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dc.contributor.advisorBaytekin, Bilge
dc.contributor.authorÖzel, Mertcan
dc.date.accessioned2019-08-16T08:37:56Z
dc.date.available2019-08-16T08:37:56Z
dc.date.copyright2019-07
dc.date.issued2019-07
dc.date.submitted2019-07-06
dc.identifier.urihttp://hdl.handle.net/11693/52339
dc.descriptionCataloged from PDF version of article.en_US
dc.descriptionThesis (M.S.): Bilkent University, Department of Chemistry, İhsan Doğramacı Bilkent University, 2019.en_US
dc.descriptionIncludes bibliographical references. (leaves 83-91).en_US
dc.description.abstractContact electrification (C.E.), a phenomenon studied for millennia, develops contact charges on material surfaces, when two materials are contacted and then separated. Accumulation of contact charges and their uncontrolled sudden discharges on dielectric polymers pose major drawbacks in industries i.e. pharmaceutical, (micro)electronics, and space, causing million-dollar losses annually. The overall mechanism of C.E. is unclear until now, however, recent efforts have proven that chemical bond-breakages on polymer surfaces result in mechanoions – which are indeed the contact charges on the surfaces. These studies also showed that removing mechanoradicals (co-formed upon bond-breaking) by molecular radical scavengers destabilizes the mechanoions (charges) and render the doped polymer material antistatic. This method of static charge mitigation has an advantage over the conventional methods (e.g. doping with metals, carbon powder, conductive polymers, or surface humidity enhancers) because it is not based on an increase in surface conductance and smaller doping concentrations are needed to achieve antistatic behavior. However, currently used molecular radical scavenger doping is generally not cost effective method to be upscaled for industrial use. Lignin; however, is a “low-cost” material (the second most abundant polymer on earth, a by-product of paper production) that can act as a radical scavenger. In this thesis work, lignin was extracted from some examples of both hard and softwood. Firstly, it was verified that lignin doping in low concentrations (1 – 5% w/w) reduce the contact charge accumulation on common polymers such as on a crosslinked elastomer polydimethylsiloxane, and on thermoplastics polypropylene, polyethylene, polylactic acid, and polystyrene. Then, the mechanism of the observed charge dissipation was discussed in the light of the results obtained from surface conductance of polymers upon doping, 31P NMR and solid state 13C-NMR spectroscopy, total phenol content, and the reacted number of radicals before and after grinding - which was shown essential to get homogeneous doping- of lignin. The results pointed out a mechanism involving a radical scavenging activity without any change in the surface conductance of the material, similar to that with molecular radicals. The understanding of lignin’s charge dissipation mechanism will be helpful in industrial utilization of lignin as an antistatic additive and in assessment of the limitations of this utilization.en_US
dc.description.statementofresponsibilityby Mertcan Özelen_US
dc.format.extentxvii, 91 leaves : illustrations, charts (some color) , 30 cm.en_US
dc.language.isoEnglishen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectAntistatic additivesen_US
dc.subjectContact electrificationen_US
dc.subjectPolydimethylsiloxaneen_US
dc.subjectThermoplastic polymersen_US
dc.subjectRadical scavengersen_US
dc.subjectStatic electricityen_US
dc.subjectTriboelectricityen_US
dc.titleCharge dissipation mechanism of low-cost antistatic additive lignin in contact charged polymersen_US
dc.title.alternativeDokunma ile elektriklenen polimerlerde düşük maliyetli antistatik katkı malzemesi olarak kullanılan lignin’in yük sönümleme mekanizmasıen_US
dc.typeThesisen_US
dc.departmentDepartment of Chemistryen_US
dc.publisherBilkent Universityen_US
dc.description.degreeM.S.en_US
dc.identifier.itemidB152746
dc.embargo.release2020-02-06


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