Compatibilization Of Polymer Blends Research Articles

Chemically treated polyethersulfone/polyacrylonitrile blend ultrafiltration membranes for better fouling resistance

Membranes with high permeation combined with high rejection rate and high fouling resistance are in high demand in market. The stability of membrane is necessary in aqueous applications for separation of biological products such as proteins. Polyethersulfone (PES) is hydrophobic material hence it fouls rapidly during aqueous biological and macromolecular solute separations. Membrane with hydrophilic characteristics have drawn considerable attention in practical use in recent years because of its better fouling resistance. This paper is an attempt to prepare hydrophilic PES membranes by blending polyethersulfone (PES) and polyacrylonitrile (PAN) in dimethylformamide (DMF) solvent in different proportions. Blend ultrafiltration membranes of PES and PAN were prepared on non-woven polyester fabric using motor driven prototype membrane casting machine according to phase inversion method. It has been observed that these membranes foul rapidly during ultrafiltration of macromolecular solutes. To improve fouling resistance membrane surfaces modified by treatment with aqueous alkali solutions of different concentration at room temperature. Unmodified and modified membranes were characterized using aqueous solution of inorganic solutes (NaCl & Na 2SO 4) and organic solutes (polyethyleneglycol [PEG], dextran [DXT], poly (sodium 4-styrene sufonate) [PSSA]). Modified membrane had shown high flux recovery ratio compared to unmodified membranes, this improvement in the fouling resistance is due to hydrophilicity of membrane surface. Hydrophilicity was confirmed by advanced contact angle using DATA Physics direct contact angle tensiometer. Compatibility ofpolymer blends was confirmed by measuring glass transition temperature using differential scanning calorimetry (DSC). For measurement of rejection of macromolecular solutes gel permeation chromatography was used.

A Novel Strategy for the Preparation of Reactively Compatibilized Polymer Blends with Oligomers Containing α‐Methyl Styrene Units

AbstractA novel strategy to prepare reactively compatibilized polymer blends is reported. An oligomer that consists of AMS (α‐methyl styrene) and GMA (glycidyl methacrylate) is initially synthesized. When this oligomer is melt blended with poly(propylene) (PP), the GMA units in the oligomer are successfully grafted onto the PP chain, which is proven by measuring the FT‐IR spectrum of the blended PP. When the oligomer is added to a blend of PP/Ny66, an in‐situ compatibilization occurs, which leads to an increase in torque values during blending, a decrease in crystallinity degree of Ny66, and is observed by SEM images of the resulting blends. The compatibilizing effects of the oligomer are also observed in PP/Ny6 and polyethylene/Ny6 blends. A relevant compatibilization mechanism is proposed.magnified image

Study on Properties of Polymer Blends from Polypropylene with Polycaprolactone and Their Biodegradability

The main problem in preparation of polymer blends is compatibility between polymers mixtures with different properties. This paper describes properties of polymer blends prepared from modified polypropylene (PP) and poly-e-caprolactone (PCL). The preparation of these polymer blends involves modification of PP by oxidation with hydrogen peroxide. A part of the polymer blends consisting oxidized PP and PCL was compatible polymer blends, and the highest compatible polymer blends was obtained in the PP/PCL ratio of 70/30 (% w/w) with low crystallinity. The mechanical properties of polymer blends decreased with increasing of PCL proportion in the polymer blends. Enzymatic degradability of PP-PCL polymer blends were lower than that of PCL, and increased slowly with increasing of PCL content in the polymer blends. The use of oxidized PP in preparation of polymers blends with PCL effectively improves the degradability of the polymer blends due to the increase of compatibility of each component in polymer blends. Furthermore, biodegradation process might occur through hydrolysis of PCL and compatible parts of polymer blends to result in hydroxyl and carboxylate functional groups in the end of polymer chain.

Influence of solid surface on the compatibility in polymer blends produced in situ

Blends of linear polyurethane and poly(methyl methacrylate) were obtained in situ in the course of simultaneously proceeding reactions of polymerization and polyaddition. The effect of filler nanoparticles on the thermodynamic properties of the systems was investigated. Introduction of filler into the monomer mixture before curing increases the compatibility of final systems, as follows from diminishing thermodynamic interaction parameters. The reverse correlation has been established between the interaction parameter and the fraction of an interfacial region between two phases, its origin being the result of incomplete phase separation. Introducing filler into the reaction system determines simultaneously the increasing compatibility and increasing fraction of an interfacial region, i.e., prevents phase separation. Both effects are due to increasing of the interaction between two polymeric components at the interface with solid and changing conditions of incomplete phase separation in the course of reaction.

