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Lewandowska H, Sadło J. Radical Composition and Radical Reaction Kinetics in the Probe-Irradiated XLPE Samples as a Potential Source of Information on Their Aging Degree. MATERIALS (BASEL, SWITZERLAND) 2022; 15:5723. [PMID: 36013865 PMCID: PMC9414847 DOI: 10.3390/ma15165723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/16/2022] [Accepted: 08/17/2022] [Indexed: 06/15/2023]
Abstract
Polyethylene is a model polyolefin, and a widely used material for the manufacture of many products, including cable sheaths. Understanding degradation mechanisms at the atomic scale leading to oxidation during aging is crucial for many long-term applications. The concentrations of radicals derived from oxidation and chain scission during radio-oxidation, as well as their ratio, are important parameters controlling the predominance of chain scission or crosslinking of the polymer. In this work, we propose a cryogenic EPR technique for measuring oxidation- and fragmentation-derived radicals as a less-destructive method for the evaluation of cable insulation aging and performance capability. We investigate the effect of the low-dose and high-dose radiation aging on the formation of free radicals in the polymer matrix that are both unprotected and protected by antioxidants. The stability of radicals after aging is a determinant of macroscopic processes and structural changes during aging. Under the conditions of the higher dose rate, the peroxy radical buildup is lower per dose. Peroxy radical buildup is followed by decay during aging, in accordance with POOH content. Our results allow the prediction of the capability of the antioxidant to protect the XLPE material in the function of dose and time.
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Kabir SF, Adlington K, Parsons AJ, Ahmed I, Irvine DJ. Comparison of thermal, thermomechanical, and rheological properties of blends of divinylbenzene‐based hyperbranched and linear functionalized polymers. J Appl Polym Sci 2020. [DOI: 10.1002/app.48547] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sumaya F. Kabir
- Department of Mechanical, Materials, and Manufacturing Engineering, Faculty of EngineeringUniversity of Nottingham Nottingham NG7 2RD UK
| | - Kevin Adlington
- Department of Chemical and Environmental Engineering, Faculty of EngineeringUniversity of Nottingham, University Park Nottingham NG7 2RD UK
| | - Andrew J. Parsons
- Department of Mechanical, Materials, and Manufacturing Engineering, Faculty of EngineeringUniversity of Nottingham Nottingham NG7 2RD UK
| | - Ifty Ahmed
- Department of Mechanical, Materials, and Manufacturing Engineering, Faculty of EngineeringUniversity of Nottingham Nottingham NG7 2RD UK
| | - Derek J. Irvine
- Department of Chemical and Environmental Engineering, Faculty of EngineeringUniversity of Nottingham, University Park Nottingham NG7 2RD UK
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Smith LM, Aitken HM, Coote ML. The Fate of the Peroxyl Radical in Autoxidation: How Does Polymer Degradation Really Occur? Acc Chem Res 2018; 51:2006-2013. [PMID: 30016062 DOI: 10.1021/acs.accounts.8b00250] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bolland and Gee's basic autoxidation scheme (BAS) for lipids and rubbers has long been accepted as a general scheme for the autoxidation of all polymers. This scheme describes a chain process of initiation, propagation, and termination to describe the degradation of polymers in the presence of O2. Central to this scheme is the conjecture that propagation of damage to the next polymer chain occurs via hydrogen atom transfer with a peroxyl radical. However, this reaction is strongly thermodynamically disfavored for all but unsaturated polymers, where the product allylic radical is resonance-stabilized. Paradoxically, there is no denying that the autocatalytic degradation and oxidation of saturated polymers still occurs. Critical analysis of the literature, described herein, has begun to unravel this mystery. One possibility is that the BAS still holds for saturated polymers but only at unsaturated defect sites, where H transfer is thermodynamically favorable. Another is that peroxyl termination rather than H transfer is dominant. If this were the case, tertiary peroxyl radicals (formed at quaternary centers or quaternary branching defects) may terminate to form alkoxy radicals, which can much more readily undergo chain transfer. This process would lead to the creation of hydroxy groups on the degraded polymer. On the other hand, primary and secondary peroxyl radicals would terminate to form nonradical products and halt further degradation. As a result, under this scenario the degree of branching and substitution would have a major effect on polymer stability. Herein we survey studies of polymer degradation products and of the effect of polymer structure on stability and show that indeed peroxyl termination is competitive with peroxyl transfer and possibly dominant under some conditions. It is also feasible that oxygen may not be the only reactive atmospheric species involved in catalyzing polymer degradation. Herein we outline plausible mechanisms involving ozone, hydroperoxyl radical, and hydroxyl radical that have all been suggested in the literature and can account for the experimentally observed formation of hydroperoxides without invoking peroxyl transfer. We also show that oxygen itself has even been reported to slow the degradation of poly(methyl methacrylate)s, which might be expected if peroxyl radicals are unreactive toward hydrogen transfer. Discrepancies between the rate of oxidation and the rate of degradation have been observed for polyolefins and also support the counterintuitive notion that oxygen stabilizes these polymers against degradation. We show that together these studies support alternative mechanisms for polymer degradation. A thorough assessment of kinetic studies reported in the literature indicates that they are limited by their propensity to use models based on the BAS, disregarding the chemical differences intrinsic to each class of polymer. Thus, we propose that further work must be done to fully grasp the complex mechanism of polymer degradation under ambient conditions. Nonetheless, our analysis of the literature points to measures that can be used to enhance or prevent polymer degradation and indicates that we should focus beyond just the role of oxygen toward the specific chemical nature and environment of the polymer at hand.
