Melt‐state miscibility of poly(ethylene‐co‐1‐octene) and linear polyethylene

On purpose to examine the effect of branch length on the miscibility of polyolefin blends, miscibility behavior of linear polyethylene/poly(ethylene‐co‐1‐octene) blend was studied and compared to that of linear polyethylene/poly(ethylene‐co‐1‐butene) blend. Miscibility of the blend was determined by observing the morphology quenched from the melt, and by using the relation between interaction parameter and copolymer composition. When the weight composition and molecular weight was the same, poly(ethylene‐co‐1‐octene) was slightly more miscible with linear polyethylene than poly(ethylene‐co‐1‐butene) was. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Melt rheological and thermodynamic properties of polyethylene homopolymers and poly(ethylene/α-olefin) copolymers with respect to molecular composition and structure

Various types of polyethylene homopolymers and copolymers, including linear high-density polyethylene (HDPE), branched low-density polyethylene (BLDPE), poly(ethylene vinyl acetate) copolymer (EVA), heterogeneous linear poly(ethylene/α-olefin) copolymer (het-LEAO) or commonly known as linear low-density polyethylene, homogeneous linear poly(ethylene/α-olefin) copolymer (hom-LEAO), and homogeneous branched poly(ethylene/α-olefin) copolymer (hom-BEAO), were evaluated for their melt rheological and thermodynamic properties with emphasis on their molecular structure. Short-chain branching (SCB) mainly controls the density, but it has little effect on the melt rheological properties. Long-chain branching (LCB) has little effect on the density and thermodynamic properties, but it has drastic effects on the melt rheological properties. LCB increases the pseudo-plasticity and the flow activation energy for both the polyethylene homopolymer and copolymer. Compared at a same melt index and a similar density, hom-LEAO has the highest viscosity in processing among all polymers due to its linear molecular structure and very narrow molecular weight distribution. Small amounts of LCB in hom-BEAO very effectively reduce the average viscosity and also improve the flow stability. Both hom-LEAO and hom-BEAO, unlike het-LEAO, have thermodynamic properties similar to BLDPE. © 1996 John Wiley & Sons, Inc.     

Rheological properties and morphological evolutions of polypropylene/ethylene‐butene copolymer blends

This work aims at studying the extensional rheological behavior of polypropylene (PP), ethylene‐butene copolymer (PEB) and their blends in the melt. The weight fraction of the PEB in the blend is 20 and 40%, respectively. Dynamic mechanical analysis shows that these two blends exhibit two tanδ peaks corresponding to the glass transitions of the PP and PEB, respectively. Differential scanning calorimeter results indicate that the presence of the PEB does not alter the melting and crystallization temperatures of the PP. Master curves at 170°C are constructed for the storage and loss modulus as well as complex viscosity. The extensional behavior of the PP, PEB, and their two blends is studied. The PEB enhances the strain hardening of the PP. Changes in the blend morphology during the extensional analysis are also studied. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Effect of mixing conditions on the rheological and optical properties of chemically modified poly(ethylene terephthalate‐co‐ethylene isophthalate)

The optical properties and rheological properties were studied for binary reactive blends composed of poly(ethylene terephthalate‐co‐ethylene isophthalate) [P(ET–EI)] and a styrene–acrylate based copolymer with glycidyl functionality. The blade rotation speed in the internal mixer greatly affected the structure and properties for the blend system. Intensive mixing at a high rotation speed enhanced the optical transparency because of the reduced particle size of the dispersed phase. The graft copolymer generated by the reaction between P(ET–EI) and the modifier was responsible for the fine morphology. Furthermore, the copolymer also enhanced the elastic nature in the molten state because it acted as a long‐chain branched polymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Fabrication of super water repellent silver flake/copolymer blend films and their potential as smart fabrics

