Phase Separation Dynamics of Blends of Telechelic Epoxy Terminated Polybutadiene and Maltene

1995 ◽  
Vol 68 (1) ◽  
pp. 158-166 ◽  
Author(s):  
Tsunehiro Yamamoto ◽  
Thein Kyu
Keyword(s):  
Phase Separation ◽  
Scaling Laws ◽  
Phase Region ◽  
Solution Temperature ◽  
Two Phase ◽  
Time Resolved ◽  
Thermally Induced ◽  
Dynamical Scaling ◽  
Upper Critical Solution Temperature ◽  
Deep Temperature

Abstract Thermally induced phase separation in a mixture of telechelic epoxy terminated polybutadiene (ETPB) and maltene has been studied by means of time-resolved light scattering and optical microscopy. Maltene, consisting of various hydrocarbon derivatives, was extracted from asphalt with n-heptane and isolated by centrifugation. The cloud point studies of the ETPB/maltene mixture showed an upper critical solution temperature (UCST) which is thermally reversible. Several deep temperature quench experiments were conducted at an off-critical composition (27/73 ETPB/maltene) from a single phase (80°C) to a two-phase region (27, 29, 31 and 33 °C). The time-evolution of the structure factor for the late stage of spinodal decomposition (SD) was analyzed in the framework of nonlinear and dynamical scaling laws. The reverse quench experiments were also undertaken to elucidate the phase dissolution process.

The Effect of Molecular Architecture on the Phase Diagram and Mobility of a Polymer Blend Exhibiting a Lower Critical Solution Temperature: Cycles Mixed with Linear Chains.

1991 ◽  
Vol 248 ◽  
Author(s):  
Maria M. Santore ◽  
Gregory McKenna ◽  
Charles Han
Keyword(s):  
Phase Diagram ◽  
Phase Separation ◽  
Lower Critical Solution Temperature ◽  
Phase Region ◽  
Solution Temperature ◽  
Free Energy Function ◽  
Molecular Architecture ◽  
Two Phase ◽  
Critical Solution Temperature ◽  
Linear Chains

AbstractWe examine the role of molecular architecture on the phase diagram of the PS/PVME (poly[styrenel /poly[vinyl methyl ether]) blend, a mixture which in previous studies with linear chains exhibited a lower critical solution temperature, (LCST) i.e. it phase separated on heating. In this investigation, two blends with components exceeding the critical molecular weight for entanglement were compared: one consisting of linear PS and PVME and a second with cyclic PS and linear PVME. Cloud point experiments over a broad composition range reveal that the blend containing cyclic PS undergoes phase separation at temperatures 7-8 °C higher than the analogous linear blend. In other words, the mixture of cycles and linear chains is more thermodynamically stable than the mixture of two linear chains.The LCST nature of the system facilitates examining chain mobility by considering the phase separation kinetics. Time-resolved light scattering studies of blends near their critical compositions tracked the spinodal decomposition following a rapid temperature jump from the one-phase to the two-phase region. An analysis of the scattering intensity growth ultimately led to mutual diffusion coefficients whose temperature dependence confirmed the observed cloud points. An approximation of the second derivative of the free energy function based on SANS studies of the linear PS/PVME blend allowed us to estimate mutual mobilities. The values determined for the cycle-containing blend were considerably lower than those for the blend of linear chains at these molecular weights.

“Dynamics of Phase Segrewation in Poly-P-Phenylene Terephtualamide and Amorphous Nylon Molfcular Composites”

1989 ◽  
Vol 171 ◽  
Author(s):  
Thein Kyu ◽  
Jan Chang Yang ◽  
Tsuey Ing Chen
Keyword(s):  
Temperature Jump ◽  
Phase Segregation ◽  
Solution Temperature ◽  
Distilled Water ◽  
Two Phase ◽  
Time Resolved ◽  
Critical Solution Temperature ◽  
Dynamical Scaling ◽  
Molecular Composites ◽  
Phase Temperature

ABSTRACTTime-resolved light scattering has been employed to elucidate the dynamics of phase segregation of poly-p-phenylene terephthalamide (PPTA)/ amorphous nylon (AN) molecular composites. Miscible PPTA/AN blends can be prepared from sulfuric acid solution by rapidly coagulating the solution in distilled water. The composites, however, undergo phase segregation upon thermal treatment and exhibit a miscibility window reminiscent of a lower critical solution temperature (LCST). Several temperature-jump experiments were undertaken from ambient to a two-phase temperature region of 240, 250 and 260°C. Time-evolution of scattering profiles are analyzed in accordance with non-linear and dynamical scaling theories.

