scholarly journals Nonlinear Thermopower Behaviour of N-Type Carbon Nanofibres and Their Melt Mixed Polypropylene Composites

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 269
Author(s):  
Antonio J. Paleo ◽  
Beate Krause ◽  
Maria F. Cerqueira ◽  
Enrique Muñoz ◽  
Petra Pötschke ◽  
...  
Keyword(s):  
Localized States ◽  
Multiwall Carbon Nanotube ◽  
Variable Range Hopping ◽  
Fermi Energy Level ◽  
Temperature Dependent ◽  
Carbon Nanofibres ◽  
Polypropylene Composites ◽  
Carbon Nanofibre ◽  
Temperature Dependent Electrical Conductivity ◽  
Multiwall Carbon

The temperature dependent electrical conductivity σ (T) and thermopower (Seebeck coefficient) S (T) from 303.15 K (30 °C) to 373.15 K (100 °C) of an as-received commercial n-type vapour grown carbon nanofibre (CNF) powder and its melt-mixed polypropylene (PP) composite with 5 wt.% of CNFs have been analysed. At 30 °C, the σ and S of the CNF powder are ~136 S m−1 and −5.1 μV K−1, respectively, whereas its PP/CNF composite showed lower conductivities and less negative S-values of ~15 S m−1 and −3.4 μV K−1, respectively. The σ (T) of both samples presents a dσ/dT < 0 character described by the 3D variable range hopping (VRH) model. In contrast, their S (T) shows a dS/dT > 0 character, also observed in some doped multiwall carbon nanotube (MWCNT) mats with nonlinear thermopower behaviour, and explained here from the contribution of impurities in the CNF structure such as oxygen and sulphur, which cause sharply varying and localized states at approximately 0.09 eV above their Fermi energy level (EF).

scholarly journals Temperature dependent switching of magnetoresistance in multiwall carbon nanotube-polypyrrole composite fibrils

2019 ◽  
Vol 126 (22) ◽  
pp. 225901
Author(s):  
Reena Rani ◽  
Meenu Sharma ◽  
Sonam Rani ◽  
Aditi Shankar ◽  
V. Prasad ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Multiwall Carbon Nanotube ◽  
Temperature Dependent ◽  
Polypyrrole Composite ◽  
Multiwall Carbon

scholarly journals Charge Transport Mechanism in Thin Cuticles Holding Nandi Flame Seeds

2009 ◽  
Vol 2009 ◽  
pp. 1-9
Author(s):  
Wycliffe K. Kipnusu ◽  
Gabriel Katana ◽  
Charles M. Migwi ◽  
I. V. S. Rathore ◽  
Joshua R. Sangoro
Keyword(s):  
Transport Mechanism ◽  
Localized States ◽  
Variable Range Hopping ◽  
Charge Transport Mechanism ◽  
Conductivity Measurements ◽  
Ohmic Conduction ◽  
Metal Sample ◽  
Temperature Dependent ◽  
Density Of Localized States ◽  
High Fields

Metal-sample-metal sandwich configuration has been used to investigate DC conductivity in 4 m thick Nandi flame [Spathodea campanulata P. Beauv.] seed cuticles. characteristics showed ohmic conduction at low fields and space charge limited current at high fields. Charge mobility in ohmic region was . Temperature-dependent conductivity measurements have been carried out in the temperature range 320 K 450 K. Activation energy within a temperature of 320 K–440 K was about 0.86 eV. Variable range hopping (VRH) is the main current transport mechanism at the range of 330–440 K. The VRH mechanism was analyzed based on Mott theory and the Mott parameters: density of localized states near the Fermi-level and hopping distance  cm, while the hopping energy () was in the range of 0.72 eV–0.98 eV.

Coupled electro-mechanical properties of multiwall carbon nanotube/polypropylene composites for strain sensing applications

2013 ◽  
Vol 48 (21) ◽  
pp. 7587-7593 ◽  
Author(s):  
O. Zetina-Hernández ◽  
S. Duarte-Aranda ◽  
A. May-Pat ◽  
G. Canché-Escamilla ◽  
J. Uribe-Calderon ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotube ◽  
Multiwall Carbon Nanotube ◽  
Strain Sensing ◽  
Polypropylene Composites ◽  
Sensing Applications ◽  
Multiwall Carbon

Influence of Multiwall Carbon Nanotube on mechanical and wear properties of Copper – Iron composite

2020 ◽  
Vol 17 (1) ◽  
pp. 7570-7576 ◽  
Author(s):  
H. Sh. Hammood ◽  
S. S. Irhayyim ◽  
A. Y. Awad ◽  
H. A. Abdulhadi
Keyword(s):  
Carbon Nanotubes ◽  
Volume Fraction ◽  
Hybrid Composites ◽  
Hydraulic Press ◽  
Dry Sliding Wear ◽  
Multiwall Carbon Nanotube ◽  
Wear Properties ◽  
Sem Images ◽  
Wear Rates ◽  
Multiwall Carbon

Multiwall Carbon nanotubes (MWCNTs) are frequently attractive due to their novel physical and chemical characteristics, as well as their larger aspect ratio and higher conductivity. Therefore, MWCNTs can allow tremendous possibilities for the improvement of the necessarily unique composite materials system. The present work deals with the fabrication of Cu-Fe/CNTs hybrid composites manufactured by powder metallurgy techniques. Copper powder with 10 vol. % of iron powder and different volume fractions of Multi-Wall Carbon Nanotubes (MWCNTs) were mixed to get hybrid composites. The hybrid composites were fabricated by adding 0.3, 0.6, 0.9, and 1.2 vol.% of MWCNTs to Cu- 10% Fe mixture using a mechanical mixer. The samples were compressed under a load of 700 MPa using a hydraulic press to compact the samples. Sintering was done at 900°C for 2 h at 5ºC/min heating rate. The microscopic structure was studied using a Scanning Electron Microscope (SEM). The effect of CNTs on the mechanical and wear properties, such as micro-hardness, dry sliding wear, density, and porosity were studied in detail. The wear tests were carried out at a fixed time of 20 minutes while the applied loads were varied (5, 10, 15, and 20 N). SEM images revealed that CNTs were uniformly distributed with relative agglomeration within the Cu/Fe matrix. The results showed that the hardness, density, and wear rates decreased while the percentage of porosity increased with increasing the CNT volume fraction. Furthermore, the wear rate for all the CNTs contents increased with the applied load.

scholarly journals All-Fiber Pyro- and Piezo-electric Nanogenerator for IoT Based Self-Powered Health-Care Monitoring

2021 ◽  
Author(s):  
Biswajit Mahanty ◽  
Sujoy Kumar Ghosh ◽  
Kuntal Maity ◽  
KRITTISH ROY ◽  
Subrata Sarkar ◽  
...  
Keyword(s):  
Health Care ◽  
Carbon Nanotube ◽  
Vinylidene Fluoride ◽  
Electrospun Nanofibers ◽  
Multiwall Carbon Nanotube ◽  
Poly Vinylidene Fluoride ◽  
Self Powered ◽  
Health Care Monitoring ◽  
Multiwall Carbon ◽  
Piezo Electric

In this work, an all-fiber pyro- and piezo-electric nanogenerator (PPNG) is designed by multiwall carbon nanotube (MWCNT) doped poly(vinylidene fluoride) (PVDF) electrospun nanofibers as the active layer and interlocked conducting...

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