Domain Size Of Dispersed Phase Research Articles

Effect of EVA copolymer containing different VA content on the thermal and rheological properties of bio-based high-density polyethylene/ethylene vinyl acetate blends

The effect of ethylene vinyl acetate (EVA) concentration and vinyl acetate (VA) content of EVA on the mechanical, morphological, and rheological properties of bio-based high-density polyethylene (BioPE)/EVA blends was investigated. The blends were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and rheological measurements under oscillatory shear flow. The degree of crystallinity of BioPE decreased with the increase in the EVA concentration and was unaffected with the increase in the VA content. DMTA results showed a decrease in the storage modulus (E′) with the increase in EVA content and that the BioPE/EVA19 blends showed higher E′ values than BioPE/EVA28 blend. The impact strength substantially increased with the addition of EVA concentration above 5 mass% and was higher for the blends containing the highest VA content. The blends containing a higher content of VA exhibited the higher EVA dispersed phase domain size, which increased with the increase in EVA concentration. The complex viscosity increased with the increase in the EVA content, being higher for the BioPE/EVA blends containing higher VA content. The storage modulus increased, at low frequencies, with the increase in the EVA content and can be ascribed to the increase in the EVA dispersed phase domain size.

Halloysite Nanotubes Filled in Asymmetric Blend of Polyamide 6, 12/poly (Ethylene‐Octene) Elastomer: Tough‐to‐Brittle Transition in Nanocomposites

SummaryA tough‐to‐brittle transition is distinctly observed with a critical correspondence to dispersed phase domain size in halloysite nanotubes filled ternary nanocomposites based on compositionally asymmetric and toughened blend of polyamide 6, 12 (PA‐6, 12)/poly(ethylene‐octene) copolymer‐g‐maleic anhydride (POE‐g‐MA) as the matrix. The maxima in the resistance to fracture initiation and crack propagation resistance normalized fracture initiation as a measure of toughness followed by a significant drop with a direct correspondence to brittleness‐index (BI), comprehensively establishes such a transition. Microscopically a smooth transition in the deformation mechanism above a domain‐size (Dn) of ∼0.43 μm with an intrinsic brittleness‐index (BI) of ∼0.57 (×1012 Pa−1) seem to be responsible for the same.

Preparation and Properties of Thermally Stable Lignin-based Copolymer/PP Blends by Melt Process

Lignin-based polycaprolactone (LigPCL) copolymer was synthesized by both the ring opening reaction of e- caprolactone with the hydroxyl groups in the lignin and the concomitant polymerization of e-caprolactone. FTIR spectra showed C=O (1755 cm ) and C-O (1202 cm ) peaks confirming that the esterification reaction took place successfully between lignin and e-caprolactone. T , at which the weight loss of 2% occurs, of pristine lignin and LigPCL were mea- sured as 63 and 211 C, respectively, and so the synthesized LigPCL had superior thermal stability to the lignin. PP/Lig- PCL blends were prepared at various contents of LigPCL up to 30 wt% by a melt extrusion process. In proportion to the content of the LigPCL, tensile strengths, flexural strengths, and tensile modulus of PP/LigPCL blends greatly decreased, but elongations at break of those greatly increased. To improve the compatibility between PP and LigPCL, maleic anhydride-grafted polypropylene (PP-g-MA) was added. SEM images for the fracture surfaces of the blends showed that the PP-g-MA was effective in reducing the domain size of dispersed phase. Thus, T , tensile strength, tensile modulus, and elongation at break of a 70/30 blend of PP/LigPCL were enhanced by 6 C, 17%, 31%, and 79%, respec- tively, by the addition of PP-g-MA. This work clearly demonstrates that thermoplastic LigPCL could be desirably syn- thesized and applied for value added and eco-friendly products through common melt processes used for polymer blend or composites manufacturing.

Super-toughening polyamide-612 by controlling dispersed phase domain size: Essential work of fracture assessment

A new pathway to super-toughen polyamide-612 (PA-612) by incorporating domains of soft poly(octene-co-ethylene)-g-maleic anhydride (POE-g-MA) via melt blending leading to more than ∼1100% increase in notched Izod impact strength vis-à-vis fracture toughness enhancement is demonstrated. Fourier transform infra red (FTIR) studies showed effective phase interactions between PA-612 and POE-g-MA whereas dynamic mechanical analysis (DMA) revealed a reduction in loss-peak intensity at ∼45°C with increase in the soft phase fraction. The optimal dependence of fracture-toughness (in plane-stress) on domain-size (Dn) of dispersed-phase in the form of a reduction in resistance to crack initiation indicated by essential work of fracture (we) and linear increase in resistance to crack propagation indicated by non-essential work of fracture (βwp) of the blends ⩾10wt% of POE-g-MA content is correlated to an increase in domain-size ⩾∼0.3μm. Fracture surface morphology indicated crazing to be responsible for the transition in fracture behavior, i.e. remarkable toughening of PA-612 at the critical rubber phase domain size range of ∼0.2–0.3μm.

