Phase behavior of ternary polymer blends

The effect of varying interaction parameters on the phase diagrams of ternary polymer blends was explored by simulating spinodals through use of the Flory-Huggins lattice theory. Results indicate that miscibility is favored for the case of ternary mixtures of marginally miscible or marginally immiscible pairs where all pair interactions are nearly athermal. Miscibility is restricted for asymmetric ternary blends when one of the polymer pairs is either strongly miscible or strongly immiscible. For symmetric blends of partially immiscible pairs, both two-phase and three-phase miscibility gaps are predicted.     

Phase behavior of ternary polymer blends with hydrogen bonding

Atactic poly (methyl methacrylate) (aPMMA) was found to be almost completely immiscible with poly(vinyl acetate) (PVAc). Both aPMMA and PVAc are known to be miscible with poly(vinyl phenol) (PVPh) according to literature. Adding of PVPh into immiscible aPMMA/PVAc mixtures is likely to improve their miscibility. Therefore, PVPh can be used as cosolvent to cosolubilize aPMMA and PVAc. A ternary blend consisting of aPMMA, PVAc, and PVPh was prepared and determined calorimetrically in this article. According to the calorimetry data, the ternary blend was determined to be miscible. The reason for the observed miscibility is because the interactions between PVAc and PVPh are similar to those between aPMMA and PVPh. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2797–2802, 2004     

Phase behavior of ternary polymer blends with favorable interactions

Atactic poly(methyl methacrylate) (aPMMA) and poly(vinyl pyrrolidone) (PVP) with a weight‐average molecular weight of 360,000 g/mol were found to be immiscible on the basis of preliminary studies. Poly(styrene‐co‐vinyl phenol) (MPS) with a certain concentration of vinyl phenol groups is known to be miscible with both aPMMA and PVP. Is it possible to homogenize an immiscible aPMMA/PVP pair by the addition of MPS? For this question to be answered, a ternary blend consisting of aPMMA, PVP, and MPS was prepared and measured calorimetrically. The role of MPS between aPMMA and PVP and the effects of different concentrations of vinyl phenol groups on the miscibility of the ternary blends were investigated. According to experimental results, increasing the vinyl phenol contents of MPS has an adverse effect on the miscibility of the ternary blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2064–2070, 2005     

Phase behavior of hydrogen‐bonded ternary polymer blends

Although poly(ethyl methacrylate) (PEMA) and poly(methyl methacrylate) (PMMA) are only slightly different in structure, they are known to be immiscible. Polystyrene is not miscible with PEMA or PMMA. However, when polystyrene is modified to contain certain vinyl phenol groups to become poly(styrene‐co‐vinyl phenol) (PSVPh), it can be miscible with both PEMA and PMMA. What is the miscibility of a ternary blend consisting of PEMA, PMMA, and PSVPh? For this question to be answered, binary blends of PEMA (or PMMA) were first made with PSVPh. Their miscibility was examined. Then, ternary blends composed of PEMA, PMMA, and PSVPh were prepared and measured calorimetrically. The role of PSVPh between PEMA and PMMA and the effect of different contents of vinyl phenol groups on the miscibility of the ternary blends were investigated. On the basis of experimental results, increasing the vinyl phenol contents of PSVPh seemed to have an adverse effect on the miscibility of the ternary blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2088–2094, 2003     

Phase behavior of ternary PBT–PC/phenoxy blends

Ternary polymer blends were obtained by melt mixing, mixing up to 30% poly(butylene terephthalate) (PBT) with polycarbonate (PC) and phenoxy in an attempt to improve the miscibility of the PC/phenoxy binary blend. Although most of the blends with a PBT content higher than 10% appear as transparent, two T_g's appeared at all the blend compositions. These T_g's correspond to PC-rich and phenoxy-rich phases where a low amount of the main component of the other phase and all PBT are dissolved in amounts that are a function of the PC/phenoxy ratio of the blend. Increasing the PBT contents in the blends closes to linearity the torque versus composition plot, so that a relationship between miscibility level and viscosity exists in these blends.     

