Highly electrically conducting poly(L-lactic acid)/graphite composites prepared via in situ expansion and subsequent reduction of graphite

2018 ◽  
Vol 38 (2) ◽  
pp. 167-177 ◽  
Author(s):  
Bai Xue ◽  
Lanxiang Ji ◽  
Jianguo Deng ◽  
Junhua Zhang
Keyword(s):  
Electrical Conductivity ◽  
Lactic Acid ◽  
Percolation Threshold ◽  
Reduction Process ◽  
Expanded Graphite ◽  
Xrd Analysis ◽  
Expandable Graphite ◽  
Subsequent Reduction ◽  
Electrically Conducting

AbstractIn this paper, highly electrically conductive polymeric composites were obtained by low-temperature expandable graphite (LTEG) filling poly(L-lactic acid) (PLLA) in the presence of ascorbic acid via anin situexfoliation and subsequent reduction process during the melt blending. The electrical conductivity of the PLLA/reduced and expanded graphite (R-EG) composites was determined by a four-point probe resistivity determiner and compared with that of the PLLA/expanded graphite (EG) composites. The percolation threshold of PLLA/R-EG blends decreased from 11.2 wt% to 7.1 wt%, which illustrated the superiority of R-EG to the electrically conducting ability of PLLA composites. At the graphite concentration near the percolation threshold, the electrical conductivity of PLLA/R-EG composites was much higher than that of PLLA/EG composites. The effectivein situexpansion and reduction of LTEG were crucial to the overall electrical conductivity of the blends, which was confirmed by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. Dynamic rheology analysis confirmed that the connected networks that were the major cause of the rapid increase in electrical conductivity were much more easily formed for PLLA/R-EG blends than those of PLLA/EG blends. Thermogravimetric analysis (TGA) was applied to determine the decomposition and thermal stability of the PLLA/R-EG composites.

Preparation of Expanded Graphite and Graphite Nanosheets for Improving Electrical Conductivity of Polyester Coating Films

2021 ◽  
Vol 21 (12) ◽  
pp. 5846-5858
Author(s):  
Yun Ding ◽  
Mingxia Tian ◽  
Aili Wang ◽  
Hengbo Yin
Keyword(s):  
Electrical Conductivity ◽  
Thermal Expansion ◽  
Milling Time ◽  
Expanded Graphite ◽  
Graphite Powder ◽  
Expandable Graphite ◽  
Coating Films ◽  
Natural Graphite ◽  
Graphite Nanosheets ◽  
Volumetric Rate

Expanded graphite and graphite nanosheets were facilely prepared by the thermal expansion of expandable graphite at 800 °C and sand milling of expanded graphite in water, respectively. When the expandable graphite precursor was prepared by the oxidation and intercalation of natural graphite (5 g) using KMnO4 (6 g) as an oxidant in a concentrated sulfuric acid solution (120 mL) at room temperature (25 °C) for 8 h, the expanded graphite with a maximum volumetric rate of 317 mL g−1 was prepared after the thermal expansion of the expandable graphite precursor at 800 °C for 60 s. The oxidation extent of natural graphite with KMnO4 is crucial for the preparation of expanded graphite. The thicknesses of graphite nanosheets decreased from 8.9 to 3.2 nm when the sand milling time of the expanded graphite in deionized water was prolonged from 6 to 24 h. The prolonging of the sand milling time not only decreased the layer number of the graphite nanosheet but also increased the d002 spacing due to the shocking and shearing forces. The addition of the expanded graphite powder and graphite nanosheets in a polyester paint efficiently improved the electrical conductivity of the resultant polyester coating films.

Effect of Inorganic Doping on the Thermoelectric Behavior of Polyaniline Nanocomposites

2020 ◽  
Vol 835 ◽  
pp. 200-207
Author(s):  
Mariamu K. Ali ◽  
Ahmed Abd Moneim
Keyword(s):  
Electrical Conductivity ◽  
Conducting Polymers ◽  
Inorganic Nanoparticles ◽  
Inorganic Materials ◽  
Environmental Stability ◽  
Subsequent Reduction ◽  
Preparation Methods ◽  
Reduced Graphene

