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Abstract
In Part 1 of this study, two-dimensional solution-state nuclear magnetic resonance spectroscopy (2D solution NMR) found no covalent bonds between wood polymers and polymeric methylene diphenyl diisocyanate (pMDI) under the experimental conditions used. However, 2D solution NMR could not identify whether or not pMDI had entered the cell wall and if so, whether it polymerized in situ to create a polyurea interpenetrating polymer network (IPN). Here in Part 2, we employ recently developed nano-indentation techniques to assess the properties of cell walls in pMDI-infiltrated wood. The elastic modulus and hardness of the cell walls increased after pMDI modification, suggesting that pMDI infiltrated the cell walls to form a polyurea IPN inside the cell walls.
Keywords
Adhesives,
testing,
glue,
adhesion,
plant cell walls,
loblolly pine,
chemical reactions,
nanotechnology,
mechanical properties,
elasticity,
modulus of elasticity,
hardness,
strains,
stresses,
gluing,
wood bonding,
bonding,
methylene diphenyl diisocyanate,
polymers,
polymerization,
durability,
chemical modification of wood,
nanoindentation,
bondline,
swelling,
atomic force microscopy,
AFM
Citation
Jakes, J.E.; Yelle, D.Y.; Beecher, J.F.; Frihart, C.R.; Stone, D.S. 2010. Characterizing polymeric methylene diphenyl diisocyanate reactions with wood. 2, Nano-indentation. Wood Adhesives 2009 [electronic resource]. FPS proceedings no. 7216-09. Madison, WI : Forest Products Society, c2010 [1 CD-ROM]: p. 366-373: ISBN: 9781892529572: 1892529572.
