A new methodology in the study of PVAc‐based adhesive formulations

Abstract

The role of the main components of a PVAc-based wood adhesive formulation in the formation and performance of the adhesive joint was investigated. A new analytical methodology was applied to carry out the chemical separation and characterization of the adhesive components present in the bond line. By using extraction techniques on the wet and dry glues it was possible to observe the variation in the solubility of the adhesive components, for different glue formulations. The swollen-state NMR technique proved to be a very useful tool to characterize the insoluble parts present in the adhesive films. These findings, when put into relation to some specific properties of the adhesive joints, contribute to the understanding of the mechanisms involved in the adhesion process.

The reactivity of linseed and soybean oil with different epoxidation degree towards vinyl acetate and impact of the resulting copolymer on the wood durability

“…[23,24]. Waterborne dispersions containing PVAc have been extensively used as adhesives for wood or wood-based materials [25,26]. The incorporation of hydrophobic ELO ® into PVAc polymer chains results in products with improved waterproofing properties.…”

Starve fed emulsion copolymerization of vinyl acetate and 1‐hexene at ambient pressure

“…The branching reactions during copolymerization, which are indicative of a chain transfer process between the VAc–1‐hexene macroradicals through the methyl group (Scheme ), can also be followed by examining the area of the peak at 1376 cm −1 , [ s 2 ], assigned to the methyl group stretching of the VAc component . From Table , as expected, the highest rate for the undesirable chain transfer reactions is recorded at reaction times above 4 h, exactly when the contribution of VAc monomer to the copolymer structure is more pronounced.…”

“…Figure shows the IR spectra of samples taken from the emulsion mixture at reaction times of 2, 3, 4 and 5 h. To study the trend of monomer consumption during copolymerization, the area of the peak at 1649 cm −1 , [ s 1 ], related to the trans ‐vinylene double bonds, was calculated for the spectra of the samples at the various reaction times. Table gives the calculated [ s 1 ] values for each reaction time studied.…”

Effects of radio frequency and heat on wood bonding with a poly(vinyl acetate) dispersion adhesive

“…AlCl 3 is often used as the complexing agent. It is commonly believed that the addition of AlCl 3 has a dual effect: (a) it increases acidity, and thus promoting the crosslinking reaction with the specific comonomer usually added to the dispersion and (b) it interacts with the electron‐donating groups of the polymer, such as the PVOH chains and the PVAc chains containing grafted PVOH, with the formation of structures similar to chelates 13. Both occurrences appreciably improve the adhesive performances in wet conditions 10,11.…”