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Study On Hyperbranched Polysiloxane Grafted Onto Surfaces Of Kevlar Fibers

Posted on:2015-01-02Degree:MasterType:Thesis
Country:ChinaCandidate:H R ZhangFull Text:PDF
GTID:2251330428983656Subject:Materials science
Abstract/Summary:PDF Full Text Request
Aramid fibers are famous for its high strength, high modulus and excellent themalstability, these outstanding properties make it a good candidate for composites materials.However, the inert surfaces of aramid fibers are difficult to wet with organic resins, so theresultant composites do not show expected performances because of poor interfacialadhesion between the fibers and matrix. Also, Aramid fibers have poor UV-resistance, UVradiation could deteriorate the structure of aramid fibers and their mechanical properties.The target of this research was to overcome the two critical disadvantages of Aramid fiberssimultaneously by surface modification.Firstly, Hyperbranched Polysiloxane was chosen for its excellent UV-resistant andplenty of active groups, aiming to improving fibers surface adhension and UV-resistance.Aramid fibers were modified through two routes, situ synthesizing and grafting methods,respectivity.Modified Aramid fibers (HSi-g-KFs) were obtained through situ synthesizinghyperbranched polysiloxane on surfaces of Aramid fibers, through dynamic contact angleand UV acceleraiotn aging tests, it can be concluded that the surface adhension andUV-resistance of HSi-g-KF fibres have signaficant improvement. It is due to the largenumber of active groups on surfaces of hyperbranched polysiloxane (HSis) make the fiberswettability improved, its surface free energy can be1.9times the value of original fibers.At the same time, the-Si-O-and-Si-C-chains in HSis helped to improve theUV-resistance of HSi-g-KF fibres. Through adjusting the molar ratio of silane to water inreaction progress, the morphologies and performances of HSi-g-KFs fibers can bechanged.Then four kinds of hyperbranched polysiloxane (HPSis) were synthesised and graftedonto surfaces of Aramid fibers to got HPSi-g-KFs fibers. GPC and NMR test methods wereused to investigated the HPSis structure systematically, then the relationship betweenHPSis structure changes and HPSi-g-KFs fibers morphologies and performances also was further studied. It can be concluded that the surface wettability, UV-resistance andflame-retardancy of HPSi-g-KFs fibers had been improved significantly.
Keywords/Search Tags:Aramid fibers, hyperbranced polysiloxane, UV-resistance, wettability
PDF Full Text Request
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