Phase identification and interfacial transitions in ternary polymer blends by ToF-SIMS

Phase identification and the study of the interphase region in multi-component polymer blends with a chemically similar structure using conventional techniques is a challenge. In this work, the detailed morphological analysis of such systems is examined. A ternary blend comprised of poly butylene succinate (PBS); poly lactic acid (PLA); and polycaprolactone (PCL) with a partial wetting morphology is carefully selected since all three components are polyesters with low interfacial tensions. It will be shown that a novel technique by applying multivariate analysis (MVA) on time-of-flight secondary ion mass spectrometry (ToF-SIMS) data can effectively identify the complex phase structure, especially in blends with chemically similar components. Furthermore, for the first time for such systems, this technique provides detailed information about interfacial thicknesses and transitions. By employing the principal component analysis (PCA) method on the ToF-SIMS data of pure polymers, specific peaks with a certain molecular ion mass related to each polymer are determined. Using overlaid mappings on the surface of the blend by ToF-SIMS and selected ion masses to identify each polymer results in the differentiation of the various phases represented as a morphological image. In a second step, the multivariate curve resolution (MCR) method is used as a “self modeling curve resolution” for the recovery of pure components from a multi-component mixture when little or no prior information is available. Total pseudo-color RGB images of PBS/PLA/PCL show that PLA droplets unambiguously partially wet the PBS and PCL phases. Since each pixel from the analysis in the high lateral resolution image represents a 200 nm diameter, the interfacial transitions can also be studied for both PLA/PBS and PLA/PCL interfaces. The results show the concentration variation of phases across the interfaces. A complete trace line across the two interfaces (PLA/PBS and PLA/PCL) allows for the quantitative determination of interfacial thickness for the first time for such systems.     

Reactive extrusion of polyolefin ternary blends

Reactive extrusion of polypropylene (PP)/ethylene–propylene–diene terpolymer (EPDM)/high-density polyethylene (PE) (80/10/10 by weight) blends were carried out using a corotating twin-screw extruder. The effects of peroxide and coagent concentrations and extruder rpm were studied in terms of rheological, morphological, thermal, and mechanical properties of the blends. Melt viscosity of the peroxide-treated blend increased and decreased over the untreated one depending on the amount of a coagent. Morphologically, interfaces blur with only a peroxide treatment, and significant domain reduction was obtained when peroxide and a coagent were used together. Both T_m (crystalline melting temperature) and T_g (glass transition temperature) of PP increased in the blend, whereas those of PE slightly decreased. © 1996 John Wiley & Sons, Inc.     

Effects of annealing in ABS ternary blends

Acrylonitrile-butadiene-styrene terpolymer (ABS)/poly(methyl methacrylate) (PMMA) binary and ABS/PMMA/polycarbonate (PC) ternary blends were prepared using a corotating twin-screw extruder. Blend samples were annealed in a constant-temperature (215 and 225°C) hydraulic press up to 85 min. The changes in morphology and mechanical properties with annealing time were studied with transmission electron microscopys image analyzer, and tensile tester. With the increase in annealing time, the number of dispersed domains per cross-sectional area decreased and average domain size increased; this morphology coarsening became more responsible with time for the deterioration of blend properties. In ABS/PMMA/PC ternary blends, PMMA encapsulated PC in ABS matrix; this was predictable from the spreading coefficient calculation. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1531–1542, 1997     

DSC and DMTA characterization of ternary blends

The phase behavior of ternary blends made of poly(epichlorohydrin) (PECH), poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) has been investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). DMTA measurements have been shown to be more sensitive than DSC for the detection of a second phase, for the determination of the composition of each phase, and the distribution of PECH in each of them. About 70% PECH was required to obtain a single narrow T_g in the ternary system, which suggests a single homogeneous phase in the limit of sensitivity of DMTA. This study also emphasizes the importance of the composition of the immiscible polymer pair (i.e. the PVAc/PMMA pair in the PECH/PVAc/PMMA system), in addition to the thermodynamic interaction parameters, for controling the phase behavior of ternary systems.     