Two-Phase Microstructures Formed by Phase-Separation of Coherent Precipitates in Elastically Constrained Alloy Systems

2010 ◽  
Vol 638-642 ◽  
pp. 2215-2220 ◽  
Author(s):  
Minoru Doi
Keyword(s):  
Free Energy ◽  
Phase Separation ◽  
Surface Energy ◽  
Phase Region ◽  
Precipitate Phase ◽  
Two Phase ◽  
Phase Separations ◽  
Chemical Free Energy ◽  
Elastic Constraint ◽  
Alloy Systems

Coherent two-phase microstructures consisting of ordered precipitate and disordered matrix phases sometimes exhibit a phase-separation, which brings the split and/or the decelerated coarsening of precipitates. When the coherent two-phase microstructure of A1+L12 (+’) in Ni-base alloys are aged inside the two-phase region of A1+L12 , the L12 precipitate sometimes exhibit a phase-separation and A1 phase newly appears and grows in each L12 precipitate. Phase-separations of the same type to the above also take place due to ageing of coherent two-phase microstructures of A2+D03 and A2+B2 in Fe-base alloys: D03 and B2 precipitates sometimes exhibit phase-separations and A2 phase newly appears and grows in both precipitates. These types of phase-separation take place under the influence of chemical free energy. In the course of further ageing, the new disordered phases of A1 and A2 change their morphology in various ways depending on the elastic constraint: i.e. the morphology of new A1 or A2 phase is influenced by the elastic energies and the surface energy.

Modification of Interfacial Properties of Polymer Blends with Diblock Copolymer

1996 ◽  
Vol 461 ◽  
Author(s):  
S. Kim ◽  
C. C. Han
Keyword(s):  
Molecular Weight ◽  
Phase Separation ◽  
Polymer Blends ◽  
Diblock Copolymer ◽  
Diblock Copolymers ◽  
Phase Region ◽  
Domain Growth ◽  
Two Phase ◽  
Phase Separation Kinetics ◽  
Styrene Butadiene

ABSTRACTThe effect of diblock copolymer on the phase-separation process of polymer blends has been investigated by using light scattering and optical microscopic observations. To quench the system into the two phase region, a shear-jump technique is employed instead of the conventional temperature-jump technique. The samples studied are blends of low-molecular-weight polystyrene and polybutadiene with and without added styrene-butadiene block copolymer as a compatibilizer. It was observed that the addition of diblock copolymers could accelerate the phase separation kinetics depending on the shear history. As the concentration of diblock copolymer increases, the distribution of domain sizes becomes narrower and the growth rate slows down. The extent of slowing-down depends on the molecular weight and concentration of the copolymer. The time dependence of domain growth is clearly observed with optical microscopy.

Phase-Separations of Coherent Precipitates of Ordered Phases in Elastically Constrained Alloys

2006 ◽  
Vol 980 ◽  
Author(s):  
Minoru Doi ◽  
Hiroshi Kumagai ◽  
Kanako Nakashima ◽  
Takao Kozakai
Keyword(s):  
Phase Separation ◽  
Phase Region ◽  
Point Of View ◽  
Two Phase ◽  
Phase Separations ◽  
Transmission Electron ◽  
Ordered Phases ◽  
Chemical Free Energy ◽  
Fe Alloys ◽  
Means Of Transmission

AbstractPhase-separations of coherent precipitates of ordered phases were investigated by means of transmission electron microscopy (TEM) and the theoretical analysis from a thermodynamic point of view. When the two-phase microstructures of A1+L12 in elastically constrained Ni-Al-Ti and Ni-Si-Fe alloys are isothermally heated inside the two-phase region of A1+L12 , coherent L12 precipitate particles sometimes exhibit a phase-separation and A1 phase newly appears and grows in L12 particles. Phase-separations of the same type as the above are also observed in coherent two-phase microstructures of A2+D03 and A2+B2 in elastically constrained Fe-Si-V and Fe-Al-Ni alloys respectively: coherent D03 or B2 precipitates exhibit a phase-separation and A2 phase newly appears and grows in both precipitates. Such phase-separation is realized under the influence of chemical free energy and elastic energies.

