{"id":{"repo_id":"de-montfort","oai_identifier":"oai:dora.dmu.ac.uk:2086/25329"},"canonical_url":"https://search.dev.ndltd.org/etd/de-montfort/oai:dora.dmu.ac.uk:2086/25329","repository":{"repo_id":"de-montfort","name":"De Montfort University","base_url":"https://dora.dmu.ac.uk/server/oai/request"},"display":{"title":"THE NATURE OF BOND FORMATION AND FAILURE IN WOOD-ADHESIVE SYSTEMS","abstract":"This work involves an investigation into the interface or the interphase between polycondensate wood adhesives (urea-formaldehyde (UF), melamine formaldehyde (MF), and phenol-resorcinol-formaldehyde (PRF)) and wood (spruce and scots pine) in an attempt to identify bonding and failure characteristics and forces. A number of techniques were used, including spectroscopic analysis, kinetic analysis and ageing techniques. Using secondary ion mass spectrometry (SIMS) on adhesive model compounds doped and undoped wood has shown strong evidence that the adhesives interact chemically with mainly lignins and extractives and to a lesser extent with cellulose. These interactions are thought to be covalent links as only this type of bond will account for the spectral changes noted. The dopant compounds used were urea, dimetol urea, methylene diurea, phenol, 2-hydroxybenzyl alcohol, bis-(2- hydroxy-phenyl)methane and paraformaldehyde. Further, chemical interactions between the adhesives and wood have been investigated using Fourier transform infra-red spectroscopy (FTIR). This technique has aided the identification of changes in the phenolic content of wood (lignins and extractives) and also in the cellulose content. It appears that ortho- and para-substitutions of phenols are occurring and that at least one type of ether link is established between the adhesives and cellulose. The adhesive interactions with lignins and extractives seen in the SIMS work, appear, from changes in strengths of joints during ageing, to hinder good adhesion. Initially, non-extracted wood joints have strengths comparable with extracted wood, but with ageing this deteriorates to the inferior values of partially extracted wood joints. Optical reflection microscopy has shown that penetration of resin into wood resins is in the order extracted'’^ non-extracted partially extracted. This coincides with the results which show the extractives concentration on wood surfaces, partially extracted wood having the greatest, extracted the least. During ageing, the nonextracted wood comes to resemble partially extracted wood as the extractives migrate to the wood surface and this accounts for the noted deterioration of these joints. Resin-extractive interactions do not provide durable adhesion. Extraction of wood increases the accessibility of cellulose and so it may be expected that resin-cellulose bonds may provide durable adhesion. Kinetic work has however shown*that UF resin preferentially form UF-UF bonds compared to UF-celluloslc bonds. The reverse is true, however of PRF’s. Thus, it seems that in the case of UF’s, extraction provides for greater resin penetration and so results in joints with improved mechanical Interlocking. With PRF_resins, penetration is also important but there may be a major contribution from PRF-cellulose bonds. A further reason why UF adhesives are inferior to PRF’s is seen from dimensional stability experiments. -At the same temperature, UF's shrink, initially due to post-cure but subsequently due to hydrolytic degradation, approximately 50% more than PRF’s. This shrinkage will inevitably produce stresses in the glueline and so contribute to the joint failure.","abstract_html":"This work involves an investigation into the interface or the interphase between polycondensate wood adhesives (urea-formaldehyde (UF), melamine formaldehyde (MF), and phenol-resorcinol-formaldehyde (PRF)) and wood (spruce and scots pine) in an attempt to identify bonding and failure characteristics and forces. A number of techniques were used, including spectroscopic analysis, kinetic analysis and ageing techniques. Using secondary ion mass spectrometry (SIMS) on adhesive model compounds doped and undoped wood has shown strong evidence that the adhesives interact chemically with mainly lignins and extractives and to a lesser extent with cellulose. These interactions are thought to be covalent links as only this type of bond will account for the spectral changes noted. The dopant compounds used were urea, dimetol urea, methylene diurea, phenol, 2-hydroxybenzyl alcohol, bis-(2- hydroxy-phenyl)methane and paraformaldehyde. Further, chemical interactions between the adhesives and wood have been investigated using Fourier transform infra-red spectroscopy (FTIR). This technique has aided the identification of changes in the phenolic content of wood (lignins and extractives) and also in the cellulose content. It appears that ortho- and para-substitutions of phenols are occurring and that at least one type of ether link is established between the adhesives and cellulose. The adhesive interactions with lignins and extractives seen in the SIMS work, appear, from changes in strengths of joints during ageing, to hinder good adhesion. Initially, non-extracted wood joints have strengths comparable with extracted wood, but with ageing this deteriorates to the inferior values of partially extracted wood joints. Optical reflection microscopy has shown that penetration of resin into wood resins is in the order extracted'’^ non-extracted partially extracted. This coincides with the results which show the extractives concentration on wood surfaces, partially extracted wood having the greatest, extracted the least. During ageing, the nonextracted wood comes to resemble partially extracted wood as the extractives migrate to the wood surface and this accounts for the noted deterioration of these joints. Resin-extractive interactions do not provide durable adhesion. Extraction of wood increases the accessibility of cellulose and so it may be expected that resin-cellulose bonds may provide durable adhesion. Kinetic work has however shown*that UF resin preferentially form