Compatibility of polymer blends. I. Copolymers with organic solvents

AbstractIn this work, we present a theoretical discussion regarding the Flory–Huggins χ interaction parameter for 11 random copolymer‐solvent systems along with their corresponding polymer pairs. Copolymers studied are poly(acrylonitrile‐co‐butadiene) in acetonitrile, poly(styrene‐co‐acrylonitrile) in 1,2‐dichloroethane, poly(acrylonitrile‐co‐butadiene) in hexane, and poly(acrylonitrile‐co‐butadiene) in pentane. For ternary systems, the results are expressed in terms of χ1,23, which is reduced to the classical Flory–Huggins χ12 interaction parameter in case of binary mixtures. The data on χ1,23 may be used for an approximate estimation of the χ′23 interaction parameter for the limiting case of zero solvent concentration. For this purpose, at the end of each subsection of tables, the limiting value of $\chi^{\infty}_{1,23}$ is given. The limiting values of $\varphi^{\infty}_{2}$, $\varphi^{\infty}_{3}$, and χ′23 also appear at the end of each table. It should be noted that these values are obtained by the graphical extrapolation of data to zero concentration of solvent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 492–498, 2006

Study on the Polydimethylsiloxane Polyurethane Modified Novolac Type Epoxy Precursor for Manufacturing Carbon–Carbon Composites

The objective of this study is to investigate the feasibility of utilizing the aromatic amine-terminated polydimethylsiloxane polyurethane modified novolac type epoxy to prepare carbon–carbon (C–C) composite with improved mechanical and anti-oxidation properties. The curing kinetics of modified epoxy and the compatibility of polymer blend were investigated. Thermal, physical, and mechanical properties during the post-cure stage and carbonization stage were also examined. The curing kinetic studies show that epoxy matrix modified with polydimethylsiloxane polyurethane decrease the collision factor and increase the total heat of reaction and the active energy of reaction. Polydimethylsiloxane polyurethane is compatible with epoxy resin when the content is below 5 phr (parts per one hundred parts of epoxy resin). Adding polydimethylsiloxane polyurethane can reduce the weight loss of composite during the post-cure process. The volume shrinkage and porosity of carbon fiber reinforced composite and C–C composite decrease with the increase of polydimethylsiloxane polyurethane content. The polydimethylsiloxane polyurethane can increase the mechanical properties after carbonization since polydimethylsiloxane polyurethane releases the internal pressure and protects the fiber surface during the carbonization process. The novolac epoxy, with polydimethylsiloxane polyurethane modified, has better oxygen resistance and lower oxidation rate from the thermogravimetric analysis (TGA) oxidation testing results after the addition of this silicon-containing resin.

Effect of mixing protocol on compatibilized polymer blend morphology

AbstractWe investigated the effect of mixing protocol on the morphology of compatibilized polymer blends made with premade compatibilizer and reactively formed in‐situ compatibilizer in a custom‐built miniature mixer Alberta Polymer Asymmetric Minimixer (APAM). The compatibilized blends show a finer morphology than uncompatibilized blends if the polymers are mixed together in the dry state and then fed into the mixer. It is found that premelting one polymer, and premixing polymers and compatibilizer, both greatly affect the compatibilized blends' morphology. The effects are complex since the dispersed phase particle size and distribution of the compatibilized blends may be smaller or larger when compared with the uncompatibilized system, depending on the material's physical and chemical properties; for example, diblock molecular weight or the preference of copolymer to migrate to a particular phase can change the final morphology. Good mobility of the copolymer to reach the interface is crucial to obtain a finer morphology. Micelles are observed when a high molecular weight diblock copolymer P(S‐b‐MMA) is used for a PS/PMMA blend. Because of its enhanced mobility, no micelles are found for a low molecular weight diblock copolymer P(S‐b‐MMA) in a PS/PMMA blend. For PS/PE/P(S‐b‐E) blends, finer morphology is obtained when P(S‐b‐E) is first precompounded with PS. Because the block copolymer prefers the PE phase, if the P(S‐b‐E) block copolymer is compounded with PE first, some remains inside the PE phase and does not compatibilize the interface. In the case of reactive blend PSOX/PEMA, premelting and holding the polymers at high temperature for 5 min decreases final dispersed phase particle size; however, premelting and holding for 10 min coarsens the morphology. POLYM. ENG. SCI. 46:691–702, 2006. © 2006 Society of Plastics Engineers.

