Compatibilization Of Polymer Blends Research Articles

Compatibilization of Polymer Blends from Poly(butadiene‐g‐poly(styrene‐co‐acrylonitrile)) and Polycarbonate through Oxazoline‐ and Benzoxazole‐Modification of ABS

AbstractBlends of poly(butadiene‐g‐poly(styrene‐co‐acrylonitrile) (ABS) with polycarbonate (PC) are some of the most successful multiphase materials, with applications in the automotive and electronics industries. The mechanical properties of the complete incompatible blends are mainly determined by the interaction between the poly(styrene‐co‐acrylonitrile) (S/AN) component of the ABS and the PC as well as through the dispersion of the elastomeric component poly(butadiene) in the thermoplastic S/AN‐matrix.The aim of our work is to optimize the modification process by the use of new substituted amino alcohols and amino phenols, as well as the use of a more efficient catalyst. Both reactive and non reactive compatibilization of polymer blends should be performed with the new ABS‐modifications.

An analysis of the origin of coalescence suppression in compatibilized polymer blends

The course of the flow-induced coalescence and the effects of the Marangoni force and steric repulsion on the coalescence suppression in polymer blends containing a compatibilizer were analysed. The expression for coalescence probability of deformable droplets, reliably describing its dependence on the droplet size, was proposed. It was shown that a strong negative correlation exists between the Marangoni force and steric repulsion contributions and the decisive mechanism of the coalescence suppression cannot be determined from the dependence of coalescence on the shear rate. For prediction of the magnitude of the Marangoni force, the knowledge of the rate of copolymer diffusion along the interface is necessary. The influence of simultaneous collisions of three and more droplets and of droplet deformation in flow, which are not included in available theories, is discussed.

The Structures and Physicochemical Properties of Mixtures of Water-Soluble Polymers

Because data on structure, component interaction, physical properties, and compatibility of polymer blends containing native polysaccharides is very sparse, we have used optical and electron microscopy, X-ray diffraction, IR spectroscopy, sorption capacity methods, and estimation of thermodynamic data to investigate the structural, physicochemical, and physicomechanical properties of mixtures of carboxymethylcellulose with poly(vinyl alcohol) and of mixtures of chitosan with poly(vinyl alcohol), to discover relationships between the structures of the systems and their physicochemical characteristics and other properties, to determine the compatibility of components, and to discover methods and conditions for their synthesis. It was found that for some component ratios in these systems there is some interaction and some compatibility, with the result that the structures of the blends are less heterogeneous than those of the individual components. One effect of this is that the physicomechanical properties of the blends can be superior to those of the individual components, particularly for carboxymethylcellulose–poly(vinyl alcohol) mixtures.

Microhardness Studies of the Interphase Boundary in Rubber‐Softened Glassy Polymer Blends Prepared with/without Compatibilizer

The interphase boundary of incompatible polymer blends such as poly(methyl methacrylate) (PMMA)/natural rubber (NR) and polystyrene (PS)/NR, and of compatible blends such as PMMA/NR/epoxidized NR (ENR) and PS/NR/styrene–butadiene–styrene (SBS) block copolymer, where ENR and SBS were used as compatibilizers, was studied by means of microindentation hardness (H) and microscopy. Cast films of neat PMMA and PS, and blended films of PMMA/NR, PS/NR, PMMA/NR/ENR, and PS/NR/SBS were prepared by the solution method using a common solvent (toluene). Hardness values of 178 and 173 MPa were obtained on the surfaces of the neat PMMA and PS, respectively. After the inclusion of soft phases, the binary (incompatible) and the ternary (compatible) blend surfaces show markedly lower H‐values. Scanning electron and optical microscopy reveal a clear difference at the phase boundary of the surface of compatible (smooth boundary) and incompatible (sharp boundary) blends. The compatibilized blends were characterized by using microhardness measurements, as having the thinnest phase boundary (∼30 µm), while incompatible blends were shown to present a boundary of about 60 µm. The hardness values indicate that the compatibilizer is smoothly distributed across the interface between the two blend components. Results highlight that the microindentation technique, in combination with microscopic observations, is a sensitive tool for studying the breadth and quality of the interphase boundary in non‐ or compatibilized polymer blends and other inhomogeneous materials.