Phase behavior of polyarylate blends

Melt mixtures of a polyarylate based on bisphenol A and tere/isophthalates were made with poly(ethylene terephthalate), several cyclohexane dimethanol-based polyesters, polycarbonate, and the poly(hydroxy ether) of bisphenol A. The phase behavior was determined using classical methods. With minimum time and temperature exposure, polyarylate exhibits phase separation with poly(ethylene terephthalate) (PET) at >30 wt % PET. With moderate time and temperature exposure, adequate ester exchange occurs with polyarylate/PET blends to yield single-phase behavior. The activation energy of the ester-exchange reaction was determined to be 37.0 kcal/mole. Under minimum time and temperature exposure conditions, miscibility of polyarylate with three different cyclohexane dimethanol-based polyesters was observed. A polyarylate-polycarbonate 50:50 mixture was shown to be phase separated under minimum mixing conditions but capable of exchange reactions to yield single-phase behavior with proper time and temperature exposure. Likewise, a 70:30 polyarylate-poly(hydroxy ether of bisphenol A) blend was phase separated as mixed, but with further elevated temperature exposure, a cross-linked single-phase system resulted. The density versus composition of the polyarylate-PET blends was linear with the phase-separated systems but exhibited a slight densification with the miscible systems produced by higher temperature exposure. The glass transition of the miscible polyarylate-polyester blends exhibited a significant deviation (lower) than predicted by a linear or Fox equation prediction. This was attributed to the low value of ΔC_p (specific heat difference between the glass and rubber states) of polyarylate as noted by the Couchman equation to be a major factor in the T_g versus composition relationship. The optical characteristics of the blends paralleled the observed phase behavior as single-phase blends were all transparent (in the amorphous state) whereas phase-separated blends were translucent to opaque. These results clearly demonstrate the importance of ester-exchange or transesterification reactions in the phase behavior of blends of polymers capable of these reactions.     

Achieving miscible ternary polymer blends with hydrogen bonding

Poly(vinyl phenol) (PVPh) has previously been found to be successful in making immiscible poly(methyl methacrylate) (PMMA)/poly(vinyl acetate) (PVAc) miscible. Poly(ethyl methacrylate) (PEMA) with one more methyl group than PMMA is also immiscible with PVAc. PEMA and PVAc are miscible with PVPh according to the literature. To determine whether PVPh can also cosolubilize PEMA/PVAc, PVPh samples of two different molecular weights have been mixed in this study with PEMA and PVAc to produce a ternary blend. On the basis of the calorimetry data, the ternary PEMA/PVAc/PVPh blend, regardless of the molecular weight of PVPh, has been determined to be miscible. The reason for the observed miscibility is probably that the interactions between PVAc and PVPh are similar in magnitude to those between PEMA and PVPh. A modified Kwei equation based on the binary interaction parameters proposed previously is used to describe the experimental glass‐transition temperature of the miscible ternary blend almost quantitatively well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 643–652, 2006     

Hierarchically porous polymeric materials from ternary polymer blends

Hierarchically porous polymers with controllable pore size were generated through a novel polymer blending strategy in an A/B/C–B–C ternary blend system. Polylactide/high-density polyethylene/poly(styrene-ethylene/butylene-styrene) triblock copolymer (PLA/HDPE/SEBS) was used as a model system to demonstrate this technique. During melt blending, the SEBS was driven into the HDPE phase owing to the presence of the PE block in the copolymer. With proper volume fractions of PLA/HDPE/SEBS (e.g., 50/25/25), a bi-modal, dual co-continuous morphology was obtained and hierarchically porous polymeric materials were further generated by selectively removing the PLA and SEBS phases. Annealing and compositional variation were further employed to control the pore size and it is shown that the length scales of the two co-continuous morphologies can be controlled independently.     

Particles versus fibrillar morphology in polyolefin ternary blends

PP/EPR binary and PP/(EPR/PE) ternary blends were prepared based on the viscosity ratio, using a corotating twin-screw extruder. Both fibrillar structures and particle-in-matrix morphologies were created depending on the viscosity ratio of rubber domain to the matrix PP (η_EPR/η_PP, or η_EPR-PE/η_PP). With fibril formation, mechanical properties of the blends, especially the flexural modulus and notched impact strength, were significantly increased and the increase was more pronounced with the ternary blends. The fibrillar morphology and filled-out particles for particle-in-matrix morphology. © 1996 John Wiley & Sons, Inc.     

Viscosity effect in polyolefin ternary blends and composites

Ternary blends of PP (80) /rubber (EPM, EPDM) (10) / PE (10) and PP (80) / rubber (10) / CaCO₃ (10) composites were prepared in a twin-screw extruder. With polyethylene (PE) viscosity comparable to, or higher than that of rubber, the dispersed phase formed a reticulate structure with reduced size. On the contrary, when the viscosity of PE was significantly lower than that of rubber, the dispersed phase formed almost homogeneous morphology. With reticulate morphology, PE crystallinity content, hardness, modulus, and elongation at break of the ternary blend increased. In polypropylene (PP) / rubber / CaCO₃ composites, better dispersion of CaCO₃ in the PP matrix was obtained when the viscosity of rubber was significantly higher than that of matrix. With better dispersion, hardness and tensile properties were improved, but the impact strength more or less decreased. © 1993 John Wiley & Sons, Inc.     

