• Carbon letters
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• 제11권4호
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• pp.311-315
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• 2010

In this work, the effect of glycidyl methacrylate grafted multi-walled carbon nanotubes (GMA-MWCNTs) on the viscoelastic behaviors of polypropylene (PP) based nanocomposites was studied. The GMA-MWCNTs/PP was prepared using a bravender at $200^{\circ}C$ by melt mixing as a function of GMA-MWCNT content. The viscoelastic behaviors of GMA-MWCNTs/PP nanocomposites were measured by a rheometer. It was found that the GMA-MWCNTs were homogeneously dispersed in the PP matrix. The GMA-MWCNTs/PP nanocomposites showed higher storage modulus, loss modulus, and shear viscosity compared to pure PP nanocomposites and the maximum value was shown at 2.0 wt% GMA-MWCNTs loading. These results were probably attributed to the strong interfacial interaction between the GMA-MWCNT and the PP matrix.

• 폴리머
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• 제25권2호
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• pp.226-232
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• 2001

The properties of poly(ethylene terephthalate) (PET)/maleic anhydride-grafted polypropylene (MAgPP)/poly(styrene-co-maleic anhydride)(PScMA) ternary blend were investigated. The ternary blend was immiscible based on the glass transition temperatures measured by dynamic mechanical analyzer (DMA). The degradation of MAgPP during melt mixing for 30 min at 280$^{\circ}C$ did not affect the properties of the ternary blend. The interaction among the components was confirmed from the rheological properties, which was increased with the PSCMA contents. In terms of the mechanical properties, it was observed to satisfy the mixture rule for a multiple system.

• Macromolecular Research
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• 제11권4호
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• pp.224-230
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• 2003

The blends of polypropylene (PP) with glass filled thermotropic liquid crystalline polymer (LCP-g) have been prepared by melt mixing techniques at different blend ratios. The thermal, dynamic mechanical, crystalline and morphological characteristics of these blends were investigated. Higher percent crystallinity was observed for 10% level of LCP-g in the blend in comparison to that of other blend ratios. The thermal stability increased with LCP-g concentration in the blend with PP. The variation of storage modulus, stiffness and loss modulus as a function of blend ratios suggested the phase inversion at the 50% level of LCP-g in the blend. The scanning electron microscopy (SEM) photographs showed the creation of voids and destruction of the fiber structures during the dynamic mechanical measurements. Processing behavior of the blends depended on the fiber forming characteristics of LCP-g, which again varied with the molding temperatures.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2001년도 가을 학술발표회 논문집
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• pp.9-12
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• 2001

Blending is an easy and popular means to achieve a desired set of characteristic properties. The blends, by melt mixing of thermoplastic materials and elastomer, have received considerable attention in recent years. It is well known that nearly all blends comprise one polymer domain dispersed in the matrices of the other polymer [1]. (omitted)

• Carbon letters
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• 제13권1호
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• pp.51-55
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• 2012

In this work, expanded graphite (EG)-reinforced poly(ethylene terephthalate) (PET) nanocomposites were prepared by the melt mixing method and the content of the EG was fixed as 2 wt%. The effect of multi-walled carbon nanotubes (MWCNTs) as a co-carbon filler on the electrical and mechanical properties of the EG/PET was investigated. The results showed that the electrical and mechanical properties of the EG/PET were significantly increased with the addition of MWCNTs, showing an improvement over those of PET prepared with EG alone. This was most likely caused by the interconnections in the MWCNTs between the EG layers in the PET matrix. It was found that the addition of the MWCNTs into EG/PET led to dense conductive networks for easy electron transfers, indicating a bridge effect of the MWCNTs.