Rheology and Morphology of Highly Compatibilized Polymer Blends

AbstractThe rheology and morphology of highly compatibilized droplets has been studied, using both rheology and small angle light scattering. It is shown that linear viscoelastic measurements are a powerful tool to investigate the effectiveness of a compatibilizer to suppress coalescence. Moreover, such highly compatibilized droplets are insensitive to deformation and breakup. The consequences for the rheological behaviour of the blend are discussed.

Local Stiffness in Nylon 6/Rubber Blends Determined by Digital Pulsed Force Mode-SPM

The incorporation of soft rubber into a thermoplastic matrix can lead to tough blends. Generally, such binary blends are immiscible and exhibit poor mechanical properties caused by the unfavorable interactions between the two phases. Thus, there is an enormous interest in polymer blend compatibility to improve the properties of the polymer blends by the addition of an appropriate compatibilizer [1,2].

Preparation of PTBA-PAA-PMMA Compatibilizer for PET-PMMA Blends by Atom Transfer Radical Polymerization

The synthesis of diblock copolymer of tert butyl acrylate and methyl methacrylate (PTBA-b-PMMA) was prepared by Atom Transfer Radical Polymerization (ATRP). At the outset, macroinitiator of tert butyl acrylate (TBA) was prepared by using N,N,N,N,N-pentamethyldiethylenetriamine (PMDETA) ligand, Cuprous Bromide (CuBr) catalyst, and ethyl 2-bromo isobutyrate (2-EiBBr) initiator. Immediately after the intake of the utmost TBA in the macroinitiator, the second monomer, methyl methacrylate (MMA) was added to the reaction medium, for further polymerization. In these experiments the compositions of the monomers were varied, although the concentrations of ligand, catalyst and the initiator were kept constant. Subsequently, the diblock copolymers were hydrolyzed, under acidic conditions, using HCl catalyst, to obtain an amphiphilic copolymer. These block copolymers were characterized by NMR, IR, GPC, and DSC techniques. These copolymers will be used in, powder coatings, pigment dispersions, and as compatibilizers in polymer blends.

Determination of Polymer Compatibility by Viscometric Measurements on Ternary Solutions of the Two Polymers

Results on the intrinsic viscosity [η] are reported for the system solvent(1)/polymer(2)/polymer(3) in which the solvent was benzene, polymer(2) was polystyrene (PS), and polymer(3) was poly(dimethylsiloxane) PDMS. The values of [η] were then used to determine the likely compatibility of polymer blends of PS and PDMS. Initial focus was on the traditional interaction parameter b 23 (1) used by several authors to predict compatibilities, it but depends on the molar mass, weight fractions, and concentrations of each polymer. A new interaction parameter b 23 (2) that is independent of polymer(3) concentration and molar mass was evaluated for determinations of polymer compatibility.

Sorption/diffusion of aqueous mixtures of 1,4‐dioxane/tetrahydrofuran through blend membranes of poly(vinyl alcohol) and sodium alginate: Their compatibility and pervaporation separation studies

AbstractBlend membranes of poly(vinyl alcohol) (PVA) and sodium alginate (NaAlg) were prepared by solution casting and crosslinked with glutaraldehyde (GA). Polymer blend compatibility was studied in water by measuring solution viscosity at 30°C. From the viscosity data, interaction parameters were determined to find the blend compatibility. Thickness of the membranes ranged between 35 and 40 μm. Circular disc‐shaped samples were cut from the thin membranes to perform gravimetric sorption experiments in water + 1,4‐dioxane and water + tetrahydrofuran mixtures at 30°C. Diffusion coefficients were calculated using Fick's equation. Concentration profiles of liquids were computed by solving Fick's equation under suitable boundary conditions. Diffusion coefficients show a dependence on the composition of the blends as well as composition of binary mixtures. A correlation was attempted between concentration profiles and diffusion coefficients of the transporting liquids. Degree of swelling and sorption coefficients were calculated from the gravimetric sorption data. Sorption kinetics was studied using an empirical equation to understand the nature of sorption–diffusion anomalies. Membrane selectivity for water + 1,4‐dioxane and water + tetrahydrofuran mixtures were calculated from the pervaporation experiments. A correlation between sorption and membrane selectivity was attempted. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 178–188, 2005