A facile technique is demonstrated for the fabrication of super water repellent co‐polymer blend‐silver composite films from fatty acid surface functionalized fine silver flakes. Initially, high concentrations of surface functionalized silver flakes were dispersed in poly(vinyl chloride‐co‐vinyl acetate‐co‐vinyl alcohol) copolymer in solution to form electrically conducting adhesives/paints (ECAs) with a bulk resistivity of ∼3 × 10⁻⁵ Ω cm. The solvent‐borne ECAs were then blended with a water‐dispersed perfluoromethacrylate copolymer (Zonyl 8740) using a simple solvent‐inversion process to obtain super water‐repellent colloidal copolymer blend‐silver emulsions. The colloidal emulsions could be spray‐deposited on a number of fibrous substrates including fabrics and paper. A particular example is demonstrated herein by spray‐depositing these emulsions onto molten paraffin wax‐based laminates (60°C), which were partially impregnated into fabrics to fabricate highly water repellent, flexible, and thermoresponsive fabrics. A paraffin wax/polyolefin blend base film was used for the purpose. The surface topology of the superhydrophobic copolymer/silver composite films displayed fractal‐like hierarchical structures ideal for self‐cleaning hydrophobicity. On relatively low‐absorbent permeable porous surfaces such as cellulosic films (paper) impregnated with wax/polyolefin films, self‐cleaning ability of the coatings was maintained even for temperatures at which paraffin wax component of the laminated film was molten indicated by low‐water roll‐off angles. Hence, the composites have excellent compatibility with organic phase change materials such as paraffin wax and wax/polyolefin blends, and they can be used to fabricate nonwetting, thermoregulated, and electroactive fabrics. Antimicrobial properties of silver offer additional advantages for potential biomedical applications. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Structural and morphological development in poly(ethylene-co-hexene) and poly(ethylene-co-butylene) blends due to the competition between liquid-liquid phase separation and crystallization

Isothermal crystallization behavior of poly(ethylene-co-hexene) (PEH) and the 50/50 blend (H50) of PEH with amorphous poly(ethylene-co-butylene) (PEB) was studied by time-resolved synchrotron simultaneous small-angle X-ray scattering/wide-angle X-ray diffraction (SAXS/WAXD) techniques and optical microscopy (OM). The X-ray study revealed the changes of structural and morphological variables such as the scattering invariant, crystallinity and lamellar long period, et al. In H50, the lamellar morphology was found to be dependent on competition between liquid-liquid phase separation (LLPS) and crystallization. At high temperature, LLPS becomes dominating, resulted in crystallization of PEH with minimal influence of PEB. At low temperature, LLPS is suppressed, PEB component shows obvious influence on PEH crystallization, PEB is thought to be partially included into PEH lamellar stacks and PEH-PEB co-crystallization is unlikely, however, possible. Optical microscopy was used to monitor crystal nucleation and growth rates in PEH and H50, providing complementary information about the effect of temperature on LLPS and crystallization. Real-space lamellar morphologies in PEH and H50 were characterized by atomic force microscopy (AFM), PEH exhibited sheaf-like spherulites while H50 exhibited hedrites. Overall, the competition between LLPS and crystallization in H50 blend influences the structural and morphological development. Controlling the interplay between LLPS and crystallization of PEH/PEB blends, it is possible to control the structure and morphology as practically needed.     

增容剂对硅橡胶/热塑性聚氨酯热塑性硫化胶性能的影响

采用动态硫化法制备了甲基乙烯基硅橡胶（MVQ）/热塑性聚氨酯（TPU）共混型热塑性硫化胶（TPV）,考察了增容剂的种类及用量对TPV力学性能及加工流变性能的影响。结果表明,随着增容剂用量的增加,TPV的力学性能呈先上升后下降的趋势。相比于乙烯丙烯酸共聚物和乙烯与乙酸乙烯嵌段共聚物,用聚烯烃弹性体接枝马来酸酐（POE-g-MAH）作为增容剂时TPV的力学性能更为优异。3种增容剂均能提高TPV中MVQ相与TPU相的相容性。当POE-g-MAH的用量为6份时,TPV中MVQ相与TPU相的玻璃化转变温度靠近程度最大,两相界面较为模糊,增容效果最佳。     

Thermal,rheological, mechanical,and dyeing property studies of poly(ethylene‐co‐trimethylene terephthalate) copolymer filaments

The thermal and rheological properties of poly(ethylene‐co‐trimethylene terephthalate) (PETT) copolymer are investigated. The thermal behavior of PETT copolymers is dependent on the composition. The PETT‐15 and PETT‐85 copolymers can crystallize, whereas the PETT‐30 copolymer cannot crystallize at 5°C/min cooling rate. The copolymers have a good thermal stability, even though the addition of poly(trimethylene terephthalate) (PTT) chain causes a disadvantage to the thermal stability of the copolymers. Moreover, the PETT copolymers are a typical pseudoplastic fluid exhibiting shear thinning. With increasing the shear rate or the content of PTT units, the flow activation energy decreases and the sensitivity of the shear viscosity to the melt temperature declines. The PETT copolymer filaments have intermediate elastic recovery and dyeability between poly(ethylene terephthalate) (PET) and PTT filaments. With increasing the PTT content, the elastic recovery and dyeability of PETT copolymer filaments increase. That is to say, introducing PTT units as a minor component into the macromolecular chains is an available means to improve the properties of PET filament. The obtained PETT copolymer filaments blend the advantage of the mechanical property of PET and the elastic and dyeability of PTT filament together into one polymer and possess a softer feeling and a higher extension. POLYM. ENG. SCI., 50:1689–1695, 2010. © 2010 Society of Plastics Engineers     