Experimental Study on Heat Yreatment Processing of a New Low Cost Titanium Alloy Used in Aviation Field

2013 ◽  
Vol 747-748 ◽  
pp. 919-925 ◽  
Author(s):  
Guo Qiang Shang ◽  
Xin Nan Wang ◽  
Yue Fei ◽  
Jun Li ◽  
Zhi Shou Zhu ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Low Cost ◽  
Solution Treatment ◽  
Heat Treating ◽  
Optical Microscope ◽  
Phase Region ◽  
Solution Temperature ◽  
Two Phase ◽  
Common Solution ◽  
Strength And Plasticity

The effect of common solution treatment, two-step solution treatment and aging, solution treatment and aging (STA) on the microstructure and mechanical properties of a new low cost titanium alloy used in aviation field were investigated by optical microscope (OM), scanning electron microscopy (SEM) and tensile test. The results show that a typical equiaxed structure can be obtained by common solution treatment leading to a good combination of strength and plasticity. Besides, solution heat treating in the β region and subsequently ageing at a low temperature results in a significant increase in mechanical strength and a little decrease in plasticity. When the solution temperature is at α+β two-phase region (895), the low cost titanium alloy acquires the best combination of strength and ductility.

Target Morphologies in Polymer Blends

2004 ◽  
Vol 856 ◽  
Author(s):  
Nigel Clarke ◽  
Ian Henderson
Keyword(s):  
Phase Separation ◽  
Polymer Blends ◽  
Selection Process ◽  
Matrix Material ◽  
Phase Region ◽  
Wavelength Selection ◽  
Two Phase ◽  
Inhomogeneous Surface ◽  
The Matrix ◽  
Separation Results

ABSTRACTWe model a novel process for obtaining controlled morphologies in polymer blends. Particles of one type of polymer are allowed to dissolve in a matrix of a dissimilar polymer. Prior to complete dissolution the blend is quenched into the two phase region, such that phase separation takes place. The combination of the incomplete dissolution and the wavelength selection process associated with phase separation results in particles that during the ‘intermediate’ stages have a core that is significantly rich in the matrix material. The concept is extended to consider the effect of phase separation on an inhomogeneous surface chemically patterned with regions which are more attractive to one component of the blend.

Thermodynamic analysis of phase separation of a thermoplastic in a variant epoxy/monoamine-diamine system: influence of epoxy molecular structure

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Joaquin Lopez ◽  
Maite Rico ◽  
Belen Montero ◽  
Carmen Ramirez
Keyword(s):  
Molecular Structure ◽  
Phase Separation ◽  
Polymerization Process ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Crosslinked Polymer ◽  
Epoxy Amine ◽  
Upper Critical Solution Temperature ◽  
Amine System ◽  
Molecular Fractionation

Abstract A thermodynamic study of phase separation induced by the polymerization process was carried out in a variant epoxy/amine system modified with polystyrene (PS) by means of a model based on the Flory-Huggins theory in which the polydispersity of components was taken into account. Modification of the epoxy/amine system was to continually change its molecular structure from a linear polymer to a highly crosslinked polymer using a monoamine and a diamine mixed in different proportions. The cloud-point curves during polymerization for five epoxy/monoamine-diamine systems with PS blends were experimentally measured. Application of the thermodynamic model led to obtaining the corresponding phase diagrams. All studied blends showed an upper critical solution temperature behavior and an increase in miscibility was observed by increasing the monoamine/diamine ratio. The polydispersity of components caused a molecular fractionation leading to a difference in the conversion of separate phases.

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