Sliding Tribological Behavior of Carbon Nanotube/Natural Rubber Composites

Chawla, Raj

doi:10.24874/ti.2018.40.02.10

Cited by 7 publications

(4 citation statements)

References 57 publications

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“…They would be an effective tool for investigating structure–property relationships in NR-antioxidant model PNCs. Accordingly, the interfacial interactions and dynamics at the NR-antioxidant interface were computed using the COMPASS force field (the interaction potentials are discussed in the Supporting Information) with estimated physical parameters, including diffusion coefficient ( D ), binding energy, MSD, and solubility parameter (δ). − The representative amorphous cell (AC) models of different NR- PNCs are depicted in Figure .…”

Section: Resultsmentioning

confidence: 99%

Curcuma Longa-Based Green and Sustainable Antioxidants for Biopolymers

Abdul Sattar

2024

ACS Sustainable Chem. Eng.

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Unsaturated biopolymers (e.g., natural rubber (NR)) are highly vulnerable to thermo-oxidative degradation, which causes premature failure of NR products. As an indispensable antioxidant globally, 6PPD (N-(1,3-dimethyl butyl)-N′-phenyl-p-phenylenediamine) is employed to retard the thermo-oxidative aging of NR. Unluckily, 6PPD and 6PPD-quinone (an oxidative product of 6PPD) are highly harmful to aquatic and human life and, thus, obviously merit their replacement with sustainable and safer antioxidants for environmental protection. This study explored the use of natural antioxidant curcumin for NR-based polymer nanocomposites (PNCs). The combined experimental, molecular dynamics (MD), and quantum mechanics (QM) simulations are implemented to analyze the effect of isomeric forms of curcumin on the protective mechanism, oxidative stability, solubility, dispersibility, and diffusion in the NR matrix. The results revealed that both 6PPD and curcumin scavenged the free radical preferentially via a hydrogen atom transfer mechanism. The computed transition state energies show that curcumin's enolic form (i.e., Curcumin (E)) interacts preferentially with ROO. (peroxy) radicals of NR with the lower barrier energy compared to 6PPD and could protect the NR from thermo-oxidative aging. The MD simulations have shown that the interfacial interactions at the NRcurcumin interface resulted in stronger binding energies, thus improving solubility and dispersibility with lower mean square displacement than 6PPD. While the migration of antioxidants is necessary to replenish their concentrations at the tire surface, the higher diffusion rate may cause the physical loss of antioxidants and thus decrease the service life of NR-PNCs. Overall, the NR-PNCs loaded with natural antioxidant curcumin exhibited improved oxidative resistance and viscoelastic performance compared to PNCs made with 6PPD. Thus, as a sustainable and safe antioxidant, curcumin could open an essential avenue toward the substantial pollution abatement from accumulated waste NR products in making "Greener NR-PNCs.″

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Section: Resultsmentioning

confidence: 99%

Curcuma Longa-Based Green and Sustainable Antioxidants for Biopolymers

Abdul Sattar

2024

ACS Sustainable Chem. Eng.

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“…Molecular dynamics (MD) simulations were performed on model NR nanocomposites as described above. The condensed-phase optimized molecular potentials for atomistic simulation studies (COMPASS) force field − was employed to study the interfacial interactions and dynamics of model NR nanocomposites, including pristine NR, NR-6PPD, and NR-MLN, respectively (Figure ). The MD simulations were realized with detailed parameters setup as follows to facilitate computational convergence.…”

Section: Computational Methodologymentioning

confidence: 99%

Molecular Insights into Antioxidant Efficiency of Melanin: A Sustainable Antioxidant for Natural Rubber Formulations

