Multiphase Polymer Blends Research Articles

Wetting Kinetics-Controlled Interplay between Nanoparticles and Polymer Domains in Multiphase Polymer Blends

Wetting Kinetics-Controlled Interplay between Nanoparticles and Polymer Domains in Multiphase Polymer Blends

Application of Multilayered Blend Films as Soft, Stretchable, Self‐Adhesive, and Self‐Healing Absorption‐Dominant EMI Shielding and Microwave Absorber

AbstractSolution‐processable organic conductor–supramolecular elastomer blends are emerging materials for intrinsically stretchable and autonomously self‐healing organic electronics. Herein, the feasibility of a heterogenous multiphase polymer blend is demonstrated for soft, ultraflexible, self‐adhesive, and self‐healing multilayered film structures for electromagnetic interference (EMI) shielding and microwave absorber (MWA) purposes. The developed soft multilayered films achieve a 5–40 fold improvement in the thickness of the MWA compared to the current state‐of‐the‐art. The thickness normalized reflection loss (RL) is up to 65.26 dB mm−1 with 8.5 GHz bandwidth at 18–26.5 GHz. The maximum thickness normalized EMI shielding effectiveness peaks at up to 175 dB mm−1. The EMI shielding and MWA properties are maintainable up to 150% tensile strain with only a small decrease in the overall attenuation and RL. Furthermore, the developed films are capable of fully autonomously self‐healing and achieve a tough adhesion in temperatures of −30–145 °C, and underwater with maximum single‐lap shear adhesion strength of ≈481.5 kPa to soft thermoplastic polyurethane films. Thus, the developed multilayered films can be utilized for absorption‐dominant EMI shielding or MWA purposes as stretchable coatings. The developed materials also show considerable potential for emerging damage and puncture‐resistant organic soft electronics with autonomous material‐level self‐healing.

Enhancing vibration damping properties of MABS/VDT blends using SEBS-g-MAH as a compatibilizer

This investigation focuses on the enhancement of the damping properties of Methyl Methacrylate Acrylonitrile Butadiene Styrene (MABS) through the formulation of a specific blend with a styrene-based elastomer referred to as VDT, and with the incorporation of Ethylene Butylene Styrene grafted Maleic Anhydride (SEBS-g-MAH) as a compatibilizer. In contrast to traditional investigations that primarily focus on the mechanical rigidity, thermal conductivity, and electrical conductivity of materials, this research explores the enhancement of damping properties via the process of melt compounding. Using a twin-screw extruder in a precise melt-mixing process, a multiphase polymer blend is generated by including three different weight ratios (10, 20, and 30 wt.%) of VDT. Furthermore, in order to enhance the compatibility between MABS and VDT, three different weight percentages of SEBS-g-MAH (2, 4, and 6 wt.%) have been used in the blend. Tensile testing, laser confocal microscopy, dynamic mechanical analysis (DMA) and nuclear magnetic resonance (NMR), are used to thoroughly assess the compatibility and effectiveness of the blends. The results indicate that the damping performance of the blend increases in direct proportion to the amount of VDT. Conversely, the addition of SEBS-g-MAH has a non-monotonic effect: the inclusion of 4 wt.% SEBS-g-MAH leads to the most substantial improvements in both damping performance and tensile strength, exceeding the results obtained with 2 wt.% and 6 wt.% compatibilizer. The study highlights the need for carefully choosing the right wt.% of compatibilizers when aiming to formulate polymer blends with enhanced vibration dampening properties.

Reactive compatibilization of poly(lactic acid)/polystyrene blends and its application to preparation of hierarchically porous poly(lactic acid)

In this work hierarchically porous poly(lactic acid) (PLA) with bimodal pore size distribution was derived from reactively compatibilized ternary immiscible polymer blends. We first demonstrated the generation of submicron pores from cocontinuous PLA/oxazoline functional polystyrene (PS-OX) blends. The oxazoline groups in PS-OX reacted with the carboxylic acid end groups of PLA and formed graft copolymer at the interface, which significantly reduced the domain size. Hierarchically structured “tri-continuous” morphology was further obtained in a ternary PLA/PS-OX/linear low density polyethylene (LLDPE) blend. Porous PLA was made by selectively removing the PS-OX and LLDPE phases. Static annealing was used to control the pore size. The pores formed by PS-OX (∼0.5–2 μm) were one order of magnitude smaller than the pores formed by LLDPE (∼5–20 μm). The underlying thermodynamic mechanism for formation of hierarchical morphology in PLA/PS-OX/LLDPE blend was studied, and it was found that PLA/PS/PE ternary blends demonstrated complete wetting behavior with PS located at PLA/PE interface. Our results show that compatibilization with graft/block copolymer is a versatile way to achieve hierarchical microstructures in multiphase polymer blends.