Interactions in blends containing chitosan with functionalized polymers

AbstractThe phase behavior of blends containing chitosan with poly(vinyl‐alcohol) (PVA) and poly(2‐hidroxyethyl methacrylate) (P2HEM) was analyzed. Blends were obtained by casting from acetic acid solution (HAc) and 1,1,1,3,3,3 hexafluoro‐2‐propanol (HF2P) and studied by DSC, FT‐IR, and TGA. The phase behavior of the blends of chitosan with PVA and P2HEM, studied by DSC, shows that the systems behave as one‐phase systems in HAc as well as in HF2P according to the DSC results. According to the results of FT‐IR analyses of the different absorptions of the blends, relative to the pure components, they show an important shift that is considered evidence of an interaction between the components of the blends. The thermogravimetric analysis of the blends and the pure components shows that the temperature for thermal degradation of the blends is higher that that of the pure components, irrespective of the solvent casting from which the mixture was obtained. These results are interpreted as the formation of a new product that corresponds to a compatible polymer blend. The compatibilization of these systems is attributed to strong interactions, like hydrogen bonds formation between the functionalized polymers and chitosan, due to the presence of interacting functional groups in all the polymers studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1953–1960, 2005

The effect of block copolymer architecture on the coalescence and interfacial elasticity in compatibilized polymer blends

The effect of block copolymer architecture on the suppression of droplet coalescence and on the interfacial elasticity was studied in immiscible blends of polydimethylsiloxane (PDMS) and polyisoprene (PI) with a droplet-matrix morphology. The PDMS-PI diblock copolymers used in this study to compatibilize the blends differ in molecular weight and degree of asymmetry of the blocks. The general Palierne model with an interfacial shear modulus was used to analyze the dynamic measurements performed after different shear histories. It was shown that the coalescence suppression is more effective when the amount of compatibilizer increases and when the overall molecular weight of the block copolymer increases. When comparing the coalescence behavior of a blend and the inverse blend, it was shown that coalescence is suppressed more when the longest block of the block copolymer is located in the matrix. The interfacial relaxation time increases with molecular weight of the blocks for symmetric block copolymers. Asymmetry of the blocks also causes it to increase. A scaling relation is proposed for the interfacial relaxation time of PI/PDMS blends. This master curve is extended for varying viscosity ratios of the blend and with data of a polydimethylsiloxane (PDMS)/polyisobutylene (PIB) blend and a polymethylmethacrylate (PMMA)/polystyrene (PS) blend.

In situ polymerization and in situ compatibilization of polymer blends of poly(2,6-dimethyl-1,4-phenylene oxide) and polyamide 6

A novel approach of in situ polymerization and in situ compatibilization was adopted to prepare compatibilized PPO/PA6 blends. An anionic ring-opening polymerization of ε-caprolactam was proceeded in the presence of PPO, whose chain bore p-methoxyphenyl-propionate (MPAA), acting as macroactivator to initiate PA6 chain growth from the PPO chains and to form a graft copolymer of PPO and PA6 and pure PA6 simultaneously. Thus, the compatibilized blends of PPO/PA6 were obtained.

Biodegradable and functionally superior starch–polyester nanocomposites from reactive extrusion

