Coupled analysis on hyper-viscoelastic mechanical behavior and macromolecular network alteration of rubber during thermo-oxidative aging process

Understanding the aging mechanism of polypropylene (PP) is fundamental for the fabrication and application of PP-based materials. In this paper, we present our study in which we first used reactive molecular dynamics (RMD) simulations to explore the thermo-oxidative aging of PP in the presence of acetic acid or acetone. We studied the effects of temperature and oxygen on the aging process and discussed the formation pathways of typical small molecule products (H2, CO, CO2, CH4, C2H4, and C2H6). The effect of two infection agents, acetic acid and acetone, on the aging reaction was analyzed emphatically. The simulation results showed that acetone has a weak impact on accelerating the aging process, while acetic acid has a significant effect, consistent with previous experimental studies. By tracking the simulation trajectories, both acetic acid and acetone produced small active free radicals to further react with other fragment products, thus accelerating the aging process. The first reaction step of acetic acid is often the shedding of the H atom on the hydroxyl group, while the reaction of acetone is often the shedding of the H atom or the methyl. The latter requires higher energy at lower temperatures. This is why the acceleration effect of acetone for the thermo-oxidative aging of PP was not so significant compared to acetic acid in the experimental temperature (383.15 K).

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Analytical and Chemometric Characterization of Fino and Amontillado Sherries during Aging in Criaderas y Solera System

Molecules ◽

10.3390/molecules27020365 ◽

2022 ◽

Vol 27 (2) ◽

pp. 365

Author(s):

Manuel J. Valcárcel-Muñoz ◽

María Guerrero-Chanivet ◽

María del Carmen Rodríguez-Dodero ◽

María de Valme García-Moreno ◽

Dominico A. Guillén-Sánchez

Keyword(s):

Aging Process ◽

Hierarchical Cluster ◽

Biological Aging ◽

Microbiological Activity ◽

Dry Extract ◽

Oxidative Aging ◽

Physical Chemical ◽

Sherry Wine ◽

Flor Yeasts

Fino and Amontillado are Sherry wines, produced in Marco de Jerez area (southern Spain), and aged in Criaderas y Solera system. Fino Sherry wine follows a biological aging process, under a veil of flor yeasts, while Amontillado Sherry wine shares the same biological aging firstly, followed by oxidative aging, which gives them special features. Organic acids, esters, higher alcohols, phenolic compounds and total dry extract of Sherries evolve during aging due to evaporation processes, physical-chemical reactions, wood contributions and microbiological activity. During aging, Sherry wines improve their organoleptic profile, as could be proved in the tasting sessions. Hierarchical Cluster Analysis and Factor Analysis with factor extraction using Principal Components of Sherry wines studied were carried out and natural groupings of the wines according to the type of aging and their age were observed. A strong correlation between the parameters analyzed and the aging of each wine has been seen in the Multiple Linear Regression studies, establishing two different models, one for each type of Sherry wine, that, with only four of all the variables studied estimated the wine age with more than 99% of confidence. This constitutes a useful tool to control the age of these Sherry wines in the winery.

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Wine Aging Technology: Fundamental Role of Wood Barrels

Foods ◽

10.3390/foods9091160 ◽

2020 ◽

Vol 9 (9) ◽

pp. 1160

Author(s):

Maria Carpena ◽

Antia G. Pereira ◽

Miguel A. Prieto ◽

Jesus Simal-Gandara

Keyword(s):

Aging Process ◽

Storage Time ◽

Economic Implications ◽

Oxidative Aging ◽

General Terms ◽

Two Phases ◽

Light Bottle ◽

Wine Aging ◽

The Eu

The aging of wines is a process used to preserve wine but also to enhance its properties. It is a process of great interest, mainly because of the additional properties it adds to wines and because of its economic implications. Historically, barrels have been employed for centuries for preserving and aging wine due to their resistance and relative impermeability. In general terms, the wine aging process can be divided into two phases: oxidative and reductive aging. Oxidative aging traditionally takes place in barrels while reductive phase occurs in the bottle. During both processes, oxygen plays a fundamental role as well as other factors, for instance: temperature, light, bottle position, microbial growth or storage time. Likewise, during the aging process, a series of chemical reactions take place influencing the composition and organoleptic profile of wine. At this point, oxidative aging in barrels is a fundamental step. Barrels are directly involved in the produced changes on wine’s composition due to the transference of oxygen and phenolic and aromatic compounds from wood to wine. This way, barrels act as an active vessel capable of releasing compounds that affect and improve wine’s characteristics. Regarding, the importance of barrels during aging process, some attention must be given to the species most used in cooperage. These species are conventionally oak species, either French or American. However, other non-conventional species are currently being studied as possible wood sources for the production of wines, such as chestnut robinia or other oak species. In the last decades, new approaches have been developed for barrel aging to find new alternatives more suitable, affordable and feasible to sanitize the process, such as other materials different from wood or the use of wood chips, which is regulated since 2006 by the EU. However, even though some of them have shown promising data, barrels are currently the most used technology for the oxidative stage of table wines aging.

