Compatibilization of polymer blends with high‐molecular‐weight peroxides

A novel approach for the compatibilization of heterogeneous polymer blends with interface‐active high‐molecular‐weight peroxides is presented. This three‐step approach includes the synthesis of an anchor peroxide copolymer, the preparation of an interface‐active, peroxide‐containing graft copolymer (precompatibilizer) on its basis, and the localization of the precompatibilizer at the interfaces of the polymer blends during reactive blending with the in situ formation of compatibilizer macromolecules. We found that the precompatibilizer incorporating polypropylene fragments compatibilized blends of polypropylene with polystyrene, polyethylene, and unsaturated polyester resin. This verified a certain universality of the approach proposed for the compatibilization of polymer blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 232–242, 2005     

Reinforcing properties of poly(trimethyleneterephthalate) by a thermotropic liquid crystal polymer

A thermotropic liquid crystalline copolymer (TLCP) having a trimethylene terephthalate (TT) unit and a triad terephthaloyl mesogenic unit was synthesized and its blends with poly(trimethylene terephthalate) (PTT) were prepared for TLCP‐reinforced fiber spinning. The TLCP, PTT, and their blends were characterized in terms of their thermal, mechanical, and morphological properties. In the hot‐drawn fibers of 20 wt % TLCP/PTT blend, the well‐oriented fibrils were observed at higher temperature (>T_m) than the PTT melt by polarizing optical microscope. With scanning electron microscopy images of cryogenically fractured surfaces of the blends, the TLCP were well dispersed in 0.3 to 0.5 µm in domain size. Interfacial adhesion between the TLCP and PTT seemed fairly good. The TLCP acted effectively as a reinforcing material in PTT matrix, it led to an increase of initial modulus and tensile strength of the blend fibers as TLCP's content increased. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41408.     

Dielectric properties of thin films of Babassu‐based polymer and polyaniline blends

In the present work, we describe the preparation and subsequent characterization of polymeric blends consisting of a monoglyceride (MG) synthesized from the Babassu's oil and the already commonly employed polyaniline (PAni). By following changes in the complex impedance of capacitor‐like devices we observe that the presence of MG in the PAni/MG blends decreases electrical conductivity and that this decrease is a function of the content of MG in the blend, i.e., the blend with 30% of MG shows Z′ about seven times greater than the one with 10% of MG. Fourier transform infrared measurements prove the formation of MG and the presence of secondary amine groups (N? H bonds) in the blends, which allow for the chemical doping of PAni by protonation, further studies are necessary to access the viability of employing this new material as active layer in electronic organic devices. Atomic force microscopy images show the formation of agglomerates due to the presence of MG. In addition, the polymeric mixture acts only as a blend, providing a physical interaction between different components. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46198.     

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     

Effect of molecular weight on brittle‐to‐ductile transition temperature of polyetherimide

The fracture and yield strength of polyetherimide was evaluated over a temperature range of 23 to 140°C for materials with number‐average (M_n) and weight‐average molecular weight (M_w) ranging from 15.6 to 22.8 and 36.6 to 52.3 kg/mol, respectively. The brittle‐to‐ductile transition temperature, where an equal probability exists that an impact will result in a brittle or ductile failure, was determined by evaluating the temperature at which fracture and yield strength are equal. The transition temperature decreased from 155 to 60°C with increasing molecular weight and provided a measure of relative ductility between material samples. As a case study, the practical impact strength of an injection‐molded food service tray was determined at 20°C and correlated with fracture strength as a function of molecular weight. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1666–1671, 2004     

Modification via preparation for poly(3‐hydroxybutyrate) films: Water‐transport phenomena and sorption