Abdul Sattar,

Patnaik

2023

J. Phys. Chem. B

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N-(1,3-Dimethyl butyl)-N′-phenyl-p-phenylenediamine (6-PPD) is a worldwide antioxidant commonly added to delay the thermo-oxidative degradation of tire rubbers. Unfortunately, 6PPD and its transformation product 6PPD-quinone are toxic to aquatic organisms (e.g., coho salmon). Herein, we explore the free radical scavenging activity and protective mechanism of melanin (MLN) on natural rubber's (NR's) oxidative resistance using molecular dynamics (MD) and quantum mechanical (QM) calculations. The relationship between the molecular structure and the chemical nature of the antioxidant molecules via transition state calculations is explored to unravel the reaction mechanisms of antioxidants interacting with peroxy radicals (ROO • ) of NR with the estimation of reaction barriers. Following this, the radical scavenging activity of antioxidants was quantified via a hydrogen atom transfer mechanism and bond dissociation energy calculations. Parallel MD simulations were considered to study the interfacial interactions of antioxidant molecules with polymer chains and fillers with a quantifiable structure−property correlation. Given these results, the nanocomposite (NR-MLN-SiO 2 ) with natural antioxidant melanin manifested outstanding antioxidant properties by preferentially bagging the ROO • radicals, thus improving NR's thermal-oxidative aging relative to 6-PPD. The MD results revealed that the intermolecular interactions at the NR/antioxidant interface benefited the antioxidant MLN to bind tightly to the NR in NR-MLN-SiO 2 composite, thus exhibiting improved dispersion, O 2 barrier properties, and thermo-oxidative stability, which could extend the service life of NR products (e.g., tires). In addition, as a sustainable antioxidant, MLN could replace toxic antioxidants like 6-PPD. More importantly, the QM/MD simulations provided a fundamental understanding of the mechanistic pathways of antioxidant molecules in NR composites, which are conducive to designing highperformance and sustainable green elastomers.

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“…Li et al studied the tribological properties of graphene reinforced polymer composites using MD simulations [39,40]. Several research contributions have been made by Chawla et al to predict the effect of CNT reinforcement in natural rubber on its tribological and mechanical properties using MD simulations [41][42][43][44][45]. Song et al [46] carried out MD simulations to predict the mechanical and tribological properties of polytetrafluoroethylene reinforced with SWCNT.…”

Section: Introductionmentioning

confidence: 99%

Tribological Properties of Aluminium Reinforced with Differently Oriented Carbon Nanotube: A Molecular Dynamics Study

Patel

Sharma

Tiwari

2021

Surf. Topogr.: Metrol. Prop.

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Molecular dynamics (MD) simulations have been carried out to envisage the sliding friction response of single-wall carbon nanotube (SWCNT) reinforced aluminum (Al) nanocomposites and pure Al. The simulations have been performed with different sliding velocities (0.02-0.11 Å ps −1 ) using the three-layer model. The effect of carbon nanotube (CNT) reinforcement, CNT orientation, and sliding velocities on the coefficient of friction (COF), abrasion rate, and mean square displacement (MSD) have been predicted. The reinforcement of CNT decreased the COF to 0.06 by 45% and the lowest abrasion rate of 0.093%. The reinforcement of CNT in Al parallel to the sliding direction of the Fe rod indenter was found to be more effective for improvement in the tribological properties as compared to perpendicularly reinforced CNT. The increase in sliding velocity of the indenter increased the COF from 0.06 to 0.08 and decreased the abrasion rate from 0.172% to 0.094% for CNT-Al nanocomposites. The ANOVA at the 95% level of confidence revealed that the effect of sliding velocities (0.02-0.11 Å ps −1 ) of indenter was found to be insignificant for the variation in COF and significant for variation of abrasion rate while the type of reinforcement was found to be significant for both COF as well as for the abrasion rate. The MSD revealed the higher migration of Al atoms from the surface of nanocomposites at higher sliding velocity.

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Sliding Tribological Behavior of Carbon Nanotube/Natural Rubber Composites

Cited by 7 publications

References 57 publications

Curcuma Longa-Based Green and Sustainable Antioxidants for Biopolymers

Curcuma Longa-Based Green and Sustainable Antioxidants for Biopolymers

Molecular Insights into Antioxidant Efficiency of Melanin: A Sustainable Antioxidant for Natural Rubber Formulations

Tribological Properties of Aluminium Reinforced with Differently Oriented Carbon Nanotube: A Molecular Dynamics Study

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