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Coupled analysis on heterogeneous oxidative aging and viscoelastic performance of rubber based on multi-scale simulation

Journal of Applied Polymer Science ◽

10.1002/app.47452 ◽

2019 ◽

Vol 136 (18) ◽

pp. 47452 ◽

Cited By ~ 1

Author(s):

Jieying Zhi ◽

Qinglin Wang ◽

Mengjie Zhang ◽

Manjia Li ◽

Yuxi Jia

Keyword(s):

Coupled Analysis ◽

Oxidative Aging ◽

Multi Scale

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CHEMO-MECHANICAL MODEL FOR PREDICTING THE LIFETIME OF EPDM RUBBERS

Rubber Chemistry and Technology ◽

10.5254/rct.19.81469 ◽

2019 ◽

Vol 92 (4) ◽

pp. 722-748 ◽

Cited By ~ 2

Author(s):

Xavier Colin ◽

Mouna Ben Hassine ◽

Moussa Nait-Abelaziz

Keyword(s):

Mechanical Behavior ◽

Thermal Aging ◽

Mechanical Model ◽

Degradation Kinetics ◽

Weight Changes ◽

Cross Link ◽

Elementary Reactions ◽

Industrial Material ◽

Macromolecular Network ◽

Concentration Changes

ABSTRACT A chemo-mechanical model has been developed for predicting the long-term mechanical behavior of EPDM rubbers in a harsh thermal oxidative environment. Schematically, this model is composed of two complementary levels: The “chemical level” calculates the degradation kinetics of the macromolecular network that is introduced into the “mechanical level” to deduce the corresponding mechanical behavior in tension. The “chemical level” is derived from a realistic mechanistic scheme composed of 19 elementary reactions describing the thermal oxidation of EPDM chains, their stabilization against oxidation by commercial antioxidants but also by sulfide bridges, and the maturation and reversion of the macromolecular network. The different rate constants and chemical yields have been determined from a heavy thermal aging campaign in air between 70 and 170 °C on four distinct EPDM formulations: additive free gum, unstabilized and stabilized sulfur vulcanized gum, and industrial material. This “chemical level” has been used as an inverse resolution method for simulating accurately the consequences of thermal aging at the molecular (concentration changes in antioxidants, carbonyl products, double bonds, and sulfide bridges), macromolecular (concentration changes in chain scissions and cross-link nodes), and macroscopic scales (weight changes). Finally, it gives access to the concentration changes in elastically active chains from which are deduced the corresponding changes in average molar mass MC between two consecutive cross-link nodes. The “mechanical level” is derived from a modified version of the statistical theory of rubber elasticity, called the phantom network theory. It relates the elastic and fracture properties to MC if considering the macromolecular network perfect, and gives access to the lifetime of the EPDM rubber based on a relevant structural or mechanical end-of-life criterion. A few examples of simulations are given to demonstrate the reliability of the chemo-mechanical model.

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Micro-Mechanical Model for Thermo-Oxidative Aging of Elastomers

Volume 9: Mechanics of Solids, Structures, and Fluids ◽

10.1115/imece2018-88109 ◽

2018 ◽

Author(s):

Hamid Mohammadi ◽

Roozbeh Dargazany

Keyword(s):

Mechanical Model ◽

Strain Energy ◽

Aging Process ◽

Polymer Chains ◽

Constitutive Behavior ◽

Network Decomposition ◽

Oxidative Aging ◽

The One ◽

Micro Sphere ◽

Good Agreement

In this study, a micro-mechanical model for constitutive behavior of elastomers subjected to thermo-oxidative aging is proposed. The model is based on the network decomposition concept and lies within the framework of continuum mechanics. It is assumed that the aging process leads to the formation of a new network with tighter chains. Accordingly, the strain energy of the system is constituted of two independent sources, the energy of the original soft network and the one of the reformed network. These strain energies were computed by integration of entropic energy of polymer chains in each direction of a micro-sphere. The model demonstrates good agreement with different experimental data on relaxation and intermittent tests.

