The Use of Cellulose Nanofibers to Reinforce
Latex Films and Coating
Gerard Gagnon, Rikard Rigdal, Hitomi Hamada, Michael Bilodeau, and Doug Bousfield
Department of Chemical and Biological Engineering Process Development Center, University of Maine, Orono
Small-scale fibers of cellulose have great potential for use in a number of a
applications: These include serving as structural components in medical devices,
as reinforcing agents in plastic composites, or as rheology modifiers. Researchers
at UMaine have produced aqueous suspensions of nanometer-scale cellulose fiber using
chemically pretreated hardwood pulp. The fibers were prepared with high energy mixers
and then passed through a homogenizer with a 125 µm orifice. The solids of these
suspensions were between 3.0 and 4.6 wt %. Scanning electron microscope images of
freeze dried samples revealed that the vast majority of the initial, regular-sized
fibers had been broken up and images of air dry samples showed fibers with dimensions
of 50 nm to 100 nm. The viscosity curves of suspensions displayed a shear thinning
behavior which is beneficial for subsequent processing.
Dried films of styrene butadiene rubber latex containing nano-fiber cellulose were prepared using a draw down coating method. Increasing the amount of nano-fibers increased the toughness of the films. The elastic modulus decreased with longer durations of the chemical pretreatment. The presence of nano-fiber cellulose increased the stress-to-rupture of films consisting of latex and kaolin clay pigment.
This illustrates the potential of nanocellulose fibers to reinforce a wide range of polymers and composite materials.