Interfacial elasticity and coalescence suppression in compatibilized polymer blends

Shear-induced coalescence was studied in immiscible blends of polydimethylsiloxane (PDMS) and polyisoprene (PI) with a droplet-matrix morphology, using both rheology and scanning electron microscopy. Dynamic moduli of the blends compatibilized with different amounts of a PDMS–PI diblock were measured. The experimental results indicate that the blend response is characterized by two relaxation mechanisms. The general Palierne model with an interfacial shear modulus was used to analyze the data, since this model can describe the dynamic response of polymer blends in which interfacial tension gradients induce an extra relaxation mechanism besides droplet relaxation. Scanning electron microscopy was used to investigate the droplet size evolution in the blends during coalescence. For systems with a high amount of compatibilizer, it is shown that coalescence is completely suppressed under the conditions studied here.

Kinetics of the in situ polymerization and in situ compatibilization of poly(propylene) and polyamide 6 blends

AbstractIn previous articles, we reported on a novel reactive extrusion process to obtain a compatibilized blend of polymer A and polymer B. It consisted in polymerizing the monomer of polymer A in the presence of polymer B. A fraction of the latter contained initiating sites from which the polymerization of monomer A took place. As such, both polymer A and a graft copolymer of polymer A and polymer B were formed in the process. That process was called in situ polymerization and in situ compatibilization of polymer blends. Its feasibility was illustrated for in situ polymerized and in situ compatibilized poly(propylene) and polyamide 6 (PP/PA6) blends. The latter were prepared by activated anionic polymerization of ϵ‐caprolactam (CL) in the presence of PP in a batch mixer and a twin‐screw extruder, respectively. A fraction of the PP contained isocyanate groups from which PA6 grafts were formed. Sodium caprolactam (NaCL) was used as the catalyst and a diisocyanate compound was used as the activator. In this study, we report on the effects of various parameters on the kinetics of the anionic polymerization of CL in the presence of PP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1498–1504, 2004

Compatibilization of polymer blends from poly(styrene‐co‐acrylonitrile) and polycarbonate by oxazoline modification of poly(styrene‐co‐acrylonitrile) in the melt

AbstractA good way of achieving compatibility in polymer blends of poly(styrene‐co‐acrylonitrile) (S/AN) and bisphenol A polycarbonate (PC) is the chemical modification of S/AN in the melt. A catalyzed reaction of the nitrile groups with a substituted 2‐amino alcohol or 2‐amino phenol resulted in a conversion of nitrile groups of 55–75% in 60 min. The introduced heterocyclic structures were ethyl hydroxymethyl oxazoline (EHMOXA) and benzoxazole (BenzOXA), respectively. The use of dibutyltin oxide as a catalyst led to the highest efficiency. The modified polymer was characterized by Fourier transform infrared and NMR spectroscopy, elemental analysis, and reactions with organic acids and anhydrides. The modified S/AN showed good technical compatibility (single glass‐transition temperature) with PC in blends made from solution and from the melt. All blends were characterized with oscillating rheometry and differential scanning calorimetry. Rheological measurements showed that EHMOXA–S/AN reacted with PC and had crosslinked structures, whereas BenzOXA–S/AN showed compatibilization without any (crosslinking) reaction. The melt blends of BenzOXA–S/AN and PC showed a downward shift in the complex viscosity due to the influence of the BenzOXA group. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2322–2332, 2003

Molecular Structure, Crystallinity, and Morphology of Uncompatibilized and Compatibilized Blends of Polyethylene/Nylon 12

The present study is aimed at investigating differences in molecular structure, crystallinity, and morphology between uncompatibilized and compatibilized blends of high-density polyethylene (HDPE) and Nylon 12 by using Fourier-transform (FT) Raman spectroscopy, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Uncompatibilized and compatibilized blends of HDPE/Nylon 12 with a Nylon 12 content ranging from 10 to 90 wt.-% with an increment of 10 wt.-% were prepared. The compatibilized polymer blends were prepared by adding a small amount of maleic anhydride (MAH) and it was found that 0.5 wt.-% MAH yielded a good dispersion. SEM images show that both kind of blends have a different miscibility behavior. The uncompatibilized and compatibilized blends yield quite different X-ray diffraction patterns; the latter blends with a Nylon 12 content > 70 wt.-% show orientational effects in the X-ray pattern of the HDPE. The crystallinity of the HDPE of both blends was evaluated by the full width at half intensity of the (110) reflection of HDPE. To do that, the diffraction peaks were analyzed by a curve-fitting method. To evaluate the crystallinity from Raman spectra, the intensity ratio of the two bands at 1 129 and 1 110 cm−1 was used. Of note is that the 1 129 cm−1 band is caused by a symmetric CC stretching mode of all-trans (CH2)n groups arising only from HDPE. The Raman spectra and X-ray diffraction measurements revealed that when the Nylon 12 content reaches 70 wt.-%, the crystallinity of HDPE in the compatibilized blends becomes higher than that of HDPE in the uncompatibilized blends. This result is different from the general trend of crystallinity of HDPE in polymer blends. The difference suggests that the effect of the high viscosity of the Nylon-rich phase on the crystallinity is more significant than the effect of the impurity (MAH-grafted PE). It seems that the extension of the Nylon 12-rich phase during the extrusion process leads to orientational effects because of the increase in the interaction between MAH and HDPE. SEM images of HDPE/Nylon 12 compatibilized (top) and uncompatibilized (bottom) blends with a Nylon 12 content of 20 wt.-%.