The effect of the preparation technique on the sorption–diffusion parameters of poly(3‐hydroxybutyrate) (PHB) films was studied. The films formed by a single‐stage technique have an axial texture of the crystalline phase, with the polymer chain oriented predominantly perpendicularly to the film plane. Moreover, the crystallites in PHB are preferably ordered in stacks in the course of diffusion; the alignment of the crystallites noticeably decreases the “sites” of PHB (polar groups) which are accessible to water molecules. As a result, the sorption capacity decreases but the rate of diffusion increases. On the contrary, PHB films prepared by a two‐stage technique are characterized by a poor ordering of crystallites without texture organization. Here, the sorption/immobilization on the polar groups of PHB is increased, but diffusivities are decreased. Concentration dependencies of the water‐diffusion coefficient are discussed. Additional information on the existence of protein impurities in the PHB samples obtained by the above two preparation techniques was obtained by FTIR spectroscopy and H–D exchange methods. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 475–480, 2000     

Design of thermochromic polymer blends containing low‐mass compounds

We investigated the light transmittance of an immiscible polymer blend comprising a copolymer of ethylene and vinyl acetate (EVA) and a terpolymer of vinyl butyral, vinyl alcohol, and vinyl acetate (PVB). Both EVA and PVB are used in the interlayers of laminated glass. We found that the transparency of the blend depends on the ambient temperature. This can be attributed to the difference in the temperature dependence of the refractive index between EVA and PVB. The blend has good transparency at room temperature because the difference between the refractive indices of its components is minimal. At high or low temperatures, however, the blend becomes opaque owing to light scattering. The addition of a plasticizer favorably affects the temperature range over which the blend exhibits high transparency, because the refractive index and its temperature dependence are affected by the plasticizer. We also evaluated the interphase transfer of a plasticizer between EVA and PVB at various temperatures. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45927.     

Fracture toughness evaluation of K resin® grafted with maleic anhydride‐ compatibilized polyamide 6/K resin® blends

The mechanical behavior and fracture toughness of polyamide 6 (PA6)/K resin^® (K) blends, with and without maleic anhydride‐grafted K resin^® (K‐g‐MAH) incorporated, have been investigated. The results showed that the tensile strength, elongation at break and impact strength of PA6/K blends were improved considerably on incorporating K‐g‐MAH. This results from the improvement of compatibility between the PA6 and K phases. The essential work of fracture (EWF) method was employed to determine the fracture toughness of PA6/K blends with and without K‐g‐MAH incorporated. The effect of composition on the EWF parameters of the blends was particularly investigated. The results showed that a significant improvement in the specific EWF (w_e) of PA6/K blends occurred when K‐g‐MAH was incorporated. The effect of K‐g‐MAH content on the fracture toughness of the PA6/K/K‐g‐MAH blends was mainly achieved through its influence on the specific essential and nonessential work of fracture in the yielding process. Copyright © 2007 Society of Chemical Industry     

Film‐forming behavior and mechanical properties of colloidal silica/polymer latex blends with high silica load

In this article, silica sol (diameter: 8–100 nm) and polymer latex (T_g < 25°C) were mixed and dried at room temperature to prepare nanocomposite films with high silica load (≥50 wt %). Effects of silica size, silica load, and the T_g of the polymer on the film‐forming behavior of the silica/polymer latex blend were investigated. The transparency, morphology, and mechanical properties of the nanocomposite films were examined by UV–Vis spectroscopy, SEM, and nanoindentation tests, respectively. Transparent and crack‐free films were produced with silica loads as high as 70 wt %. Thirty nanometers was found to be the critical silica size for the evolution of film‐forming behavior, surface morphology, and mechanical properties. Colloidal silica particles smaller than this critical size act as binders to form strong silica skeleton. This gives the final silica/polymer nanocomposite film its porous surface and high mechanical strength. However, silica particles with sizes of 30 nm or larger tend to work as nanofillers rather than binders, causing poor mechanical strength. We also determined the critical silica load appeared for the mechanical strength of silica/polymer film at high silica load. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and properties of halogen‐free flame‐retarded phthalonitrile–epoxy blends

