Waste to Value-Added Product: Developing Electrically Conductive Nanocomposites Using a Non-Recyclable Plastic Waste Containing Vulcanized Rubber

Hoseini, Amir Hosein Ahmadian; Erfanian, Elnaz; Kamkar, Milad; Sundararaj, Uttandaraman; Liu, Jian; Arjmand, Mohammad

doi:10.3390/polym13152427

Cited by 8 publications

(11 citation statements)

References 80 publications

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“…First, the composites containing micro-scale secondary fillers have a higher electrical conductivity compared to those composed of only CNTs. This enhancement can be attributed to the excluded volume effects [ 33 , 34 , 35 ]. The inclusion of micro-scale particles into the composite reduced the available space for CNTs, resulting in increased contact between the CNTs.…”

Section: Resultsmentioning

confidence: 99%

Piezoresistive Effect of Conductive and Non-Conductive Fillers in Bi-Layer Hybrid CNT Composites under Extreme Strain

Kim,

Nam,

Kang

et al. 2023

Materials

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Polymers mixed with conductive fillers hold significant potential for use in stretchable and wearable sensor devices. Enhancing the piezoresistive effect and mechanical stability is critical for these devices. To explore the changes in the electrical resistance under high strains, typically unachievable in single-layer composites, bi-layer structures were fabricated from carbon nanotubes (CNTs) and EcoFlex composites to see unobservable strain regions. Spherical types of non-conductive fillers composed of polystyrene and conductive filler, coated with Ni and Au on non-conductive fillers, were used as secondary fillers to improve the piezoresistive sensitivity of composites, and their respective impact on the conductive network was compared. The electrical and mechanical properties were examined in the static state to understand the impact of these secondary fillers. The changes in the electrical resistance under 100% and 300% tensile strain, and their dependence on the inherent electrical properties of the secondary fillers, were also investigated. Single-layer CNT composites proved incapable of withstanding 300% strain, whereas the bi-layer structures proved resilient. By implementing cyclic stretching tests, contrary to non-conductive fillers, reduced piezoresistive influence of the conductive secondary filler under extreme strain conditions could be observed.

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Section: Resultsmentioning

confidence: 99%

Piezoresistive Effect of Conductive and Non-Conductive Fillers in Bi-Layer Hybrid CNT Composites under Extreme Strain

Kim,

Nam,

Kang

et al. 2023

Materials

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“…However, cross-linked networks still remained in the three types of RRs prepared in this work, and they impeded the even distribution of CNT particles. As shown in Figure b, the dispersion of CNT particles in HX-RR was segregated between densely cross-linked networks because the high viscosity of gel fraction prevents the random distribution of CNT particles. , Therefore, dense network domains are covered by various sizes and shapes of “CNT rings”, so-called segregated or interconnected structures. ,, This indicates heterogeneous reclamation of the rubber molecules and cross-linked networks. Specifically, the cross-linked regions or highly dense networks in HX-RR act as excluded volumes that force CNT filler to locate in the interstitial volume, , which is related to the sol fraction in RR.…”

Section: Results and Discussionmentioning

confidence: 99%

“…36,37 Therefore, dense network domains are covered by various sizes and shapes of "CNT rings", so-called segregated or interconnected structures. 24,29,38 This indicates heterogeneous reclamation of the rubber molecules and cross-linked networks. Specifically, the cross-linked regions or highly dense networks in HX-RR act as excluded volumes that force CNT filler to locate in the interstitial volume, 25,37 which is related to the sol fraction in RR.…”

Section: Morphologymentioning

confidence: 97%

“…Meanwhile, carbon black in GTR and the addition of CNT in the composite provided EMI materials with high electrical conductivity and EMI shielding effectiveness. The utilization of GTR to produce conductive materials has been reported elsewhere because carbon black in GTR would provide benefit for constructing a conductive network. − However, some waste rubber latex products such as condoms, balloons, and medical gloves are unfilled vulcanizates and lack carbon fillers. Producing advanced multifunctional materials is more challenging than with GTR.…”

Section: Introductionmentioning

confidence: 99%

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Segregated MWCNT Structure Formation in Conductive Rubber Nanocomposites by Circular Recycling of Rubber Waste

Saiwari

Nobnop

Bueraheng

et al. 2022

ACS Appl. Polym. Mater.