AbstractBiodegradable starch‐polyester polymer composites are useful in many applications ranging from numerous packaging end‐uses to tissue engineering. However the amount of starch that can form composites with polyesters without significant property deterioration is typically less than 25% because of thermodynamic immiscibility between the two polymers. We have developed a reactive extrusion process in which high amounts of starch (approx. 40 wt%) can be blended with a biodegradable polyester (polycaprolactone, PCL) resulting in tough nanocomposite blends with elongational properties approaching that of 100% PCL. We hypothesize that starch was oxidized and then crosslinked with PCL in the presence of an oxidizing/crosslinking agent and modified montmorillonite (MMT) organoclay, thus compatibilizing the two polymers. Starch, PCL, plasticizer, MMT organoclay, oxidizing/crosslinking agent and catalysts were extruded in a co‐rotating twin‐screw extruder and injection molded at 120° C. Elongational properties of reactively extruded starch‐PCL nanocomposite blends approached that of 100% PCL at 3 and 6 wt% organoclay. Strength and modulus remained the same as starch‐PCL composites prepared from simple physical mixing without any crosslinking. X‐ray diffraction results showed mainly intercalated flocculated behavior of clay at 1,3,6, and 9wt% organoclay. Scanning electron microscopy (SEM) showed that there was improved starch‐PCL interfacial adhesion in reactively extruded blends with crosslinking than in starch‐PCL composites without crosslinking. Dynamic mechanical analysis showed changes in primary α‐transition temperatures for both the starch and PCL fractions, reflecting crosslinking changes in the nanocomposite blends at different organoclay contents. Also starch‐polytetramethylene adipate‐co‐terephthalate (PAT) blends prepared by the above reactive extrusion process showed the same trend of elongational properties approaching that of 100% PAT. The reactive extrusion concept can be extended to other starch‐PCL like polymer blends with polymers like polyvinyl alcohol on one side and polybutylene succinate, polyhydroxy butyrate‐valerate and polylactic acid on the other to create cheap, novel and compatible biodegradable polymer blends with increased toughness. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1072–1082, 2005

Compatibilization of polymer blends with high‐molecular‐weight peroxides

AbstractA 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

Polymer Blend Compatibilization by Gradient Copolymer Addition during Melt Processing: Stabilization of Dispersed Phase to Static Coarsening

Polymer Blend Compatibilization by Gradient Copolymer Addition during Melt Processing: Stabilization of Dispersed Phase to Static Coarsening

Raman and Wide‐Angle X‐Ray Diffraction Studies on Molecular Structure, Crystallinity, and Morphology of Uncompatibilized and Compatibilized Blends of High Molecular Weight Polyethylene/Nylon 12

AbstractMolecular structure, crystallinity and morphology of uncompatibilized and compatibilized blends of high molecular weight polyethylene (HMWPE) and Nylon 12 were investigated by using Fourier‐transform (FT) Raman spectroscopy, wide‐angle x‐ray diffraction (WAXD), and scanning electron microscopy (SEM). One of the important purposes of the present study is to compare the present results for HMWPE/Nylon 12 with the previously obtained results for high‐density polyethylene (HDPE/Nylon 12). Uncompatibilized and compatibilized blends of HMWPE/Nylon 12 with a Nylon 12 content ranging from 10 to 90 wt% at increments of 10 wt% were prepared. The compatibilized polymer blends were prepared by adding a small amount of maleic anhydride (MAH), and SEM images show that the addition of the small amount of MAH (0.5 wt%) yields a marked improvement of dispersion of HMWPE and Nylon 12. To evaluate the crystallinity of HMWPE from Raman spectra, the relative intensities of bands at 1418 and 1129 cm−1 to the intensity of a band at 1000 cm−1 (I1418/I1000 and I1129/I1000) were estimated for all the uncompatibilized and compatibilized blends of HMWPE/Nylon 12. From the comparison of the relative intensities (I1418/I1000 and I1129/I1000) between the uncompatibilized and compatibilized blends of HMWPE/Nylon 12 it was found that when the Nylon 12 content reaches 40 wt% the crystallinity of HMWPE in the compatibilized blends becomes higher than that of HMWPE in the uncompatibilized blends. The uncompatibilized and compatibilized blends of HMWPE/Nylon 12 (50/50) show quite different x‐ray diffraction patterns; the compatibilized blend shows a significantly larger orientational effect in the x‐ray pattern of HMWPE. It seems that the increase of interaction of MAH‐HMWPE with the Nylon 12 matrix leads to the additional crystallinity.

Preparation and thermomechanical characterization of poly(vinyl chloride) blends compatible with terpolymer‐containing maleic anhydride

AbstractIn this study, I aimed to change the thermomechanical characteristics of poly(vinyl chloride) (PVC), which is widely used in commercial areas. Copolymers containing maleic anhydride (MA) units are commonly used to obtain compatible polymer blends. In our study, PVC blends were also prepared with the terpolymers with and without anhydride units. I assumed that the impact of the terpolymer on the thermomechanical characteristics of the PVC material could be more effectively controlled. For this purpose, two sets of six different blends of PVC with or without MA were synthesized, among which one was pure PVC, but the other five blends contained 2, 4, 6, 8, and 10% terpolymer. In conclusion, I observed that the terpolymer with the MA unit more regularly changed the thermomechanical characteristics of PVC. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1586–1589, 2004