Preparation and solid-state nuclear magnetic resonance characterization a styrene/butadiene/acrylonitrile (ABS)/poly(vinyl chloride) (PVC)/gypsum ternary system

Polymer blends were prepared to obtain a new material with specific characteristics. To prepare a miscible polymer blend, it is necessary to evaluate the chemical structure and molecular dynamics of all polymers involved and to thereby establish a structure–property relationship for these materials. In this work, ternary blends for application in plates chromatography were formed with styrene/butadiene/acrylinotrile (ABS), poly(vinyl chloride) (PVC), and gypsum, and were studied by solid-state carbon-13 nuclear magnetic resonance (13C NMR). Magic-angle spinning (MAS), cross-polarization magic-angle spinning (CPMAS), variable contact time (VCT), and proton spin-lattice relation time in the rotating frame (Tρ) were the techniques used to evaluate the miscibility, homogeneity, and compatibility of polymer blends at the molecular level. From the values of Tρ, it was verified that ABS/PVC/gypsum formed good polymer blends with some specific physical interaction at the molecular level. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 293–296, 2003

Fluorescence Lifetime Distributions of Labeled Amorphous Polymers in Bulk

Polystyrene, poly(methylmethacrylate), poly(cyclohexyl methacrylate) and poly(1-butylmethacrylate) were labeled with anthryl groups by copolymerization. Films of labeled polymers as well as blends of them with unlabeled polystyrene samples of different polydispersity and molecular weight, were prepared by solvent casting. The time resolved emission of anthryl groups in those films was measured by Single Photon Counting with front face excitation at the standard 30° incident angle and with much lower incident angles to photoselect chromophores on the polymer-air surface. Fluorescence decays were fitted with bimodal fluorescence lifetime distributions, which were analyzed taking into consideration some polymer characteristics and the compatibility of polymer blends. It was thus concluded that solid-like and liquid-like environments are both in the bulk and in the surface of the film although liquid-like domains are more frequent on the surface than in bulk. Polymer Tg determines the position of the two modes and polydispersity justify the broadness of the modes in the fluorescence lifetime distribution.

Molecular Dynamics Simulation of Reactive Compatibilization of Polymer Blends

Molecular dynamics simulations of reactive compatibilization of polymer blends are performed for a wide range of chain lengths and densities of reactive groups ρo. We directly observe the predicted diffusive growth as well as the saturation at later times. The crossover to the saturation regime is consistent with theoretical predictions. There is also a separate transition from second to first-order reaction kinetics. However, the crossover to first-order kinetics does not agree with predictions. Although a depletion layer builds up on a time scale ∝ ρo-2, we find that, for times less than the Rouse time τg, the copolymer per area is a function only of tρo3 for a wide range of ρo implying an additional crossover time scale which scales as ρo-3. The interface is unstable at later times for sufficiently large ρo. The surface tension vanishes before the interface roughens showing that the instability is initiated mainly by the vanishing surface tension. The time required for the surface tension to vanish scales as ρo-3. A dilute limit model is introduced to study the behavior for small ρo. In this limit, Σ(t) grows linearly with time asymptotically and the reaction rate is a slowly decreasing function of Z in agreement with theoretical predictions. For times less than τg there is a logarithmic correction to the linear growth.