Thermal properties and crystallization behavior of polyolefin ternary blends

Crystallization behaviors, spherulite growth and structure, and the crystallization kinetics of polypropylene (PP)/ethylene‐α‐olefln copolymer (mPE)/high‐density polyethylene (HDPE) ternary blends and of mPE/HDPE binary blends have been studied using polarizing optical micrography (POM) and differential scanning calorimetry (DSC). In mPE/HDPE blends, large pendant groups of mPE disturbed spherulite growth of HDPE, leading to a different crystallite morphology and isothermal kinetics. Non‐isothermal properties, morphology, and isothermal crystallization kinetics of PP in ternary blends were significantly influenced by the composition and crystallization behavior of the mPE/HDPE binary blends as well as the crystallization condition. Polym. Eng. Sci. 44:1858–1865, 2004. © 2004 Society of Plastics Engineers.     

Compatibilization and morphology development of immiscible ternary polymer blends

We report a novel and effective strategy that compatibilizes three immiscible polymers, polyolefins, styrene polymers, and engineering plastics, achieved by using a polyolefin-based multi-phase compatibilizer. Compatibilizing effect and morphology development are investigated in a model ternary immiscible polymer blends consisting of polypropylene (PP)/polystyrene(PS)/polyamide(PA6) and a multi-phase compatibilizer (PP-g-(MAH-co-St) as prepared by maleic anhydride (MAH) and styrene (St) dual monomers melt grafting PP. Scanning electron microscopy (SEM) results indicate that, as a multi-phase compatibilizer, PP-g-(MAH-co-St) shows effective compatibilization in the PP/PS/PA6 blends. The particle size of both PS and PA6 is greatly decreased due to the addition of multi-phase compatibilizer, while the interfacial adhesion in immiscible pairs is increased. This good compatibilizing effect is promising for developing a new, technologically attractive method for achieving compatibilization of immiscible multi-component polymer blends as well as for recycling and reusing of such blends. For phase morphology development, the morphology of PP/PS/PA6 (70/15/15) uncompatibilized blend reveals that the blend is constituted from PP matrix in which are dispersed composite droplets of PA6 core encapsulated by PS phase. Whereas, the compatibilized blend shows the three components strongly interact with each other, i.e. multi-phase compatibilizer has good compatibilization between the various immiscible pairs. For the 40/30/30 blend, the morphology changed from a three-phase co-continuous morphology (uncompatibilized) to the dispersed droplets of PA6 and PS in the PP matrix (compatibilized).     

Effects of the viscosity ratio on polyolefin ternary blends

Polyolefin binary and ternary blends were prepared from polypropylene (PP), an ethylene–α‐olefin copolymer (mPE), and high‐density polyethylene (HDPE) on the basis of the viscosity ratio of the dispersed phase to the continuous phase. In PP/mPE/HDPE blends, fibrils were observed when the dispersed‐phase (mPE/HDPE) viscosity was less than that of PP, or when the viscosity of mPE was less than that of PP, although the viscosity of mPE/HDPE was greater than that of PP. The notched impact strength and mechanical properties such as the yield strength, flexural modulus, and hardness of PP/mPE binary blends further increased with the addition of HDPE according to the type of HDPE. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4027–4036, 2004     

Effects of the blending sequence in polyolefin ternary blends

Ternary blends of isotactic polypropylene (PP), ethylene–octene copolymer (mPE), and high‐density polyethylene (HDPE) were prepared by melt mixing in a twin‐screw extruder with two different sequences of mixing: the simultaneous mixing of the three components (method I) and the premixing of mPE and HDPE followed by mixing with PP (method II). Regardless of the mixing sequence, mPE encapsulated HDPE in the PP matrix, although better mechanical properties were generally obtained with method II. The domain size was mainly determined by the viscosity ratio of mPE to PP in method I and by the viscosity ratio of the binary blend (mPE/HDPE) to PP in method II. Specimens prepared by injection molding gave much finer dispersions than compression‐molded specimens. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 804–811, 2004