scholarly journals Influence of Carbon Nanotube-Pretreatment on the Properties of Polydimethylsiloxane/Carbon Nanotube-Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1355
Author(s):  
Astrid Diekmann ◽  
Marvin C. V. Omelan ◽  
Ulrich Giese
Keyword(s):  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Mechanical Performance ◽  
Softening Effect ◽  
Electrical Percolation ◽  
Optimum Parameters ◽  
Lauryl Ether ◽  
Solvent Residues ◽  
Electrical Percolation Threshold ◽  
Filler Dispersion

Incorporating nanofillers into elastomers leads to composites with an enormous potential regarding their properties. Unfortunately, nanofillers tend to form agglomerates inhibiting adequate filler dispersion. Therefore, different carbon nanotube (CNT) pretreatment methods were analyzed in this study to enhance the filler dispersion in polydimethylsiloxane (PDMS)/CNT-composites. By pre-dispersing CNTs in solvents an increase in electrical conductivity could be observed within the sequence of tetrahydrofuran (THF) > acetone > chloroform. Optimization of the pre-dispersion step results in an AC conductivity of 3.2 × 10−4 S/cm at 1 Hz and 0.5 wt.% of CNTs and the electrical percolation threshold is decreased to 0.1 wt.% of CNTs. Optimum parameters imply the use of an ultrasonic finger for 60 min in THF. However, solvent residues cause a softening effect deteriorating the mechanical performance of these composites. Concerning the pretreatment of CNTs by physical functionalization, the use of surfactants (sodium dodecylbenzenesulfonate (SDBS) and polyoxyethylene lauryl ether (“Brij35”)) leads to no improvement, neither in electrical conductivity nor in mechanical properties. Chemical functionalization enhances the compatibility of PDMS and CNT but damages the carbon nanotubes due to the oxidation process so that the improvement in conductivity and reinforcement is superimposed by the CNT damage even for mild oxidation conditions.

scholarly journals Melt-Mixed 3D Hierarchical Graphene/Polypropylene Nanocomposites with Low Electrical Percolation Threshold

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1766 ◽  
Author(s):  
Thomas Gkourmpis ◽  
Karolina Gaska ◽  
Davide Tranchida ◽  
Antonis Gitsas ◽  
Christian Müller ◽  
...  
Keyword(s):  
Percolation Threshold ◽  
Mechanical Performance ◽  
Pristine Graphene ◽  
Melt Mixing ◽  
Electrical Percolation ◽  
Β Phase ◽  
Polypropylene Nanocomposites ◽  
Electrical Percolation Threshold ◽  
Filler Dispersion ◽  
Mixed Systems

Graphene-based materials are a family of carbonaceous structures that can be produced using a variety of processes either from graphite or other precursors. These materials are typically a few layered sheets of graphene in the form of platelets and maintain some of the properties of pristine graphene (such as two-dimensional platelet shape, aspect ratio, and graphitic bonding). In this work we present melt mixed graphene-based polypropylene systems with significantly reduced percolation threshold. Traditionally melt-mixed systems suffer from poor dispersion that leads to high electrical percolation values. In contrast in our work, graphene was added into an isotactic polypropylene matrix, achieving an electrical percolation threshold of ~1 wt.%. This indicates that the filler dispersion process has been highly efficient, something that leads to the suppression of the β phase that have a strong influence on the crystallization behavior and subsequent thermal and mechanical performance. The electrical percolation values obtained are comparable with reported solution mixed systems, despite the use of simple melt mixing protocols and the lack of any pre or post-treatment of the final compositions. The latter is of particular importance as the preparation method used in this work is industrially relevant and is readily scalable.

Electrical conductivity and rheological properties of carbon black based conductive polymer composites prior to and after annealing

2021 ◽  
pp. 096739112110012
Author(s):  
Qingsen Gao ◽  
Jingguang Liu ◽  
Xianhu Liu
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Percolation Threshold ◽  
Rheological Properties ◽  
Network Formation ◽  
Loss Modulus ◽  
Conductive Polymer ◽  
Complex Viscosity ◽  
Electrical Percolation ◽  
Electrical Percolation Threshold