Stabilization of Dispersed Phase to Static Coarsening: Polymer Blend Compatibilization via Solid-State Shear Pulverization

Stabilization of Dispersed Phase to Static Coarsening: Polymer Blend Compatibilization via Solid-State Shear Pulverization

Raman, X-ray diffraction and differential scanning calorimetry studies of the melt-induced changes in uncompatibilized and compatibilized blends of high-density polyethylene and nylon 12

The crystallinity of non-molten and pre-molten uncompatibilized and compatibilized polymer blends of high density polyethylene (HDPE)/Nylon 12 have been investigated by using FT-Raman spectroscopy, differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD). The FT-Raman, DSC, and WAXD measurements have revealed that the crystallinity of HDPE of both uncompatibilized and compatibilized blends increases upon melting except for the compatibilized blend with the Nylon 12 content of 80 wt%. The degree of the increase is significantly larger for the uncompatibilized blends than the compatibilized blends. The FT-Raman data suggests that the crystallinity of the compatibilized blend with the Nylon 12 content of 80 wt% decreases slightly after melting. It is very likely that the compatibilized polymer blends are well oriented during the melting and molding process by an extruder because of the existence of maleic anhydride (MAH)-grafted copolymer as a compatibilizer. In contrast, it seems that the uncompatibilized polymer blends are not so much oriented and have more amorphous phase in the Nylon 12 rich region before melting. Thus, the melting process induces a recrystallization process.

Raman Mapping Study of Compatibilized and Uncompatibilized Polymer Blends of Nylon 12 and Polyethylene

Raman mapping images have been obtained for compatibilized and uncompatibilized polymer blends in films of Nylon 12 and high density polyethylene (HDPE) (blend ratios were 20/80, 50/50, and 80/20). A total of 400 Raman spectra were measured for each sample with areas of 100 μm2and in step sizes of 0.5 μm (for 20 × 20 probe spots). To develop the Raman mapping images, the intensity ratio of two bands, a band at 1635 cm−1due to Nylon 12 (amide I mode) and that at 1296 cm−1arising from both HDPE and Nylon 12 (CH2twisting) is used. The Raman mapping images of the uncompatibilized polymer blends show a clear “sea-island” structure while those of the compatibilized polymer blends exhibit a compatibilized structure. The Raman mapping images enable simultaneous exploration of the morphology and molecular structure of the blends. We have also developed a Raman mapping image that represents the variation of crystallinity in the uncompatibilized film.

Effects of EPDM-based compatibilizer on the thermal stability of polyamide blends

Blending different polymers opens up a range of possibility for the development of novel materials with interesting properties. In most cases, however, the immiscibility of polymers results in the loss of mechanical properties due to their incompatibility. Therefore, an appropriate compatibilization of polymer blends is required to overcome this drawback. This chapter presents the compatibilization of polymer blends by means of reactive coupling agents, which can be considered as one of the most industrially viable solutions. Reactive coupling agents can be simply added into polymer blends during melt processing. Performant linkages between coupling agents and target polymers will be formed at elevated temperatures, leading to a high compatibilization effect. Although many coupling agents were intensively applied in the field of composite materials, this review summarizes only the applications of reactive coupling agents in binary and ternary polymer blends. In this study, coupling agents are presented according to the type of their reactive groups: silane, carbodiimide, isocyanate, bisoxazoline, biscaprolactam, epoxide, anhydride, as well as catalysts for interchange reactions. The mechanism and compatibilizing effect of coupling agents are discussed.

Glass transition and exclusion model in crystallization of polyether–polyester block copolymers with amide linkages

Polyether–polyester block copolymers having various polyetheramide contents were synthesized. Single glass transition intermediated in temperature between the glass transition temperatures of polyester and polyetheramide components was found for all of polyether–polyesters. The compositional variation of glass transition exhibited a similar trend to the predicted result of thermodynamic theory for compatible polymer blends. The incompatible pair of homopolyester and homopolyether was forced to be compatible after copolymerization. A modified theoretical prediction for the glass transition of copolymers based on the thermodynamic theory is proposed. Consistent results between theoretical prediction and experimental measurements were found. Unlike homopolyesters, the glass transition temperature of copolymer amorphous domains gradually decreases with crystallization time. An exclusion model for the crystallization of polyester segments in copolymers is proposed. The temperature width of the glass transition increases with crystallization time. The broadening towards the low temperature side in glass transition is interpreted as the evidence of crystallization-induced partial phase separation. Instead of forming macroscopic segregation, the excluded polyether segments resided in-between crystalline polyester lamellae and mix with amorphous polyesters to generate amorphous domains exhibiting concentration gradient along the lamellar basal surface normal. Further increasing the polyetheramide segment content brings the excluded polyetheramide segments to form domains among the crystallized polyester spherulites so as to inhibit the occurrence of spherulitic impingement.