Blends of poly(propylene) and polyacetal compatibilized by ethylene vinyl alcohol copolymers

Polymer blends of poly(propylene) (PP) and polyacetal (polyoxymethylene, POM) with ethylene vinyl alcohol (EVOH) copolymers were investigated by differential scanning calorimetry (DSC), rheological, tensile, and impact measurements, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The PP–POM–EVOH blends were extruded with a co‐rotating twin‐screw extruder. The ethylene group in the EVOH is partially miscible with PP, whereas the hydroxyl group in the EVOH can form hydrogen bonding with POM. The EVOH tends to reside along the interface, acting as a surfactant to reduce the interfacial tension and to increase the interfacial adhesion between the blends. Results from SEM and mechanical tests indicate that a small quantity of the EVOH copolymer or a smaller vinyl alcohol content in the EVOH copolymer results in a better compatibilized blend in terms of finer phase domains and better mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1471–1477, 2003     

Binary and ternary blends of polyethylene,polypropylene, and polyamide 6,6: The effect of compatibilization on the morphology and rheology

The effects of two compatibilizing agents, polystyrene–poly(ethylene butylene)–polystyrene copolymer (SEBS) and SEBS‐grafted maleic anhydride (SEBS‐g‐MAH), on the morphology of binary and ternary blends of polyethylene, polypropylene, and polyamide 6,6 were investigated with scanning electron microscopy and melt rheology measurements. The addition of the compatibilizers led to finer dispersions of the particles of the minor component and a decrease in their size; this induced a significant change in the blend morphology. The rheological measurements confirmed the increased interaction between the blend components, especially with SEBS‐g‐MAH as the compatibilizer. New covalent bonds could be expected to form through an amine–anhydride reaction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1976–1985, 2004     

A facile preparation of highly interconnected macroporous PLGA scaffolds by liquid-liquid phase separation II

A regular and well-interconnected macroporous (from 50 to 200 μm) poly(d,l-lactic acid-co-glycolic acid) (PLGA) scaffold was fabricated by means of the thermally induced phase separation (TIPS) method. Poly(l-lactic acid) (PLLA) was blended with PLGA to increase the viscosity of polymer solution; a block copolymer of poly(ethylene glycol) (PEG) with PLGA was added as a surfactant to decrease the interfacial tension between the polymer-rich and polymer-lean phases. The effect of TIPS parameters including the concentration of diblock copolymer and PLGA/PLLA ratio was also studied. The cloud-point curve shifted to higher temperatures with both increasing the PLLA composition in the PLGA/PLLA blend and the PEG contents in the additives (PEG itself and PEG-PLGA diblocks). This shifting to higher temperature increases the quenching depth during phase separation. Addition of a PEG-PLGA diblock copolymer (0.5 wt% in solution) to the PLGA/PLLA (1/1) blend polymer in a dioxane/water solution stabilized the morphology development during TIPS with respect to interconnection and macropores, and avoided segregation or sedimentation in the late stage.     

Shape memory property and underlying mechanism by the phase separation control of poly(ϵ‐caprolactone)/poly(ether‐b‐amide)

In this work, a poly(?‐caprolactone)/poly(ether‐b‐amide) blend with weight ratio 35/65 was prepared by solution mixing and compression molding. A simple and sensible method to control the phase separation structure was introduced by adjusting the temperature and time for the process of phase separation. Samples with obviously different morphology were obtained and the microstructure was studied by phase contrast optical microscopy, SEM and DSC. The shape memory properties were measured using dynamic mechanical analysis. The results show that the shape memory performance of the blend is closely related to the phase morphology, and the blend with co‐continuous structure has a better shape memory property. A model is put forward to illustrate schematically the microstructural evolution during the shape memory process. © 2018 Society of Chemical Industry     

Compatibility effect of reactive copolymers on polypropylene/polyamide 6 blends from commingled plastic wastes

