Mark F. Sonnenschein

Hollow fiber microfiltration membranes from poly(ether ether ketone) (PEEK)

A procedure for obtaining high performance large internal diameter (ID; >1 mm) hollow fiber microfiltration membranes from poly(ether ether ketone) (PEEK) is presented. A simple mixture of isomers of diphenylphthalate is a good solvent for employing the thermal-phase inversion process to obtain PEEK membranes. Obtaining large ID hollow fibers with substantial transmembrane flux requires sufficient melt strength during spinning to prevent excessive draw of the extruding fiber. The use of a second leachable polymer to the blend satisfies the conditions, and polysulphone (PS) is found to provide superior membranes relative to either poly(etherimide) (PEI) or poly(ether sulphone) (PES) as a second polymer. PEEK membranes obtained by this process yield better chemical resistance to a concentrated warm surfactant/oil solution.

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.

Micro- and ultrafiltration film membranes from poly(ether ether ketone) (PEEK)

Film membranes from the thermoplastic poly(ether ether ketone) (PEEK) have been extruded and tested for their microfiltration and ultrafiltration performance. High-performance asymmetric membranes have been obtained by extruding polymer blends of PEEK, polysulphone, and a small molecule solvent mixture, and then by removing the polysulphone and solvent in a subsequent extraction step. The process for making ultrafiltration membranes differs from microfiltration membranes only in the relative blend components, and the temperature of the film pick-up rolls. Processing parameters with important effects on the membrane performance have been identified. Microfiltration membranes are characterized by their pore-size distributions and SEM, and ultrafiltration membranes by their rejection of bovine serum albumin, bubble point, and SEM. Composite membrane for nanofiltration utilizing the PEEK ultrafiltration membrane as a substrate performed similarly to a commercial membrane for the same purpose. This work details the best method for making PEEK film membranes published to date.

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.