In situ copolymerization and compatibilization of polyester and polystyrene blends. II. Thermally and chemically induced reaction and mechanical properties

The basic studies of in situ compatibilization process between polystyrene (PS) and polybutylene terephthalate (PBT) are carried out by adding various functionalized polystyrenes with mono, di, tetra hydroxy functions. The tensile mechanical properties of these in situ compatibilized blends are investigated. It is important to control the thermal degradation of PBT during the high temperature processing in order to generate the reaction between the functionalized polystyrene and PBT and result in the improvement in their mechanical properties. However, the excess degradation deteriorates the tensile properties of the in situ copolymerized and compatibilized polymer blends. It is found that the usage of Titanium butoxide (TNBT) was effective to promote the thermal degradation of PBT and the copolymerization of PBT with the functionalized polystyrenes. On the other hand, Triphenyl phosphite (TPP) was used to prevent the excess thermal degradation and induce the possible end capping reaction of PBT. The addition of 5% PS-F4 (tetra functionalized polystyrene) in PS/PBT 10/90 blend at 270°C with 1% TPP exhibits the best improvement in the elongation at break among the mono-, di- and tetra-functionalized polystyrenes. The increase of amount of the functionalized polystyrenes into the PS/PBT blends decreased the elongation to break, the yield strength, and the energy to break. More functional groups in the functionalized polystyrenes are more effective in promoting in situ compatibilization. Furthermore, the one-step mixing in which all the ingredients were blended together for 10 min has better elongation to break than the two steps mixing. The detailed characterization of rheological, morphological and mechanical properties of various blends of functionalized PS/PBT and PS/PBT with different functionalized polystyrenes and the additives are described.

Concentrated emulsion pathway to self-compatibilization of polymer blends

Self-compatibilization is a novel method for preparing compatibilized polymer blends via concentrated emulsion polymerization. In this method, two partially polymerized concentrated emulsions are mechanically mixed, and then they are subjected to complete polymerization. Some compatibilizers are generated at the interfaces between the two kinds of cells, which compatibilize the homopolymers generated simultaneously inside the cells. In particular, when a rigid polymer was blended in this manner with a flexible one, tough materials were obtained. This review describes various ways to generate such self-compatibilized materials. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 757–764, 2001

Morphology evolution in PS/LDPE blends in a twin screw extruder: Effects of compatibilizer

In order to understand the mixing in polymer extrusion, the morphology of PS/LDPE blends compatibilized with SEBS was simulated based on the Lee and Park model. Experiments were performed in a co-rotating twin screw extruder and a Haake mixer, and the morphology of the compatibilized blends of various compositions was compared with the non-compatibilized ones. The size of the dispersed phase of the compatibilized blend was smaller than the non-compatibilized one, and the blend of the PE matrix had a smaller size in the dispersed phase than the non-compatibilized one. Simulation results were agreed well with experiments, and the Lee and Park model could be applied in the extrusion analysis of compatibilized polymer blends.

Morphology of compatibilized polymer blends in terms of particle size–asphericity map

Morphology of reactively compatibilzed polymer blends was discussed in terms of particle asphericity ( ζ)–size ( a) map. Reactive melt blending of polysulfone (PSU) with polyamide 6 (PA) was carried out at 20/80 (PSU–PA) wt ratio by adding a few wt% of reactive PSUs; maleic anhydride-grafted PSU (PSU–MAH) or phthalic anhydride-terminated PSU (PSU–PhAH). Morphology development was investigated by light scattering, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM picture was analyzed by a new digital image analysis (DIA), based on the effective ellipse method. The new DIA allows us to analyze the particle size, the shape (asphericity) and their distributions, which are reminiscent of size reduction process and shape relaxation during melt blending. In in situ graft copolymer-forming (PSU–MAH) systems, the ζ– a map shifted rather vertically to higher asphericity and smaller particle sides as the loading amount of reactive PSU increased, suggesting an emulsifying effect of the in situ-formed graft copolymer. By contrast, in in situ block copolymer-forming (PSU–PhAH) systems, the ζ– a map shifted rather horizontally to the smaller particle-side with an increase in the loading amount of reactive PSU. The difference in the ζ– a map between the in situ graft copolymer- and block copolymer-forming systems was interpreted by the “pull-out or not” of the in situ-formed copolymers from the interfacial region by shear forces during mixing. The pull-out of in situ-formed block copolymer was confirmed by TEM: tiny domains (20–40 nm in diameter) coexisted with the bigger particles (μm) with low ζ (probably, “naked particles”-not or less covered with the copolymers).