• Polymer(Korea)
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• v.26 no.2
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• pp.237-244
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• 2002

Mechanical properties, flow characteristics and chemical resistance of polycarbonate (PC)/polybutylene terephthalate (PBT) /impact modifier (IM) blends were investigated over the various composition ranges of PC and PBT. Mechanical properties of the PC/PBT/IM blends for different IMs, butadiene based IM and butyl acrylate based IM, were studied for various compositions of the IMs. Impact strength at low temperature was also observed. For the study of chemical resistance of the PC/PBT/IM blends, the blonds were dipped in organic solvent, thinner, and then variations of mechanical properties were analyzed. Tensile and flexural strengths were increased linearly and heat distortion temperature (HDT) also increased as PC content in the blends increased. Impact strength increased drastically as PC content increased up to 50 wt% and stayed stable value. Flowability decreased as PC content increased. Impact strengths of the blend were various for different IMs. Butyl acrylate based IM showed slightly higher impact strength than butadiene based IM for the temperature above $0^{\circ}C$. However, butadiene based IM showed remarkably higher impact strength than butyl acrylate based IM for the temperature below $0^{\circ}C$. Through the experiment of chemical resistance it was observed that tensile and flexural strengths decreased, and impact strength increased as PC content in the blends increased. PC in the blend would become mild and ductile when it contacted with organic solvent. Thus the impact strength increased while tensile and flexural strength decreased.

• Polymer(Korea)
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• v.36 no.5
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• pp.549-554
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• 2012

It was known that triphenyl phosphate wasn't homogeneously dispersed in HDPE/EPDM/boron carbide blends, which caused the decrease in mechanical properties. HDPE, EPDM, boron carbide, and triphenyl phosphate were blended with PE-g-MAH(polyethylene-graft-maleic anhydride) as a compatiblizer for improving the miscibility of triphenyl phosphate. Tensile strength of HDPE/EPDM/boron carbide blends decreased with increasing the contents of triphenyl phosphate for flammability. However, the mechanical properties of HDPE/EPDM/boron carbide/triphenyl phosphate blends increased by the addition of compatiblizer because triphenyl phosphate was homogeneously mixed in the blend system. The homogeneous dispersibility of triphenyl phosphate was confirmed by using scanning electron microscopy (SEM). Increased thermal stability and flammability derived from high miscibility of triphenyl phosphate were confirmed by the results of thermogravimetric analysis (TGA) and limiting oxygen index (LOI). A self-extinguishing HDPE/EPDM/boron carbide/triphenyl phosphate blend was successfully fabricated with more than 21% LOI.

• Polymer(Korea)
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• v.33 no.4
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• pp.290-296
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• 2009

The morphology and mechanical properties of epoxy/polyamide/MPD/2E4MZ-CN reactive blends with various amount of catalyst were investigated. The cure behaviors, mechanical strengths, and morphological changes of the epoxy blend systems were analyzed by using DSC, UTM, and SEM, respectively. The amount of catalyst ranged from 0 to 3 phr, and the cure reaction occurred at $170^{\circ}C$ for 30 min. The maximum peaks in heat flow during cure reactions appeared at slightly lower temperature with increasing catalyst content, indicating that the cure reactions start at lower temperature by adding catalyst and polyamide rarely hinders the cure reaction paths. The co-continuous morphology was found in epoxy/polyamide(20 phr) blends and by adding catalyst to the blends much clearer and uniform co-continuous phase was observed. The surface tension of the mechanical test specimen was increased due to the AP plasma surface treatment, and then adhesion strength was increased by over 20% by adding 2 phr of catalyst to the blends. When considering morphological tuning of the blends by means of catalyst incorporation, it is expected that the increased elongation and adhesion strength can be achieved in the structural adhesive systems.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.616-626
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• 1993

Polyurethane(PU) have an excellent flexibility and toughness so that it has been widely used as an elastomer. PMMA was blended with PU to improve the impact property. Five types of PU, having different molecular weight and different polyol types, were prepared and blended with PMMA in order to investigate the effect of molecular weight and polyol type of PU on property of PU-PMMA blend. Tensile strength of PU-PMMA blend was determined by Inston. Differential Scanning Calorymetry(DSC) and Scanning. Elctron Microscopy(SEM) were used to observe morphology change and glass transition temperature changes of PU-PMMA blends. Transparency of PU-PMMA blends was determined by haze meter. But, owing to intrinsic incompatability of PU-PMMA, Low impact strength of PMMA wasn't improved through PU-PMMA blend. therefore, polyurethane dimethacrylate(PUD), having similiar chemical structure to PU and two vinyl group at both ends, was prepared and reacted with methyl methacrylate(MMA) to form crosslinked copolymer Mechanical property of this crosslinked polymer, such as impact strength and transparency, was investigated by Instron, Izod type (Cantilever beam) impact tester and haze meter. Results of these measurements showed that crosslinked copolymer of PUD-MMA was better impact resistance than PMMA and maintained similar transparency to PMMA.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.557-561
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• 2007

