Reaction-induced phase decomposition in polymer blends
TL;DR: In this paper, a spinodal decomposition induced by chemical reaction is observed in an epoxy/ polyethersulphone (PES) system having a lower critical solution temperature (LCST) type phase diagram.
About: This article is published in Progress in Polymer Science.The article was published on 1995-01-01. It has received 374 citations till now. The article focuses on the topics: Spinodal decomposition & Lower critical solution temperature.
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TL;DR: Shape memory polymers (SMPs) as mentioned in this paper represent a highly interesting class of materials and have gained significant interest in recent years, thus, the variety of materials investigated virtually exploded and several promising shape memory effects have been developed.
711 citations
25 Apr 2012
TL;DR: In this paper, the authors describe 3D polymer networks formed by the chemical reaction between monomers (curing), which determines the properties of thermosetting polymers: unlike thermoplastics, this kind of polymers does not melt, and once the network has been formed the material cannot be reprocessed.
Abstract: Epoxy resins are a family of thermosetting materials widely used as adhesives, coatings and matrices in polymer composites because of the low viscosity of the formulations, good insulating properties of the final material even at high temperatures and good chemical and thermal resistance (May, 1988). Epoxy thermosets can be described as 3D polymer networks formed by the chemical reaction between monomers (“curing”). This 3D covalent network structure determines the properties of thermosetting polymers: unlike thermoplastics, this kind of polymers does not melt, and once the network has been formed the material cannot be reprocessed. Maybe one of the main advantages of epoxy thermosets is that the starting monomers have low viscosity so that complex geometries can be easily shaped and fixed after curing the monomers. Thus the formation of the network via chemical reaction is a key aspect in this kind of materials.
343 citations
Cites background from "Reaction-induced phase decompositio..."
...Morphology development in modified thermosets takes place essentially between the “cloud point” conversion (beginning of the phase separation) and the gel point conversion (Bucknall & Partridge, 1986; Inoue, 1995; Mezzenga et al., 2000a), although it keeps evolving up to the vitrification of the system....
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...…development in modified thermosets takes place essentially between the “cloud point” conversion (beginning of the phase separation) and the gel point conversion (Bucknall & Partridge, 1986; Inoue, 1995; Mezzenga et al., 2000a), although it keeps evolving up to the vitrification of the system....
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01 Jan 1997
TL;DR: In this paper, a thermodynamic description of reaction-induced phase separation is made, using the Flory-Huggins equation at two approximation levels, i.e. a quasi-binary approach and a multicomponent treatment taking polydispersity of constituents into account.
Abstract: Thermosetting polymers are frequently used in formulations, including rubbers, thermoplastic polymers or oils, etc, in an amount of the order of 2–50 wt% with respect to the thermoset. This extra component, called the modifier, may initially be immiscible or may phase-separate during cure. This last process, i.e the reaction-induced phase separation, is the subject of this review. A thermodynamic description of the process is made, using the Flory-Huggins equation at two approximation levels, i.e. a quasi-binary approach and a multicomponent treatment taking polydispersity of constituents into account. Thermodynamic factors affecting the phase separation process are thus established. Nucleation and growth (NG) and spinodal demixing (SD) are considered as possible phase separation mechanisms. Factors promoting one or the other process are discussed. The control of morphologies generated is analyzed on the basis of thermodynamic and kinetic arguments. Ideas for obtaining particular morphologies enhancing particular properties are put forward.
334 citations
TL;DR: The way in which equilibrium thermodynamic driving forces may interface with the fundamentally out-of-equilibrium nature of living cells and time and/or space-dependent concentration profiles may modulate the phase behavior of biomolecules in living cells is discussed.
Abstract: Exciting recent developments suggest that phase transitions represent an important and ubiquitous mechanism underlying intracellular organization. We describe key experimental findings in this area of study, as well as the application of classical theoretical approaches for quantitatively understanding these data. We also discuss the way in which equilibrium thermodynamic driving forces may interface with the fundamentally out-of-equilibrium nature of living cells. In particular, time and/or space-dependent concentration profiles may modulate the phase behavior of biomolecules in living cells. We suggest future directions for both theoretical and experimental work that will shed light on the way in which biological activity modulates the assembly, properties, and function of viscoelastic states of living matter.
306 citations
Cites background from "Reaction-induced phase decompositio..."
...Before doing so, we note that evidence of reaction-induced phase separation and reaction-induced-arrest of phase separating patterns in undriven systems can be found in studies of various materials such as curing polymer blends [180] and polymerizing monomer solutions [181]....
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TL;DR: In this paper, a review of the development of crosslinked epoxy-based polymers and also photo-curable polymers based on multifunctional acrylates with improved toughness is presented.
261 citations
References
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TL;DR: The theory of phase separation from a single phase fluid by a spinodal mechanism is given in this paper, where the predicted structure may be described in terms of a superpositioning of sinusoidal composition modulations of a fixed wavelength, but random in amplitude, orientation, and phase.
Abstract: The theory of phase separation from a single phase fluid by a spinodal mechanism is given. The predicted structure may be described in terms of a superpositioning of sinusoidal composition modulations of a fixed wavelength, but random in amplitude, orientation, and phase. Sections through a calculated structure are shown. These show that the structure has many of the geometrical features found in phase separable glasses, in particular the high degree of connectivity among particles of each phase.
1,591 citations
TL;DR: In this paper, the influence of hydrodynamic interactions on the coarsening rate of a cloud of droplets combining through diffusive coalescence is examined in detail, and the competing LifshitzSlyozov or evaporation-condensation mechanism is dominant.
Abstract: The influence of hydrodynamic interactions on the coarsening rate r of a mist of droplets combining through diffusive coalescence is examined in detail. For a sufficiently rarified mist, the competing LifshitzSlyozov or evaporation-condensation mechanism is dominant, but the volume fraction of precipitate actually produced in most off-critical quench experiments probably favors direct coalescence, When the minority phase is continuous, as in a quench at the critical concentration, surface-tension eA'ects lead to a crossover from r -t'" to r -t, where t is the time.
948 citations
TL;DR: Proprietes mecaniques de melange resines epoxyde-caoutchoucs liquides (copolymeres d'acrylonitrile et de carboxybutadiene) as discussed by the authors.
Abstract: Proprietes mecaniques de melange resines epoxyde-caoutchoucs liquides (copolymeres d'acrylonitrile et de carboxybutadiene). Mecanisme etudie par dilatometrie en etirage uniaxial
737 citations
TL;DR: In this article, the weak nonexponential relaxation of alloys was explained in terms of a cluster reaction and diffusion process, and the experimental observability of this slowing down was discussed.
Abstract: The weak nonexponential relaxation $\ensuremath{\propto}{t}^{\ensuremath{-}{a}^{\ensuremath{'}}}$ recently found in computer experiments on the phase separation of alloys is explained in terms of a cluster reaction and diffusion process. The nonlinear features of this process can be accounted for by a time-dependent diffusion constant. Estimates for the resulting exponents [${a}^{\ensuremath{'}}=\frac{1}{(3+d)}$] are consistent with the computer simulations. The experimental observability of this slowing down is discussed.
618 citations