Investigation of Phase Separation in a Partially Miscible Polymer Blend by Rheology

Li, Runming; Yu, Wei; Zhou, Chixing

doi:10.1080/00222340701457519

Cited by 19 publications

(6 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The time dependency of storage modulus in PMMA/SMA blends during LLPS is shown in Figure 18b (185). It is interesting to see that G decreases monotonically in a near-critical blend, whereas G increases and then decreases in an off-critical blend.…”

Section: Series Shearmentioning

confidence: 95%

Rheological Measurements

2013

Encyclopedia of Polymer Science and Technology

Self Cite

View full text Add to dashboard Cite

Rheology is the science to study the flow and deformation of matter. It becomes an important field in material science and engineering, food, biotechnology, and so on. The objects in rheological study are not the ideal solid and ideal fluid, which can be described by the Hookean elastic model and the Newtonian viscous model, respectively. Instead, the rheological study often focuses on materials that can exhibit viscous, elastic, and plastic behavior under different flow conditions. They are often termed as complex fluids or soft matter, which include polymers, gels, suspensions, emulsions, biofluids, foods, inks (1). In contrast to hydrodynamics, which often accounts for the complex flow behavior of simple fluids, simple geometry is utilized in rheological measurements to understand the rather complicated relationship between the mechanical input and output of complex fluids. The real flow fields encountered in many applications (such as polymer extrusion, injection molding, blow molding, fiber spinning, inkjet printing, coating) are rather complicated (2). It becomes a problem whether the rheological measurements that performed under simple flow fields are useful in understanding the complicated flow behaviors of complex fluids. Fortunately, it has been proved in many examples that the properties determined from simple rheological measurements are sufficient to quantify the material parameters in various constitutive equations, which have been used widely and successfully to simulate the flow behaviors in polymer processing (3-11). The most frequently used simple flow fields are simple shear flow and simple extensional flow.The simplest geometry that defines the simple shear is two infinite parallel plates separated by a distance h. The liquid is set between two plates with one plate moving parallel to the other (Fig. 1). In reality, when the length L and the width B are much larger than the gap h, the flow in the center regime resembles the flow between two infinite plates. It means that the edge effects are ignored in most experimental shear geometries. In rheological measurements, the flow between two plates should be laminar. Moreover, it is usually assumed that the velocity across the gap satisfies a linear profile. As shown in Fig. 1, if the bottom plate is fixed and the upper plate moves horizontally with the velocity V, the fluid velocity varies linearly from 0 at the bottom plate to V at the upper plate if the no-slip boundary condition is satisfied. The linear velocity profile generates a constant velocity gradient, which is known as the shear rate. Then, the flow field between two parallel plates is homogeneous in the shear rate. The homogeneous assumption is nontrivial in the rheological tests since the actual velocity

show abstract

Section: Series Shearmentioning

confidence: 95%

Rheological Measurements

2013

Encyclopedia of Polymer Science and Technology

Self Cite

View full text Add to dashboard Cite

show abstract

“…A phase diagram provides important information for partially miscible polymer blends. The phase boundary is usually obtained by measuring the discontinuity of some physical properties with the temperature, such as the cloud point or the transmittance temperature, 40 the storage modulus of the bulk 41 or the change of the heat ow. 42 Since the two components in this work possess nearly identical refractive indices (R I,PLA ¼ 1.44-1.46, R I,PEG ¼ 1.46), 1,36 it is difficult to detect their liquidliquid phase separation temperatures via optical methods.…”

Section: Phase Diagrammentioning

confidence: 99%

Liquid–liquid phase separation and its effect on the crystallization in polylactic acid/poly(ethylene glycol) blends

Zhou

2014

RSC Adv.

Self Cite

View full text Add to dashboard Cite

show abstract

“…These methods utilize the dynamic viscoelastic data at various temperatures, and the accuracy of the transition temperature thus determined is affected by the width of the temperature range examined. On the other hand, temperature ramp has been also widely used to determine the phase transition temperature. ,,,− With increasing temperature, the storage modulus G ′ usually decreases owing to the enhanced chain mobility. However, when the blend enters transition region, the decreases in G ′ can be compensated by an increase due to contribution from interface and concentration fluctuation, thereby slowing this decrease and sometimes even increasing the storage modulus.…”

Section: Introductionmentioning

confidence: 99%

Phase Separation of Poly(methyl methacrylate)/Poly(styrene-co-acrylonitrile) Blends with Controlled Distribution of Silica Nanoparticles

Huang

Gao

et al. 2012

Macromolecules

Self Cite

View full text Add to dashboard Cite

Effects of selective location of silica nanoparticles on the phase separation of poly(methyl methacrylate)/poly(styrene-coacrylonitrile) (PMMA/SAN) blends were investigated via combination of rheological method and optical microscopy. Through grafting polystyrene chain to the surface of silica nanoparticles, the silica nanoparticles were controlled to selectively locate at interfaces or in the PMMA-rich domains. Power-law analysis of the moduli and shifted Cole−Cole plots were applied to determine rheological transition temperature (apparent binodal temperature) of blend with near-critical and off-critical compositions for both neat blends and particle-filled blends. The particle location had significant influence on the rheological transition temperature but little impact on optically determined binodal temperature. This discrepancy was discussed through morphology observation via transmission electron microscopy (TEM) for blends under different phase separation conditions. It was found that nanoparticles retard coarsening of morphology during phase separation. The most striking slowdown was found in off-critical blends with nanoparticles located on the interface. On the other hand, nanoparticles preferentially locating in the minor phase could act as nucleation sites but decreased the total number of nuclei. The difference in the rheological transition temperatures is ascribed to the effect of nanoparticles on the components' viscoelasticity and the morphology during phase separation.

show abstract

Investigation of Phase Separation in a Partially Miscible Polymer Blend by Rheology

Cited by 19 publications

References 37 publications

Rheological Measurements

Rheological Measurements

Liquid–liquid phase separation and its effect on the crystallization in polylactic acid/poly(ethylene glycol) blends

Phase Separation of Poly(methyl methacrylate)/Poly(styrene-co-acrylonitrile) Blends with Controlled Distribution of Silica Nanoparticles

Contact Info

Product

Resources

About