Polypropylene (PP)/corn starch master batch (starch-MB) blends with different PP compositions of 40, 50, 60, and 80 wt% were prepared by melt compounding at $200^{\circ}C$, using lab scale Brabender mixer. The chemical structures and thermal properties of the PP/starch-MB blends were investigated by FT-IR, differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). The chemical structure was confirmed by the existence of hydroxy group. There was no district change in melting temperature and melting enthalpy, and TGA curve indicated a decrease in degradation temperature with starch-MB content. The porosity change of blend was measured by scanning electron microscope (SEM), the degree of porosity on the blend surface increased with the starch-MB content. The rheological properties indicated an increase in complex viscosity, shear thinning tendency and elasticity with the starch-MB concentration. These effects were confirmed by an oscillatory viscometer at $200^{\circ}C$. From these results, it is found that 40 wt% is the optimum starch-MB concentration. The fiber was fabricated from PP60/MB40 with 40 wt% starch-MB and the porosity and tensile properties were investigated.

• Elastomers and Composites
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• v.37 no.2
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• pp.79-85
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• 2002

Ethyl-branched polyethylene [PE(2)] containing 2mole% ethyl branch and three ethylene-propylene rubbers (EPR's) having the same ethylene(E)-propylene(P) molar ratio(E/P=50/50) with different stereoregularity, that is, random EPR (r-EPR), alternating-EPR (alt-EPR) and isotactic-alternating-EPR (iso-alt-EPR) were mixed for the investigation or their properties depending on the stereoregularity. Crystallinity of the prepared blends decreased with increasing content of amorphous EPR because of a decrease in both the degree of annealing and kinetics of diffusion of the crystallizable polymer content. With blend composition, crystallinity was reduced with the stereoregularity in EPR. The thermodynamic interaction parameter(x) for the three blend systems approximately equals to zero near the melting point. These systems were determined to be miscible on a molecular scale near or above the crystalline melting point or the crystalline PE(2). From the measurement of $T_m$ vs. $T_c$, the behavior of PE(2) is mainly due to a diluent effect of EPR component. The spherulite size measured by small angle light scattering (SALS) technique depended upon blend composition, and stereoregularity of EPR. The size of spherulite was enlarged with the content of rubbery EPR and the decrease of stereoregularity in EPR.

• Membrane Journal
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• v.34 no.3
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• pp.192-203
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• 2024

The advancement of commercially viable gas separation membranes plays a pivotal role in improving CO₂ separation efficiency. High-molecular-weight poly(ethylene oxide) (high-Mw PEO) emerges as a promising option due to its high CO₂ solubility, affordability, and robust mechanical attributes. However, the crystalline nature of high-Mw PEO hinders its application in gas separation membranes. This study proposes a straightforward blending approach by incorporating various polymeric additives into high-Mw PEO to address this challenge. Four commercially available, water-soluble polymers, i.e. poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), poly(acrylic acid) (PAA), and poly(vinyl pyrrolidone) (PVP) are examined as additives to enhance membrane performance by improving miscibility and reducing PEO crystallinity. Contrary to expectations, PEG and PPG fail to inhibit the crystalline structure of PEO and result in membrane flaws. Conversely, PAA and PVP demonstrate greater success in altering the crystal structure of PEO, yielding defect-free membranes. A thorough investigation delves into the correlation between changes in the crystalline structure of high-Mw PEO blend membranes and their gas separation performance. Drawing from our findings and previously documented outcomes, we offer insights into designing and selecting additive polymers for high-Mw PEO, aiming at the creation of cost-effective, commercially viable CO₂ separation membranes.

