{"title":"Experimental and simulation studies of degraded EPDM composite in the coupled gamma radiation-thermal environments","authors":"Qiang Liu, Ruiyang Dou, Yiqian Zhang, Wei Huang, Xianfu Meng, Hongbing Chen","doi":"10.1016/j.polymdegradstab.2024.110899","DOIUrl":null,"url":null,"abstract":"<div><p>The degradation behaviors, mechanisms and compatibility are not well understood and hard to be harnessed for EPDM composite in the coupled gamma radiation-thermal environments. This contribution performs a thorough study accordingly with 0 ∼ 200 kGy dose under temperatures varying from room temperature to 90 °C in N<sub>2</sub>/O<sub>2</sub> mixture atmosphere. Radiation-thermal aging leads to annealing effect and chemi-crystallization that rebuilds the semi-crystalline structure and invokes competitive filler migration, reconfiguration and loss. Crosslinking reactions prevail the scission during the investigated conditions. However, the surface oxidation and damage are not severe. In-situ nondestructive gas-phase FTIR sensitively find the formed various gaseous products, whose generation kinetics behaviors are temperature and dose dependent. Most surprisingly, the radiolysis caused carbonyl sulfide and carbon disulfide are discovered with indispensable gamma radiation, which manifest temperature reined conversion thermodynamics and kinetics behavior. The qualitative and quantitative analysis of gas products is also validated by GC and GC-MS tests. The evolved semi-crystalline structure, macromolecular chain network and filler network significantly impact the mechanical property, but the barrier property and hydrophobic property are slightly influenced. The inverse temperature effect occurred at 50 °C for the mechanical properties, which show abnormal rejuvenation behavior due to the counteraction between aging induced change in molecular structure, aggregation structure and filler reconfiguration, migration and loss. The multiscale structure-property-behavior relationships possess good interdependency, indicating the main aging mechanism and failure mode are almost invariant. By ReaxFF simulation, the complex degradation mechanism for EPDM composite at atomic scale is revealed for the first time.</p></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":null,"pages":null},"PeriodicalIF":6.3000,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Polymer Degradation and Stability","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S014139102400243X","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"POLYMER SCIENCE","Score":null,"Total":0}
引用次数: 0
Abstract
The degradation behaviors, mechanisms and compatibility are not well understood and hard to be harnessed for EPDM composite in the coupled gamma radiation-thermal environments. This contribution performs a thorough study accordingly with 0 ∼ 200 kGy dose under temperatures varying from room temperature to 90 °C in N2/O2 mixture atmosphere. Radiation-thermal aging leads to annealing effect and chemi-crystallization that rebuilds the semi-crystalline structure and invokes competitive filler migration, reconfiguration and loss. Crosslinking reactions prevail the scission during the investigated conditions. However, the surface oxidation and damage are not severe. In-situ nondestructive gas-phase FTIR sensitively find the formed various gaseous products, whose generation kinetics behaviors are temperature and dose dependent. Most surprisingly, the radiolysis caused carbonyl sulfide and carbon disulfide are discovered with indispensable gamma radiation, which manifest temperature reined conversion thermodynamics and kinetics behavior. The qualitative and quantitative analysis of gas products is also validated by GC and GC-MS tests. The evolved semi-crystalline structure, macromolecular chain network and filler network significantly impact the mechanical property, but the barrier property and hydrophobic property are slightly influenced. The inverse temperature effect occurred at 50 °C for the mechanical properties, which show abnormal rejuvenation behavior due to the counteraction between aging induced change in molecular structure, aggregation structure and filler reconfiguration, migration and loss. The multiscale structure-property-behavior relationships possess good interdependency, indicating the main aging mechanism and failure mode are almost invariant. By ReaxFF simulation, the complex degradation mechanism for EPDM composite at atomic scale is revealed for the first time.
期刊介绍:
Polymer Degradation and Stability deals with the degradation reactions and their control which are a major preoccupation of practitioners of the many and diverse aspects of modern polymer technology.
Deteriorative reactions occur during processing, when polymers are subjected to heat, oxygen and mechanical stress, and during the useful life of the materials when oxygen and sunlight are the most important degradative agencies. In more specialised applications, degradation may be induced by high energy radiation, ozone, atmospheric pollutants, mechanical stress, biological action, hydrolysis and many other influences. The mechanisms of these reactions and stabilisation processes must be understood if the technology and application of polymers are to continue to advance. The reporting of investigations of this kind is therefore a major function of this journal.
However there are also new developments in polymer technology in which degradation processes find positive applications. For example, photodegradable plastics are now available, the recycling of polymeric products will become increasingly important, degradation and combustion studies are involved in the definition of the fire hazards which are associated with polymeric materials and the microelectronics industry is vitally dependent upon polymer degradation in the manufacture of its circuitry. Polymer properties may also be improved by processes like curing and grafting, the chemistry of which can be closely related to that which causes physical deterioration in other circumstances.