We report the compatibility effect on a recycled polypropylene/nylon (75/25) blend processed with reactive copolymers on the basis of morphological, mechanical, and rheological characteristics. Via a scanning electron microscopy investigation, we found improved surface morphologies with regular and fine domains in a recycled polypropylene/nylon (75/25) blend compatibilized with copolymers containing maleic anhydride as a reactive functional group [styrene–(ethylene/butylene)–styrene‐graft‐maleic anhydride copolymer and polypropylene‐graft‐maleic anhydride]. Large increases in both the mechanical and rheological properties with the addition of the styrene–(ethylene/butylene)–styrene‐graft‐maleic anhydride copolymer could be interpreted with respect to a specific structure at the interface, showing a strong interfacial adhesion between recycled polypropylene and nylon. To confirm the existence of this structure, we used various dynamic rheological parameters: the Cox–Merz rule, storage modulus, and phase angle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1188–1193, 2006     

Influence of carbon black and carbon nanotubes on the conductivity,morphology, and rheology of conductive ternary polymer blends

The influence of carbon black (CB) and multiwall carbon nanotubes (CNT) with different colloidal properties on the phase morphology, electrical properties, and rheological behavior in a polypropylene (PP)/poly(methyl methacrylate) (PMMA)/ethylene acrylic acid copolymer (EAA) ternary polymer blend was studied. A PP/PMMA/(EAA‐CNT) system was compared to two different PP/PMMA/(EAA‐CB) systems. The relationship between the phase morphology, electrical percolation threshold, and rheological behavior was analyzed. The critical percolation threshold for the ternary system was found to be around 0.5 vol% for the PP/PMMA/(EAA‐CB1) and 0.2 vol% for the PP/PMMA/(EAA‐CB2) and PP/PMMA/(EAA‐CNT), which were more than 8 times lower than for the single phase systems. The rheological threshold coincided with the electrical resistivity percolation threshold inversion point. It was proposed that beyond a critical loading of conductive filler particles in the minor EAA phase, especially for high aspect ratio fillers such as the CB2 and CNT, phase separation is slowed significantly due to the aggregation of particles into a network formation within the EAA phase causing a significant increase in phase viscosity. The results are consistent with the hypothesis that the kinetics of phase separation and resulting formation of a tri‐continuous morphology are dictated by the viscosity of the minor phase relative to the two major phases. POLYM. ENG. SCI., 57:1329–1339, 2017. © 2017 Society of Plastics Engineers     

Primary structure and physical properties of poly(ethylene terephthalate)/poly(ethylene naphthalate) resin blends

The morphology and properties of blends of poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) that were injection molded under various conditions were studied. Under injection molding conditions that make it possible to secure transparency, blends did not show clear crystallinity at blending ratios of more than 20 mol% in spite of the fact that crystallinity can be observed in the range of PEN content up to 30 mol%. Because both transparency and crystallinity could be secured with a PEN 12 mol% blend, this material was used in injection molding experiments with various injection molding cycles. Whitening occurred with a cycle of 20 sec, and transparency was obtained at 30 sec or more. This was attributed to the fact that transesterification between PET and PEN exceeded 5 mol% and phase solubility (compatibility) between the PET and PEN increased when the injection molding time was 30 sec or longer. However, when the transesterification content exceeded 8 mol%, molecularly oriented crystallization did not occur, even under stretching, and consequently, it was not possible to increase the strength of the material by stretching. PET/PEN blend resins are more easily crystallized by stretch heat‐setting than are PET/PEN copolymer resins. It was understood that this is because residual PET, which has not undergone transesterification, contributes to crystallization. However, because transesterification reduces crystallinity, the heat‐set density of blends did not increase as significantly as that of pure PET, even in high temperature heat‐setting. Gas permeability showed the same tendency as density. Namely, pure PET showed a substantial decrease in oxygen transmission after high temperature heat‐setting, but the decrease in gas permeability in the blend material was small at heat‐set temperatures of 140°C and higher.     

Separation of polyolefins based on comonomer content using high‐temperature gradient adsorption liquid chromatography with a graphitic carbon column

This report describes the application of a recently developed polyolefin characterization tool based upon gradient adsorption high‐temperature liquid chromatography (HT‐LC) using a graphitic carbon stationary phase to polyolefin homopolymer and previously unreported copolymer systems. Polyolefin‐based materials find utility in a broad range of applications and are differentiated by parameters such as molecular weight and comonomer content. Polymer comonomer distribution is commonly determined by crystallinity‐based separations (ATREF, CRYSTAF). These techniques, however, are time consuming. In addition, some semicrystalline polymers undergo cocrystallization, impacting the techniques' universal utility. Adsorption‐based HT‐LC can ideally overcome the limitations of crystallinity‐based separations, shedding new light on the composition of randomly‐polymerized polyolefins. In this report the basic separation capability of the adsorption HT‐LC technique, using a graphitic carbon column, is demonstrated for poly (ethylene‐co‐octene) and poly(ethylene‐co‐propylene) systems and compared with select precipitation/redissolution HT‐LC and ATREF results. Select results in this paper are also compared and contrasted to other recent publications on similar separations of polyolefins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical,rheological, thermal,and morphological properties of blends based on poly(propylene)/poly(propylene‐co‐1‐octene)/poly(ethylene‐co‐1‐octene)

