• Journal of the Korean Applied Science and Technology
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• v.28 no.3
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• pp.299-305
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• 2011

Alloys of nylon(PA6) and ethylene-propylene-diene polymer, modified with maleic anhydride(MEPDM) were prepared using a melt kneading process. This study focuses on the effects of the content of MEPDM in PA6 blend on the mechanical and thermal properties of such blends where MEPDM is the dispersed phase. Mechanical properties were examined by stress-strain measurements and impact strength test. Both impact strength of PA6/MEPDM at room temperature and at $-20^{\circ}C$ were improved up to 400-550% with the amounts of MEPDM. However, PA6/MEPDM containing 3-5 wt% of MEPDM showed the about $700kg_f/m^2$ of the maximum tensile strength but 8.5 % of the lowest elongation. For certain compositions of PA6 with rubbery MEPDM, the interesting reduction of elongation is caused by the reaction of the polyamide amine end groups with maleic anhydride portion in MEPDM, that provided a reinforcement in the PA6 matrix. In addition, the introduction of antistatic agent on the surface of alloys causes significant reduction of their surface electrostatic resistance.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.9-17
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• 1999

Viscoelastic characteristics of cured phenolic resin/carbon fiber composite materials were investigated through glass transition and degradation reaction processes in the high temperature region up to $400^{\circ}C$. A typical glass transition of the cross-linked thermoset polymer was followed by irreversible degradation reactions, which were exhibited by the increasing storage modulus and loss modulus peak. A degradation master curve was constructed by using the vertical and horizontal shift factors, both of which complied well with the Arrhenius equation in light of the kinetic expression of degradation rate constants. Using an analogy to the Havriliak-Negami equation in dielectric relaxation phenomena, a viscoelastic modeling methodology was developed to characterize the frequency- and temperature-dependent complex moduli of the degrading thermoset polymer composite systems. The temperature-dependent relaxation time of the degrading composites was determined in a continuous fashion and showed a minimum relaxation time between the glass transition and degradation reaction regions. The capability of the developed modeling methodology was demonstrated by describing the complex behavior of the viscoelastic complex moduli of reacting phenolic resin composite systems.

• Polymer(Korea)
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• v.25 no.5
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• pp.691-698
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• 2001

Nanocomposites based on epoxy acid nanoclay were prepared employing organically modified mica type silicate (OMTS), diglycidyl ether of bisphenol A (DGEBA) type epoxy. curing agent (dicyandiamide; DICY), and catalyst (benzyl dimethyl amine; BDMA). Both melt mixing and solution mixing were und for the sample preparation and structural developments with curing reaction were analyzed using X-ray diffractometer (XRD) and small angle X-ray scattering (SAXS). Because of the different curing rate between extra-gallery and intra-gallery reactions of epoxy mixtures, only intercalated structure was observed for the sample prepared by melt mixing while fully exfoliated structure was observed for the sample prepared by solution mixing. Mechanical properties of exfoliated epoxy nanocomposite were investigated using a dynamic mechanical analyzer (DMA). The dynamic storage modulus of the nanocomposite in both glass and rubbery plateau regions were increased with increasing OMTS contents, but glass transition temperatures ($T_g$) remained unchanged. Thermal properties of epoxy nanocomposite were investigated using thermogravimetric (TGA) and limit oxygen index (LOI) methods. Thermal decomposition onset points and LOI values were increased with increasing OMTS contents due to barrier effects of OMTS sheets.

• Macromolecular Research
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• v.11 no.5
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• pp.375-381
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• 2003

Silver salt complex membranes with glassy poly(methyl methacrylate) (PMMA) unexpectedly showed higher propylene permeance than those with rubbery poly(butyl methacrylate) (PBMA) where as neat PMMA is much less permeable to propylene than that of neat PBMA. Such unusual facilitated olefin transport has been systematically investigated by changing the side chain length of polymethacrylates (PMAs) from methyl, ethyl to butyl. The ab initio calculation showed almost the same electron densities of the carbonyl oxygens in the three PMAs, expecting very similar intensity of the interaction between carbonyl oxygen and silver ion. However, the interaction intensity decreases with the length of the alkyl side chain: PMMA > PEMA > PBMA according to wide angle X-ray scattering and FT-Raman spectroscopy. The difference in the interaction intensity may arise from the difference in the hydrophilicity of the three PMAs, as confirmed by the contact angle of water, which determines the concentrations of the ionic constituents of silver salts: free ion, contact ion pair and higher order ionic aggregate. However, propylene solubilities and facilitated propylene transport vary with the side chain length significantly even at the same concentration of the free ion, the most active olefin carrier, suggesting possible difference in the prohibition of the molecular access of propylene to silver ion by the side chains: the steric hindrance. Therefore, it may be concluded that both the hydrophilicity and the steric hindrance associated with the side chain length in the three PMAs are of pivotal importance in determining facilitated olefin transport through polymer/silver salt complex membranes.

