• Polymer(Korea)
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• v.29 no.1
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• pp.19-24
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• 2005

Polymer blends containing polypropylene (PP) with compatibilizers were prepared using twin screw extruder. Physical properties were investigated using universal test machine (UTM) and Izod impact tester. In the PP/acrylonitrilebutadiene-styrene (ABS) blends, mechanical strength was increased with the addition of PP-g-styrene acryloritrile (PP-g-SAN) compatibilizer, and the ductility was increased with the addition of ethylene-ethyl acrylate-maleic anhydride (E-EAMAH-g-SAN) compatibilizer. For the PP/ABS/ polycarbonate (PC)/Nylon-6,6 blends, impact strength was increased with the addition of ethylene glycidylmethacrylate (E-GMA compatibilizer) up to 0.5 phr. In the case of the PP/ABS/PC/Nylon-6,6/poly(methyl methacrylate) (PMMA)/poly(oxymethylene) (POM)/poly(vinyl acetate) (PVC)/poly(butylene terephthalate) (PBT) blends, mechanical properties were increased by the complex compatibilizing effects of PP-g-SAN, E-EA-MAH-g-SAN and E-GMA, respectively.

• Microbiology and Biotechnology Letters
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• v.33 no.3
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• pp.189-193
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• 2005

IgE-dependent histamine-releasing factor(HRF) was initially described as a secretagogue for secretion of histamine from IgE+ basophils from a subset of allergic donors. Previously, we identified that S98 residue of HRF was phosphorylated using anti-HRFpS98 antibody which specifically recognizes the phosphorylated serine residue of HRF and HRFS98A mutant construct. In vitro kinase assay, only wild type HRF was phosphorylated by PKC, and S98A HRF was not affected by PKC. In this study, we attempted to characterize the phosphatase which specifically dephosphorylates HRF by immunoprecipitation and pull-down assay. In RBL-2H3 cells, HRF interacted only with calcineurin (also called as PP2B, calcium/calmodulin-dependent phosphatase) but not with PP1 or PP2A. The results suggest that HRF is most likely dephosphory-lated by calcineurin.

• Polymer(Korea)
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• v.27 no.5
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• pp.458-463
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• 2003

The effect of ozone surface treatment of montmorillonite (MMT) was investigated in thermal stabilities of polypropylene (PP) nanocomposites. Sodium montmorillonite (Na$\^$+/-MMT) was organically modified with dodecylammonium chloride. The surface properties of MMT, including the specific surface area (S$\_$BET/), equilibrium spreading pressure ($\pi$$\_$e/), and London dispersive component (${\gamma}$s$\^$L/), were studied by the BET method with $N_2$ adsorption. Also, the thermal stabilities of the nanocomposites were investigated in DSC and TGA. As experimental results, $\pi$$\_$e/ and ${\gamma}$s$\^$L/ of the ozonized dodecylammonium chloride (DA-MK ( $O_3$)) were increased in about 1.7 and 3.5 mJ/ $m^2$, resulting from the increasing of the micropores. From the DSC results, it was found that the melting temperature and crystallization temperature of PP/DA-MK and PP/DA-MK ( $O_3$) were higher that those of pure PP. These results were explained that dodecylammonium chloride of nano-scale led to a nucleation effect for PP crystallization. Also, it was found that E$\_$t/ of the PP/DA-MK ( $O_3$) nanocomposies was increased within about 64 kJ/mol. These results were probably explained by the improvement of dispersivity of DA-MK ( $O_3$) in a PP matrix.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.74-85
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• 2010

In order to formulate the compounded polypropylene(C-PP) which is suitable to an automotive door trim panel, 9 sorts of properties were measured after manufacturing the C-PP using an extruder and an injection machine with polypropylene(PP), ethylene-octene rubber(EOR) and talc. Mixture design, especially extreme vertices design, in DOE with MINITAB - commercial software was used to analyze the data. The relations between each property and each component, for example, $y=0.00907222x_1+0.00870556x_2+0.0155722x_3$ for specific gravity, were found out by the regression analysis and the variance analysis. The optimized formulation of the C-PP for an automotive door trim panel was acquired at PP(77.6962), EOR(11.0238) and talc(10.2800) by use of the response optimizer(mixture) in MINITAB.

• International Journal of Concrete Structures and Materials
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• v.18 no.2E
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• pp.103-109
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• 2006

Spalling is defined as damages to concrete exposed to high temperature during fire, causing cracks and localized bursting of small pieces of concrete. As the concrete strength increases, the degree of damage caused by spalling becomes more serious due to impaired permeability. It is reported that polypropylene(PP) fiber has an important role in protecting concrete from spalling, and the optimum dosage of PP fiber is 0.2%. However, this study was conducted on non-reinforced concrete specimens. The high-temperature behavior of high-strength reinforced concrete columns with various concrete strength and various quantity of PP fibers is investigated in this study. The results revealed that the ratio of unstressed residual strength of columns increased as the concrete strength increased and as the quantity of PP fiber increased from 0% to 0.2%. However, the effect of PP fiber quantity on residual strength of column was barely above 0.2%.

