Hybrid silane-crosslinking polymers: a potential alternative to polyurethane wood adhesives? A preliminary investigation by TMA
In the last years, the research on wood adhesives has focused on matching technical performance with low health and environmental impacts. This study presents the first development of a new adhesive technology based on hybrid silane-crosslinking polymers that can combine both silicone’s and polyurethane’s adhesive properties. The advantage of hybrid silane-crosslinking polymers is the absence of potential harmful chemicals, such as isocyanates and solvents. Two hybrid formulations were characterized by thermo-mechanical analysis (TMA) and glued wood product elasticity is discussed in this brief original.
SYNTHESIS, CHARACTERIZATION AND APPLICATION OF CHITOSAN BASED NANOCOMPOSITES
....................................................................................................................... x List of publications .......................................................................................................... xiii List of Abbreviations and Symbols................................................................................... xv List of Figures ................................................................................................................. xxii List of Tables ................................................................................................................. xxvi CHAPTER-1 ....................................................................................................................... 1
Thermal stability of structural one-component polyurethane adhesives for wood : Structure-property relationship
The relationship between the chemical structure of commercial polyurethanes and temperature-dependent creep properties was determined in full scale tests and the results were compared with thermomechanical analysis. Comparison of mechanical performance with 13C-NMR spectroscopy studies elucidated important structure-property relationships, which either allow the reduction or elimination of temperature-dependent creep in one-component polyurethanes (1C-PUR) adhesives for wood. The combination of the relative content of still reactive, free NCO groups on the polyurethane, careful selection of the degree of resin polymerization and a slower rate of reaction are the three most significant parameters that have to be controlled to overcome the problem of temperature-dependent creep found in 1C-PUR adhesives. The results obtained indicate that adhesives presenting a combination of a higher content of still unreacted NCO groups, a lower degree of polymerization and slower reaction rate are capable to counteract problems of high sensitivity of polyurethane to temperature-dependent creep. Two commercial polyurethanes that fulfil the latter requirements and exhibit almost no creep were identified and characterized. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5698–5707, 2006