Understanding the Role of N-Methylolacrylamide (Nma) Distribution in Poly(Vinyl Acetate) Latex Adhesives

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dc.contributor.authorBrown, Nicole Robitailleen
dc.contributor.committeecochairFrazier, Charles E.en
dc.contributor.committeecochairLoferski, Joseph R.en
dc.contributor.committeememberGibson, Harry W.en
dc.contributor.committeememberDillard, John G.en
dc.contributor.committeememberKamke, Frederick A.en
dc.contributor.departmentWood Science and Forest Productsen
dc.date.accessioned2014-03-14T20:08:16Zen
dc.date.adate2004-04-15en
dc.date.available2014-03-14T20:08:16Zen
dc.date.issued2003-12-11en
dc.date.rdate2008-04-15en
dc.date.sdate2004-03-17en
dc.description.abstractThis work addresses the distribution of N-methylolacrylamide (NMA) units in crosslinking poly(vinyl acetate) (PVAc) adhesives. In this case, distribution refers to the three potential locations of polymerized NMA units in a latex: the water-phase, the surface of polymer particles, and the core of the polymer particles. The objective is to identify the distribution of NMA in three latices and to determine whether NMA distribution correlates with durability related performance. NMA distribution was studied via a series of variable temperature solution NMR experiments, while the durability-related performance was studied via mode I fracture mechanics tests. Studying the distribution of NMA required the use of isotopically labeled NMA. Both 15N-NMA and 13C, 15N-NMA were synthesized. Three NMA/vinyl acetate (VAc) latices were prepared. The NMA feed strategy was varied during each of the three emulsion copolymerizations. Latex characterization methods including differential scanning calorimetry (DSC), rheometry, particle size analysis, and scanning electron microscopy (SEM) were used to study the three latices. The solution NMR method to identify NMA distribution was performed on untreated latices and on washed latices. Washing techniques included membrane dialysis and centrifugation. Results revealed that the three latices had different NMA distributions, and that the distributions were related to the expected differences in microstructure. Latex 3 had ~ 80% core-NMA, while Latex 2 had ~ 80% surface-NMA. Latex 1 had a high proportion of surface-NMA (~60%), but also had the highest proportion of water-phase NMA (~ 20%). This high proportion of water-phase NMA could be responsible for the unique morphology Latex 1 exhibited in SEM studies. Mode I opening fracture mechanics studies were used to study adhesive performance. Specimens were analyzed after exposure to accelerated aging treatments. Latex 2 and Latex 3 exhibited very similar results, despite having very different NMA distributions. All three latices showed good durability related performance. In Latex 2 and Latex 3, the critical strain energy release rates (Gc) after accelerated aging treatments were statistically the same as the Gc of the control specimens. The most interesting finding was that the Latex 1 Gc values were significantly higher after accelerated aging. Latex 1 also had the highest proportion of water-phase NMA. Bondline images and SEM micrographs both indicated that the integrity of Latex 1 was least affected by the accelerated aging treatments.en
dc.description.degreePh. D.en
dc.identifier.otheretd-03172004-125608en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-03172004-125608/en
dc.identifier.urihttp://hdl.handle.net/10919/26446en
dc.publisherVirginia Techen
dc.relation.haspartDISS-FINAL-NO-CH-4-GOOD.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectN-methylolacrylamideen
dc.subjectNMAen
dc.subject13C 15N-NMAen
dc.subject15N-NMAen
dc.subjectpoly(vinyl acetate)en
dc.subjectPVAcen
dc.subjectemulsion polymerizationen
dc.subjectmonomer distributionen
dc.subjectdurabilityen
dc.subjectsolution NMRen
dc.subjectfracture mechanicsen
dc.subjectwood adhesivesen
dc.subject13C-NMAen
dc.titleUnderstanding the Role of N-Methylolacrylamide (Nma) Distribution in Poly(Vinyl Acetate) Latex Adhesivesen
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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