• Journal of Digital Convergence
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• v.16 no.12
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• pp.163-173
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• 2018

This study examined the difference between the information asymmetry in pre- and post K-IFRS adoption used each samples. Efficient market assumption suggests that capital markets already have recognized real value of PP&E and applied those values for estimating the item, in which case PP&E revaluation is not additional information in the capital market but simply an activity to makes costs. This study examined whether the information asymmetry had reduced significantly after adopting K-IFRS or not, verified each period samples those are pre- and post-adopting the asset revaluation since it could have been adopted in advance from 2008. As study results, I confirmed PP&E revaluation affected to reduce the information asymmetry in pre- adopting K-IFRS, but not in post- adopting K-IFRS. These results could be one of proofs which are supported that capital market have been judging PP&E revaluation as the window dressing.

• Macromolecular Research
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• v.17 no.11
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• pp.886-893
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• 2009

Surface modifications using a radio frequency Ar-plasma treatment were performed on a polypropylene (PP) blend used for automotive bumper fascia. The surface characterization and morphology were examined. With increasing aging time, there was an increase in wettability, oxygen containing polar functional groups (i.e., C-O, C=O and O-C=O) due to oxidation, the amount of tale, and bearing depth and roughness on the PP surface, while there was a decrease in the number of hydrocarbon groups (i.e., C-C and C-H). AFM indicated that the Ar-plasma-treatment on a PP blend surface transforms the wholly annular surface into a locally dimpled surface, leading to an improvement in wettability. SEM showed that the PP layer observed in the non-plasma-treated sample was removed after the Ar-plasma treatment and the rubber particles were exposed to the surface. The observed surface characterization and morphologies are responsible for the improved wettability and interfacial adhesion between the PP blend substrate and bumper coating layers.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.467-472
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• 2011

This study investigated illite/polypropylene (PP) composite filament formation via melt-spinning and evaluated their physical properties to prepare functional fibers using natural materials. When composite filaments were formed, the composite filaments exhibited smaller fiber diameters compared to that of neat PP filament because of the lubricant effect of illite induced by its layered structure. Moreover, fluorination effect increased interfacial affinity and dispersion in the polymer, resulting in smaller diameter of fluorinated illite/PP composite filament, which was 2/3 of the neat PP filament diameter. Addition of raw and fluorinated illite improved thermal stability of illite/PP composite filament. Raw illite/PP composite filament cannot be used for a practical application, because it broke during drawing process, whereas the fluorinated illite/PP composite filament can be used for a practical application, because it exhibited similar tensile strength of the neat PP filament and 50% increased modulus. Even with improved illite/PP interfacial affinity and illite dispersion in the polymer, illite/PP composite filament formed microcomposite, because non-expandable illite had strongly bound layers, resulting in only a little illite exfoliation and PP intercalation into illite.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.69-73
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• 2010

The melt grafting of unsaturated silanes onto polypropylene (PP) in a twin-screw extruder and crosslinking in hot water were studied to enhance impact strength of polypropylene. The influence of grafting formulations on the melt flow rates of grafted PP and the gel percentages of crosslinked PP was investigated. 3-methacryloylpropyltrimethoxysilane (VMMS) unsaturated silane monomer was used. Benzoyl peroxide, (BPO) and Dicumyl peroxide (DCP) were used as an initiator. When benzoyl peroxide (BPO) was used as an initiator, higher gel percentage and impact strength than those of DCP has been observed. The maximum impact strength was obtained with 0.7 phr of BPO and 2phr of VMMS. The value is 8.7 kgf-cm/cm and it is on a parity with the value of with 20 phr of EOR mixed to PP.

• Polymer(Korea)
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• v.26 no.3
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• pp.287-292
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• 2002

Graft copolymerization of styrene and glycidyl methacrylate (GMA) to the peroxidized polypropylene (PP) fabric with E-beam in $O_2$ atmosphere was carried out in vapor phase with benzoyl peroxide (BPO) as an initiator. The degree of grafting of copolymers was increased with the increase of the reaction temperature and the highest degree of grafting was obtained at $70^{\circ}C$ with styrene, and at $80^{\circ}C$ with GMA. The highest degree of grafting of styrene grafted PP according to reaction time was higher than that of GMA grafted PP. In vapor phase graft polymerization, the degree of grafting of copolymers according to water composition in monomer mixture was effected by the boiling temperature of monomers.