High-strength and super-tough PA6/PS/PP/SEBS quaternary blends compatibilized by using a highly effective multi-phase compatibilizer: Toward efficient recycling of waste plastics

It is well known that polyolefins, styrene polymers and engineering plastics occupy the largest share of the plastic market and constitute nearly 80% of the world's plastic. However, these plastics are usually used or recycled in mixed state and immiscible with each other. It is hard to define or separate these plastics, respectively, from recycled materials. In this letter, a maleic anhydride (MAH) and styrene (St) dual monomers grafted poly [styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS), SEBS-g-(MAH-co-St) was developed as a multi-functionalized compatibilizer for combining engineering plastics, styrene polymers and polyolefins. With the help of the compatibilizer, the model quaternary blend PA6/PS/PP/SEBS (70/10/10/10) transforms from brittle into tough blends, and shows controllable morphologies and significantly improved mechanical properties. This highly efficient compatibilization strategy casts new light on both the development of high-performance multi-phase polymer blends and the recycling of waste plastics.

Viscoelastic properties of polystyrene/polyamide-6 blend compatibilized with silica/polystyrene Janus hybrid nanoparticles

The greatest challenge in the field of multiphase polymer blend research is the compatibility of the phases, which is responsible for the overall microstructure. The control of the interfacial interactions between the components is therefore a necessity. Here, we investigate the compatibilization in a polystyrene/polyamide-6 (PS/PA6) blend. Silica/polystyrene Janus hybrid nanoparticles (JHNPs) were synthesized and used as compatibilizing agents in PS/PA6 blends. Four levels of incorporation were tested (1.5, 3, 5, and 10 phr) in a PS/PA6 (80/20 wt. %) blend. Due to their intrinsic amphiphilic properties, the JHNPs migrate to the interface of the PS/PA6 blend. We demonstrate that silica/polystyrene JHNPs act as compatibilizing agents in PS/PA6 blends. These nanoparticles allow the combination of a “Pickering effect” of a solid particle with a “copolymer effect.” Microscopic analysis confirms the emulsifying ability of these asymmetric nanoparticles. Rheological measurements show an increase in the viscosit...

Morphology development and superior mechanical properties of PP/PA6/SEBS ternary blends compatibilized by using a highly efficient multi-phase compatibilizer

Multi-phase compatibilizers are potentially attractive, not only for the preparation of ternary or multi-phase immiscible polymer blends with high performance, but also for recycling and reuse of waste plastics mixture. In this study, the maleic anhydride (MAH) and styrene (St) dual monomers grafted PP, PP-g-(MAH-co-St) is prepared as a multi-phase compatibilizer, which exhibits highly effective compatibility on the PP/PA6/SEBS (70/15/15) ternary blends. Scanning electron microscopy (SEM) reveals that, with increasing the compatibilizer, the morphology evolves from the individual PA6 particle encapsulated by SEBS to several smaller-size PA6 particles partially encapsulated by SEBS phase, then to the tiny PA6 particles and some larger-size SEBS agglomerates predominantly dispersed separately in PP matrix. The morphology development predicted by spreading coefficients shows a consummate consistency with that observed by SEM. Moreover, the good compatibilization and corresponding morphologies result in superior enhancement of mechanical properties. Compared to the uncompatibilized blend, adding 15 wt% multi-phase compatibilizer to the blend leads to the best mechanical properties with the yield stress, stress at break, strain at break and impact failure energy improved significantly by 23%, 132%, 647% and 220%, respectively. The results verify that the domains with small-size PA6 particles (0.3–0.4 μm) partially encapsulated by SEBS (0.5–0.7 μm) in PP matrix are very effective to enhance the mechanical properties of the blends. The morphologies of large-size PA6 particles encapsulated by SEBS or tiny PA6 particles and some larger-size SEBS agglomerates dispersed separately in PP matrix for the enhancement in mechanical properties of the blends are very limited. Consequently, the enhanced interfacial interactions and the morphology with the rigid particles partially encapsulated by a rubber-like phase in matrix are crucial for the ternary polymer blends.

Broadband stimulated Raman microscopy with 0.1 ms pixel acquisition time.

