Rheological Behavior for Polymer Melts and Concentrated Solutions——Part Ⅶ: A Quantitative Verification for the Molecular Theory of Non-linear Viscoelasticity with Entanglement Constraints in Polymer Melts

Based on the molecular theory of non-linear viscoelasticity with constrained entanglements in polymer melts, the material functions in simple shear flow were formulated, the theoretical relations between. eta((gamma) over dot), psi (10)((gamma) over dot) and shear rate ((gamma) over dot), and topologically constrained dimension number n ' and a were derived. Linear viscoelastic parameters (eta (0) and G(N)(0)) and topologically constrained dimension number (n ' a and <(<upsilon>)over bar>) as a function of the primary molecular weight (M-n), molecular weight between entanglements (M-C) and the entanglement sites sequence distribution in polymer chain were determined. A new method for determination of viscoelastic parameters (eta (0), psi (10), G(N)(0) and J(e)(0)), topologically constrained dimension number (n ', a and v) and molecular weight (M-n, M-c and M-e) from the shear flow measurements was proposed. It was used to determine those parameters and structures of HDPE, making a good agreement between these values and those obtained by other methods. The agreement affords a quantitative verification for the molecular theory of nonlinear viscoelasticity with constrained entanglement in polymer melts.

Synthesis and ring-opening copolymerization of cyclic aryl ester dimers

Two kinds of cyclic aryl ester dimers have been synthesized by reaction of phthaloyl dichloride with bisphenols via interfacial polycondensation. The cyclic dimers readily undergo anionic ring-opening polymerization or copolymerization in the melt by using sodium benzoate as the initiator, producing linear, high molecular weight polyesters. The contents of cyclic dimers in the homopolymers P1, P2, and copolymer P12 are 13.7%, 10.2%, 2.9%, respectively, which indicates that ring-opening copolymerization of cyclic dimers may impel the conversion of cyclic dimers and decrease the content of cyclic dimers in the resulting copolymer. Moreover, the isothermal chemorheology of the ring-opening copolymeriza- tion of cyclic dimers indicates that the reactive molten mixture has low shear viscosity and the viscosity increases slowly in the initial stage of ring-opening polymerization.

Characterization strategy of polymeric transition metal species transformation for high-purity metal recovery

The aqueous metal species with similar chemical properties are usually extracted together,limiting deep separation for high-purity metal.However,rare attention has been paid to metal speciation characterization and transformation during separation.Herein,the hydrolysis evolution of polymeric metal species was investigated systematically by electrospray ionization time-of-flight mass spectrometry(ESI-TOF-MS).The transformation evolutions were visualized with respect to characteristic vanadium species(V_(1),V_(2),V_(3),V_(4) and V_(10)),chromium species(Cr_(1) and Cr_(2)),tungsten(W_(1),W_(2),W_(4),W_(6) and W_(10))and molybdenum(Mo_(1),Mo_(2) and Mo_(4))species.The key characteristics(such as specfic pHs and concentrations)for speciation variation were revealed.The polymerization behavior of several transition metals can be semiquantitative characterized by this strategy.The sufficient speciation transformation provides a solid base for metal speciation chemistry,and guides further development of high-purity metal recovery.