Phase Behavior Of Blends Research Articles

Crystallization behavior and compatibility analysis of palm kernel stearin/anhydrous milk fat blends and application.

In this paper, the compatibility, phase behavior, and crystallization properties of the binary blends of palm kernel stearin (PKS) and anhydrous milk fat (AMF) were investigated by analyzing the solid fat content (SFC), thermal properties, polymorphism, and microstructure, with the aim of providing theoretical guidance for the blending of oils. The results showed that the PKS content primarily determined the SFC trend of the binary blends. However, the binary blends demonstrated poor miscibility and eutectic behavior was predominantly observed in the system, particularly at higher temperatures. Only α and β' forms appeared in this blended system. Simultaneously, the addition of PKS elevated the liquid phase transition temperature of the binary blends, considerably significantly increased their crystallization rate when the addition of PKS was more than 20% and increased the density and size of the fat crystals. Finally, the mixing design optimization method was used to get the most suitable ratio of the binary blends in the refrigerated cream system with PKS:AMF to be 0.914:0.086. The cream prepared with the above binary blends was indeed superior in overrun and firmness and had high stability. PRACTICAL APPLICATION: Some fats with special advantages are often limited in their wide application because of their poor crystallization ability. In this paper, the crystallization ability of fats is improved, and their application scenarios are increased through the combination of fats, so as to provide reference for the production of special fats for food.

Phase behavior of triblock copolymer and homopolymer blends: Effect of copolymer topology

Two distinct linear triblock copolymers with different block sequences, ABA or BAB, are obtained when two identical AB diblock copolymers are jointed at their B or A ends, respectively, resulting in three homologous, AB diblock, ABA, and BAB triblock copolymers with the same chemical composition but different topologies. We demonstrate that the topological effect on the phase behaviors of these copolymers is amplified when A homopolymers are added to the system. Specifically, the phase behaviors of binary blends composed of ABA or BAB linear triblock copolymers and A homopolymers are studied by using the random-phase approximation (RPA) and self-consistent field theory (SCFT). The RPA analysis predicts that the Lifshitz point for the ABA/A blends behaves like a second-order transition but that for the BAB/A blends behaves like a first-order transition. The Lifshitz point of the BAB/A mixtures is found to occur at a much lower homopolymer concentration than that of the ABA/A mixtures, indicating a poorer miscibility of the A homopolymers into the BAB than ABA triblocks, which is also confirmed by SCFT. For sphere-forming triblock copolymers mixed with homopolymers, the poorer miscibility and the more diffused distribution of the A homopolymers in the BAB/A blends result in a phase behavior drastically different from that of the ABA/A and AB/A blends. The ABA/A blends stabilize the Frank-Kasper (FK) phases similar to the AB/A blends, but the stability window of FK phases becomes negligibly small in the corresponding BAB/A blends. Our results demonstrate that the topological effect of block copolymers on the equilibrium phase behaviors can be more prominent in multicomponent systems and thus more attention should be paid to copolymer topologies in the design of polymeric blends. Published by the American Physical Society 2024

Bicontinuous microemulsion in binary blends of complementary diblock copolymers.

The phase behavior of binary blends of AB diblock copolymers of compositions f and 1 - f is examined using field-theoretic simulations. Highly asymmetric compositions (i.e., f ≈ 0) behave like homopolymer blends macrophase separating into coexisting A- and B-rich phases as the segregation is increased, whereas more symmetric diblocks (i.e., f ≈ 0.5) microphase separate into an ordered lamellar phase. In self-consistent field theory, these behaviors are separated by a Lifshitz critical point at f = 0.2113. However, its lower critical dimension is believed to be four, which implies that the Lifshitz point should be destroyed by fluctuations. Consistent with this, it is found to transform into a tricritical point. Furthermore, the highly swollen lamellar phase near the mean-field Lifshitz point disorders into a bicontinuous microemulsion (BμE), consisting of large interpenetrating A- and B-rich microdomains. BμE has been previously reported in ternary blends of AB diblock copolymer with its parent A- and B-type homopolymers, but in that system the homopolymers have a tendency to macrophase separate. Our alternative system for creating BμE is free of this macrophase separation.

Compositional asymmetry in a crystalline-amorphous block copolymer influences the phase and crystallization behaviors of its blend with an amorphous block copolymer.