Femtosecond stimulated Raman microscopy (FSRM) is a nonlinear technique for rapid broadband Raman imaging. It utilizes a few femtosecond probe pulse and a narrow bandwidth pump pulse. Using a fast (20 kHz) multi-channel detector, stimulated Raman spectra can be recorded with an acquisition time as short as 0.1 ms. In this Letter, spectra of neat benzonitrile at different acquisition speeds are presented to benchmark the FSRM setup. Furthermore, chemical maps of a multi-phase polymer blend are recorded using the fastest acquisition rate possible with the current instrument.

Laser Beam Activation of CNT‐Filled Polymer Blends

Abstract3D‐Molded Interconnect Devices enable the placement of electronic circuits on three‐dimensional plastic components. The following article breaks new ground in order to add reasonably to existing 3D‐MID procedures. An essential aspect was the shortening of the process chain of the conventional MID procedures through laser‐direct structuring. Thus the metallising steps are no longer necessary and a 3D circuit carrier structure can be created directly on any plastic component. The research work focused on the space‐resolved modification of the electric conductivity of non‐conductive plastic components through a newly‐developed procedure of laser beam functionalisation. The principle is based on the application of multi‐phase polymer blends with matrix‐disperse phase structures in which carbon nanotubes are located. They cross‐link on the component surface through a partial laser activation and create a conductive area.

Porous composite structures derived from multiphase polymer blends

Porous biopolymer structures have attracted a lot of attention in the recent years because of their potential applications in tissue engineering. In this work, porous structures of poly(lactic-co-glycolic acid) (PLGA) reinforced with organically modified montmorillonite (Cl15A) were fabricated. A ternary, co-continuous blend consisting of PLGA/PS/Cl15A (PS: Polystyrene) was prepared by melt extrusion. Then, a porous PLGA composite was created by the sacrificial extraction of the PS phase. The morphological characterization revealed the creation of a well-formed 3D porous network consisting of Cl15A-reinforced PLGA. Quantitative results obtained from the scanning electron microscopy (SEM) micrographs of the fabricated porous structures show that small variations in the clay loading affect the geometrical characteristics (% porosity and pores average diameter) of these porous structures. The results suggest that these porous PLGA/clay structures may be promising candidates for mechanically strong scaffolds in tissue engineering applications, but this remains upon testing. POLYM. ENG. SCI., 55:1856–1863, 2015. © 2014 Society of Plastics Engineers

Rheology of multiphase polymer blends with and without reactive compatibiliser: evaluation of interfacial tension using theoretical predictions

The phase morphology and rheology of polyamide 12/polypropylene (PA12/PP) blends have been studied. Effects of blend ratio and reactive compatibilisation on the rheological properties of compatibilised and uncompatibilised blends were analysed. The viscosity ratio between the polymers was found to be sensitive to frequency. The complex viscosity and dynamic modulus increased with increase in the amount of compatibiliser, up to critical micelle concentration. The interfacial tension between the polymers was calculated from the storage modulus of the blends using Palierne and Choi-Schowalter models. It was found that the rheological properties of both compatibilised and uncompatibilised blends are intimately related to their phase morphology.

Electrically conductive multiphase polymer blend carbon-based composites

The present review focuses on summarizing key advances made on controlling polymer blend morphology to improve electrical conductivity in carbon-based polymer composite materials, including those based on carbon black, carbon nanotubes, and graphene. Fundamentals for controlling polymer morphology and the distribution of conductive fillers in various polymer composite systems and the impact on the electrical, rheological, mechanical, and thermal properties are reviewed. The concept of triple percolation and its beneficial effect on electrical conductivity is then reviewed. A high level overview of key theories and mechanisms related to phase morphology, percolation, and conductive properties in polymer composites is provided. POLYM. ENG. SCI., 54:1–16, 2014. © 2013 Society of Plastics Engineers

Shape-Dependent Localization of Carbon Nanotubes and Carbon Black in an Immiscible Polymer Blend during Melt Mixing

In melt mixed multiphase polymer blends, the mechanisms determining the spatial distribution and localization of solid particles smaller than the blend domain sizes are still not completely understood. From theoretical considerations of a previous paper of one of the authors, it was derived that the transfer dynamics as well as the stability of different solid fillers at the blend interface reveal a strong dependence on the particle’s aspect ratio. Low interfacial stabilities and high transfer speeds between the blend phases can be deduced for fillers with very high aspect ratios, entitled as the “Slim-Fast Mechanism” (SFM). The SFM appears suitable to explain in retrospect important features of several previous studies that address the localization of differently shaped nanoscaled particles in polymer blends. The SFM was evaluated by investigating the simultaneous transfer of multiwalled carbon nanotubes (MWCNTs) and carbon black (CB) from a poly(styrene acrylonitrile) (SAN) precompound into the thermody...