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Affiliation(s)
- Leesa M. Smith
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Heather M. Aitken
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Michelle L. Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
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Zhu Y, Zhang D, Zhang Z, Wang Z. The Effect of Polymer Structures on Complete Degradation: A First-Principles Study. ChemistryOpen 2018; 7:463-466. [PMID: 29930892 PMCID: PMC6009993 DOI: 10.1002/open.201800078] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Indexed: 11/25/2022] Open
Abstract
The widespread application of hydrocarbon polymer materials has spurred an increasing interest in the study of their dissociation mechanism, which is related to key issues such as environmental protection. In this work, the last-step dissociation characteristics of carbon chain polymers were investigated. By using density functional theory, we considered all possible structures, including three typical normal linkage polymers and four typical abnormal linkage ones. In these structures, it can be found that the energy barrier required for the complete degradation of chain-end saturated and unsaturated polymers are in the range of 3.42 to 4.78 eV and 0.35 to 1.31 eV, respectively. It shows that the unsaturated polymer is easier to degrade. Interestingly, as for three linkages of the polymer, the calculated results further suggest that the energy barrier of head-to-head, head-to-tail, and tail-to-tail linkages of the polymer dissociating to produce the monomer increase, no matter if the chain-end is saturated or not. Therefore, we form a regular understanding of how to achieve the complete degradation of the polymer. In addition, analyses of the bond characteristics and electronic structures agree with the results of the energy barrier measurements. Meanwhile, the spin population analysis presents an obvious net spin transfer process in depolymerization reactions. We hope that the current results can provide a basic insight into polymer degradation.
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Affiliation(s)
- Yu Zhu
- Institute of Atomic and Molecular PhysicsJilin UniversityChangchun130012P. R. China
- Jilin Provincial Key Laboratory of Applied Atomic and Molecular SpectroscopyJilin UniversityChangchun130012P. R. China
| | - Depeng Zhang
- Institute of Atomic and Molecular PhysicsJilin UniversityChangchun130012P. R. China
- Jilin Provincial Key Laboratory of Applied Atomic and Molecular SpectroscopyJilin UniversityChangchun130012P. R. China
| | - Zhanwen Zhang
- Institute of Atomic and Molecular PhysicsJilin UniversityChangchun130012P. R. China
- China Academy of Engineering PhysicsMianyang621900P. R. China
| | - Zhigang Wang
- Institute of Atomic and Molecular PhysicsJilin UniversityChangchun130012P. R. China
- Jilin Provincial Key Laboratory of Applied Atomic and Molecular SpectroscopyJilin UniversityChangchun130012P. R. China
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Chammingkwan P, Yamaguchi F, Terano M, Taniike T. Influence of isotacticity and its distribution on degradation behavior of polypropylene. Polym Degrad Stab 2017. [DOI: 10.1016/j.polymdegradstab.2017.07.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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6
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Initiation of oxidative degradation in polypropylene reactor powder produced by Ziegler-Natta catalyst. Polym Degrad Stab 2017. [DOI: 10.1016/j.polymdegradstab.2017.01.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Zhao S, Cheng L, Leng J, Guo L, Gao Y, Zheng Y, Cao D. Synergistic enhancement of glass fiber and tetrapod-shaped ZnO whisker on the mechanical and thermal behavior of isotactic polypropylene. J Appl Polym Sci 2016. [DOI: 10.1002/app.44217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Songfang Zhao
- School of Material Science and Engineering, University of Jinan; Jinan Shandong 250022 China
| | - Lei Cheng
- College of Materials Science and Engineering, Fuzhou University; Fuzhou Fujian 350108 China
| | - Jinfeng Leng
- School of Material Science and Engineering, University of Jinan; Jinan Shandong 250022 China
| | - Lingzhi Guo
- School of Material Science and Engineering, University of Jinan; Jinan Shandong 250022 China
| | - Yongju Gao
