Engineering Commons^™

From Elastic Deformation To Terminal Flow Of A Monodisperse Entangled Melt In Uniaxial Extension, Yangyang Wang, Shi-Qing Wang

Shi-Qing Wang

Using a well-entangled monodisperse styrene-butadiene random-copolymer (SBR) melt as a model system, we illustrate generic features of uniaxial extension behavior that may be shared by all well-entangled thermoplastic and elastomeric materials. Depending on the imposed extensional rate, the same sample may behave like a viscous liquid or an elastic "solid." Analogous to the recently revealed shear inhomogeneity, the SBR melt inevitably undergoes cohesive failure in the form of sample breakage whenever the Weissenberg number is much greater than unity, making it challenging to reach steady state. In the elastic deformation regime where the external deformation rate is faster than Rouse …

Photopolymerization-Induced Crystallization And Phase Separation In Poly(Ethylene Oxide)/Triacrylate Blends, Soo Jeoung Park, Thein Kyu

Thein Kyu

The present article describes experimental and theoretical investigations of miscibility and crystallization behavior of blends of poly(ethylene oxide) (PEO) and triacrylate monomer (TA) using differential scanning calorimetry and optical microscopy. The PEO/TA blends manifested a single T(g) varying systematically with composition suggestive of a miscible character in their amorphous states. Moreover, there occurs melting point depression of PEO crystals with increasing TA. A phase diagram was subsequently established that exhibited a solid+liquid coexistence region bound by the liquidus and solidus lines, followed by an upper critical solution temperature (UCST) at a lower temperature. The emerging phase morphology was investigated to …

Theory And Computation Of Photopolymerization-Induced Phase Transition And Morphology Development In Blends Of Crystalline Polymer And Photoreactive Monomer, Pankaj Rathi, Thein Kyu

Thein Kyu

A hypothetical phase diagram of a crystalline polymer/photoreactive monomer mixture has been calculated on the basis of phase field (PF) free energy of crystal solidification in conjunction with Flory-Huggins (FH) free energy of liquid-liquid demixing to guide the morphology development during photopolymerization of poly(ethylene oxide)/triacrylate blend. The self-consistent solution of the combined PF-FH theory exhibits a crystalline-amorphous phase diagram showing the coexistence of solid+liquid gap bound by the liquidus and solidus lines, followed by an upper critical solution temperature at a lower temperature. When photopolymerization was triggered in the isotropic region, i.e., slightly above the crystal melting transition temperatures, the …

Effects Of Photointensity Gradient On Directional Crystal Growth In Blends Of Crystalline Polymer And Photoreactive Monomer Undergoing Photopolymerization-Induced Phase Transformation, Pankaj Rathi, Soo Park, Thein Kyu

Thein Kyu

Effects of light intensity gradient on development of intricate hierarchical morphology of semicrystalline polyethylene oxide (PEO) and photoreactive diacrylate (DA) blends undergoing photopolymerization-induced crystallization have been demonstrated experimentally and theoretically. The melting temperature of PEO was found to decline upon addition of DA monomer. A solid-liquid phase diagram has been established by self-consistently solving the combined phase field free energy of crystal solidification and Flory-Huggins (FH) free energy of liquid-liquid demixing. Dynamic calculations were performed using time-dependent Ginzburg-Landau (model C) equations by incorporating the combined phase field and FH free energy densities coupled with the photopolymerization kinetics. The spatiotemporal development …

Miscibility And Characterization Of The Ternary Crystalline System: Poly(Vinyl Butyral)/Poly(Vinyl Alcohol)/Nylon6, William Macknight, H. Jeong, M. Rooney, D. J. David, F. E. Karasz, T. Kajiyama

William MacKnight

No abstract provided.

Miscibility Of Polyvinyl Butyral/Nylon 6 Blends, William Macknight, H. Jeong, M. Rooney, D. J. David, F. E. Karasz, T. Kajiyama

William MacKnight

No abstract provided.

Surface Segregation In Polymer Blends: A Monte Carlo Simulation, William Macknight, P. Cifra, F. E. Karasz

William MacKnight

Effect Of Pressure On Phase Behavior In Polymer Blends Of Poly(2,6-Dimethyl-1,4-Phenylene Oxide) And Poly(O-Fluorostyrene-Co-P-Fluorostyrene) Copolymers, William Macknight

William MacKnight

No abstract provided.

Effect Of Pressure On Phase Behavior In Polymer Blends Of Poly(2,6-Dimethyl-1,4-Phenylene Oxide) And Poly(Styrene-Co-P-Fluorostyrene) Copolymers, William Macknight, Yoji Maeda, F. E. Karasz, R. Vukovic

William MacKnight

No abstract provided.