UF-UF bonds compared to UF-celluloslc bonds. The reverse is true, however of PRF’s. Thus, it seems that in the case of UF’s, extraction provides for greater resin penetration and so results in joints with improved mechanical Interlocking. With PRF_resins, penetration is also important but there may be a major contribution from PRF-cellulose bonds. A further reason why UF adhesives are inferior to PRF’s is seen from dimensional stability experiments. -At the same temperature, UF's shrink, initially due to post-cure but subsequently due to hydrolytic degradation, approximately 50% more than PRF’s. This shrinkage will inevitably produce stresses in the glueline and so contribute to the joint failure.","abstract_has_math":false,"creators":["Phanopoulos, Christopher"],"institution":"De Montfort University","degree_name":"PhD","degree_level":"Doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1986,"date_issued":"1986-11","date_published":"1986-11","updated_at":"2026-07-24T06:18:44Z","subjects":[],"languages":[],"rights":[],"rights_urls":["https://dora.dmu.ac.uk/bitstreams/f15b026c-58d1-4a87-9a53-5fc0a16fb4d0/download"],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Phanopoulos, Christopher"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.issued","label":"Date","values":["1986-11"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Faculty of Computing, Engineering and Media"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["De Montfort University"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://hdl.handle.net/2086/25329"]},{"key":"dc:type","label":"Dc Type","values":["Thesis or dissertation"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["PhD"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["https://dora.dmu.ac.uk/bitstreams/f15b026c-58d1-4a87-9a53-5fc0a16fb4d0/download"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://dora.dmu.ac.uk/bitstreams/00cc15e7-2c9e-408c-a821-bfaa3a752977/download"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This work involves an investigation into the interface or the interphase between polycondensate wood adhesives (urea-formaldehyde (UF), melamine formaldehyde (MF), and phenol-resorcinol-formaldehyde (PRF)) and wood (spruce and scots pine) in an attempt to identify bonding and failure characteristics and forces. A number of techniques were used, including spectroscopic analysis, kinetic analysis and ageing techniques. Using secondary ion mass spectrometry (SIMS) on adhesive model compounds doped and undoped wood has shown strong evidence that the adhesives interact chemically with mainly lignins and extractives and to a lesser extent with cellulose. These interactions are thought to be covalent links as only this type of bond will account for the spectral changes noted. The dopant compounds used were urea, dimetol urea, methylene diurea, phenol, 2-hydroxybenzyl alcohol, bis-(2- hydroxy-phenyl)methane and paraformaldehyde. Further, chemical interactions between the adhesives and wood have been investigated using Fourier transform infra-red spectroscopy (FTIR). This technique has aided the identification of changes in the phenolic content of wood (lignins and extractives) and also in the cellulose content. It appears that ortho- and para-substitutions of phenols are occurring and that at least one type of ether link is established between the adhesives and cellulose. The adhesive interactions with lignins and extractives seen in the SIMS work, appear, from changes in strengths of joints during ageing, to hinder good adhesion. Initially, non-extracted wood joints have strengths comparable with extracted wood, but with ageing this deteriorates to the inferior values of partially extracted wood joints. Optical reflection microscopy has shown that penetration of resin into wood resins is in the order extracted'’^ non-extracted partially extracted. This coincides with the results which show the extractives concentration on wood surfaces, partially extracted wood having the greatest, extracted the least. During ageing, the nonextracted wood comes to resemble partially extracted wood as the extractives migrate to the wood surface and this accounts for the noted deterioration of these joints. Resin-extractive interactions do not provide durable adhesion. Extraction of wood increases the accessibility of cellulose and so it may be expected that resin-cellulose bonds may provide durable adhesion. Kinetic work has however shown*that UF resin preferentially form UF-UF bonds compared to UF-celluloslc bonds. The reverse is true, however of PRF’s. Thus, it seems that in the case of UF’s, extraction provides for greater resin penetration and so results in joints with improved mechanical Interlocking. With PRF_resins, penetration is also important but there may be a major contribution from PRF-cellulose bonds. A further reason why UF adhesives are inferior to PRF’s is seen from dimensional stability experiments. -At the same temperature, UF's shrink, initially due to post-cure but subsequently due to hydrolytic degradation, approximately 50% more than PRF’s. 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The adhesive interactions with lignins and extractives seen in the SIMS work, appear, from changes in strengths of joints during ageing, to hinder good adhesion. Initially, non-extracted wood joints have strengths comparable with extracted wood, but with ageing this deteriorates to the inferior values of partially extracted wood joints. Optical reflection microscopy has shown that penetration of resin into wood resins is in the order extracted'’^ non-extracted partially extracted. This coincides with the results which show the extractives concentration on wood surfaces, partially extracted wood having the greatest, extracted the least. During ageing, the nonextracted wood comes to resemble partially extracted wood as the extractives migrate to the wood surface and this accounts for the noted deterioration of these joints. Resin-extractive interactions do not provide durable adhesion. 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