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Four-point bending mechanical behavior of aged asphalt mixtures containing charcoal

International Journal for Innovation Education and Research ◽

10.31686/ijier.vol7.iss10.1794 ◽

2019 ◽

Vol 7 (10) ◽

pp. 460-472

Author(s):

Alemar Pereira Torres ◽

Igor Nonato Almeida Pereira ◽

Juliano Rodrigues Spínola ◽

Alex Gomes Pereira ◽

Consuelo Alves da Frota

Keyword(s):

Mechanical Behavior ◽

Aging Process ◽

Mechanical Characteristics ◽

Asphalt Mixtures ◽

Bending Test ◽

New Materials ◽

Molding Process ◽

Four Point Bending ◽

Aged Asphalt ◽

Four Point Bending Test

The asphalt coating is the layer responsible for resisting the traffic stresses of a highway. However, the search for new materials to mitigate environmental impacts and improve pavement quality is increasing. Thus, the mechanical behavior of asphalt mixtures was analyzed through the four-point bending test after the molding process and aged, with the participation of residues in the form of charcoal. The frequencies of 1Hz, 3Hz, 5Hz, 10Hz, 20Hz and 1Hz are considered at temperatures of 25°C and 40°C. The aging process contributed to improve the mechanical characteristics of the charcoal mixture at a temperature of 25 ° C, considering that there was an increase in stiffness at frequencies from 1 to 20 Hz, as well as a reduction in phase angle at frequencies of 3 Hz. , 5 Hz, 10 Hz and 20 Hz.

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Optical Characterization of Asphalt Binders Containing Wax Additives

Advances in Civil Engineering ◽

10.1155/2020/4170691 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7

Author(s):

Mithil Mazumder ◽

Raju Ahmed ◽

Moon-Sup Lee ◽

Soon-Jae Lee

Keyword(s):

Optical Properties ◽

Aging Process ◽

Significant Contribution ◽

Asphalt Binder ◽

Optical Characterization ◽

Crumb Rubber ◽

Asphalt Binders ◽

Oxidative Aging ◽

Modified Binder

In between thermal-oxidative (heat and oxygen) and photo-oxidative (ultraviolet irradiation and oxygen) aging process of bitumen, photo-oxidative aging mainly depends on the optical properties of the asphalt binder. The higher the reflection (or the lower the absorption of the binders), the better the pavement serviceability. The literature review indicates that there is limited research conducted on the optical properties of the binder with wax additives. In this paper, the optical properties of commonly used binders (PG 64-22, Rubber modified binder, and SBS modified binder) containing wax additives (LEADCAP and Sasobit) were investigated using UV-Vis spectrometer. The result of this study showed that (1) the addition of modifiers (crumb rubber and SBS) with the base binder slightly increases the absorption of the binder; (2) the binder types and aging level have significant contribution on optical properties; (3) in general, the aged binders were observed to have higher reflectivity compared to the unaged binders; and (4) the addition of wax additives is observed to have a significant effect on the optical properties.

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Investigation of UV Absorber Residue Improving Aging Properties of Bitumen

Materials Science Forum ◽

10.4028/www.scientific.net/msf.847.413 ◽

2016 ◽

Vol 847 ◽

pp. 413-417 ◽

Cited By ~ 2

Author(s):

Li Gao ◽

Jian Ying Yu ◽

Min Wu ◽

Li Hui Xue

Keyword(s):

Aging Process ◽

Retention Rate ◽

Modified Bitumen ◽

Uv Aging ◽

Oxidative Aging ◽

Uv Absorber ◽

Aging Index ◽

Modify Bitumen ◽

Aging Properties ◽

Aging Resistance

Ultraviolet (UV) absorber residue was used to modify bitumen. Effects of UV absorber residue on thermo-oxidative and UV aging properties of bitumen were evaluated by conventional physical properties and SARA (saturates, aromatics, resins and bitumenenes) analysis. The results showed that the viscosity aging index (VAI) and softening point increment (SPI) of bitumen decreased significantly due to introduction of the UV absorber residue, and the ductility retention rate (DRR) was evidently higher compared to the pristine bitumen. SARA show that UV absorber residue can effectively restrain the gelatinization of bitumen resulted from aging. As a consequence, the UV absorber residue modified bitumen displays enhanced aging resistance properties, which can be attributed to the physical sorption of activated carbon to lighter components in the thermo-oxidative aging process and the absorption of UV absorption residue to the ultraviolet light in the process of UV aging.

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Environmental Factors on Aging of Nitrile Butadiene Rubber (NBR) - A Review

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1033-1034.987 ◽

2014 ◽

Vol 1033-1034 ◽

pp. 987-990 ◽

Cited By ~ 4

Author(s):

Qing Yun Tang ◽

Wei Fang Zhang

Keyword(s):

Mechanical Properties ◽

Aging Process ◽

Physical And Mechanical Properties ◽

External Factors ◽

Future Research ◽

Butadiene Rubber ◽

Liquid Environment ◽

Oxidative Aging ◽

Nitrile Butadiene Rubber ◽

Micro Analysis

Nitrile butadiene rubber (NBR) comes into widespread applications due to the excellent performances, but it is susceptible to aging during its storage and usage periods. This paper surveys the external factors that act on the aging process of NBR. The aging of NBR in liquid environment, and non-liquid environment such as thermo-oxidative aging, ozone aging, stress aging and radiation aging, are considered. The emphasis of present works is test of physical and mechanical properties of NBR, and the micro analysis should gain special attention. One direction of future research on NBR aging is the coupling effects of various factors included in this paper.

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