Wood-adhesive interactions in a PVAc latex

Holzforschung ◽  
2008 ◽  
Vol 62 (4) ◽  
Author(s):  
Francisco López-Suevos ◽  
Charles E. Frazier
Keyword(s):  
Vinyl Acetate ◽  
Coupling Model ◽  
Wood Adhesive ◽  
Poly Vinyl Alcohol ◽  
Accelerated Weathering ◽  
Adhesive Interaction ◽  
Adhesive Interactions ◽  
Weather Resistance ◽  
Induced Changes ◽  
Neat Films

Abstract Static rheological analysis based on time/temperature equivalence was applied to freestanding poly(vinyl acetate-co-N-methylolacrylamide) (PVAc-co-NMA) adhesive films and to wood-bonded films (composites) containing two types of crosslinking: 1) AlCl3 catalysis of NMA comonomer, and 2) the same AlCl3 catalysis plus additional crosslinking using a phenolic resol additive, PF. The glass/rubber relaxations for bulk poly(vinyl acetate), PVAc, and in some cases for the poly(vinyl alcohol) interfacial agent (PVOH) also, were evaluated by the empirical Kohlrausch-Williams-Watts (KWW) coupling model. The KWW coupling analysis revealed that accelerated weathering dramatically decreased PVAc segmental coupling in neat films; the PF additive slightly mitigated this weathering effect. In comparison to neat films, composite specimens exhibited increased PVAc coupling for all sample types, demonstrating a significant wood-adhesive interaction. In contrast to neat films, the PF additive completely negated the effects of accelerated weathering in composite specimens. Since PF prevented weathering-induced changes to the PVAc relaxation (in composites), the phenolic additive influenced the bulk adhesive and its effects were not restricted to PVOH crosslinking at the interparticle boundaries. The wood-adhesive interaction was not only detected through the PVAc relaxation but also in the PVOH glass transition. Furthermore, the PF borne weather resistance was dependent upon the presence or absence of wood, suggesting a PF/wood interaction. It is unknown if the putative PF/wood interaction is direct or possibly indirect through wood alteration of PVAc and PVOH.

Polyurethan VC, a Virtually Crosslinked Elastomer

1962 ◽  
Vol 35 (3) ◽  
pp. 742-752 ◽  
Author(s):  
C. S. Schollenberger ◽  
H. Scptt ◽  
G. R. Moore
Keyword(s):  
Room Temperature ◽  
Weather Conditions ◽  
Outdoor Exposure ◽  
Accelerated Weathering ◽  
High Tensile Strength ◽  
Beneficial Effects ◽  
Ultraviolet Absorbers ◽  
Weather Resistance ◽  
Induced Changes ◽  
Ozone Resistance

Abstract Many of the outstanding physical properties that characterize elastomeric Polyurethans have been realized in a soluble, thermoplastic variety, Polyurethan VC, which displays the superficial properties of a rubbery vulcanizate at room temperature and so is considered to be virtually crosslinked. High tensile strength as well as good tear, abrasion, solvent, oil, and ozone resistance characterizes this polymer. Since these properties are realized in the unvulcanized state, many useful applications of the readily processable polymer can be made, avoiding the complications which attend the use of conventional (vulcanizing) urethan elastomers. Outdoor exposure and indoor accelerated weathering studies demonstrated a deficiency in the weather resistance of the raw polymer. Weather-induced changes, believed to be due to ultraviolet-initiated autoxidation, have been estimated by noting changes in the stress-strain properties as well as the ultraviolet and infrared absorption spectra of the polymer on exposure to natural and artificial weather conditions. The beneficial effects of certain carbon blacks, conventional antioxidants, and ultraviolet absorbers on the weather resistance of the polymer have been described.

Compatibility of nylon 6 with poly(vinyl alcohol), hydroxylated poly(vinyl acetate) and poly(vinyl acetate)

1993 ◽  
Vol 31 (3) ◽  
pp. 359-365 ◽  
Author(s):  
Chang-Sik Ha ◽  
Won-Ki Lee ◽  
Tae-Woo Roe ◽  
Won-Jei Cho
Keyword(s):  
Vinyl Acetate ◽  
Vinyl Alcohol ◽  
Nylon 6 ◽  
Poly Vinyl Alcohol

scholarly journals Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce Wood

Coatings ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 8 ◽  
Author(s):  
Jonathan Haase ◽  
Lukie Leung ◽  
Philip Evans
Keyword(s):  
Plasma Treatment ◽  
Black Spruce ◽  
Accelerated Weathering ◽  
Polyurethane Coatings ◽  
Plasma Treatments ◽  
Spruce Wood ◽  
Coating Type ◽  
Weather Resistance ◽  
Wood Surfaces ◽  
Modified Wood

We hypothesize that plasma treatments that increase the adhesion and penetration of transparent water, and solvent-borne polyurethane coatings into black spruce wood will improve the performance of coated wood exposed to accelerated weathering. We tested this hypothesis by modifying wood samples with plasma for 30, 180, 600, and 1200 s, and measuring coating penetration and adhesion using light microscopy and a mechanical pull-off test, respectively. Plasma treatment did not improve coating adhesion, but the solvent-borne coating showed deeper penetration into plasma-modified wood, and its resistance to accelerated weathering was better on plasma-modified wood than on untreated controls. Plasma treatments enhanced the penetration of water-borne polyurethane into wood, but the treatments did not improve weather-resistance of the coating. Plasma treatment increased the wettability of wood surfaces, and prolonged plasma treatment etched cell walls, increasing their porosity. These effects may explain the positive effect of plasma treatment on coating penetration, and the increased weather-resistance of the solvent-borne polyurethane on plasma-modified wood. In conclusion, our results indicate that the ability of plasma treatment to improve coating performance on black spruce depends on the coating type, and the effects of the treatment on the surface microstructure of wood.

Sign in / Sign up

Export Citation Format

Share Document