This study determined the phase and crystallization behaviors of blends composed of asymmetric polystyrene-block-poly(ethylene oxide) (PS-PEO) and symmetric polystyrene-block-poly(methyl methacrylate) (PS-PMMA). The PS blocks in the various binary block copolymers exhibited nearly identical molecular weights, whereas the molecular weight ratios of PEO and PMMA varied. The compatibility of the PEO and PMMA chains aided the binary block copolymers in co-ordering in a lamellar microdomain morphology, with the PEO and PMMA blocks sharing a common microdomain. Adding short tethered PMMA chains to long tethered PEO chains led to a decrease in the common microdomain spacing and an increase in the grafting density. These behaviors increased PEO chain stretching, causing macrophase separation. The mismatch in PEO and PMMA block lengths divided the common PEO/PMMA microdomain into two sections: the coexisting PEO/PMMA section close to the microdomain interface and the neat PEO section far away from it. The high-glass-transition-temperature PMMA reduced PEO chain mobility, inhibiting PEO crystallization in the coexisting PEO/PMMA section but not in the neat PEO section. When the block length ratio of PEO to PMMA decreased, the neat PEO section narrowed. The increase in the extent of PEO confinement led to a reduction in PEO crystallizability.

Ion conduction and phase behaviour in dual cation polyelectrolyte blends for sodium-ion batteries

The goal of this work is to develop polymer-based solid-state electrolytes for sodium-ion battery applications. Two polymers are blended in order to reduce the Tg and decouple ionic conductivity from polymer segmental motion. Furthermore, the addition of plasticizers further enhances the ionic conductivity.

Impact of aging on the phase behavior of cocoa butter and copra oil blends

Aging of cocoa butter (CB)/copra oil (CO) binary blends (noted CB/CO) is investigated through a multi-technique approach. Indeed, the phase behavior of non-aged and 30 days-aged cocoa butter/copra oil binary blends (CB/CO) at 4°C is studied, using a combination of Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD). During subsequent heating from 4°C to 40°C, solid fat content depression between 15°C and 20°C is shown with NMR, with the most pronounced occurring at two different compositions for the non-aged (60% CO addition in CB) and for the 30 days-aged mixtures (80% CO addition in CB). In agreement, DSC exposes melting enthalpy and melting temperature depression for the aged-blend 80/20 CB/CO. XRD highlights fat interactions at the nanoscopic scale and allows the precise attribution of polymorphic transitions perceived with DSC. The melt-mediated transformation of CB crystals from β'2-2L to β2-3L is shown in non-aged blends containing 0% to 10% of CO in CB, whereas it is shown to occur in blends containing 0% to 60% CO in CB for the 30 days aged-blends. As a result of this study, all the results obtained with the various methods are used to build the very first complete pseudo-phase diagram of 4°C-aged CB/CO blends, it highlights the shift of the eutectic points after 30 days of storage. We think that such a fundamental work can bring new understanding of a well-known issue as encountered in chocolate-based products storage.

Phase Behavior of Binary Blends of Diblock Copolymers: Progress and Opportunities.

The phase behavior of binary blends of diblock copolymers has been examined extensively in the past decades. Experimental and theoretical studies have demonstrated that mixing two different block copolymers provides an efficient and versatile route to regulate their self-assembled morphologies. A good understanding of the principles governing the self-assembly of block copolymer blends has been obtained from the study of A1B1/A2B2 diblock copolymer blends. The second (A2B2) diblocks could act synergistically as fillers and cosurfactants to regulate the domain size and interfacial properties, resulting in the formation of ordered phases not found in the parent (A1B1 or A2B2) diblock copolymer melts. The study of A1B1/A2B2 block copolymer blends further provides a solid foundation for future research on more complex block copolymer blends.

Complex Phase Behavior in Binary Blends of AB Diblock Copolymer and ABC Triblock Terpolymer

Blending block polymers with different block compositions provides an opportunity to create nanostructures that are not accessible from neat block copolymer melts. In this study, we investigate the equilibrium phase behavior in binary blends composed of an AB diblock copolymer and an ABC triblock terpolymer, using self-consistent field theory (SCFT). Blending these simple linear block polymers results in complex phase behaviors, including unusual core–shell network phases with asymmetric core and shell volume fractions and a new cylinder-in-O70 hybrid network phase. The phase diagrams with respect to segregation strength and blend composition reveal an unexpected morphological richness, including 15 ordered phases, illustrating the potential inherent in blending these relatively simple components.