Segmental mobility in the vicinity of Tg in PS/SBR blends: Nanodomain size prediction of the dispersed phase

AbstractThe blends of polystyrene (PS) and styrene‐butadiene rubber (SBR) are melt‐blended at different ratios to form physical thermoplastic elastomers. This polymeric blend is expected to behave more or less similar to chemically synthesized block copolymers such as styrene‐butadiene block copolymers (SBS). In this study, mechanical and the thermomechanical properties of this blend are investigated and compared to those of SBS copolymer. As far as morphology is considered, the blend shows a two‐phase morphology with an interface, which shows very weak interactions. According to the observed morphology and the domain size of dispersed phase the blends are of good integrity. The mechanical properties of the blends confirm the integrity of the blend and effective interface stress transfer. The tensile and Izod impact properties of the blends shows improvements upon increase in SBR content of the blend. As SBR content augments the elongation at break increases, whereas tensile dissipated energy and impact resistance go through a maximum. Therefore, blend with SBR‐content in 60–75% range can be considered as preferred one. In a wide range of concentration a phase inversion was observed and Tg‐depression was detected also for the SBR phase. This Tg‐depression was correlated to the changes in dynamics of segments (segmental mobility) near the surfaces. Using the proposed relationships between Tg‐depression and the thickness of the thin films, it was tried to calculate domain size of SBR inclusions in PS matrix. A rough correlation between SBR domain sizes in SEM images and calculated thicknesses using Tg‐depression in thin films was found. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Compatibilizer‐tracer: A powerful concept for polymer‐blending processes

AbstractPolymer blending is a very important polymer processing operation. It aims at preparing new polymer materials by blending existing polymers without the need of creating new molecules. For immiscible polymer blends, it is always challenging, if not impossible, to choose an appropriate compatibilizer and assess its compatibilizing efficiency under pilot or industrial polymer‐blending conditions. The concept of compatibilizer‐tracer developed in this work is able to take this challenge. This is shown using polystyrene (PS)/polyamide 6 (PA6) blends and fluorescent labeled graft copolymers of PS and PA6 as compatibilizer‐tracer. Transient experiments allow using very small amounts of compatibilizer‐tracer to obtain emulsification curves, namely, the evolution of the dispersed phase domain size as a function of the compatibilizer‐tracer concentration. Other potential applications of this concept are discussed and its limitations are investigated. © 2010 American Institute of Chemical Engineers AIChE J, 58: 1921–1928, 2012

Compatibilization of PP/SEBS-MAH blends by grafting Glycidyl Methacrylate onto Polypropylene

In this paper, the glycidyl methacrylate(GMA) was grafted to Polypropylene(PP) macromolecular backbone by melt radical grafting. The grafted PP-g-GMA was used to compatibilize PP/SEBS-g-MAH blend in a Haake apparatus. The result of Fourier Transform Infrared(FTIR) spectrum showed that the GMA had been grafted to PP. And the reaction between epoxy groups in the GMA and MAH groups in SEBS-g-MAH had taken place. The result of torque test showed that the torque values of the compatibilized blends were higher than that of the uncompatibilized blends. The observation of Scanning Electron Microscopy (SEM) showed that the dispersed phase domain size of compatibilized blends decreased evidently than uncompatibilized blends. When the content of SEBS-g-MAH was 16 wt % and the PP-g-GMA was 2 wt % in the blend, the rubber particle size had a minimum value. Those indicated that the PP-g-GMA could compatibilize PP/ SEBS-g-MAH blends effectively. Notched Izod impact tests showed the addition of PP-g-GMA in the PP/SEBS-g-MAH blends induced a remarkable improvement of toughness and yielded a tougher PP blends.