Polyaniline (PANI) has been considered for thermoelectric (T.E) applications due to its facile preparation methods, easy doping-dedoping processes and its environmental stability. Like other conducting polymers (CPs), it has low thermal conductivity (usually below 1 Wm-1K-1) which is favorable for T.E applications, however studies have shown that it still suffers from low power factors as a result of low electrical conductivity. For this reason, PANI has been compounded with other materials such as polymers, inorganic nanoparticles and carbon nanoparticles to enhance its electrical conductivity, power factors (PF) and ultimately zT value.This work is focused on the synthesis and characterization of n-type polyaniline nanocomposites doped with reduced graphene oxide (rGO). The rGO was prepared through oxidation of graphite and subsequent reduction and incorporated into polyaniline through in situ polymerization and the resulting nanocomposites were characterized. Addition of rGO resulted in enhancement of the electrical conductivity of polyaniline from 10-3 S/cm to 10-1 S/cm which is two orders of magnitude higher. This contributed to the enhanced PF, an indication that thermoelectric behavior of conducting polymers can be boosted through compounding with inorganic materials.

scholarly journals Processing-structure-property correlations of in situ Al/TiB2 composites processed by aluminothermic reduction process

2018 ◽  
Vol 25 (5) ◽  
pp. 869-879
Author(s):  
A.S. Vivekananda ◽  
S. Balasivanandha Prabu ◽  
R. Paskaramoorthy
Keyword(s):  
Process Parameters ◽  
Particle Distribution ◽  
Reduction Process ◽  
Xrd Analysis ◽  
Parent Material ◽  
Structure Property ◽  
Influence Of Process Parameters ◽  
Average Hardness ◽  
Al Matrix

AbstractThis paper reports the influence of process parameters on the size and distribution of in situ titanium diboride (TiB2) particles within the aluminium (Al) matrix. TiB2 particles were formed as a result of the in situ reaction of potassium hexafluorotitanate (K2TiF6) and potassium tetra fluoroborate (KBF4) with molten Al. Two process parameters, namely, the addition time (AT) and holding time (HT) of precursor salts, were considered. The Al/TiB2 composites were produced by allowing the in situ reaction to occur at various ATs (10, 20, and 30 min) and HTs (20, 30, and 40 min). Results showed that the formation of TiB2 was confirmed by XRD analysis. The microstructure, TiB2 particle size, hardness, yield strength (YS), and ultimate tensile strength (UTS) were strongly affected by the said process parameters. The variations in hardness and UTS were highly consistent with those found in the microstructure of the composites. Compared with the Al parent material, the increase in the average hardness and UTS of the composite were 51% and 44%, respectively. This improvement was achieved for the composite sample fabricated with 20 min of AT and 30 min of HT. At this condition, the composite displayed near-uniform particle distribution.

Polyphenylene sulfide- expanded graphite nanocomposites

2016 ◽  
Vol 30 (12) ◽  
pp. 1603-1614 ◽  
Author(s):  
BTS Ramanujam ◽  
S Radhakrishnan ◽  
SD Deshpande
Keyword(s):  
Percolation Threshold ◽  
In Situ Polymerization ◽  
Expanded Graphite ◽  
Polyphenylene Sulfide ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Graphite Nanosheets ◽  
Electrical Percolation ◽  
Scanning Electron Microcopy

Polyphenylene sulfide (PPS)-expanded graphite (ExGr) conducting nanocomposites have been prepared by powder mixing and in situ polymerization routes after sonicating ExGr particles in acetone. Synthesized PPS has been used to make powder mixed composites. The powder mixed composites exhibit a percolation threshold of 3 wt% due to the formation of graphite nanosheets. When PPS-ExGr composites are prepared by in situ polymerization route, very low electrical percolation threshold less than 0.5 wt% ExGr is obtained. The low percolation threshold obtained is attributed to better dispersion of ExGr nanosheets in the polymer matrix when compared to powder mixed composites. The synthesized PPS has been characterized by X-ray diffraction, differential scanning calorimetry, and infrared spectroscopy. The formation of graphite nanosheets has been confirmed by transmission and scanning electron microcopy analysis.

scholarly journals Electrical Conductivity of PA6/Graphite and Graphite Nanoplatelets Composites using Two Processing Streams

2021 ◽  
Vol 5 (1) ◽  
pp. 19-31
Author(s):  
M. Umar ◽  
M. I. Ofem ◽  
A. S. Anwar ◽  
M. M. Usman
Keyword(s):  
Electrical Conductivity ◽  
Percolation Threshold ◽  
Carbon Composite ◽  
Graphite Nanoplatelets ◽  
Particulate Carbon ◽  
The Matrix ◽  
Sonication Technique ◽  
Carbon Fillers ◽  
Made In