Halogen‐free flame‐retarded blends composed of 2,2‐bis[4‐(3,4‐dicyanophenoxy) phenyl] propane (BAPh) and epoxy resin E‐44 (EP) were successfully prepared with 4,4′‐diaminodiphenyl sulfone as a curing additive. The structure of the copolymers was characterized by Fourier transform infrared spectroscopy, which showed that epoxy groups, a phthalocyanine ring, and a triazine ring existed. The limiting oxygen index values were over 30, and the UL‐94 rating reached V‐0 for the 20 : 80 (w/w) BAPh/EP copolymers. Differential scanning calorimetry and dynamic rheological analysis were employed to study the curing reaction behaviors of the phthalonitrile/epoxy blends. Also, the gelation time was shortened to 3 min when the prepolymerization temperature was 190°C. Thermogravimetric analysis showed that the thermal decomposition of the phthalonitrile/epoxy copolymers significantly improved with increasing BAPh content. The flexible strength of the 20:80 copolymers reached 149.5 MPa, which enhanced by 40 MPa compared to pure EP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Determination of the phase diagram of HBA‐HNA liquid crystalline polymer/polycarbonate blends

The phase diagram of blends of liquid crystalline polymer (LCP) and polycarbonate (PC) was constructed. The effect of temperature on morphological development in melt‐blended samples was examined with a polarized light microscope, in conjunction with a heating stage. Phase separation in the blend was observed as the temperature was increased. For a particular LCP/PC blend composition, two‐phase separation temperatures (T_sp1 and T_sp2) were determined. Consequently, the corresponding phase diagram relating to phase separation was constructed. It was divided into three regions. No phase separation occurred when the blend was below T_sp1. However, a slight phase separation was detected when the temperature was between T_sp1 and T_sp2. Moreover, pronounced phase separation was observed when the blend was at a temperature above T_sp2. The phase‐separated structure varied according to the initial composition of the blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Steady viscosity of a polymer/liquid crystal biphasic system

Steady shear viscosities of blends of poly(butyl acrylate) and cholesteryl oleyl carbonate were studied under a cone and plate fixture. Unique shear behavior was observed for the polymer/low molar mass liquid crystal mixture. The viscosity of the liquid crystal‐rich phase increases with polymer content until a maximum is reached. The height of the viscosity maximum decreases with the magnitude of the shear stress and disappears when the stress reaches 200 Pa. Addition of liquid crystal to the polymer‐rich phase causes a viscosity reduction, and at higher stress levels, the viscosity reduction becomes more effective with the same amount of liquid crystal addition. The viscosity reduction may be related to the fibril morphology of the liquid crystal and the viscosity maximum can be interpreted by the emulsion effect being counteracted by a viscosity reduction effect. A shear‐thickening behavior was observed in the intermediate shear rates for the blends with a volume fraction of poly(butyl acrylate) between 9.4 and 49.8%. This is a novel liquid–liquid system that exhibits a shear thickening behavior. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 25–30, 2004     

Mathematical expressions for calculation of oil‐polymer blends

A study of the recent literature emphasized the importance of blending polymers with oils for improving the performance characteristics (like flexibility, corrosion resistance, etc.) of adhesives, coatings and laminates. Investigation of the available data revealed that several properties of such oil‐polymer blends could be correlated by molar refraction (R_M), with reasonable accuracies. The properties of the linseed oil‐polystyrene (PS) and linseed oil‐polymethyl methacrylate (PMMA) blends studied are iodine value (IV), hydroxyl value (HV), inherent viscosity (η), melting temperature (T_M), and glass transition temperature (T_g). In the case of safflower, palm and peanut oil‐sucrose polyester formulations, the viscosity at 40 °C (η₄₀) and the melting point T_M have been correlated by R_M with the average absolute deviations (ē) of 17.8% and 3.0%, respectively. Using the orientation polarization P_O (to represent polarity) in addition to R_M, η₄₀ and T_M of oil‐polyester formulations could be calculated with ē values of 8.9% and 1.7%, compared to 17.8% and 3.0% using R_M alone. The results indicated the importance of P_O in improving the accuracy of predictions for properties.     