Effect of poly[oligo(ethylene glycol) methyl ether methacrylate] side chain length on the brush swelling behavior in A/B/A-B ternary blends with polystyrene.

The phase behavior of ternary blends composed of two homopolymers (A, B) and their corresponding diblock copolymer (A-B) has been widely studied, with emphasis on the volumetrically symmetric isopleth and the formation of bicontinuous microemulsions. However, almost all the previous studies employed linear polymers, and little is known about the impact of polymer architecture on the phase behavior of such ternary blends. Here, we report the self-assembly of three sets of ternary blends of polystyrene (PS) and poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMAn), with different lengths of oligo(ethylene glycol) side chains n. Small-angle X-ray scattering was used to probe the phase behavior at different compositions and temperatures. The order-to-disorder transition temperature was found to be impacted by the side chain length. It was also observed that longer side chains lead to poorer miscibility of homopolymers in the corresponding block, resulting in a more "dry-brush" like swelling behavior.

Tuning conformational asymmetry in particle-forming diblock copolymer alloys.

Self-consistent field theory is employed to compute the phase behavior of binary blends of conformationally asymmetric, micelle-forming diblock copolymers with miscible corona blocks and immiscible core blocks (a diblock copolymer "alloy"). The calculations focus on establishing conditions that promote the formation of Laves phases by tuning the relative softness of the cores of the two different Laves phase particles via independent control of their conformational asymmetries. Increasing the conformational asymmetry of the more spherical particles of the Laves structure has a stabilizing effect, consistent with the expectations of increased imprinting of the Wigner-Seitz cells on the core/corona interface as conformational asymmetry increases. The resulting phase diagram in the temperature-blend composition space features a more stable Laves phase field than that predicted for conformationally symmetric systems. The phase field closes at low temperatures in favor of macrophase separation between a hexagonally-packed cylinder (hex) phase and a body-centered cubic phase. Companion calculations, using an alloy whose components do not produce a hex phase in the neat melt state, suggest that the Laves phase field in such a blend will persist at strong segregation.

Crystallization and phase behavior in mixture systems of anhydrous milk fat, palm stearin, and palm oil: Formation of eutectic crystals

The comparison between the crystallization and phase behavior of binary blends of anhydrous milk fat (AMF)/palm stearin (POs) and POs/palm oil (PO) was investigated. POs/POs blends showed good compatibility, while the compatibility of AMF/POs blends showed no ideal and was dominated by eutectic behavior. And the eutectic growth of blends was found to be a phenomenon that the triacylglycerol (TAG) of AMF grew on the peripheral of POs seed crystals. In binary blends, the addition of POs not only increased the liquid phase transition temperature but also induced the formation of β crystal forms in more than 70% POs. The addition of soybean oil to binary blends could improve the compatibility of the ternary system. It eventually provided potential formulations for the production of non-hydrogenated puff pastry margarine.

Impact of Composition and Placement of Hydrogen-Bonding Groups along Polymer Chains on Blend Phase Behavior: Coarse-Grained Molecular Dynamics Simulation Study

Impact of Composition and Placement of Hydrogen-Bonding Groups along Polymer Chains on Blend Phase Behavior: Coarse-Grained Molecular Dynamics Simulation Study

Phase behaviour of model triglyceride ternary blends: triolein, tripalmitin and tristearin.

We investigate the phase behavior of model ternary triacylglycerol blends, comprising triolein (C57H104O6, OOO), tripalmitin (C51H98O6, PPP) and tristearin (C57H110O6, SSS), building upon extensive characterisation of single and binary mixtures, in order to rigorously map the thermal transitions of model natural 'fats'. A combination of calorimetry, X-ray diffraction, and FTIR spectroscopy is employed to determine crystallisation and melting temperatures and identify the corresponding phases in the complex ternary system. We recover the eutectic behaviour of SSS-PPP blends and the invariability of OOO neat transitions, and resolve the complex β' + β ternary surface, reflecting the roles of unsaturation and polymorphism of its constituents. Our results provide a representation of the OOO:PPP:SSS:temperature phase behaviour into a triangular prism, consistent with binary pair-wise data, which can inform a range of food science, cosmetic, pharmaceutical and cleaning applications that depend strongly on the physical-chemistry of such multicomponent 'triglycerides'.

