Polymeric Materials From Agricultural Commodities

The guayule shrub (Parthenium Argentatum Grey) is processed into the following five major components of potential utility as polymeric materials: (1) high molecular weight natural rubber, (2) low molecular weight natural rubber, (3) organic soluble resins, (4) water soluble extracts, and (5) bagasse. This research has emphasized the isolation, characterization, and derivation of guayule coproducts

Laser Flash Photolysis of a Methylene 4, 4\u27-Diphenyldiisocyanate (MDI) Based Polyurethane and Model Carbamates

Transient species in the laser flash photolysis of solutions of methylene 4,4-diphenyldiisocyanate MDI based polyurethanes and small molecule models have been detected. One of the transient species, a substituted anilinyl radical, is not quenched by oxygen while a second transient is extinguished by the introduction of oxygen. Based on the spectral results, a plausible mechanism is offered for the primary photochemical reactions of MDI based polyurethanes

Reaction Calorimetry As a Tool to Determine Diffusion of Vegetable Oil Macromonomers In Emulsion Polymerization

Reaction calorimetry proved to be a useful technique to determine unsaturated macromonomer incorporation in emulsion polymerization. Vegetable oil macromonomer (VOMM) incorporation into emulsion polymerization is complicated by diffusion issues through the aqueous phase. Special techniques such as high shear and miniemulsion polymerization assist incorporating VOMM into latexes, but the film performance resembles polymer blends rather than crosslinked systems. Fatty acid surfactants with different ethoxylate lengths were acrylated and used as model macromonomers for this study. Monomer diffusion through the water phase was investigated by monitoring particle size, residual monomer, and heat evolution during polymerization using dynamic laser light scattering, gas chromatography, and reaction calorimetry, respectively. Macromolecules of lower hydrophobicity incorporated better in conventional emulsion polymerization. No special technique was required to obtain coagulum-free latexes and glossy films. Specifically for acrylated fatty acids, an average ethoxylate chain of 10 units was sufficient to facilitate diffusion through the aqueous phase. (c) 2006 Elsevier B.V. All rights reserved