Film ◽  
Nanocomposite Films ◽  
Electrical Characteristics ◽  
Liquid Form ◽  
Mwcnt Content ◽  
Electrical Percolation ◽  
Glass Substrates ◽  
Multi Walled Carbon Nanotubes ◽  
Electrical Percolation Threshold ◽  
Walled Carbon Nanotubes

Electrical characteristics and morphology of nanocomposite films composed of two different polystyrene (PS) latexes impregnated with multi-walled carbon nanotubes (MWCNT) in the range between 0 wt% and 20 wt% were assessed by considering photon transmission (UV-Vis) technique and electrical conductivity measurements. Emulsion polymerization technique was employed both to synthesize very fine PS particles dispersed in water and to tailor the sizes of the PS particles as 382 nm and 560 nm, respectively. PS/MWCNT nanocomposite films were obtained from the liquid form on glass substrates via drop-casting method and all they dried at 40 QUOTE C. Each dried sample was then annealed at varying temperatures between 100 QUOTE C and 250 QUOTE C for 10 min. The surface conductivity QUOTE of each annealed film at 250 QUOTE C was measured and was found to increase dramatically above a certain mass fraction of MWCNT content, QUOTE . Each set of PS/MWCNT nanocomposite film had a similar electrical percolation threshold of QUOTE =1.5 wt% as the MWCNT content and critical exponents of QUOTE were found to be 2.64 and 1.19 for 382 nm and 560 nm PS latex systems, respectively.

Study on the residual performance of RC beams exposed to processed temperatures and fire

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sachin Vijaya Kumar ◽  
N. Suresh
Keyword(s):  
Failure Modes ◽  
Elevated Temperatures ◽  
Slow Heating ◽  
Maximum Temperature ◽  
Rc Beams ◽  
Heating Rates ◽  
Fast Heating ◽  
Content Type ◽  
Temperature Increment ◽  
Residual Performance

PurposeThe Reinforced Concrete(RC) elements are known to perform well during exposure to elevated temperatures. Hence, RC elements are widely used to resist the extreme heat developing from accidental fires and other industrial processes. In both of the scenarios, the RC element is exposed to elevated temperatures. However, the primary differences between the fire and processed temperatures are the rate of temperature increase, mode of exposure and exposure durations. In order to determine the effect of two heating modalities, RC beams were exposed to processed temperatures with slow heating rates and fire with fast heating rates.Design/methodology/approachIn the present study, RC beam specimens were exposed to 200 °C, to 800 °C temperature at 200 °C intervals for 2 h' duration by adopting two heating modes; Fire and processed temperatures. An electrical furnace with low-temperature increment and a fire furnace with standard time-temperature increment is adapted to expose the RC elements to elevated temperatures.FindingsIt is observed from test results that, the reduction in load-carrying capacity, first crack load, and thermal crack widths of RC beams exposed to 200 °C, and 600 °C temperature at fire is significantly high from the RC beams exposed to the processed temperature having the same maximum temperature. As the exposure temperature increases to 800 °C, the performance of RC beams at all heating modes becomes approximately equal.Originality/valueIn this work, residual performance, and failure modes of RC beams exposed to elevated temperatures were achieved through two different heating modes are presented.

Characterization of Polyvinyl Acetate/Multi Walled Carbon Nanotube Nanocomposites

2016 ◽  
Vol 721 ◽  
pp. 13-17
Author(s):  
Juris Bitenieks ◽  
Remo Merijs Meri ◽  
Janis Zicans ◽  
Mārtiņš Kalniņš
Keyword(s):  
Polyvinyl Acetate ◽  
Nanocomposite Films ◽  
Solution Casting ◽  
Casting Technique ◽  
Multi Walled Carbon Nanotube ◽  
Multi Walled Carbon Nanotubes ◽  
Solution Casting Technique ◽  
Dielectrical Properties ◽  
Walled Carbon Nanotubes

Nanocomposite films from polyvinyl acetate (PVAc) dispersion and multi walled carbon nanotubes (MWCNTs) were prepared by solution casting technique. Stress-strain properties showed increase in elastic modulus and yield strength. Mechanical properties characterized by dynamic mechanical thermal analysis represented increase in storage modulus below glass transition temperature. Studied dielectrical properties of PVAc/MWCNT nanocomposites revealed formation of conductive MWCNT network in PVAc matrix.

scholarly journals Heating Performance of MWCNT Module according to Size Effect

2021 ◽  
Vol 21 (5) ◽  
pp. 175-182
Author(s):  
Sohyeon Park ◽  
Sungju An ◽  
Heeyoung Lee ◽  
Donghwi Kim ◽  
Wonseok Chung
Keyword(s):  
Carbon Nanotubes ◽  
Size Effect ◽  
Temperature Change ◽  
Supply Voltage ◽  
Maximum Temperature ◽  
Vehicular Traffic ◽  
Heating Efficiency ◽  
Heating Performance ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Black ice is a road-freezing phenomenon that occurs on the surfaces of roads and is caused by sub-zero temperatures. Black ice is dangerous to vehicular traffic because it is difficult for a driver to detect its presence on roads. Further, it causes vehicles to lose traction on roads, thus causing accidents. Therefore, this study aims to solve this problem by utilizing a heating module with multi-walled carbon nanotubes (MWCNTs) and analyzing the heating efficiency according to the size effect of the heating module. The heating modules were divided into cubes (50 × 50 × 50 mm3) and cuboids (100 × 300 × 60 mm3). The parameters considered were the size of the heating module, number of curing days, and supply voltage. The maximum temperature change of the cubes was 75.7 ℃, and the maximum temperature change of the cuboids was 78% of the cube. The thermal images demonstrated that the cuboids exhibited better thermal dispersibility than that exhibited by the cubes. Therefore, the heating efficiency of the cuboids was inferred to be excellent. Thus, the cuboid heating module can be used to reduce the risk of accidents occurring caused by black ice.

