The effect of mixing on the modes of dispersion and rheological properties of two-phase polymer blends in extrusion

1975 ◽  
Vol 19 (10) ◽  
pp. 2831-2843 ◽  
Author(s):  
Chang Dae Han ◽  
Young Woo Kim ◽  
S. J. Chen
Polymer ◽  
2002 ◽  
Vol 43 (16) ◽  
pp. 4467-4477 ◽  
Author(s):  
Sandra Steinmann ◽  
Wolfram Gronski ◽  
Christian Friedrich

Author(s):  
Chang Dae Han

Polymer researchers have had a long-standing interest in understanding the evolution of blend morphology when two (or more) incompatible homopolymers or copolymers are melt blended in mixing equipment. In industry, melt blending is conducted using either an internal (batch) mixer (e.g., a Banbury mixer or a Brabender mixer) or a continuous mixer (e.g., a twin-screw extruder or a Buss kneader). There are many factors that control the evolution of blend morphology during compounding, the five primary ones being (1) blend composition, (2) rheological properties (e.g., viscosity ratio) of the constituent components, (3) mixing temperature, which in turn affects the rheological properties of the constituent components, (4) the duration of mixing in a batch mixer or residence time in a continuous mixer, and (5) rotor speed in a batch mixer or screw speed in a continuous mixer (i.e., local shear rate or shear stress). When two immiscible polymers are compounded in mixing equipment, two types of blend morphology are often observed: dispersed morphology and co-continuous morphology. Numerous investigators have reported on blend morphology of immiscible polymers, and there are too many papers to cite them all here. Some investigators (Han 1976, 1981; Han and Kim 1975; Han and Yu 1972; Nelson et al. 1977; van Oene 1978) examined blend morphology to explain the seemingly very complicated rheological behavior of two-phase polymer blends, and others (Favis and Therrien 1991; He et al. 1997; Ho et al. 1990; Miles and Zurek 1988; Scott and Macosko 1995; Shih 1995; Sundararaj et al. 1992, 1996) investigated blend morphology as affected by processing conditions. Today, it is fairly well understood from experimental studies under what conditions a dispersed morphology or a co-continuous morphology may be formed, and whether a co-continuous morphology is stable, giving rise to an equilibrium morphology, or whether it is an unstable intermediate morphology that eventually is transformed into a dispersed morphology (Lee and Han 1999a, 1999b, 2000). Let us consider the morphology evolution in an immiscible blend consisting of two semicrystalline polymers, A and B, in a compounding machine, and let us assume that the melting point (Tm,A) of polymer A is lower than the melting point (Tm,B) of polymer B.


2000 ◽  
Vol 44 (6) ◽  
pp. 1227-1245 ◽  
Author(s):  
M. Moan ◽  
J. Huitric ◽  
P. Médéric ◽  
J. Jarrin

2005 ◽  
Vol 15 (5) ◽  
pp. 314-325 ◽  
Author(s):  
C. Lacoste ◽  
L. Choplin ◽  
P. Cassagnau ◽  
A. Michel

Abstract Polymer melts can be mixed with many monomers, plasticizers, antistatics or foaming additives. Properties of such mixtures can change during blending because of chemical reactions like polymerization or crosslinking. The process may be carried out either in stirred tanks, extruders or in motionless mixers. In this paper we focused on the mixing time and the diffusion time of reagent, plasticizer and polymer thanks to rheological tools, and on the way how rheological properties can be studied during chemical reaction in polymer blending. The concept of rheoreactor and Couette analogy were introduced since we have a reactor on our disposal that can mix solution and measure rheological properties without taking sample. This apparatus appears to be an appreciable tool in complement of internal mixers that are specific to polymer blending. For example, we show the importance of the competition between mixing time and reaction time for reactive systems.


Author(s):  
Abdalsalam Ihmoudah ◽  
Mohamed M. Awad ◽  
Mohammad Azizur Rahman ◽  
Stephen D. Butt

Abstract Two-phase flow of gas/yield Pseudoplastic fluids can be found in different industrial applications like the chemical processes, oil industry, and petroleum transport in pipelines. In this study, experimental and numerical investigation of the influence of Rheological properties of non-Newtonians fluids in two-phase flow (gas/yield Pseudoplastic fluids) on slug characteristics in an upward vertical flow were performed. Different concentrations of Xanthan gum solutions (0.05%, 0.10%, and 0.15%, by w/w), which are referred to as non-Newtonian, yield Pseudoplastic behavior used as the working liquids and air as a gas. The experiments were conducted in an open-loop re-circulating system has a total length of 65 m to ensure phase mixing, and authorize flow regime patterns to develop. The vertical pipe has a diameter of 76.3 mm. API-compliant 8-speed rotational viscometer model 800 was used to measure the rheological properties of non-Newtonian fluids. Flow visualization and recording videos were achieved by A high-speed camera to a comparison between behavior of Newtonian and non-Newtonian fluids in the two-phase model. Pressure transducers used to measure high-response pressure. Computational fluid dynamics software (ANSYS fluent 2019 R3) was used for the numerical investigation. The volume of fluid (VOF) model has been chosen for tracking immiscible fluids. CFD simulation results compared to the experimental data. The slug behavior and shape were noticed to be affected by changing the rheological properties of the liquid phase. with increasing XG concentration at the same operations conditions, we found that non-uniform and random distribution of small bubbles due to the effective viscous force of a liquid phase.


1986 ◽  
Vol 17 (2) ◽  
pp. 175-188 ◽  
Author(s):  
YASUHIKO SHIINOKI ◽  
TOSHIMASA YANO

2013 ◽  
Vol 807-809 ◽  
pp. 2616-2619
Author(s):  
Yin Qing Liu ◽  
Mei Wei Wang ◽  
Hai Qing Cui

The equation of the limit replacement width of the one-dimension two-phase flow of Bingham fluid replacing Power law fluid in eccentric annulus was established, the numerical solution method of the equation mentioned above was given and taking the 3 wells, such as the He 104-27 well etc for examples, the limit replacement widths of cement slurry displacing mud, whose rheological properties can be described as Bingham and Power law modles respectively, were calculated, by using the equation and the numerical solution method mentioned above, and compared with those of cement slurry displacing mud, whose rheological properties are all described as Binghanm modle.


1996 ◽  
Vol 461 ◽  
Author(s):  
S. Kim ◽  
C. C. Han

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.


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