Benjamin L. Wendt

Efficacy of polymeric MDI/polyol mixtures for binding wood boards

Components of polyurethane synthesis are tested for their ability to bind pine wood into boards and are compared to the efficiency of using only the isocyanate component of polyurethane synthesis. A variety of polyols are tested varying equivalent weight, functionality, reactivity as determined by the availability of primary hydroxyl endgroups, and viscosity. The boards are fabricated at a variety of densities and under a variety of conditions. The results show that board properties using only the isocyanate component are always superior to those including a polyol component, but the board properties are not always a simple function of the amount of isocyanate put in the board. Furthermore, it is observed that the lower the room temperature surface tension between the polyol and isocyanate, the better the measured board properties; but, the higher the observed surface tension, the better the board will self-release from the metal caul plates.

Colloidal encapsulation of hydrolytically and oxidatively unstable organoborane catalysts and their use in waterborne acrylic polymerization.

Trialkylborane catalysts and their amine complexes are hydrolytically and oxidatively unstable, decomposing in water very rapidly to trialkylboroxin, borate esters, and boric acid. However, trialkylborane-amine complexes will rapidly partition to a colloidal phase and remain surprisingly stable for long periods of time (>3 months) until such time as the catalyst is brought into an environment convenient for phase transfer. We show that tributylborane-amine complexes can be stored in aqueous solutions of several water-miscible polymers. We show by diffusion-oriented spectroscopy (DOSY) NMR experiments that the tributylborane-amine catalyst diffuses at nearly the same rate as the colloidal phase, providing strong evidence that they coexist. The aqueous colloidal catalysts can then be mixed with polymerizable monomers such as acrylates to produce good-quality polymers. We show that these colloid-encapsulated catalysts are also useful in producing adhesives capable of adhering low-surface-energy plastic substrates, even when formulated in systems containing 45% water. This is the first report of a waterborne structural adhesive.