scholarly journals Structure and electrical conductivity of polyvinyl alcohol films with multi-walled carbon nanotubes, cured in a magnetic field

2021 ◽  
Vol 13 (4) ◽  
pp. 457-464
Author(s):  
Sergey V. Vasin ◽  
◽  
Azat M. Nizametdinov ◽  
Viacheslav A. Sergeev ◽  
Michael S. Efimov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Polyvinyl Alcohol ◽  
Nanocomposite Films ◽  
Polymerization Process ◽  
Degree Of Orientation ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Control Samples

The results of the study of the effect of the permanent magnetic field of a neodymium magnet on the polymerization process and the electrophysical characteristics of polyvinyl alcohol (PVA) films with the inclusion of multi-walled carbon nanotubes (MWCNTs) are presented. When studying the morphology of films using a scanning electron microscope, it was found that nanocomposite films with a thickness of 30 microns, cured in the presence of a magnetic field with the direction of the magnetic induction vector perpendicular to the surface of the films, have a homogeneous structure, while a significant number of MWCNTs agglomerations are observed in control samples of films. Measurements of the conductivity of films in the direction of the MWCNTs orientation at direct and alternating current showed that the conductivity of films obtained in a magnetic field significantly (by almost two orders of magnitude) exceeds the conductivity of control samples. The obtained results are analyzed on the basis of known models of electrical conductivity of nanocomposites with oriented MWCNTs. The degree of orientation of the MWCNTs during the curing of films in a magnetic field is estimated, taking into account the increase in the viscosity of the nanocomposite during the curing process.

scholarly journals Effect of Multi-Walled Carbon Nanotubes on Improving the Toughness of Reactive Powder Concrete

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2625 ◽  
Author(s):  
Jintao Liu ◽  
Hang Jin ◽  
Xin Zhao ◽  
Cheng Wang
Keyword(s):  
Carbon Nanotubes ◽  
Energy Absorption ◽  
Tensile Load ◽  
Microscopic Analysis ◽  
Reactive Powder Concrete ◽  
Aspect Ratios ◽  
Capability Indices ◽  
Multi Walled Carbon Nanotubes ◽  
Reactive Powder ◽  
Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNTs) have great potential to improve the strength and microstructure of traditional cement-based materials. In this research, different aspect ratios of MWCNTs (F-type and L-type) were dispersed into water using surfactants, and then incorporated into reactive powder concrete (RPC) for improving mechanical and microstructure properties. With the addition of 0.025 wt.% F-MWCNTs, the 28 days compressive strength and initial-cracking flexural strength increased by 7.2% and 36%, respectively. Moreover, the first-cracking tensile strengths of the composites containing L-MWCNTs were improved by 16%. Energy absorption capability indices were formulated based on tensile load–displacement curves, and results showed that the energy absorption capabilities of RPC at initial cracking improved as a result of the incorporation of MWCNTs. Furthermore, microscopic analysis indicated that MWCNTs decelerate crack development at the nanoscale and improve the initial-cracking tensile strength of RPC.

scholarly journals Mechanical, Thermal and Electromagnetic Shielding Effectiveness of MWCN-ABS Films

2021 ◽  
Author(s):  
R. B. Jagadeesh Chandra ◽  
B. Shivamurthy ◽  
M. Sathish Kumar ◽  
B. H. S. Thimmappa
Keyword(s):  
Thermal Stability ◽  
Electrical Conductivity ◽  
Tensile Strength ◽  
Petri Dish ◽  
Nanocomposite Films ◽  
Heating Process ◽  
Shielding Effectiveness ◽  
X Band ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

AbstractThe multi-walled carbon nanotubes (MWCNTs) and the poly(acrylonitrile-co-butadiene-co-styrene) (ABS) granulates are dispersed in acetone separately using a magnetic stirrer followed by ultrasonication. Further, both the solutions were mixed with magnetic stirring followed by ultrasonication. Neat-ABS film, 0.25 wt%, 0.5 wt% and 1 wt% of MWCNT-ABS nanocomposite films of the average thickness of 140 µm are fabricated by the solution molding using a petri dish, followed by room temperature curing and further hot compression to maintain uniform thickness. The tensile properties, thermal stability, electrical conductivity, and EMSE of all films are investigated. The results indicate that the addition of MWCNTs to ABS enhanced the mechanical properties and electrical conductivity, thermal stability, and EMSE. The 0.25 wt% MWCNT-ABS nanocomposite films show attractive mechanical, electrical, thermal, and EMSE as compared to neat-ABS films. More than 0.25 wt% MWCNTs in the ABS matrix deteriorates the tensile strength. However, 0.5 wt% MWCNT-ABS nanocomposites exhibit better tensile strength, Young’s modulus, electrical conductivity, and EMSE than neat-ABS. In this research, we used a low quantity of MWCNTs and followed a one-time heating process in the entire fabrication, and produced MWCNT-ABS nanocomposite films with reasonable properties. Hence, this may be one of the options to produce nanocomposites suitable for EMS materials. We recommend that these films may be used as interlayers to develop an X-band range electromagnetic wave shielding material.

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