Improved electrical conductivity of PDMS/SCF composite sheets with bolting cloth prepared by a spatial confining forced network assembly method

Abstract

A novel method of Spatial Confining Forced Network Assembly (SCFNA) for preparation of high-performance electrically conductive polymeric composites was proposed in this paper. Differing from the self-assembly mechanism, as in traditional compounding processes, the SCFNA process could provide conductive fillers with an effective forced networking assembly action to get a more compacted network. High electroconductive polydimethylsiloxane (PDMS)/short carbon fiber (SCF) binary composites with a low percolation threshold of 0.15 wt% were prepared by the SCFNA method. A rapid increase in electrical conductivity from 1.71 Â 10 À12 S m À1 of PDMS to 1.67 Â 10 2 S m À1 was achieved with 4 wt% short carbon fibers. It was shown that a continuous and compact SCF network was built in a PDMS matrix. Furthermore, when the bolting cloth as a sarking was co-compressed with the mixture, a much lower percolation threshold of 0.06 wt% and a higher electrical conductivity of 3.22 Â 10 2 S m À1 with 4 wt% of SCF were obtained due to volume exclusion. Compared with the conventional compounding method, the electro-conductive properties of the composites prepared by the above mentioned method can be enhanced up to several times, or even by orders of magnitudes. Moreover, if the mesh number of the bolting cloth is large enough, the carbon fibers will be impeded from penetrating the bolting cloth together with the polymer when they are co-compressed, thus an electrically conductive film with single or double insulating face could be prepared through this method.

A mathematical model for predicting conductivity of polymer composites with a forced assembly network obtained bySCFNAmethod

“…The matrix material, filler type, and composite preparation method determine the features of structure formation. In earlier papers , we have proposed a new method of Spatial Confining Forced Network Assembly (SCFNA) based on a direct effect on the particles of the filler in polymer composite materials. This impact can significantly condense the conductive chains of filler inside the polymer matrix and reduce the percolation threshold of the material.…”

Development of a Flex and Stretchy Conductive Cotton Fabric Via Flat Screen Printing of PEDOT:PSS/PDMS Conductive Polymer Composite

“…As a result, PDMS-based flexible composites have been studied by many researchers. For example, high strain biocompatible PDMS-based conductive graphene and multi-walled carbon nanotube as a nano-composite strain sensors [16],electrically conductive PDMS-grafted carbon nanotubes-reinforced silicone elastomer [17], enhanced conductivity behavior of PDMS hybrid composites containing exfoliated graphite nano-platelets and carbon nano-tubes [18], high electro-conductive PDMS/short carbon fiber binary composites with electrical conductivity of 1.67 × 10 2 S/m [19], conductive elastomers based on multi-walled carbon nanotubes in PDMS with up to 0.01 S/cm conductivity [20], silver nano-wire network embedded in PDMS as a stretchable, transparent, and conductive substrate with 15 Ohm/sq [20], and stretchable electronics based on Ag-PDMS PCB (Printed circuit board) with a typical resistance of 2 Ohms/cm [21], have been reported.…”

“…As a result, PDMS-based flexible composites have been studied by many researchers. For example, high strain biocompatible PDMS-based conductive graphene and multi-walled carbon nanotube as a nano-composite strain sensors [16],electrically conductive PDMS-grafted carbon nanotubes-reinforced silicone elastomer [17], enhanced conductivity behavior of PDMS hybrid composites containing exfoliated graphite nano-platelets and carbon nano-tubes [18], high electro-conductive PDMS/short carbon fiber binary composites with electrical conductivity of 1.67 × 10 2 S/m [19], conductive elastomers based on multi-walled carbon nanotubes in PDMS with up to 0.01 S/cm conductivity [20], silver nano-wire network embedded in PDMS as a stretchable, transparent, and conductive substrate with 15 Ohm/sq [20], and stretchable electronics based on Ag-PDMS PCB (Printed circuit board) with a typical resistance of 2 Ohms/cm [21], have been reported.It was noticed that the common limitations of the conductive polymer composite-based conductive textiles reported in many works of the literature are that they possess inadequate flexibility, stretchability, and biocompatibility. Moreover, technical and scientific experimental evidence about the effect the conductive polymer composite has on the textile bulk properties like flexural rigidity, tensile strength, and extension at break, were not reported, which does not allow to determine if the fabrics still remain a true textile or if they lost their texture.Therefore, another approach is introduced in this work to produce a PEDOT:PSS Clevios PH 1000 (Figure 1a) and PDMS-b-PEO (Figure 1b) conductive polymer composite-based fabric.…”

Mechanically Enhanced Electrical Conductivity of Polydimethylsiloxane-Based Composites by a Hot Embossing Process

“…Electrically conducting polymer composites can be prepared by incorporating conductive fillers into an insulating polymer matrix, and provides the advantages of ease of processing and an ability to tailor the electrical properties based on composite architecture [1][2][3][4][5][6]. The electrical conductivity of polymer composites rely on the nature of the conductive fillers and the formation of a continuous and percolated conducting pathway in the insulating polymeric matrix [7][8][9][10][11]. The dispersion of conducting fillers such as carbon nanotubes (CNTs), carbon fibers, graphene and carbon black, in a polymer matrix have been improved by using in situ polymerization [12] or forming segregated microstructures under specific processing conditions [13].…”

“…As a result, the enhancement of electrical conductivity of polymer composites is very limited [21][22][23][24]. To promote the maximum electrical conductivity of polymer composites, we proposed a Spatial Confining Forced Network Assembly (SCFNA) method to increase the packing density of the conducting network in the composites by mechanical compression [8,[25][26], which reduced the separation distance between the fillers by excluding insulting polymer phase out of the network. This mechanical compression approach effectively enhanced the electrical conductivity of polypropylene/short carbon fiber (SCF) composites by 2-4 orders of magnitude [25] and thermal conductivity of PDMS/SCF composites by 7.79 times higher when reduced the sample thickness to 0.3 ~ 0.5 mm [26].…”