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Aspects of Wood Adhesion: Applications of 13C CP/MAS NMR and Fracture Testing

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dc.contributor.authorSchmidt, Robert G.en
dc.contributor.committeechairFrazier, Charles E.en
dc.contributor.committeememberWightman, James P.en
dc.contributor.committeememberKamke, Frederick A.en
dc.contributor.committeememberWard, Thomas C.en
dc.contributor.committeememberGlasser, Wolfgang G.en
dc.contributor.departmentWood Science and Forest Productsen
dc.date.accessioned2014-03-14T20:21:30Zen
dc.date.adate1998-03-31en
dc.date.available2014-03-14T20:21:30Zen
dc.date.issued1998-01-28en
dc.date.rdate1998-03-31en
dc.date.sdate1998-01-28en
dc.description.abstractPhenol Formaldehyde (PF) and polymeric isocyanate (pMDI) are the two main types of adhesives used in the production of structural wood-based composites. Much is unknown about various aspects of adhesion between these two types of resins and wood. The present research describes the development of techniques which will permit an enhanced understanding of 1.) the extent of cure of PF within a wood based composite, 2.) the scale of molecular level interactions between PF and pMDI and wood, 3.) mechanical performance and durability of wood-adhesive bonds. Correlations were established between conventional methods of characterization of neat PF (thermomechanical analysis, swelling studies) and measurements made using 13C CP/MAS NMR. These correlations were then utilized to characterize PF cured in the presence of wood. The use of 13C labeled PF allowed estimates of relative degrees of resin conversion to be made. The use of 13C and deuterium labeled PF allowed qualitative estimates of resin molecular rigidity to be made. The scale of molecular level interactions between PF and pMDI and wood was probed using NMR relaxation experiments. Evidence was shown to suggest the formation of an interpenetrating polymer network (IPN) morphology existing at both types of wood-resin interphases. The formation of the IPN morphology was strongly influenced by resin molecular weight, cure temperature and the presence of solvent. A new test geometry for the evaluation of the fracture toughness of wood-adhesive bonds was developed. Consistent and reliable results were obtained. It was found that low molecular weight PF possessed enhanced durability over high molecular weight.en
dc.description.degreePh. D.en
dc.identifier.otheretd-22798-141819en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-22798-141819/en
dc.identifier.urihttp://hdl.handle.net/10919/30352en
dc.publisherVirginia Techen
dc.relation.haspartSCHMIDT.PDFen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectinterpenetrating network formationen
dc.subjectIPNen
dc.subjectpMDIen
dc.subjectisocyanateen
dc.subjectphenol formaldehydeen
dc.subjectPFen
dc.subjectmechanisms of adhesionen
dc.titleAspects of Wood Adhesion: Applications of 13C CP/MAS NMR and Fracture Testingen
dc.typeDissertationen
thesis.degree.disciplineWood Science and Forest Productsen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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