Reactive Extrusion of Polypropylene and Nylon Blends from Commingled Plastic Wastes

AbstractReactive extrusion for recycled PP/nylon blends from commingled plastic wastes was investigated through thermal, morphological, mechanical and rheological studies. From SEM investigation, we found improved surface morphologies with homogeneous domains in the recycled 75/25 PP/nylon blends compatibilized with copolymers containing maleic anhydride (MA) as a reactive functional group; SEBS‐g‐MA, PP‐g‐MA, PE‐g‐MA. Especially, SEBS‐g‐MA thermoplastic elastomer which is highly reactive with amine terminal group of nylon, resulted in a large increase of impact strength above nearly 200%. This compatibilization effect resulted from the increase of interfacial adhesion and the reduction of domain size of dispersed phase in PP/nylon blend system. To confirm the existence of this network structure, we measured a dynamic rheological properties.

Compatibilization of PP/EPDM blends by grafting acrylic acid to polypropylene and epoxidizing the diene in EPDM

AbstractIn this article, ethylene–propylene–diene‐rubber (EPDM) was epoxidized with an in situ formed performic acid to prepare epoxided EPDM (eEPDM). The eEPDM together with the introduction of PP‐g‐AA was used to compatibilize PP/EPDM blends in a Haake mixer. FTIR results showed that the EPDM had been epoxidized. The reaction between epoxy groups in the eEPDM and carboxylic acid groups in PP‐g‐AA had taken place, and PP‐g‐EPDM copolymers were formed in situ. Torque test results showed that the actual temperature and torque values for the compatibilized blends were higher than that of the uncompatibilized blends. Scanning electron microscopy (SEM) observation showed that the dispersed phase domain size of compatibilized blends and the uncompatibilized blends were 0.5 and 1.5 μm, respectively. The eEPDM together with the introduction of PP‐g‐AA could compatibilize PP/EPDM blends effectively. Notched Izod impact tests showed that the formation of PP‐g‐EPDM copolymer improved the impact strength and yielded a tougher PP blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3949–3954, 2006

Mixing immiscible blends in an intermeshing counter‐rotating twin screw extruder

AbstractDomain size of 10% dispersed polystyrene in polyethylene was followed in a 34‐mm intermeshing counter‐rotating twin screw extruder. Variables studied included the effects of barrel temperature, screw speed, viscosity ratio of dispersed‐to‐continuous phase, and parallel melt versus preblended solids feeds. After steady state was achieved, die samples were quenched for later photomicrographing. The extruder was then stopped and quenched, with subsequent pulling of the screws. From 7 to 12 additional samples were taken along the 18/1 L/D extruder for determination of the mechanism of dispersion and dispersed phase domain size by optical microscopy. At low temperatures, the polystyrene tended to fracture with sharp edges. The fine particles formed in the initial breakup underwent no further size reduction. At higher temperatures, fractured segments had rounder edges, but the size of the small domains remained constant throughout the axial length. There was some evidence of flocculation and coalescence prior to exit through the die. © 2006 Wiley Periodicals, Inc. Adv Polym Techn 25: 81–89, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20065

Compatibilization of immiscible poly(l-lactide) and low density polyethylene blends

Blends of poly(l-lactide) (PLA) and low density polyethylene (LDPE) were prepared by melt mixing in order to improve the brittleness of PLA. A reactive compatibilizer with glycidyl methacrylate (GMA), PE-GMA, was required as a compatibilizer due to the immiscibility between PLA and LDPE. It contributes to reduce the domain size of dispersed phase and enhance the tensile properties of PLA/LDPE blends, especially for PLA matrix blends. A reaction product between PLA and PE-GMA, which was formed during melt-mixing and considered to act as a reactive compatibilizer, was characterized using1H-NMR spectroscopy.

Dynamic Rheological Properties of Polypropylene/Polyamide-6 Blends Modified with a Maleated Thermoplastic Elastomer

The effects of added maleated thermoplastic elastomer (TPEg) on rheological properties and morphologies of polypropylene (PP)/polyamide-6 (PA6) blends are examined. For comparison, non-maleated version (TPE) is also added to the above binary blends. The magnitude of complex viscosity and viscoelastic moduli of PP/ PA6/TPE blends gradually decrease with the content of TPE. However, for PP/PA6/TPEg blends, these above parameters increase dramatically with increasing content of reactive TPEg and shear-thinning behavior becomes more obvious. SEM micrographs show that the addition of TPEg effectively increases compatibility between PP and PA6 and results in a considerable decrease in the domain size of dispersed phase; whereas the ternary blends containing nonreactive TPE exhibit a typical characteristic of immiscible blends with a very coarse morphology. TEM results further reveal that for PP/PA6/TPEg blends, a core-shell structure consisting of PA6 particles encapsulated with POE are probably formed in PP matrix.