- Nano Science and Technology Institute, University of Science and Technology of China (USTC); Suzhou 215123 China
| | - Yuying Zheng
- College of Materials Science and Engineering, Fuzhou University; Fuzhou Fujian 350108 China
| | - Duxia Cao
- School of Material Science and Engineering, University of Jinan; Jinan Shandong 250022 China
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Khan MJH, Hussain MA, Mujtaba IM. Developed Hybrid Model for Propylene Polymerisation at Optimum Reaction Conditions. Polymers (Basel) 2016; 8:E47. [PMID: 30979141 PMCID: PMC6432575 DOI: 10.3390/polym8020047] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 01/20/2016] [Accepted: 01/28/2016] [Indexed: 11/16/2022] Open
Abstract
A statistical model combined with CFD (computational fluid dynamic) method was used to explain the detailed phenomena of the process parameters, and a series of experiments were carried out for propylene polymerisation by varying the feed gas composition, reaction initiation temperature, and system pressure, in a fluidised bed catalytic reactor. The propylene polymerisation rate per pass was considered the response to the analysis. Response surface methodology (RSM), with a full factorial central composite experimental design, was applied to develop the model. In this study, analysis of variance (ANOVA) indicated an acceptable value for the coefficient of determination and a suitable estimation of a second-order regression model. For better justification, results were also described through a three-dimensional (3D) response surface and a related two-dimensional (2D) contour plot. These 3D and 2D response analyses provided significant and easy to understand findings on the effect of all the considered process variables on expected findings. To diagnose the model adequacy, the mathematical relationship between the process variables and the extent of polymer conversion was established through the combination of CFD with statistical tools. All the tests showed that the model is an excellent fit with the experimental validation. The maximum extent of polymer conversion per pass was 5.98% at the set time period and with consistent catalyst and co-catalyst feed rates. The optimum conditions for maximum polymerisation was found at reaction temperature (RT) 75 °C, system pressure (SP) 25 bar, and 75% monomer concentration (MC). The hydrogen percentage was kept fixed at all times. The coefficient of correlation for reaction temperature, system pressure, and monomer concentration ratio, was found to be 0.932. Thus, the experimental results and model predicted values were a reliable fit at optimum process conditions. Detailed and adaptable CFD results were capable of giving a clear idea of the bed dynamics at optimum process conditions.
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Affiliation(s)
- Mohammad Jakir Hossain Khan
- Department of Chemical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia.
| | - Mohd Azlan Hussain
- Department of Chemical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia.
- UM Power Energy Dedicated Advanced Centre (UMPEDAC).
| | - Iqbal Mohammed Mujtaba
- Chemical Engineering Division, School of Engineering, University of Bradford, Bradford BD7 1DP, UK.
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Shibryaeva LS, Rishina LA, Shatalova OV, Krivandin AV. Thermal oxidation of isotactic polypropylene synthesized with a metallocene catalyst. POLYMER SCIENCE SERIES B 2011. [DOI: 10.1134/s1560090411120050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Nakatani H, Ogura M, Yoshikawa T, Miyazaki K, Okazaki N, Terano M. Preparation of polybutene-1/multiwall carbon nanotube composite by oxidation and limonene radical grafting and its characterization. POLYM INT 2011. [DOI: 10.1002/pi.3133] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Nakatani H, Ichizyu T, Miura H, Terano M. Preparation of modified polybutene-1 by oxidation and limonene radical grafting using an Nd2
O3
-assisted radical initiator system and its characterization. POLYM INT 2010. [DOI: 10.1002/pi.2902] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Nakatani H, Ichizyu T, Miura H, Terano M. Novel modification of polybut-1-ene using auto-oxidation controlled by addition of limonene monomer. POLYM INT 2009. [DOI: 10.1002/pi.2723] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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