• 반도체디스플레이기술학회지
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• 제10권1호
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• pp.107-111
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• 2011

Polypropylene(PP)/carbon fiber(CF)/multi-walled carbon nanotube(MWCNT) nanocomposites along with various CF and MWCNT contents were prepared in a Twin screw extruder. Electrical, mechanical property and morphology were investigated with a variation of CF and MWCNT contents. From the surface resistance of PP/CF/MWCNT composites, MWCNT can increase the conductivity of composites compared with PP/CF composites without MWCNT. It is suggested that MWCNT and CF can make the conductive network in the polymer matrix. Flexural modulus and Izod impact strength of the PP/CF/MWCNT composites were improved with the increase of CF contents. Morphology showed that length of CF in polymer matrix was shortened by torque during melt mixing with MWCNT. As a result of this phenomenon, the impact strength of composites was somewhat decreased.

• Macromolecular Research
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• 제8권4호
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• pp.186-191
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• 2000

Clay-dispersed nanocomposites have been prepared by simple melt-mixing of three components, i.e. poly (styrene co-acrylonitrile) copolymer (SAN), poly ($\xi$-caprolactone ) (PCL), and an organophilic clay(Cloisite(R) 30A). In the present study, poly($\xi$-caprolactone) was added in the mixtures in order to facilitate the intercalation of SAN into the gallery of silicate layers, and the molecular weight effects of PCL on the dispersion of silicate layers were compared by changing the amount of added PCL. The degree of dispersion of 10-$\AA$-thick silicate layers of clay in the nanocomposites was investigated by using an X-ray diffractometer and a transmission electron microscope. It was found that PCL added in the mixture facilitate the intercalation of SAN copolymers into the galleries of silicate layers modified with an organic intercalant, resulting in the better dispersion of clay. It was, also, observed that the processing temperature influences the degree of clay dispersion.

• 한국세라믹학회지
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• 제31권4호
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• pp.399-406
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• 1994

The SiC/MoSi2 composite material was prepared by infiltration with the mixture of metal Si and MoSi2 into the preform of $\alpha$-SiC and graphite under the vacuum atmosphere of 10-1 torr. The mechanical properties, phases and microstructural characteristics have been investigated by employing an universal testing machine, scanning electron microscope and X-ray diffractometer. With the increase of MoSi2/Si mixing content, the quantity of the residual silicon phase was decreased and the hardness and fracture toughness of composite materials were increased. Also, as the infiltration temperature increased, a lot of fine-grained $\beta$-SiC phases, which were produced from the reaction of graphite and liquid silicon melt, were transformed to $\alpha$-SiC phases.

• Macromolecular Research
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• 제10권6호
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• pp.365-368
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• 2002

Thermoplastic polyurethanes (TPUs) with different hard segment length has been prepared from a fixed molar ratio of poly(tetramethylene ether glycol), 4,4'-diphenylmethane diisocyanate, and 1,4-butanediol by different polymerization procedures. Results reveal that the on-set temperature of endotherms ( $T_{cc}$ ) due to the crystallization of hard segments by cooling the TPUs from melt and the peak temperature of endotherms due to the melting of hard segments ( $T_{mh}$ ) by heating the TPUs increased and levelled off with increasing the hard segment length of TPUs. It has also been observed that soft segment glass transition temperature ( $T_{gs}$ ) of TPU decreased slightly with increasing the hard segment length, which explains less mixing of soft segments and hard segments. In tensile measurement of TPUs, strain hardening is observed with increasing the hard segment length, which is attributed to the strain induced crystallization of soft segments.

• Bulletin of the Korean Chemical Society
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• 제21권1호
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• pp.69-74
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• 2000

Applicability of Thermal field flow fractionation (ThFFF) was investigated for the analysis of masticated natural rubber (NR) adhesives produced bya hot melt mastication process. An optimum ThFFF condition for NR analysis was found by using tetrahydrofuran (THF) as a solvent/carrier and a field-programming. Low flowrate (0.3 mL/min) was used to avoid stopping the flow for the sample relaxation. Measured molecular weight distribution was used to monitor degradation of rubber during the mastication process. Rubber samples collected at three different stages of the mastication process and were analyzed by ThFFF. It was found that in an anaerobic process rubber degradation occurs at the resin-mixing (compounding) zone as well as in the initial break-down zone, while in an aerobic process most of degradation occurs at the initial breakdown zone. It was also found that E-beam radiation on NR causes a slight increase in the NR molecular weight due to the formation of a branched structure.