Binary Blends of Diblock Copolymers: An Efficient Route to Complex Spherical Packing Phases

AbstractThe phase behavior of binary blends composed of AB and AB diblock copolymers is systematically studied using the polymeric self‐consistent field theory, focusing on the formation and relative stability of various spherical packing phases. The results are summarized in a set of phase diagrams covering a large phase space of the system. Besides the commonly observed body‐centered‐cubic phase, complex spherical packing phases including the Frank–Kasper A15, and the Laves C14, C15 phases could be stabilized by the addition of longer AB‐copolymers to asymmetric AB‐copolymers. Stabilizing the complex spherical packing phases requires that the added AB‐copolymers have a longer A‐block and an overall chain length at least comparable to the host copolymer chains. A detailed analysis of the block distributions reveals the existence of inter‐ and intra‐domain segregation of different copolymers, which depends sensitively on the copolymer length ratio and composition. The predicted phase behaviours of the AB/AB diblock copolymer blends are in good agreement with previous experimental and theoretical results. The study demonstrates that binary blends of diblock copolymers provide an efficient route to regulate the emergence and stability of complex spherical packing phases.

Coupling effect of pressure and flow fields on the crystallization of Poly(vinylidene fluoride)/Poly(methyl methacrylate) miscible blends

During polymer processing, the polymeric blends are inevitably subjected to coupled external fields (flow, pressure, and temperature), which have great effects on the phase behavior, crystallization behavior, crystalline structure, and final properties of blends. A typical crystalline/amorphous miscible blend system, poly(vinylidene fluoride)/Poly(methyl methacrylate) (PVDF/PMMA) blend, is chosen to understand the coupling effect of processing fields on crystallization behavior of the blends. It is found that shear flow can induce locally oriented trans conformation, which finally transforms into polar β/γ phases during isothermal crystallization under pressure. Interestingly, under pressure, β and γ phases exhibit different sensitivities to shear rate. The γ phase is easily formed at low shear rate, while higher shear rate is required to induce β phase formation, which could be related to the sequence length of the oriented trans conformation induced by shear flow. As for the addition of PMMA, the hydrogen bonding interactions between carbonyl groups of PMMA and hydrogen atom of PVDF could stabilize the shear-induced local trans conformation and subsequently lead to more β/γ phases. Meanwhile, different from PVDF crystallized under static condition, the shear flow and PMMA synergistically induce the transformation from spherulitic to shish-kebab-like structure and highly oriented thick β phase with higher melting point. To the best of our knowledge, it is the first time to reveal the unique crystallization behaviors of PVDF/PMMA blends induced by flow field coupled with pressure. This work could provide a significant guidance for the control of crystal polymorphs of PVDF/PMMA miscible blends during processing.

Thermal characterisation of metal stearate lubricant mixtures for polymer compounding applications

Metal stearate blends are potential lubricants and filler dispersants in polymer compounding. Therefore, the thermal phase behaviour of binary blends of calcium stearate and magnesium stearate with zinc stearate was investigated. Cooling curve studies indicated lower melting temperatures in both systems. X-ray diffraction studies revealed that this was due to the formation of solid solutions of variable composition rather than to eutectic formation. Rheology measurements showed that true fluidification only happened well above the apparent melting points established from cooling curves. Calcium carbonate filled polyethylene containing metal stearate mixtures showed lower melt viscosities than were achievable using only calcium- or magnesium stearate as the lubricant. These results suggest that metal stearate blends, in combination with a judiciously selected wax component, may offer advantages in lowering compound melt viscosity and facilitating better particle dispersion.

