Rheology of polymer blends: non-linear model for viscoelastic emulsions undergoing high deformation flows

Non-linear rheology of a mixture of two viscoelastic immiscible liquids undergoing high deformation flow was considered. Using Grmela's formalism (Grmela 1986, 1989, 1993a, b) and the coarse grained picture given by Onuki (1987) and Doi and Ohta (1991), we have derived a set of highly non-linear time-dependent transport equations that take into account a direct coupling between the rheology and morphology. Breakup, coalescence, and the high deformation of the interface were considered. Models of Doi and Ohta (1991), Lee and Park (1994), and Grmela et al. (1998) are recovered as special cases. The parameters of?the model were given a physical meaning in both shear and elongational flows and the predictions of the model were ¶compared to the predictions of the previous models on the basis of experimental results obtained on two model?blends PDM/PB polydimethylsiloxane/poly(1-butene) and PP/PS polypropylene/polystyrene blends.     

Pointwise a priori bounds for a strongly coupled system of reaction–diffusion equations with a balance law

We consider a reaction–diffusion system with a full matrix of diffusion coefficients satisfying a balance law on a bounded domain with no-flux boundary conditions. We demonstrate that global solutions exist for polynomial reaction terms provided some conditions on the diffusion coefficients are satisfied. The proof makes use of comparison results and Solonnikov's estimates concerning linear parabolic equations in Banach spaces. © 1998 B. G. Teubner Stuttgart—John Wiley & Sons, Ltd.     

Preparation,characterization and ion adsorption properties of functionalized polystyrene modified with 1,4-phenylene diisocyanate and diethylenetriamine

In the present work, linear polystyrene (PS) was functionalized by a sulfonation reaction providing sulfonated polystyrene (PSS). Then, the PSS polymer chains were cross-linked with the 1,4-phenylene diisocyanate (PPDI) group in tetrahydrofuran (THF), which led to a PSS-PPDI polymer. The PSS-PPDI was grafted by diethylenetriamine (DETA) in a solution of THF to obtain polymer PSS-PPDI-DETA. Their structures were characterized by infrared spectroscopy (ATR-FTIR), elemental analysis (EA), differential scanning calorimetry (DSC), thermogravemetric (TGA), thermodynamic (DTA) and differential thermogravimetric (DTG) analysis. Subsequently, the obtained polymers were tested for their ability to remove some metal ions from aqueous media such as Zn²⁺, Cd²⁺ and Co²⁺.     

Investigation on the pre-compensation and post-compensation cascaded multi-channel-chirped fiber Bragg gratings for a repeaterless transmission system

We experimentally designed dispersion-managed repeaterless transmission systems with a pre-compensation and post-compensation technique using multi-channel-chirped fiber Bragg gratings. The repeaterless transmission link supports a single channel(1548.51 nm) with a 10 Gbps repeaterless transmission system over 300 km standard single-mode fiber(SSMF). In the system design, two distributed Raman amplifiers(DRAs) were used to improve the signal level propagated along the 300 km SSMF. The co-propagating DRA provided 15 dB on–off gain and the counter-propagating produced 32 dB on–off gain at the signal wavelength. The experiment results show that the post-compensation configuration achieves an optimal performance with a bit error rate at 1 × 10~(-9).     

On optimal solutions of general continuous-singular stochastic control problem of McKean-Vlasov type

In this paper, we establish general necessary optimality conditions for stochastic continuous-singular control of McKean-Vlasov type equations. The coefficients of the state equation depend on the state of the solution process as well as of its probability law and the control variable. The coefficients of the system are nonlinear and depend explicitly on the absolutely continuous component of the control. The control domain under consideration is not assumed to be convex. The proof of our main result is based on the first- and second-order derivatives, with respect to measure in Wasserstein space of probability measures, and by using variational method.     

Effects of the ionization in the tautomerism of uracil: A reaction electronic flux perspective

The one‐step tautomerization processes of uracil and its radical cation and radical anion have been investigated in the light of the reaction force and reaction electronic flux (REF) formalisms. The relative energies of the different tautomers as well as the corresponding tautomerization barriers have been obtained through the use of the G4 high‐level ab initio method and by means of B3LYP/6‐311+G(3df,2p)//B3LYP/6‐311+G(d, p) calculations. Systematically, the enol radical cations are more stable in relative terms than the neutral, due to the higher ionization energy of the diketo forms with respect to the enolic ones. Conversely, the enol radical anions, with the only exception of the 2‐keto‐N1 anion, are found to be less stable than the neutral. The effects of the ionization are also sizable on the tautomerization barriers although this effect also depends on the particular tautomerization process. The reaction force analysis shows that all reactions are mainly activated through structural rearrangements that initiate the electronic activity. This electronic activity is monitored along the reaction coordinate through the REF that obeys a delicate balance between the acid and basic character of the atoms involved in the hydrogen transfer. © 2015 Wiley Periodicals, Inc.     

On the Structures,Lifetimes, and Infrared Spectra of Alkylmercury Hydrides

A series of six small alkylmercury hydrides of the general formula RHgH with R=methyl, ethyl, n‐propyl, isopropyl, n‐butyl, and 3‐butenyl were obtained by reduction in vacuo of the corresponding mercury halide with tributyltin hydride in the presence of a radical inhibitor. These very reactive compounds, which have to be removed from the reaction mixture as they are formed, were characterized by ¹H NMR and ¹³C NMR spectroscopy. The IR spectra of n‐propyl‐, isopropyl‐, n‐butyl‐, and 3‐butenylmercury hydride were recorded for the first time. All compounds were then studied by density functional theory calculations on the basis of a recent theoretical assessment for alkylmercury compounds performed by our group. Comparison of the experimental and theoretical results allowed the assignment of the vibrational modes in an unambiguous way, in spite of the low intrinsic stability of some of the derivatives investigated. The experimental procedure implemented for registering the IR spectra of these unstable species in the gas phase allowed us to obtain reasonable estimates of their lifetimes.     

The influence of porosity of ammonium perchlorate (AP) on the thermomechanical and thermal properties of the AP/polyvinylchloride (PVC) composite propellants

The influence of porous ammonium perchlorate (P_OAP) on the thermomechanical and combustion behavior of solid rocket propellants based on polyvinylchloride binder has been investigated. Differential scanning calorimetry, differential thermogravimetry, dynamic mechanical thermal analysis, and scanning electronic microscopy measurements were used for thermomechanical and thermal decomposition properties assessment. The results obtained indicate that lower glass transitions of the propellants and catalytic effect of combustion are obtained with P_OAP.