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Thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process
Polycarbosilane (PCS) fibers were cured by a process of alternating air and vacuum atmosphere periodically at thermal oxidation temperature. It was found that the oxygen diffusion in the micron PCS fibers could be observed and controlled by this novel curing process. The out surface layer of the cur...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Royal Society of Chemistry
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9055389/ https://www.ncbi.nlm.nih.gov/pubmed/35519766 http://dx.doi.org/10.1039/d0ra04888g |
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author | Li, Xiaohong Xu, Zhaofang Chen, Lu Hong, Liu Li, Yang |
author_facet | Li, Xiaohong Xu, Zhaofang Chen, Lu Hong, Liu Li, Yang |
author_sort | Li, Xiaohong |
collection | PubMed |
description | Polycarbosilane (PCS) fibers were cured by a process of alternating air and vacuum atmosphere periodically at thermal oxidation temperature. It was found that the oxygen diffusion in the micron PCS fibers could be observed and controlled by this novel curing process. The out surface layer of the cured fibers was rich in oxygen while the inner core had a lower status. Chemical structure analysis indicated that the groups of Si–H, Si–CH(2)–Si, and Si–CH(3) in the out surface layer were oxidized into oxygen containing structures such as Si–OH, Si–O–Si and C[double bond, length as m-dash]O. Ascribe to the controlled oxygen diffusion, the oxidation degree of the inner core was much lower than the surface layer. The oxygen containing structures, Si–H bond reaction degree, molecular weight and ceramic yield of the cured PCS fibers increased with thermal oxidation temperature and alternating cycles. Theoretical calculation results demonstrated that the Si–H bonds reacted with oxygen was the main reason which made the PCS fiber increase weight. This modified process was a high effective surface layer oxidation curing method. Moreover, silicon carbide (SiC) or silicon nitride (Si(3)N(4)) ceramic fibers with skin-core or hollow structure also could be prepared from the surface cured PCS fibers with proper following process. |
format | Online Article Text |
id | pubmed-9055389 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | The Royal Society of Chemistry |
record_format | MEDLINE/PubMed |
spelling | pubmed-90553892022-05-04 Thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process Li, Xiaohong Xu, Zhaofang Chen, Lu Hong, Liu Li, Yang RSC Adv Chemistry Polycarbosilane (PCS) fibers were cured by a process of alternating air and vacuum atmosphere periodically at thermal oxidation temperature. It was found that the oxygen diffusion in the micron PCS fibers could be observed and controlled by this novel curing process. The out surface layer of the cured fibers was rich in oxygen while the inner core had a lower status. Chemical structure analysis indicated that the groups of Si–H, Si–CH(2)–Si, and Si–CH(3) in the out surface layer were oxidized into oxygen containing structures such as Si–OH, Si–O–Si and C[double bond, length as m-dash]O. Ascribe to the controlled oxygen diffusion, the oxidation degree of the inner core was much lower than the surface layer. The oxygen containing structures, Si–H bond reaction degree, molecular weight and ceramic yield of the cured PCS fibers increased with thermal oxidation temperature and alternating cycles. Theoretical calculation results demonstrated that the Si–H bonds reacted with oxygen was the main reason which made the PCS fiber increase weight. This modified process was a high effective surface layer oxidation curing method. Moreover, silicon carbide (SiC) or silicon nitride (Si(3)N(4)) ceramic fibers with skin-core or hollow structure also could be prepared from the surface cured PCS fibers with proper following process. The Royal Society of Chemistry 2020-07-10 /pmc/articles/PMC9055389/ /pubmed/35519766 http://dx.doi.org/10.1039/d0ra04888g Text en This journal is © The Royal Society of Chemistry https://creativecommons.org/licenses/by-nc/3.0/ |
spellingShingle | Chemistry Li, Xiaohong Xu, Zhaofang Chen, Lu Hong, Liu Li, Yang Thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process |
title | Thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process |
title_full | Thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process |
title_fullStr | Thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process |
title_full_unstemmed | Thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process |
title_short | Thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process |
title_sort | thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process |
topic | Chemistry |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9055389/ https://www.ncbi.nlm.nih.gov/pubmed/35519766 http://dx.doi.org/10.1039/d0ra04888g |
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