• Membrane Journal
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• v.24 no.3
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• pp.185-193
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• 2014

PDMS (polydimethylsiloxane)-HNT (halloysite nanotube) composite membranes were prepared with different amounts tendency of HNT 5, 10, 20 and 30 wt% and rubbery polymer PDMS. The characteristics of these membranes were studied by FT-IR, XRD, TGA, and SEM. Gas permeation experiment were performed under condition of $25^{\circ}C$ and $3kg/cm^2$. Gas permeability of $N_2$, $H_2$, $CH_4$, and $CO_2$ and selectivity were investigated by increasing the amount of HNT contents in the PDMS. In $H_2$, $N_2$, $CH_4$, and $CO_2$ gases, as increasing HNT contents from 0 to 30 wt%, decreasing value of the permeability were observed. The selectivity of ($CO_2/N_2$) was shown in the range of 14 to 44 and the range of selectivity of ($CO_2/CH_4$) was 3.0 to 7.0.

• Membrane Journal
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• v.20 no.3
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• pp.203-209
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• 2010

Amphiphilic graft copolymers based on poly(epichlorohydrine) (PECH) were synthesized using atom transfer radical polymerization (ATRP). Successful graft polymerization of poly(methyl methacrylate)(PMMA) and poly(butyl methacrylate) (PBMA) from PECH was confirmed by nuclear magnetic resonance ($^1H$ NMR) and FT-IR spectroscopy. Upon the introduction of KI or LiI to the graft copolymers, the ether stretching bands were shifted to a lower wavenumber due to coordinative interactions. Ionic conductivities of PECH-g-PBMA complexes were always higher than those of PECH-g-PMMA complexes, resulting from higher mobility of rubbery PBMA chains. The maximum ionic conductivity of $2.7{\times}10^{-5}\;S/cm$ was obtained at 10 wt% of KI for PECH-g-PBMA electrolytes.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.305-313
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• 2013

In this study, we investigated effects of thermal annealing on the thermal properties and microphase separation behaviors of glycidyl azide-based thermoplastic polyurethane elastomers (ETPE). The GAP-based ETPEs were characterized by attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), and gel permeation chromatography (GPC). The effects of annealing temperature conditions ($80{\sim}130^{\circ}C$, 1 h or 24 h) on the properties of the ETPEs were investigated. The intensity of azide group absorption peak of ATR-FTIR spectra and the solubility of ETPE for methylene chloride and dimethylformamide solvent decreased after the annealing at $130^{\circ}C$ for 1 h and at $105^{\circ}C$ for 24 h. With increasing the annealing temperature from $80^{\circ}C$ to $110^{\circ}C$, the high temperature rubbery plateau region of storage modulus curves from DMA thermogram for GAP-based ETPEs was extended to the higher temperature.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.193-199
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• 1998

The mixtures of ultra-high molecular weight polythylene (UHMWPE), high density polyethylene (HDPE), process oil (mineral oil) and potassium hexatitanate whisker were melted and mixed at $150^{\circ}C$ for 30min, and prepared by compression molding to the specimen of separator of about $200{\mu}m$ thickness at the same temperature and 5000 psi. Thereafter the pores were formed by extracting process oil with organic solvents. In this study, the range of PR (the ratio polymer to process oil) was varied from 0.1 to 0.5 because the specimen turned into rubbery phase at which PR was below 0.1 whereas it changed into gel phase at which PR was above 0.5. When the specimen was treated with nonpolar organic solvents, process oil was extracted nearly 98%. Tensile strength was $31kg/cm^2$ at PR = 0.426, and resistance of specimen was $37m{\Omega}/cm^2$ at PR = 0.186, and $53m{\Omega}/cm^2$ at PR = 0.426. The $N_2$ adsorption-desorption isotherm showed a hysteresis representing regions of capillary condensation, and the surface area at PR = 0.186 was relatively large as $130cm^2/g$. Potassium hexatitanate whisker was randomly dispersed in between PE layers. It might be that the whisker is intercalated through the PE thin layers oriented by compression.

• 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.