The effect of addition of propylene copolymer, produced by metallocene catalysts, on the mechanical, rheological, and morphological properties of blends based on poly(propylene) (PP) and ethylene–1‐octene copolymer (EOC) was evaluated. It was observed that the addition of 2 wt % propylene–1‐octene copolymer (POC) improved the impact strength of the EOC/PP blends. The rheological analysis indicated that the addition of propylene copolymer produced materials with improved processability. Thermal and morphological analysis showed that the POC acts as a compatibilizer on the EOC/PP blends. © 2003 Wiley Periodicals, J Appl Polym Sci 89: 1690–1695, 2003     

Crystallization behavior of PEO in blends of poly(ethylene oxide)/poly(2‐vinyl pyridine)‐b‐(ethylene oxide) block copolymer

The crystallization behavior of two molecular weight poly(ethylene oxide)s (PEO) and their blends with the block copolymer poly(2‐vinyl pyridine)‐b‐poly(ethylene oxide) (P2VP‐b‐PEO) was investigated by polarized optical microscopy, thermogravimetric analysis, differential scanning calorimetry, and atomic force microscopy (AFM). A sharp decreasing of the spherulite growth rate was observed with the increasing of the copolymer content in the blend. The addition of P2VP‐b‐PEO to PEO increases the degradation temperature becoming the thermal stability of the blend very similar to that of the block copolymer P2VP‐b‐PEO. Glass transition temperatures, T_g, for PEO/P2VP‐b‐PEO blends were intermediate between those of the pure components and the value increased as the content of PEO homopolymer decreased in the blend. AFM images showed spherulites with lamellar crystal morphology for the homopolymer PEO. Lamellar crystal morphology with sheaf‐like lamellar arrangement was observed for 80 wt% PEO(200M) and a lamellar crystal morphology with grain aggregation was observed for 50 and 20 wt% blends. The isothermal crystallization kinetics of PEO was progressively retarded as the copolymer content in the blend increased, since the copolymer hinders the molecular mobility in the miscible amorphous phase. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Thermodynamically induced self‐assembled electrically conductive networks in carbon‐black‐filled ternary polymer blends

By calculating the surface tensions of the components, composites with innovative thermodynamically induced self‐assembled electrically conductive networks were designed, prepared and investigated. Carbon black (CB) was added into a ternary blend system comprised of poly(methyl methacrylate) (PMMA), ethylene–acrylic acid copolymer (EAA) and polypropylene (PP). Scanning electron microscopy images show that the PMMA/EAA/PP ternary blend forms a tri‐continuous phase structure like a sandwich, in which PMMA and PP form a co‐continuous phase while EAA spreads at the interface of the PMMA and PP phases as a sheath. The micrographs and resistivity–temperature characteristic curve results indicate that CB fillers are selectively located at the interface of the PMMA and PP phases, namely the EAA phase. The percolation threshold of PMMA/EAA‐CB/PP composites is 0.2 vol%, which is only one‐fifth of that of PP/CB composites. Copyright © 2011 Society of Chemical Industry     

Differential scanning calorimetric and free volume study of reactive compatibilization by EPM‐g‐MA of poly(trimethylene terephthalate)/EPDM blends

Differential scanning calorimetry (DSC) and positron annihilation lifetime measurements have been carried out to study the effect of the compatibilizer maleic anhydride grafted ethylene propylene copolymer (EPM‐g‐MA) in poly trimethylene terephthalate and ethylene propylene diene monomer (PTT/EPDM) immiscible blends. The DSC results for the blends of 50/50 and 30/70 compositions show two clear glass transition temperatures, indicating that the blends are two‐phase systems. With the addition of compatibilizer, the separation between the two glass transitions decreased, suggesting an increased interaction between the blend components with compatibilizer. At 5 wt % of compatibilizer, the separation between the T_gs reduced in both 50/50 and 30/70 blends. The positron results for the blends without compatibilizer showed an increase in relative fractional free volume, as the EPDM content in the blend is increased. This suggests the coalescence of free volume of EPDM with the free volumes of PTT due to phase separation. However, the effect of compatibilizer in the blends was clearly seen with the observed minimum in free volume parameters at 5% of the compatibilizer, further suggesting that this percent of compatibilizer seems to be the optimum value for these blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 740–747, 2006