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The reclamation and devulcanization processes of rubber waste change its cross-link density and sol−gel proportions, which are essential in the reprocessing of reclaimed rubber (RR), especially in the dispersion of nanofillers throughout the RR matrix. In this work, conductive elastomers based on RR/carbon nanotubes (CNTs) were prepared. Proper control of the quality of RR is needed to ensure the effective formation of conductive pathways within the matrix. Therefore, this work aimed to control a segregated CNT network by manipulating how the RR is prepared. Three alternative devulcanization conditions were tested: (a) physical reclaiming, (b) thermomechanical reclaiming, and (c) thermochemical reclaiming. These techniques resulted in three types of RRs. Nanocomposite based on the physically RR presented the highest tensile strength, reaching approximately 15 MPa with addition of 2 phr of CNT. This was due to a comparatively lesser destruction of the rubber network and the formation of a segregated structure of CNT filler in the nanocomposite. Therefore, the conductive performance was significantly enhanced from 4.5 × 10 −10 S/cm for unfilled to 1.25 × 10 −6 S/cm with CNT dose as low as 1 vol %. The segregated CNT network, whose formation was assisted by gel fraction and excluded volume in RR, also resulted in a very low electrical percolation threshold φ c , which was significantly reduced from 0.78 vol % for low cross-linked RR to 0.14 vol % for high cross-linked RR. This could reduce CNT filler use by 80% whereas 100% of pristine rubber would be replaced, and mechanical and electrical properties would improve. The approach described in this work will be helpful in manufacturing conductive rubber products efficiently yet sustainably with recycling of rubber waste.

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“…For PVDF nanocomposites containing (N-MWNTs) 20 and (N-MWNTs) 40 , G ′ is greater than G ″ in the small amplitude region. This solid-like behavior ( G ′ > G ″) signifies the presence of a percolated network and the ability of these N-MWNTs to form an integrated 3D network [ 55 ]. This initial solid-like behavior undergoes a solid-to-liquid-like transition ( G ′ < G ″) by increasing the amplitude of deformation.…”

Section: Resultsmentioning

confidence: 99%

A Simple Approach to Control the Physical and Chemical Features of Custom-Synthesized N-Doped Carbon Nanotubes and the Extent of Their Network Formation in Polymers: The Importance of Catalyst to Substrate Ratio

et al. 2021

Self Cite

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This study intends to reveal the significance of the catalyst to substrate ratio (C/S) on the structural and electrical features of the carbon nanotubes and their polymeric nanocomposites. Here, nitrogen-doped carbon nanotube (N-MWNT) was synthesized via a chemical vapor deposition (CVD) method using three ratios (by weight) of iron (Fe) catalyst to aluminum oxide (Al2O3) substrate, i.e.,1/9, 1/4, and 2/3, by changing the Fe concentration, i.e., 10, 20, and 40 wt.% Fe. Therefore, the synthesized N-MWNT are labelled as (N-MWNTs)10, (N-MWNTs)20, and (N-MWNTs)40. TEM, XPS, Raman spectroscopy, and TGA characterizations revealed that C/S ratio has a significant impact on the physical and chemical properties of the nanotubes. For instance, by increasing the Fe catalyst from 10 to 40 wt.%, carbon purity increased from 60 to 90 wt.% and the length of the nanotubes increased from 1.2 to 2.6 µm. Interestingly, regarding nanotube morphology, at the highest C/S ratio, the N-MWNTs displayed an open-channel structure, while at the lowest catalyst concentration the nanotubes featured a bamboo-like structure. Afterwards, the network characteristics of the N-MWNTs in a polyvinylidene fluoride (PVDF) matrix were studied using imaging techniques, AC electrical conductivity, and linear and nonlinear rheological measurements. The nanocomposites were prepared via a melt-mixing method at various loadings of the synthesized N-MWNTs. The rheological results confirmed that (N-MWNTs)10, at 0.5–2.0 wt.%, did not form any substantial network through the PVDF matrix, thereby exhibiting an electrically insulative behavior, even at a higher concentration of 3.0 wt.%. Although the optical microscopy, TEM, and rheological results confirmed that both (N-MWNTs)20 and (N-MWNTs)40 established a continuous 3D network within the PVDF matrix, (N-MWNTs)40/PVDF nanocomposites exhibited approximately one order of magnitude higher electrical conductivity. The higher electrical conductivity of (N-MWNTs)40/PVDF nanocomposites is attributed to the intrinsic chemical features of (N-MWNTs)40, such as nitrogen content and nitrogen bonding types.

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Waste to Value-Added Product: Developing Electrically Conductive Nanocomposites Using a Non-Recyclable Plastic Waste Containing Vulcanized Rubber

Cited by 8 publications

References 80 publications

Piezoresistive Effect of Conductive and Non-Conductive Fillers in Bi-Layer Hybrid CNT Composites under Extreme Strain

Piezoresistive Effect of Conductive and Non-Conductive Fillers in Bi-Layer Hybrid CNT Composites under Extreme Strain

Segregated MWCNT Structure Formation in Conductive Rubber Nanocomposites by Circular Recycling of Rubber Waste

A Simple Approach to Control the Physical and Chemical Features of Custom-Synthesized N-Doped Carbon Nanotubes and the Extent of Their Network Formation in Polymers: The Importance of Catalyst to Substrate Ratio

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