TY - JOUR
T1 - Assessment of covalent bond formation between coupling agents and wood by FTIR spectroscopy and pull strength tests
AU - Rasmussen, Jonas Stensgaard
AU - Barsberg, Søren Talbro
AU - Venås, Thomas Mark
AU - Felby, Claus
PY - 2014/10/1
Y1 - 2014/10/1
N2 - In the focus was the question whether metal alkoxide coupling agents –
titanium, silane, and zirconium – form covalent bonds to wood and how
they improve coating adhesion. In a previous work, a downshift of the
lignin infrared (IR) band ∼1600 cm-1 was shown to be
consistent with the formation of ether linkages between lignin and
titanium coupling agent. In the present work, changes were found in the
attenuated total reflectance-Fourier transform IR (ATR-FTIR) spectra of
lignin and wood mixed with silane, and titanium coupling agents, and to a
lesser extent for a zirconium coupling agent. This was seen as evidence
for covalent bonds between lignin phenolics and the coupling agents. No
spectral changes were observed when the coupling agents were mixed with
the wood constituents cellulose and hemicellulose. For verification of
the results, a modified EN 311 wet adhesion pull strength test was
performed with softwood panels painted with a solvent-borne
alkyd/acrylic coating. The results revealed an improved adhesion for all
tested coupling agents compared to the untreated reference. The
spectroscopic and pull test results underline that the presence of the
lignin moiety in wood is of central importance for improved wood coating
adhesion.
AB - In the focus was the question whether metal alkoxide coupling agents –
titanium, silane, and zirconium – form covalent bonds to wood and how
they improve coating adhesion. In a previous work, a downshift of the
lignin infrared (IR) band ∼1600 cm-1 was shown to be
consistent with the formation of ether linkages between lignin and
titanium coupling agent. In the present work, changes were found in the
attenuated total reflectance-Fourier transform IR (ATR-FTIR) spectra of
lignin and wood mixed with silane, and titanium coupling agents, and to a
lesser extent for a zirconium coupling agent. This was seen as evidence
for covalent bonds between lignin phenolics and the coupling agents. No
spectral changes were observed when the coupling agents were mixed with
the wood constituents cellulose and hemicellulose. For verification of
the results, a modified EN 311 wet adhesion pull strength test was
performed with softwood panels painted with a solvent-borne
alkyd/acrylic coating. The results revealed an improved adhesion for all
tested coupling agents compared to the untreated reference. The
spectroscopic and pull test results underline that the presence of the
lignin moiety in wood is of central importance for improved wood coating
adhesion.
U2 - 10.1515/hf-2013-0121
DO - 10.1515/hf-2013-0121
M3 - Journal article
SN - 0018-3830
VL - 68
SP - 799
EP - 805
JO - Holzforschung
JF - Holzforschung
IS - 7
ER -