Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"urea-formaldehyde"”.
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Studies of the formation and properties of urea-formaldehyde resin adhesives
Urea-formaldehyde (UF) resin is used primarily as an adhesive for manufacturing wood panels (medium density fiberboard, particleboard and plywood). These are important New Zealand export products. A better understanding of the formation of UF resin will allow maximisation of its adhesive properties …
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A chromatographic investigation into the reactions of urea and formaldehyde.
… studies into the chromatographic separation of urea formaldehyde resins have been made. Those that have been undertaken are of doubtful or limited value. A rapid reproducible method for investigating the molecular mass distribution of urea formaldehyde resins by size exclusion chromatography has …
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Mathematical Modelling of a Tubular Reactor for Continuous Production of Synthetic Resins
… tubular reactor for continuous operation and the urea-formaldehyde resin system is selected for detailed examination. To account theoretically for the performance of the tubular reactor two mathematical models are developed, The first model, which ignores all but the bulk transports, is a …
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Effects of Thermomechanical Refining on Douglas fir Wood
… conductometric titration of free phenols, and formaldehyde determination. Formaldehyde was generated via the C2 lignin acidolysis pathway, but C3 cleavage was the dominant lignin reaction. Observations suggested that in-line formaldehyde monitoring might be useful for process control during …
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Wetting and Penetration Behavior of Resin/Wood Interfaces
… than aqueous resins, with exception of urea-formaldehyde. Wetting and penetration of pMDI was studied on 5 wood species using the Lucas-Washburn equation. The wetting behaviors exhibited grain and species effects, which had implications on the resin availability for flake/strand-based …
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Structure-property relationships of lignin-based isocyanate and amine adhesives for wood
… for the lignin based adhesives was better than a urea formaldehyde reference. Structure property relationships were determined by correlating data obtained by the analysis of (in vivo) cured adhesive films and (in vitro) adhesive strength data resulting from shear block testing. The results …
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Autonomic healing of low-velocity impact damage in woven fiber-reinforced composites
… of catalyst microspheres encapsulated by poly(urea-formaldehyde) (UF) were explored. To investigate the effect of encapsulating catalyst microspheres with UF on the mechanical properties, UF encapsulated wax microspheres were fabricated and investigated. Tapered double cantilever beam samples …
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Economic Feasibility of Implementing a Resin Distribution Measurement System for MDF Fiber
… to measure resin distribution of phenol-formaldehyde adhesive on several types of wood surfaces. However, a technique that quantitatively measures UF resin on wood surfaces has been a problem because UF resin is colorless on wood fiber. The first objective of this study was to develop a …
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Exposure to hazardous air pollutants in homes
… p-dichlorobenzene (p-DCB), ethylbenzene, formaldehyde, methylene chloride, methyl tert-butyl ether (MTBE), styrene, trichloroethylene and tetrachloroethylene. Results indicate that Hispanics and non-Hispanic whites had median cumulative cancer risks (CCR) of 520×10-6 and 440×10-6, …
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Effects of a Control Release Nitrogen Fertilizer and Thinning on the Nitrogen Dynamics of a Mid-Rotation Loblolly Pine Stand in the Piedmont of Virginia
… of the southeastern USA. Fertilization with urea is the most common method used to correct this deficiency. Previous studies show that urea fertilization produces a rapid pulse of available nitrogen (N) with only a portion being utilized by plantation trees. Controlled release fertilizers …
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THE NATURE OF BOND FORMATION AND FAILURE IN WOOD-ADHESIVE SYSTEMS
… 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 …
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Design and Engineering of Carbon Fixing Material Systems
… and methane into monomeric chemicals such as formaldehyde. A mathematical analysis of CO₂ photoreduction revealed that carbon conversion and material growth rates which rival that of living plants can be obtained with currently employed photocatalytic materials under ambient conditions. This …
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Isotope ratios in source determination of formaldehyde emissions
Formaldehyde emissions from non-structural wood composites are regulated and the regulation target is urea-formaldehyde (UF) resin. UF resins are hydrolytically unstable and constantly emit formaldehyde as a function of temperature and relative humidity. When heated, wood also generates …
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Mechanisms of biogenic formaldehyde generation in wood
This work addresses biogenic formaldehyde (CH₂O) generated by wood during the manufacture of non-structural wood-based composites, from which CH₂O emissions are regulated. The target for regulation has been anthropogenic CH₂O released from hydrolytically unstable amino resins like …