Three commercial filaments for Fused Deposition Modeling (FDM) were selected to study the influence of polymer formulation on the printing quality and mechanical properties of FDM specimens. The three filaments were all based on polylactic acid (PLA) as the matrix, and they are sold as PLA filaments. The printing quality was tested by printing one complex shape with overhang features. The marked shear thinning behavior for two filaments was observed by rheology. The filaments were also studied by scanning electron microscopy and thermogravimetric analysis (TGA) to unveil their composition. The filaments with the best printing quality showed the presence of mineral fillers, which explained the melt behavior observed by rheology. The tensile testing confirmed that the filled PLA was the best-performing filament both in terms of printing quality and thermomechanical performance, with a p-value = 0.106 for the tensile modulus, and a p-value = 0.615 for the ultimate tensile strength.
Low molecular weight thermoplastic PES :\ud
PEES (polyethersulfone : polyetherethersulfone) copolymer,\ud
bearing amine reactive end groups, was blended with a\ud
diglycidyl ether of bisphenol A (EPON828) epoxy resins.\ud
Two different curing agents, MDEA [methylene bis(2,6-diethylaniline)]\ud
and 3,3DDS (3,3-diamino diphenyl sulfone),\ud
were used separately to compare flow behavior, curing kinetics,\ud
and morphology of the final samples. Emphasis was\ud
placed on different phase behaviors of the cured systems,\ud
attributed to different solubilities of thermoplastic in the\ud
thermoset system as well as to the reactivity of the two\ud
curing agents. The presence of PES : PEES was shown not to\ud
affect the reaction rate of epoxy blends with respect to the\ud
neat resin by the reactive nature of its end groups
Two commercially available epoxy-fluorinated monomers, 3-(perfluorooctyl)-1,2-propenoxide and 3-(1H, 1H, 9H-hexadecafluorononyloxyl)-1,2 propenoxide, were used as modifying additives for UV curable systems. These two fluorinated monomers were mixed, in small amounts (less than 1% w/w) with a hydrogenated epoxy monomer 1,4-cyclohexanedimethanol-diglycidyl ether. The mixtures were coated on glass substrate and UV-cured, giving rise to transparent films. Notwithstanding their very low concentrations, the fluorinated monomers caused a change in the surface properties of the films, without changing their curing conditions and their bulk properties. The air side of the coatings became highly hydrophobic, while the substrate side was unmodified. As shown by XPS measurements, the fluorinated monomers were able to concentrate selectively on the air side of the films, forming a fluorinated layer.
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