Ionomer compatibilised PA6/EVA blends: mechanical properties and morphological characterisation

The compatibilisation of PA6/EVA blends with the addition of an ionomer on the mechanical properties and morphology were studied as a function of ionomer concentration with the primary aim of enhancing the impact strength of PA6 by EVA. The level of EVA was kept at 20%, which formed the dispersed phase, and the ionomer content was varied from 0 to 1.6wt%. It was found that notched Izod impact strength of PA6/EVA/ionomer blends increased with the incorporation of ionomer to about three times of the value for uncompatibilised PA6/EVA blends. Further, it was observed that on incorporation of the ionomer the tensile strength also increased significantly. Analysis of the tensile data using predictive theories indicated an enhanced interaction of the dispersed phase and the matrix. SEM studies of cryogenically fractured surfaces indicated a decrease in dispersed phase domain size with the addition of the ionomer, while the impact fractured surfaces of PA6/EVA blends indicated extensive deformation with the formation of rumples indicating increased interfacial adhesion as compared to PA6/EVA blends. An attempt has been made to evaluate the compatibilising efficiency of ionomer in PA6/EVA blends.

Mechanical properties and morphology of PA6/EVA blends

AbstractThe mechanical properties of blends of polyamide6 (PA6) and ethylene vinyl acetate (EVA) at a blending composition of 0–50 wt % EVA were studied. The notched Izod impact strength of PA6 increased with the incorporation of EVA, the increase being more than 100% compared to PA6 at 10% EVA. The tensile strength and the tensile modulus of the blends decreased steadily as the weight percent of EVA increased. Analysis of the tensile data using predictive theories indicated the extent of the interaction of the dispersed phase and the matrix up to 20 wt % EVA. SEM studies of the cryogenically fractured surfaces indicated increase in the dispersed phase domain size with EVA concentrations. On the other hand, impact fractured surfaces of PA6/EVA blends indicated debonding of EVA particles, leaving hemispherical bumps, indicating inadequate interfacial adhesion between PA6 and EVA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1593–1606, 2002

The compatibilizing effect of poly(styrene-co-4-vinylpyridine) copolymers on the polystyrene-polyethylene-based ionomer blends

The compatibilizing effect of styrene-co-4-vinylpyridine (SVP) random copolymers on the immiscible polystyrene (PS)–polyethylene-based ionomer (Surlyn) blends was examined by means of scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and tensile test. For the binary SVP–Surlyn and ternary PS–Surlyn–SVP blends, the domain size of dispersed phase decreases dramatically with the increase in the vinyl pyridine (VP) content of the SVP copolymers. The mechanical properties are improved with increasing the VP content in copolymers. FTIR results suggest that the compatibilization in this blend system is attributed to the ion–dipole interaction between the polar VP groups of SVP copolymer and ionic groups of Surlyn. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 807–816, 1998

Effects of the molecular structure of styrene-isoprene block copolymers on the interfacial characteristics of polystyrene/polyisoprene blends

The effects of the molecular structure of the styrene-isoprene block copolymer on the interfacial tension, the morphology and the interfacial adhesion of polystyrene/polyisoprene were investigated. A reduction in interfacial tension is observed with the addition of a small amount of copolymer, followed by a leveling off as the copolymer concentration exceeds the critical micelle concentration. The reduction in interfacial tension between polystyrene and polyisoprene is more significant when the isoprene-rich diblock copolymer is added than the cases when the symmetric or styrene-rich diblock copolymer is added. The interfacial tension data seem to be consistent with the phase morphology and the interfacial adhesion: the lower the interfacial tension, the smaller the domain size of dispersed phase and the better the interfacial adhesion. © 1996 John Wiley & Sons, Inc.

Effect of molecular weight of functionalized polystyrene on the compatibility of blends of polyamide 6 and polystyrene

The effect of polystyrene modified with maleic anhydride (MPS) on the compatibility of the immiscible blends of polyamide 6 and polystyrene was investigated as a function of the molecular weight of MPS. The MPS was prepared by melt extrusion in a twin screw extruder and the content of maleic anhydride in the MPS was below 1 wt%. The compatibilizing ability of the MPS was examined through several experimental techniques such as scanning electron microscopy and measurements of mechanical and rheological properties. The interfacial adhesion between two separated phases was also measured using a butt joint test. The compatibilizing ability of the MPS was very dependent on the molecular weight of the MPS. The MPS of high molecular weight seems to be more effective in reducing the domain size of dispersed phase and in increasing the interfacial adhesion.