Pretreatment of Hevea Latex by Sorbitol: Improving the Efficacy of Silica Dispersion by a Biomimetic Approach

Bera, Abhijit; Manna, Bharat; Ganguly, Debabrata; Amarnath, S. K. P.; Nanda, Samik; Ghosh, Amit; Chattopadhyay, Santanu

doi:10.1021/acsapm.2c01588

Cited by 4 publications

(2 citation statements)

References 41 publications

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“…Natural rubber (NR) obtained from Hevea brasiliensis is a strategically important biopolymer used in diverse applications − (tires, seals, gloves, etc.) due to its exceptional entropy-elasticity.…”

Section: Introductionmentioning

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: Introductionmentioning

confidence: 99%

Curcuma Longa-Based Green and Sustainable Antioxidants for Biopolymers

Abdul Sattar

2024

ACS Sustainable Chem. Eng.

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“…Biopolymers such as natural rubber (NR) are extensively utilized in vehicle tires due to their unique high elasticity, outstanding resilience, and insulation properties. − However, the presence of several methyl groups, unstable CC bonds, and active allyl hydrogens in the NR molecular chain limits its applicability due to thermo-oxidative aging, thereby dramatically shortening the service life of NR products (e.g., tires). External stimuli, including light, heat, ozone, and oxygen, could significantly deteriorate the physical or chemical properties of NR products. − Thus, enhancing the NR’s oxidative aging resistance is of primary importance for physical or chemical property enhancement and for economic reasons.…”

Section: Introductionmentioning

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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