UF/pMDI Wood Adhesives: Networks Blend versus Copolymerization
-
C. Simon
Summary
Kinetic evidence from thermomechanical analysis experiments and 13C NMR evidence were used to show that the strength of a joint bonded with UF/pMDI glue-mixtures is improved by coreaction between pMDI and UF resin methylol groups forming methylene cross-links. These are predominant, as opposed to the formation of urethane bridges which still appear to form, but are in great minority. The coreaction occurs in the presence of water and under the predominantly acidic hardening conditions characteristic of aminoplastic resins (in presence of a hardener). Coreaction occurs to a much lesser extent under alkaline conditions (without UF resins hardeners). The predominant reaction is therefore different in UF/pMDI and PF/pMDI adhesive systems. The same reaction observed for the UF/pMDI system at higher temperatures was also observed in PF/pMDI systems, but only at lower temperatures. The water introduced into the UF/pMDI mixture by addition of the UF resin solution was shown not to react with pMDI to increase the strength of the hardened adhesive to a significant degree.
Copyright © 2002 by Walter de Gruyter GmbH & Co. KG
Artikel in diesem Heft
- Weight Loss and Cell Wall Degradation in Rubberwood Caused by Sapstain Fungus Botryodiplodia theobromae
- Changes of EPR Spectra of Wood Impregnated with Copper-Based Preservatives during Exposure to Several Wood-Rotting Fungi
- Quantitative Analyses of Morphological Variation of Cross-Sectional Tracheids of Hinoki (Chamaecyparis obtusa Endl.) Near Knot by Image Processing
- Direct Effects of Wood Characteristics on Pulp and Handsheet Properties of Eucalyptus globulus
- Identification of the Lignan Nortrachelogenin in Knot and Branch Heartwood of Scots Pine (Pinus sylvestris L.)
- Chemical Composition of Lipophilic and Phenolic Constituents of Barks from Pinus nigra, Abies bornmülleriana and Castanea sativa
- Pinus pinaster Oleoresin in Plus Trees
- Determination of Polyphenolic Content of Bark Extracts for Wood Adhesives
- Softwood Bark Pyrolysis Oil-PF Resols. Part 2. Thermal Analysis by DSC and TG
- Softwood Bark Pyrolysis Oil-PF Resols. Part 3. Use of Propylene Carbonate as Resin Cure Accelerator
- Steam Explosion of Aspen Wood. Characterisation of Reaction Products
- Characterization of Black Liquors from Soda-AQ Pulping of Reed Canary Grass (Phalaris arundinacea L.)
- Modification of the Nitrogen Content and C:N Ratio of Sitka Spruce Timber by Kiln and Air Drying
- High Resolution Measurement of the Surface Layer Moisture Content during Drying of Wood Using a Novel Magnetic Resonance Imaging Technique
- Longitudinal Permeability and Diffusivity of Steam in Beech Determined with a Wicke-Kallenbach-Cell
- UF/pMDI Wood Adhesives: Networks Blend versus Copolymerization
Artikel in diesem Heft
- Weight Loss and Cell Wall Degradation in Rubberwood Caused by Sapstain Fungus Botryodiplodia theobromae
- Changes of EPR Spectra of Wood Impregnated with Copper-Based Preservatives during Exposure to Several Wood-Rotting Fungi
- Quantitative Analyses of Morphological Variation of Cross-Sectional Tracheids of Hinoki (Chamaecyparis obtusa Endl.) Near Knot by Image Processing
- Direct Effects of Wood Characteristics on Pulp and Handsheet Properties of Eucalyptus globulus
- Identification of the Lignan Nortrachelogenin in Knot and Branch Heartwood of Scots Pine (Pinus sylvestris L.)
- Chemical Composition of Lipophilic and Phenolic Constituents of Barks from Pinus nigra, Abies bornmülleriana and Castanea sativa
- Pinus pinaster Oleoresin in Plus Trees
- Determination of Polyphenolic Content of Bark Extracts for Wood Adhesives
- Softwood Bark Pyrolysis Oil-PF Resols. Part 2. Thermal Analysis by DSC and TG
- Softwood Bark Pyrolysis Oil-PF Resols. Part 3. Use of Propylene Carbonate as Resin Cure Accelerator
- Steam Explosion of Aspen Wood. Characterisation of Reaction Products
- Characterization of Black Liquors from Soda-AQ Pulping of Reed Canary Grass (Phalaris arundinacea L.)
- Modification of the Nitrogen Content and C:N Ratio of Sitka Spruce Timber by Kiln and Air Drying
- High Resolution Measurement of the Surface Layer Moisture Content during Drying of Wood Using a Novel Magnetic Resonance Imaging Technique
- Longitudinal Permeability and Diffusivity of Steam in Beech Determined with a Wicke-Kallenbach-Cell
- UF/pMDI Wood Adhesives: Networks Blend versus Copolymerization