Melt rheological properties of PBT/SEBS and reactively compatibilized PBT/SEBS/SEBS‐g‐MA polymer blends

Melt rheological properties of PBT/SEBS and PBT/SEBS/SEBS‐g‐MA blends at SEBS volume fraction (Φ_d) = 0.00–0.38 were studied at 240°C, 250°C and 260°C using a capillary rheometer. The compatibilizer SEBS‐g‐MA addition resulted in significant reduction in the dynamic interfacial tension which in turn led to increased phase adhesion. The power law exponent n decreased with increasing Φ_d and increasing temperature for both the compatiblized and uncompatiblized blends. The consistency index of PBT/SEBS increased with increasing Φ_d but were smaller than those of PBT/SEBS/SEBS‐g‐MA blends. Melt elasticity such as die swell and first normal stress difference increased with Φ_d. Variations of first normal stress coefficient function (ψ₁), recoverable shear strain (γ_R), relaxation time (λ), and shear compliance (J_c) values versus shear rate were analyzed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41402.     

Bipolar polymer semiconductor blends of C60‐end‐capped poly(4‐diphenylaminostyrene) and poly(4‐diphenylaminostyrene): One‐pot synthesis and charge‐transport properties

Three types of fullerene (C₆₀)‐end‐capped poly(4‐diphenylaminostyrene) (C₆₀–PDAS) and poly(4‐diphenylaminostyrene) (PDAS) blends were prepared to investigate their potential as bipolar polymer semiconductors. The concentration of C₆₀ in the C₆₀–PDAS/PDAS blends strongly affected the hole and electron drift mobility values; the hole drift mobility decreased with an increase in the C₆₀ concentration. However, the electron drift mobility increased with an increase in the C₆₀ concentration. The hole and electron drift mobility values were almost the same for the 1/2 C₆₀–PDAS/PDAS blend; therefore, this polymer blend was thought to be a bipolar polymer semiconductor. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Morphology and thermal properties of two polymethacrylates modified by a polymer liquid crystal

We have studied blends of a polymer liquid crystal (PLC) with poly(cyclohexylethyl methacrylate) (PCHEMA) or poly(cyclohexylpropyl methacrylate) (PCHPMA). The PLC is PET/0.6PHB where PET = poly(ethylene terephthalate), PHB = p-hydroxybenzoic acid and 0.6 is the mole fraction of the latter in the copolymer. The microstructure was studied by scanning electron microscopy (SEM). PCHEMA + PLC (20 wt% of the latter, blend E) has a fine texture with LC islands evenly distributed in the matrix and good adhesion between the phases resulting from their partial miscibility. The PCHPMA + PLC (20 wt% of the latter, blend P) shows only limited compatibility. The SEM results are confirmed by values of the glass transition temperatures T_g determined via thermal mechanical analysis. The T_g value of the blend E is shifted towards the T_g of PLC; T_g of blend P is practically equal to that of PCHPMA. The linear isobaric expansivity α_L values for both blends are lower than the respective values for pure PCHPMA and PCHEMA. Thermal stabilities of the blends determined by thermogravimetry are also better than those of pure polymethacrylates. The temperature of 50% weight degradation for blend E is higher than that for pure PCHEMA by more than 60 K Copyright © 2004 Society of Chemical Industry     

Miscibility enhancement of PP/PBT blends with a side‐chain liquid crystalline ionomer

Side‐chain liquid crystalline ionomer (SLCI) containing sulfonic acid groups with a polymethylhydrosiloxane main‐chain was used in the blends of polypropylene (PP) and polybutylene terephthalate (PBT) as a compatibilizer. The crystalline behavior, morphological, and mechanical properties of the blends were investigated in detail by differential scanning calorimetry (DSC), polarizing optical microscope (POM), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Revealed by the shift of T_m in DSC thermogram and the shift of the absorbed peak in FTIR spectra, specific interaction led to stronger interfacial adhesion between these phases, which resulted in much finer dispersion of the minor PBT phase in PP matrix. The SLCI containing sulfonate acid groups acted as physical crosslinking agent along the interface, which compatibilized PP/PBT blends. The mechanical property of the blends including 4 wt % SLCI contents was better than that of other SLCI contents in the blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Compatibilization of nylon 6/liquid crystalline polymer blends with three types of compatibilizers

