Frontal Polymerization of a Thin Film on a Wood Substrate
Karan Bansal
John A. Pojman
Dean Webster
Mohiuddin Quadir
10.1021/acsmacrolett.9b00887.s007
https://acs.figshare.com/articles/media/Frontal_Polymerization_of_a_Thin_Film_on_a_Wood_Substrate/11627730
Frontal polymerization
has been explored as a technique to form two-dimensional thin films
(<0.5 mm) on wood. We used trimethylolpropane triacrylate with
a thermal free-radical initiator. The viscosity of the resin was adjusted
by incorporating fumed silica within the formulation. As filler materials,
either calcium carbonate or graphene nanoplatelets was used to evaluate
the effect of filler type and content on front propagation. We observed
that resin viscosity and film thickness critically affected the qualitative
and quantitative propagation of the thermal front resulting in the
formation of the coating. A workable coating was formed at a viscosity
of 0.6 Pa·s, which was obtained when 3 phr (parts per hundred
resin) of fumed silica was used in the resin formulation. Wet film
thickness for this resin system was also found to have a limiting
value, and full propagation of the front to result in a conformal
coating required at least 15 mil (1 mil = 25 μm) of wet film
thickness. Filler materials affected film propagation as a function
of particle size and thermal properties. While 15 phr calcium carbonate
could be incorporated with the resin, only 5 phr graphene nanoplatelets
could be loaded within the matrix to ensure complete propagation of
the front. Interestingly, for graphene fronts, velocity and temperature
reduced systematically as a function of filler content. Filler type
and content affected porosity and roughness of the coating, which
was quantified by computerized tomography to understand the relationship
between porosity and adhesion of the coated film with the wood substrate.
2020-01-16 13:08:02
content
5 phr graphene nanoplatelets
Wet film thickness
25 μ m
resin
filler
film thickness
propagation
15 phr calcium carbonate
coating
viscosity
Wood Substrate Frontal polymerization