The effect of annealing on the electrical and rheological properties of polymer (poly (methyl methacrylate) (PMMA) and polystyrene (PS)) composites filled with carbon black (CB) was investigated. For a composite with CB content near the electrical percolation threshold, the formation of conductive pathways during annealing has a significant impact on electrical conductivity, complex viscosity, storage modulus and loss modulus. For the annealed samples, a reduction in the electrical and rheological percolation threshold was observed. Moreover, a simple model is proposed to explain these behaviors. This finding emphasizes the differences in network formation with respect to electrical or rheological properties as both properties belong to different physical origins.

scholarly journals Electrically Conductive Compounds of Polycarbonate, Liquid Crystalline Polymer, and Multiwalled Carbon Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Penwisa Pisitsak ◽  
Rathanawan Magaraphan ◽  
Sadhan C. Jana
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Multiwalled Carbon ◽  
Electrical Percolation ◽  
Twin Screw ◽  
Electrical Percolation Threshold ◽  
In Parenthesis

A thermotropic liquid crystalline polymer (LCP) was blended with polycarbonate (PC) and multiwalled carbon nanotube (CNT) with the goal of improving electrical conductivity and mechanical properties over PC. The LCP was anticipated to produce fibrillar domains in PC and help improve the mechanical properties. The study was carried out using two grades of LCP—Vectra A950 (VA950) and Vectra V400P (V400P). The compounds contained 20 wt% LCP and 0.5 to 15 wt% CNT. The compounds were prepared by melt-blending in a twin-screw minicompounder and then injection molded using a mini-injection molder. The fibrillar domains of LCP were found only in the case of PC/VA950 blend. However, these fibrils turned into droplets in the presence of CNT. It was found that CNT preferentially remained inside the LCP domains as predicted from the value of spreading coefficient. The electrical conductivity showed the following order with the numbers in parenthesis representing the electrical percolation threshold of the compounds: PC/CNT (1%) > PC/VA950P/CNT (1%) > PC/V400P/CNT (3%). The storage modulus showed improvements with the addition of CNT and VA950.

Ultralow Electrical Percolation Threshold in Poly(styrene-co-acrylonitrile)/Carbon Nanotube Nanocomposites

2013 ◽  
Vol 52 (8) ◽  
pp. 2858-2868 ◽  
Author(s):  
Nilesh Kumar Shrivastava ◽  
Supratim Suin ◽  
Sandip Maiti ◽  
Bhanu Bhusan Khatua
Keyword(s):  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Electrical Percolation ◽  
Electrical Percolation Threshold

scholarly journals Attaining Toughness and Reduced Electrical Percolation Thresholds in Bio-Based PA410 by Combined Addition of Bio-Based Thermoplastic Elastomers and CNTs

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3420
Author(s):  
Itziar Otaegi ◽  
Nora Aranburu ◽  
Gonzalo Guerrica-Echevarría
Keyword(s):  
Electrical Conductivity ◽  
Thermoplastic Elastomers ◽  
Electrical Percolation ◽  
Mechanical And Electrical Properties ◽  
Multi Walled Carbon Nanotubes ◽  
Electrical Percolation Threshold ◽  
Percolation Thresholds ◽  
Ductile Behavior ◽  
Walled Carbon Nanotubes ◽  
The Impact

Multi-walled carbon nanotubes (CNTs) were added to provide electrical conductivity to bio-based polymer blends with improved toughness (based on commercially available Pebax thermoplastic elastomers and bio-based polyamide 4,10). A preliminary study including three different Pebax grades was carried out to select the grade and the composition that would best improve the impact properties of PA410. Thus, tough multiphasic PA/Pebax/CNT nanocomposites (NCs) with enhanced electrical conductivity were obtained. The CNTs were added either: (1) in the form of pristine nanotubes or (2) in the form of a PA6-based masterbatch. Hence, PA410/Pebax/CNT ternary NCs and PA410/PA6/Pebax/CNT quaternary NCs were obtained, respectively, up to a CNT content of 1 wt%. The ternary and quaternary NCs both showed similar mechanical and electrical properties. The electrical percolation threshold decreased with respect to previously studied corresponding NCs without Pebax, i.e., PA410/CNT and PA410/PA6/CNT, due to the partial volume exclusion effect of Pebax over the CNTs that were dispersed mainly in the PA matrix; materials with percolation concentrations as low as 0.38 wt% were obtained. With respect to mechanical properties, contrary to the NCs without Pebax, all the PA/Pebax/CNT NCs showed a ductile behavior and impact strength values that were from three to five-fold higher than that of the pure PA410.

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