Polyblends of nylon 6 and liquid crystalline polymer (LCP) (Vectra A 950) are immiscible and highly incompatible, with resultant poor interfacial adhesion, large phase domains, and poor mechanical properties. In the present work, compatibilizing strategies are put forward for blends containing nylon and LCP. Effects of three types of compatibilizers, including ionomer Zn–sulfonated polystyrene (SPS), reactive copolymer styrene–maleic anhydride (SMA), functional grafted copolymers—polypropylene grafted glycidyl methacrylate (PP‐g‐GMA) and polypropylene grafted maleic anhydride (PP‐g‐MAH)—are studied in the aspects of morphology and dynamic mechanical behavior. The addition of compatibilizers decreases the domain size of the dispersed phase and results in improved interfacial adhesion between LCP and matrix. The compatibilization mechanism is discussed by way of diffuse reflectance Fourier transform spectroscopy (DRIFT), showing the reaction between compatibilizers and matrix nylon 6. Mechanical properties are improved by good interfacial adhesion. The contribution of SMA to mechanical properties is more obvious than that of Zn‐SPS and grafted PPs used. The blending procedure is correlated with the improvement of mechanical properties by the addition of compatibilizer. Two‐step blending is demonstrated as an optimum method to obtain composites with better mechanical properties as a result of a greater chance for LCP to contact the compatibilizer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1452–1461, 2003     

Reinforcement of the interface in drawn polymer blends PS/PA‐12

The origin of the reinforcement effect in uniaxially drawn films on the basis of immiscible blends composed of crystalline matrix of polyamide‐12 (PA) and glassy polystyrene (PS) dispersed phase has been investigated. Other conditions being equal, the effect becomes the more pronounced the lager the draw ratio and the finer the PS dispersion. Since the latter factor is itself a strong function of phase viscosity ratio (μ), the following two techniques of adjusting the optimal value of μ ≈ 1 have been adopted. According to the first one, a selective plasticizer, which is a good solvent for the PS minor phase and a nonsolvent for the PA matrix phase, was added to the more viscous PS. According to the second approach, the value of μ was varied by the use of PS samples of different molecular weights. It was shown that significant reinforcement effect appears on drawing regardless of the method of adjusting optimal phase viscosity ratio. These data as well as the results obtained with the help of IR‐dichroism and transmission electron microscopy techniques evidence that the formation of a much more ordered crystalline morphology of the PA matrix located at the PS/PA interfaces and a large interface area are mainly responsible for the discussed reinforcement phenomenon. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1299–1305, 2007     

Thermal properties,structure and morphology of PEEK/thermotropic liquid crystalline polymer blends

The dynamic crystallization and subsequent melting behaviour of poly(aryl ether ether ketone), PEEK, and its blends with a thermotropic liquid crystalline polymer, Vectra^®, have been studied using differential scanning calorimetry, optical microscopy and wide‐angle and small‐angle X‐ray diffraction (WAXS and SAXS) techniques in a wide compositional range. Differences in crystallization rates and crystallinities were related to the structural and morphological characteristics of the blends measured by simultaneous real‐time WAXS and SAXS experiments using synchrotron radiation and optical microscopy. The crystallization process of PEEK in the blends takes place in the presence of the nematic phase of Vectra and leads to the formation of two different crystalline families. The addition of Vectra reduces the crystallization rate of PEEK, depending on composition, and more perfect crystals are formed. An increase in the long period of PEEK during heating was generally observed in the blends at all cooling rates. Copyright © 2003 Society of Chemical Industry