Artificial Neural Network Modeling and Mechanism Study for Relaxation of Deformed Rubber

Abstract

An artificial neural network (ANN) was developed to estimate the relaxation property of diene rubber. Regularization was introduced into the ANN and the average prediction accuracy was 98.72%. The sensitivity analysis shows that compressive strain is the crucial influence on the relaxation property. Diene rubber shows a higher relaxation at low compressive strain than at high compressive strain. Molecular simulations show that rubber at low compressive strain possesses high fractional free volume, molecular chain movement, and ozone permeability. The chemical characterization of cross-link density and 2D-FTIR correlation analysis show that the rubber network at low compressive strain is seriously degraded by random scission and the generation rate of the carbonyl group is faster than that of ozonide group, indicating chain scission predominates in ozonation. These fundamental studies are expected to provide a comprehensive understanding of the relaxation property of deformed rubber and guidance for the design of antiaging materials.

Molecule Dynamics Simulation of the Effect of Oxidative Aging on Properties of Nitrile Rubber

“…To further analyze the influence of hydroxyl groups and carbonyl groups on motion ability of rubber chains, the MSD was used to estimate self-diffusion coefficients by using the Einstein equation [30,39,43,44], which is expressed as:…”

“…The volume of rubber models is mainly composed of the volume of the rubber chain and the free volume caused by thermal movement of rubber chain. With increase of temperature, the conformational entropy increased and chain segments motioned significantly, leading to an increase of FFV [30]. Additionally, the application of compressive strain limited the thermal movement of the rubber molecular chains, resulting in efficient molecular packing and a decrease of FFV.…”

“…In recent years, molecular dynamics (MD) simulation has been employed as an effective theoretical tool to comprehend quantitatively the structure-performance relationships of polymer materials at the molecular scale, especially in modification of polymers and diffusion of small molecules in polymers [28,29]. Although the molecular dynamics simulation methods were preliminarily applied to estimate the thermal oxidative aging mechanism of rubber materials [30][31][32], the chemical reactions such as oxidation products during the aging process are not fully considered by researchers. For example, Wang et al [30] found that rubber at low compressive strain possesses high fractional free volume, molecular chain movement, and ozone permeability by molecular dynamics simulation.…”

“…Although the molecular dynamics simulation methods were preliminarily applied to estimate the thermal oxidative aging mechanism of rubber materials [30][31][32], the chemical reactions such as oxidation products during the aging process are not fully considered by researchers. For example, Wang et al [30] found that rubber at low compressive strain possesses high fractional free volume, molecular chain movement, and ozone permeability by molecular dynamics simulation. Zhi et al [31] studied the heterogeneous oxidative aging and viscoelastic performance of rubber based on multi-scale simulation.…”

Chain dynamics evolution of ethylene‐propylene‐diene monomer in response to hot humid and salt fog environment

“…In fundamental, the stronger the polymer chain mobility, the more serious the chain relaxation behavior, which will affect the free volume and viscosity of the material. For example, Wang et al 14 proved that the mobility of molecular chains is proportional to the free volume fraction, which is conducive to the penetration of ozone molecules into the rubber to destroy the structure and increase the permanent deformation. Xu et al 15 used MD simulation to study the oxidative aging behavior of asphalt.…”