The percolation threshold (PT) of any polymer/particulate carbon composite depends on the processing, the dispersed state of the filler, the matrix used and the morphology attained. Sonication technique was used to make PA6/G and PA6/GNP composites employing in situ polymerisation, after which their electrical conductivity behaviours were investigated. While overhead stirring and horn sonication were used to distribute and disperse the carbon fillers, the composites were made in 2 streams 40/10 and 20/20. The 40/10 stream implies that while dispersing the carbon fillers in PA6 monomer, 40% amplitude of sonication was applied for 10 minutes whereas the 20/20 stream implies 20% amplitude of sonication for 20 minutes. In both streams, the dispersing strain imparted on the monomer/carbon mixture was 400 in magnitude. Purely ohmic electrical conductivity behaviour was attained at 9.75 G wt. % for IG 40/10 system. For composites in the IG 20/20 system, same was attained at 10.00 G wt. %. Electrical conductivity sufficient for electrostatic discharge applications was achieved above 15 G wt. % in the IG 40/10 system. Using the power law percolation theory, percolation threshold was attained at 9.7 G wt. % loading in IG 40/10 system, while same was attained at 7.6 G wt. % loading in IG 20/20 system. For the GNP based systems, percolation threshold occurred at 5.2 GNP wt. % in the INP 40/10 system whereas same occurred at 7.4 GNP wt. % in the IG 20/20 system.

Structure and Electrical Conductivity of Polystyrene/Carbon Black Composites Prepared by Microlayer Coextrusion

2016 ◽  
Vol 717 ◽  
pp. 38-46 ◽  
Author(s):  
Chang Jin Li ◽  
Liang Zhao Xiong ◽  
Cong Ji Yuan ◽  
Zhi Wei Jiao ◽  
Wei Min Yang
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Electrical Resistivity ◽  
Carbon Black ◽  
Percolation Threshold ◽  
Layered Structure ◽  
Electrically Conducting ◽  
Percolation Effect ◽  
Multilayered Composites ◽  
Double Percolation

Electrically conducting composites with a structure of alternating (A-B-A)n layers were prepared by a novel microlayer coextrusion, which were consisted of alternating layers of polystyrene (PS) and layers of carbon black (CB)-filled polystyrene (PSCB). The co-continuous structure with selective location of CB in PSCB layers was controllable by changing the number of multiplying elements, and decreased the percolation threshold and electrical resistivity of multilayered composites because of the double percolation effect. In addition, the multilayered composites exhibited better mechanical properties than that of the conventional blends, which were related to the layered structure and small size of CB aggregates.

scholarly journals Selective Localization of Carbon Black in Bio-Based Poly (Lactic Acid)/Recycled High-Density Polyethylene Co-Continuous Blends to Design Electrical Conductive Composites with a Low Percolation Threshold

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1583 ◽  
Author(s):  
Xiang Lu ◽  
Benhao Kang ◽  
Shengyu Shi
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Lactic Acid ◽  
Carbon Black ◽  
Percolation Threshold ◽  
High Density Polyethylene ◽  
Poly Lactic Acid ◽  
Electrically Conductive ◽  
Selective Localization

The electrically conductive poly (lactic acid) (PLA)/recycled high-density polyethylene (HDPE)/carbon black (CB) composites with a fine co-continuous micro structure and selective localization of CB in the HDPE component were fabricated by one-step melt processing via a twin-screw extruder. Micromorphology analysis, electrical conductivity, thermal properties, thermal stability, and mechanical properties were investigated. Scanning electron microscope (SEM) images indicate that a co-continuous morphology is formed, and CB is selectively distributed in the HDPE component. With the introduction of CB, the phase size of the PLA component and the HDPE component in PLA/HDPE blends is reduced. In addition, differential scanning calorimetry (DSC) and thermos gravimetric analysis (TGA) results show that the introduction of CB promotes the crystallization behavior of the PLA and HDPE components, respectively, and improves the thermal stability of PLA70/30HDPE/CB composites. The electrically conductive percolation threshold of the PLA70/30HDPE/CB composites is around 5.0 wt %, and the electrical conductivity of PLA70/30HDPE/CB composites reaches 1.0 s/cm and 15 s/cm just at the 10 wt % and 15 wt % CB loading, respectively. Further, the tensile and impact tests show that the PLA70/30HDPE/CB composites have good mechanical properties. The excellent electrical conductivity and good mechanical properties offer the potential to broaden the application of PLA/HDPE/CB composites.

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