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TEMPO-oxidized Nanocelluloses: Surface Modification and use as Additives in Cellulosic Nanocomposites

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dc.contributor.authorJohnson, Richard Kwesien
dc.contributor.committeechairZink-Sharp, Audrey G.en
dc.contributor.committeememberRoman, Marenen
dc.contributor.committeememberFrazier, Charles E.en
dc.contributor.committeememberGlasser, Wolfgang G.en
dc.contributor.committeememberRenneckar, Scott H.en
dc.contributor.committeememberEsker, Alan R.en
dc.contributor.departmentMacromolecular Science and Engineeringen
dc.date.accessioned2014-03-14T20:17:34Zen
dc.date.adate2010-12-01en
dc.date.available2014-03-14T20:17:34Zen
dc.date.issued2010-08-18en
dc.date.rdate2010-12-01en
dc.date.sdate2010-10-22en
dc.description.abstractThe process of TEMPO-mediated oxidation has gained broad usage towards the preparation of highly charged, carboxyl-functionalized polysaccharides. TEMPO-oxidized nanocelluloses (TONc) of high surface charge and measuring 3 to 5 nm in width have been recently prepared from TEMPO-oxidized pulp. This study examines as-produced and surface-hydrophobized TONc as reinforcing additives in cellulosic polymer matrices. In the first part of the work, covalent (amidation) and non-covalent (ionic complexation) coupling were compared as treatment techniques for the hydrophobization of TONc surfaces with octadecylamine (ODA). Subsequently, TONc and its covalently coupled derivative were evaluated as nanofiber reinforcements in a cellulose acetate butyrate (CAB) matrix. The properties of the resulting nanocomposites were compared with those of similarly prepared ones reinforced with conventional microfibrillated cellulose (MFC). It was found that both ionic complexation and amidation resulted in complete conversion of carboxylate groups on TONc surfaces. As a result of surface modification, the net crystallinity of TONc was lowered by 15 to 25% but its thermal decomposition properties were not significantly altered. With respect to nanocomposite performance, the maximum TONc reinforcement of 5 vol % produced negligible changes to the optical transmittance behavior and a 22-fold increase in tensile storage modulus in the glass transition region of CAB. In contrast, hydrophobized TONc and MFC deteriorated the optical transmittance of CAB by ca 20% and increased its tensile storage modulus in the glass transition region by only 3.5 and 7 times respectively. These differences in nanocomposite properties were attributed to homogeneous dispersion of TONc compared to aggregation of both the hydrophobized derivative and the MFC reference in CAB matrix. A related study comparing TONc with MFC and cellulose nanocrystals (CNC) as reinforcements in hydroxypropylcellulose (HPC), showed TONc reinforcements as producing the most significant changes to HPC properties. The results of dynamic mechanical analysis and creep compliance measurements could be interpreted based on similar arguments as those made for the CAB-based nanocomposites. Overall, this work revealed that the use of TONc (without the need for surface hydrophobization) as additives in cellulosic polymer matrices leads to superior reinforcing capacity and preservation of matrix transparency compared to the use of conventional nanocelluloses.en
dc.description.degreePh. D.en
dc.identifier.otheretd-10222010-182711en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-10222010-182711/en
dc.identifier.urihttp://hdl.handle.net/10919/29342en
dc.publisherVirginia Techen
dc.relation.haspartJohnson_RK_D_2010.pdfen
dc.relation.haspartJohnson_RK_2010_Copyright.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectionic complexationen
dc.subjectamidationen
dc.subjectoctadecylamineen
dc.subjectsurface modificationen
dc.subjectnanocompositeen
dc.subjectTEMPO-oxidizeden
dc.subjectnanocelluloseen
dc.subjectthermal decompositionen
dc.titleTEMPO-oxidized Nanocelluloses: Surface Modification and use as Additives in Cellulosic Nanocompositesen
dc.typeDissertationen
thesis.degree.disciplineMacromolecular Science and Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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