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.396-401
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• 2013

Alternating copolymers, poly[9-(2-octyl-dodecyl)-9H-carbazole-alt-4,7-di-thiophen-2-yl-benzo[1,2,5]thiadiazole] (PCD20TBT) and poly[9,10-bis-(2-octyl-dodecyloxy)-phenanthrene-alt-4,7-di-thiophen-2-yl-benzo[1,2,5]thiadiazole] (PN40TBT), were synthesized by the Suzuki coupling reaction. The copolymers were soluble in common organic solvents such as chloroform, chlorobenzene, 1,2-dichlorobenzene, tetrahydrofuran and toluene. The maximum absorption wavelength and the band gap of PCD20TBT were 535 nm and 1.75 eV, respectively. The maximum absorption wavelength and the band gap of PN40TBT were 560 nm and 1.97 eV, respectively. The HOMO and the LUMO energy level of PCD20TBT were -5.11 eV and -3.36 eV, respectively. As for PN40TBT, the HOMO and the LUMO energy level of PCD20TBT were -5.31 eV and -3.34 eV, respectively. The polymer solar cells (PSCs) based on the blend of copolymer and PCBM (1 : 2 by weight ratio) were fabricated. The power conversion efficiencies of PSCs based on PCD20TBT and PN40TBT were 0.52% and 0.60%, respectively. The short circuit current density ($J_{SC}$), fill factor (FF) and open circuit voltage ($V_{OC}$) of the device with PCD20TBT were $-1.97mA/cm^2$, 38.2% and 0.69 V. For PN40TBT, the $J_{SC}$, FF, and $V_{OC}$ were $-1.77mA/cm^2$, 42.9%, and 0.79 V, respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.11.2-11.2
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• 2011

Polymer based organic photovoltaics have attracted a great deal of attention due to the potential cost-effectiveness of light-weight and flexible solar cells. However, most BHJ polymer solar cells are not thermally stable as subsequent exposure to heat drives further development of the morphology towards a state of macrophase separation in the micrometer scale. Here we would like to show three different approaches for developing new electroactive polymers to improve the thermal stability of the BHJ solar cells, which is a critical problem for the commercialization of these solar cells. For one of the examples, we report a new series of functionalized polythiophene (PT-x) copolymers for use in solution processed organic photovoltaics (OPVs). PT-x copolymers were synthesized from two different monomers, where the ratio of the monomers was carefully controlled to achieve a UV photo-crosslinkable layer while leaving the ${\pi}-{\pi}$ stacking feature of conjugated polymers unchanged. The crosslinking stabilizes PT-x/PCBM blend morphology preventing the macro phase separation between two components, which lead to OPVs with remarkably enhanced thermal stability. The drastic improvement in thermal stabilities is further characterized by microscopy as well as grazing incidence X-ray scattering (GIXS). In the second part of talk, we will discuss the use of block copolymers as active materials for WOLEDs in which phosphorescent emitter isolation can be achieved. We have exploited the use of triarylamine (TPA) oxadiazole (OXA) diblock copolymers (TPA-b-OXA), which have been used as host materials due to their high triplet energy and charge-transport properties enabling a balance of holes and electrons. Organization of phosphorescent domains in TPA-b-OXA block copolymers is demonstrated to yield dual emission for white electroluminescence. Our approach minimizes energy transfer between two colored species by site isolation through morphology control, allowing higher loading concentration of red emitters with improved device performance. Furthermore, by varying the molecular weight of TPA-b-OXA and the ratio of blue to red emitters, we have investigated the effect of domain spacing on the electroluminescence spectrum and device performance.

• Polymer(Korea)
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• v.25 no.3
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• pp.441-449
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• 2001

Compatibilization of blends based on poly(phenylene ether) (PPE) and polyamide (PA) has been practiced with the incorporation of a copolymer formed by grafting polystyrene onto polybutadiene latex (g-BS) which is further functionalized with maleic anhydride (MAH) (g-BS*) to impart reactivity with amine groups of PA. The major focus has been placed on the effect of the various structural factors in g-BS8 on the phase morphology and mechanical performance of the blends. For the balance of impact strength and heat resistance, it was important to locate g-BS n particles inside of the PPE phase, which was accomplished by the proper control of the molecular weight and amount of PS in g-BS*. For g-BS*'s having constant molecular weight and amount of PS, the reduction of MAH content or increase of rubber particle size in g-BS* resulted in the increase of domain size and consequently loss in mechanical properties. Based on the comparison made with the conventional PPE/PA blend comprising MAH grafted PPE as a compatibilizer, it was confirmed that the comparable level of mechanical performance can be achieved by an appropriate g-BS* type material with improved whiteness index.