2002 Progress Report: Fundamental Studies of Wood Interface Modification for Formaldehyde Pollution Avoidance and PreventionEPA Grant Number: R828565
Title: Fundamental Studies of Wood Interface Modification for Formaldehyde Pollution Avoidance and Prevention
Investigators: Meister, John J.
Current Investigators: Meister, John J. , Choi, Gun Y.
Institution: Forest Products Research Center
EPA Project Officer: Hahn, Intaek
Project Period: September 15, 2000 through September 14, 2003
Project Period Covered by this Report: September 15, 2001 through September 14, 2002
Project Amount: $324,254
RFA: Technology for a Sustainable Environment (1999) RFA Text | Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development
The objective of this research project involves our fundamental study of thermoplastics, which tacify the wood interface that will determine if lignin copolymer-plastic blends can act as a binder in wood laminates or composites. These plastic binders would replace formaldehyde-based adhesives and remove the source of the major domestic, environmental exposure to formaldehyde.
Three ply, Douglas Fir plywood was made with graft copolymer and pure polystyrene binders. The plywoods were tested for delamination and compared to a commercial, Douglas Fir plywood. After 84 total cycles of soaking and drying, the plywood bound with 18 weight percent lignin copolymer and polystyrene showed less than one-fifth of the delamination of the polystyrene control, but 7 percent more delamination than the commercial, Douglas Fir plywood. All of these samples outperformed commercial, urea-formaldehyde bound Maple plywood.
The low yield and high variability found in some lignin graft copolymer reactions run in late 2001 were traced to a contamination of the commercial lignin used, Indulin AT. The lignin now contains an inhibitor for the grafting reaction and has been replaced by washed CURAN 2711P, a commercial product of Lignotech, Inc.
The lignin graft copolymer that couples the polystyrene binder to the wood in this formaldehyde-free binder must be synthesized in a free radical, grafting reaction. Reactions run in late 2001 had yields that were one-half of what they should have been and variabilities more than five times what they should have been. The low yield and high variability were traced to a contamination of the commercial lignin, Indulin AT. The lignin now contains an inhibitor for the grafting reaction and has been replaced by washed CURAN 2711P, a commercial product of Lignotech, Inc. The average yield was 55.3 percent, with a standard deviation of 5.7 weight percent for reactions run on washed Indulin AT, versus an average yield of 96.5 percent, with a standard deviation of 1.7 weight percent for reactions with identical formulations run on washed CURAN 2711P. Washed CURAN lignin will be used in all further research work.
We are making plywood in a Carver Laboratory press at 190°C, 2.5 tons of force, and 20 minutes press time. The 18 cm on an edge, 9 mm thick panels of three ply, Douglas Fir plywood were tested for delamination (failure of the bond between plys) and tensile strength as a function of aging. Delamination was examined by the use of the American Plywood Association, wet soak/oven dry test, APA D-5. After 84 total cycles of soaking and drying, the plywood bound with 18 weight percent lignin copolymer and polystyrene showed less that one-fifth of the delamination of the polystyrene control, but 7 percent more delamination than the commercial, Douglas Fir plywood. Commercial, urea-formaldehyde bound Maple plywood delaminated completely (100 percent) after 12 cycles.
Currently, we are conducting tensile strength tests of plywood samples as a function of how many cycles of soaking and drying the samples have undergone.
Future activities of this research project are to optimize this binder and improve the application process to form the best wood composite (plywood) possible.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
|Other project views:||All 27 publications||3 publications in selected types||All 2 journal articles|
||Adcock T, Shah V, Chen M-J, Meister JJ. Graft copolymers of lignin as hydrophobic agents for plastic (wood-filled) composites. Journal of Applied Polymer Science 2003;89(5):1266-1276.||