Beeswax Fractions Used as Potential Oil Gelling Agents

AbstractThe objective of this work was the fractionation of beeswax to investigate the phase behavior of binary blends of the fractions and their potential use as gelling agents in edible oleogels. We have extracted seven distinctive fractions, using preparative flash chromatography with eluents permitted to be used in the processing of food raw materials. The odor profile of the fractions was characterized. The high purity of collected fractions was shown through thin‐layer chromatography, Fourier‐transform infrared spectroscopy, and high‐performance liquid chromatography with an evaporative light scattering detector methods for hydrocarbons (94.8%), monoesters (97.6%), and mixed mono‐, di‐, and triesters fraction (98.7%). Free fatty acids and fatty alcohol fractions had lower purity which equals 82.6% and 39%, respectively. The analysis of the binary pseudo phase diagram revealed that all fractions combined with hydrocarbons express eutectic behavior. Combinations of all other fractions resulted in the formation of solid solutions. This study shows that the texture of oleogels can be improved by using a combination of various fractions of beeswax instead of native wax.

An investigation to utilize ternary diesel-palm fatty acid distillate-10 wt% n-butanol blends as simply novel diesel substitutes

In this work, the preparation, phase behavior, properties, and utilization of commercial high speed diesel-palm fatty acid distillate-anhydrous n-butanol blends in an existing direct injection diesel engine were studied. At the chosen n-butanol content of interest (10 wt%), long-term stable liquid ternary blends with up to 30 wt% of palm fatty acid distillate could be simply prepared by splash blending. The most important properties of the ternary blends met the Thai diesel standards with good cetane numbers and lubricities, significantly higher oxygen contents with slightly lower heating values than diesel, and higher acid values but similar copper strip corrosion as diesel. Overall the engine was tested for loads of 0.70–3.50 kW at 1200 rpm, 0.99–4.95 kW at 1700 rpm, and 1.28–6.40 kW at 2200 rpm; all the stable ternary blends performed well in the test engine, similar to common diesel fuel and without any serious problem. For all speeds tested, especially at high operating loads, these oxygenated blends slightly improved brake thermal efficiencies with significantly lower emissions of smoke and carbon monoxide than for diesel; however, the oxygenated diesohol blends studied still emitted significantly higher levels of unburned hydrocarbons and nitrogen oxides than the burning of diesel fuel.

Polyethylene wax as an alternative to mineral fillers for preparation of reinforced pressure-sensitive adhesives

Phase behavior, rheology and adhesive properties of polyisobutylene-based blends containing up to 60 wt% of polyethylene wax were studied. Polyisobutylene and wax partially dissolve in each other at high temperatures, which strongly reduce the viscosity of the blends and facilitate their mixing. When cooled, the wax loses its solubility in the polymer matrix and crystallizes to form reinforcing particles. These particles increase the viscoelasticity of the blends, resulting in improved durability (up to 66-fold) and strength (up to 1.4-fold) of adhesive bonds. At the same time, the growth of viscoelasticity does not lead to a loss of tackiness of the blends, as the application of external force to form an adhesive bond destroys the percolation structure of wax particles. Because of the low specific surface area of wax particles, they increase the durability of adhesive joints worse than silica (in 380-fold) or organoclay particles (in 3300-fold). However, the use of polyethylene wax allows reducing melt viscosity by 4–5 decimal orders of magnitude in the case of highly filled adhesives.

Phase behavior and rheology of miscible and immiscible blends of linear and hyperbranched siloxane macromolecules

It is obvious that polymers of the similar composition but with different molecular weights are miscible, but what will happen if one of them is linear and another one has branched architecture? In this paper, mixtures of linear polydimethylsiloxane (PDMS) with methyl-terminated silicone MT resins are considered. Since these resins consist of hyperbranched macromolecules with nearly spherical shape and nanoscale diameters, they are both macromolecules and colloid particles at the same time. The phase states of mixtures were studied by laser interferometry method accompanied with rheological tests. The effect of molecular weight of resins and their terminal groups on miscibility was demonstrated. The methyl-terminated resins with low molecular weight are well miscible with linear PDMS macromolecules but immiscible blends are formed in the case of resin's high molecular weight. The rheology of the blends is determined by their phase state, which depends on the ratio of components and temperature. For homogeneous resin/PDMS mixtures, a slight positive deviation of viscosity from the log-additivity rule is inherent, whereas heterogeneous blends are similar in rheological behavior to a gum. Various empirical equations are considered for describing the viscosity-composition dependence; as a result, their unification to characterize blends with different phase states was proposed.