Fatigue Crack Growth Behavior of Multiphase Blends

The potential of fatigue crack growth experiments to sensitively analyze the anisotropic mechanical behavior of injection-molded, multiphase polymer blends is presented. The properties of immiscible blends based on poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and poly(styrene-co-acrylonitrile) is investigated, both in perpendicular and in parallel to the injection-direction. As a result of the limited interfacial adhesion and the orientation of the blend phases, the direction in parallel to flow revealed to be the weaker link. In order to enhance the toughness behavior, the PPE/SAN blends were systematically modified by the addition of different polystyrene-b-polybutadiene-b-poly(methyl methacrylate) triblock terpolymers (SBM), potentially acting as a compatibilizing and toughening agent. Such a compatibilization step of PPE/SAN blend leads to the formation of nanostructured morphologies. Depending on the composition of the triblock terpolymer, the resistance to crack growth was either further degraded or, in the case of high interfacial presence and compatibilization efficiency, significantly improved. The results were correlated to the fracture mechanisms of the blends as analyzed by scanning electron microscopy of the fracture surfaces. In contrast to poorly-compatibilized blends, a significant plastic deformation, an enhanced phase adhesion and a strongly reduced anisotropy could be detected in case of well-compatibilized blends. In summary, the presented study of the fatigue crack growth behavior revealed a detailed insight into the mechanical property profile of the selected multiphase blends and, moreover, demonstrated the potential of this method to sensitively analyze the anisotropy of such materials.

OS4-1-3 Fatigue crack growth behavior of multiphase blends

The potential of fatigue crack growth experiments to sensitively analyze the anisotropic mechanical behavior of injection-molded, multiphase polymer blends is presented. The properties of immiscible blends based on poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and poly(styrene-co-acrylonitrile) is investigated, both in perpendicular and in parallel to the injection-direction. As a result of the limited interfacial adhesion and the orientation of the blend phases, the direction in parallel to flow revealed to be the weaker link. In order to enhance the toughness behavior, the PPE/SAN blends were systematically modified by the addition of different polystyrene-b-polybutadiene-b-poly(methyl methacrylate) triblock terpolymers (SBM), potentially acting as a compatibilizing and toughening agent. Such a compatibilization step of PPE/SAN blend leads to the formation of nanostructured morphologies. Depending on the composition of the triblock terpolymer, the resistance to crack growth was either further degraded or, in the case of high interfacial presence and compatibilization efficiency, significantly improved. The results were correlated to the fracture mechanisms of the blends as analyzed by scanning electron microscopy of the fracture surfaces. In contrast to poorly-compatibilized blends, a significant plastic deformation, an enhanced phase adhesion and a strongly reduced anisotropy could be detected in case of well-compatibilized blends. In summary, the presented study of the fatigue crack growth behavior revealed a detailed insight into the mechanical property profile of the selected multiphase blends and, moreover, demonstrated the potential of this method to sensitively analyze the anisotropy of such materials.

Development of Micro- and Nanocellular Polymers

ABSTRACTThe batch-foaming behavior of multiphase polymer blends and block copolymers was systematically investigated using carbon dioxide as a blowing agent. Three different polymer systems were evaluated: (i) nanostructured triblock terpolymers, (ii) microstructured polymer blends, and (iii) nanostructured polymer blends. In order to obtain nanostructured blends, immis-cible blends of poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene-co-acrylonitrile) (PPE/SAN) were melt-compatibilised via polystyrene-b-polybutadiene-b-poly(methyl methacry-late) triblock terpolymers. Due to the specific interaction between the respective components, a nanostructured interphase between PPE and SAN was observed. With regard to neat block co-polymers, the self-assembly of solvent-cast SBM triblock terpolymers was exploited in order to produce nanostructured morphologies. In each case, the resulting foam morphology was charac-terized by evaluating the foam density as well as the cell size. Combined with the multiphase structure of the non-foamed material and its thermal as well as physical behavior, relationships between the foaming characteristics and the cellular morphology were established. As an exam-ple for the foaming results, submicro-cellular structures were observed by foaming nanostruc-tured polymer blends, while the cell walls still revealed the nanostructured morphology. In con-trast, batch-foaming of neat triblock terpolymers led to the formation of microcellular foams; however, as highlighted by scanning electron microscopy, the cell walls did undergo some fur-ther expansion and formed additional nano-sized cells. In the light of these results, new routes for preparing cellular polymers are derived by systematically exploiting the multiphase charac-teristics of polymer blends and block copolymers.

