Browsing by Author "Liang, Jingyu"

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    Curing Characteristics of Photopolymer Resin With Dispersed Glass Microspheres in Vat Polymerization 3D Printing
    Liang, Jingyu (Virginia Tech, 2023-07-07)
    The curing characteristics of photopolymer resin determine the relationship between the vat polymerization (VP) process parameters and the layer thickness, geometric accuracy, and surface quality of the 3D printed specimen. Dispersing filler material into the photopolymer resin changes its curing characteristics because the filler scatters and absorbs light, which modifies the curing reaction. However, the ability to cure photopolymer resin with high filler volume fraction is important to 3D print material specimens for specific engineering applications, e.g. structural polymer composite materials, electrical and thermal conductive materials, and ceramic materials for biological and high-temperature environments. We methodically measure the curing characteristics of diacrylate/epoxy photopolymer resin with dispersed glass microspheres. The experiments show that the curing depth, degree-of-cure, and surface roughness depend on both the light exposure dose and the filler fraction. We determine that the degree-of-cure increases with increasing filler fraction for constant exposure dose, and approaches 90% with increasing exposure dose, independent of the filler fraction. The geometric accuracy of the 3D printed specimens decreases with increasing exposure dose and with increasing filler volume fraction due to so-called profile broadening. Finally, we show that the average surface roughness of the 3D printed specimens decreases with increasing exposure dose and filler fraction. This work has implications for VP of photopolymer resins with high filler fraction.
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    Water soluble analogs and prodrugs of taxol
    (United States Patent and Trademark Office, 1995-05-02)
    Substituted 2'-benzoyl and 2', 7-dibenzoyl taxol derivatives are synthesized which have improved water solubility and stability while maintaining bioactivity. In a preferred embodiment, taxol 2',7-di(sodium 1,2-benzenedicarboxylate) is synthesized by reacting taxol with phthalic anhydride, and subsequently neutralizing the resulting acid by an ion exchange resin. Taxol 2'-(sodium 1,4-benzenedicarboxylate) is prepared by reacting the monobenzyl ester of 1,4-benzene dicarboxylic acid with taxol in the presence of dicyclohexyl carbodiimide and dimethylaminopyridine, hydrogenolysing the resulting ester to remove the benzyl group, and neutralizing with ion exchange resin. Other taxol prodrugs are prepared by modifications of these routes. In a preferred embodiment, the compounds prepared have improved water-solubility as compared with taxol and demonstrate activity in the M109 mouse bioassay system.