Deformation study of the dispersed phase in filled polymer blends using LCP/PP/SiO 2 as model systems

The evolution of microstructure in multiphase polymer blends often encompasses the deformation of the dispersed phase during flow. The deformation is usually complex and relies on several interdependent rhelogical and morphological parameters. The effects of inorganic particulate fillers on the deformation of dispersed phases in polymer blends have not been studied systematically despite the ubiquity of such systems. In order to carry out such a systematic study, a model blend system comprising a liquid crystalline polymer as the dispersed phase suspended in a polypropylene matrix in the presence of silica particles was used. A theoretical approach based on the capillary number is proposed for some quantitative analysis of the deformation of the dispersed phase imparted by particulate fillers and shear force. A master curve which reveals the complicated and yet crucial co-relationships between the capillary number and the effects of shear rate and filler content on the extent of deformation is established.

Blue, green, red, and white electroluminescence from multichromophore polymer blends

We extend our previous investigations of electro-optically active polymer blends to report enhanced blue, green, red, or white electroluminescence (EL) from a multicomponent multiphase polymer blend containing blue, green, and red light emitting chromophores in different proportions as required together with both hole and electron transport materials. The general architecture of the EL devices employed was indium–tin–oxide (ITO)/poly p-phenylene vinylene (PPV)/blend/Ca or Al, in which a PPV layer was interspersed between the ITO and the blend layers to provide more efficient hole injection, enhance overall emission, and increase device longevity. The relevant EL mechanisms are discussed in terms of color related and efficiency related processes. The color related EL processes involve blueshifted emissions controlled by chromophore dilution, Förster energy transfer controlled mainly by spectral overlap between absorption and emission in chromophores, and an interfacial emission from the PPV layer. The efficiency related processes involve double charge injection controlled by the nature and concentration of the hole and electron transport materials present, the confinement of injected charge carriers controlled by the blend morphology, and potential barriers within the polymer blend layer. The design of devices which emit the desired color, efficiently balance the double charge injection, and optimize the confinement of injected charge carriers to provide high quantum yields by using polymer blends, is discussed.

Study on morphology of ternary polymer blends. I. Effects of melt viscosity and interfacial interaction

AbstractThe morphology of some ternary blends was investigated. In all of the blends polypropylene, as the major phase, was blended with two different minor phases, ethylene–propylene–diene terpolymer (EPDM) or ethylene–propylene–rubber (EPR) as the first minor phase and high‐density polyethylene (HDPE) or polystyrene (PS) as the second minor phase. All the blends were investigated in a constant composition of 70/15/15 wt %. Theoretical models predict that the dispersed phase of a multiphase polymer blend will either form an encapsulation‐type phase morphology or phases will remain separately dispersed, depending on which morphology has the lower free energy or positive spreading coefficient. Interfacial interaction between phases was found to play a significant role in determining the type of morphology of these blend systems. A core–shell‐type morphology for HDPE encapsulated by rubber was obtained for PP/rubber/PE ternary blends, whereas PP/rubber/PS blends showed a separately dispersed type of morphology. These results were found to be in good agreement with the theoretical predictions. Steady‐state torque for each component was used to study the effect of melt viscosity ratio on the morphology of the blends. It was found that the torque ratios affect only the size of the dispersed phases and have no appreciable influence on the type of morphology. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1129–1137, 2001

Characterization of chemical heterogeneity in polymer systems using hydrolysis and tapping‐mode atomic force microscopy

AbstractCharacterization of polymer coatings microstructure is critical to the fundamental understanding of the corrosion of coated metals. An approach for mapping the chemical heterogeneity of a polymer system using chemical modification and tapping‐mode atomic force microscopy (TMAFM) is demonstrated. This approach is based on the selective degradation of one of the phases in a multiphase polymer blend system and the ability of TMAFM to provide nanoscale lateral information about the different phases in the polymer system. Films made of a 70:30 polyethyl acrylate/polystyrene (PEA/PS) blend were exposed to a hydrolytic acidic environment and analyzed using TMAFM. Pits were observed to form in the PEA/PS blend films, and this degradation behavior was similar to that of the PEA material. Using these results, the domains in the 70:30 blend were identified as the PS‐rich regions and the matrix as the PEA‐rich region. This conclusion was confirmed by Fourier transform infrared‐attenuated total reflection analyses that revealed the hydrolysis of the PEA material. TMAFM phase imaging was also used to follow pit growth of the blend as a function of exposure time. The usefulness of the chemical modification/AFM imaging approach in understanding the degradation process of a coating film is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci B Part B: Polym Phys 39: 1460–1470, 2001