• Fibers and Polymers
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• 제2권2호
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• pp.81-85
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• 2001

The effects of rate of phase separation to ester interchange reactions and the repulsive pair interaction energy on the phase behavior in a phase-separated immiscible polyester blend are investigated using a Monte Carlo simulation method. The time evolution of structure factor and the degree of randomness are monitored as a function of homogenization time. When the phase separation is dominant over ester interchange reactions, the domain size slowly increases with homogenization time. However, when the pair interaction becomes less repulsive, the domain size does not significantly change with homogenization time. On the other hand, when ester interchange reactions are dominant over the phase separation, the homogenization proceeds without a change in the domain size. The higher the extent of phase separation, the lower the increasing rate of the DR. However, when the phase separation is sufficiently dominant, the effect of the extent of phase separation on the increasing rate of the degree of randomness become less significant.

• 한국유변학회:학술대회논문집
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• 한국유변학회 2002년도 추계학술발표회 논문집
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• pp.67-71
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• 2002

• 한국유변학회:학술대회논문집
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• 한국유변학회 2000년도 추계 학술발표회 논문집
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• pp.99-102
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• 2000

• 한국안전학회지
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• 제21권1호
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• pp.79-85
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• 2006

Olefinic compatibilized blend(R-PP/R-PE)/layered silicate composites have been prepared by melt intercalation technique directed from $Na^{+}$ montmorillonite(MMT) or organophilic montmorillonites while using magnesium hydroxide as flame retardant. Morphology and flammability properties were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), thermogravimetry analysis(TGA), limiting oxygen index(LOI), UL94 test. It is found that the compatibilized blend/layered silicate(Cloisite 20A) nanocomposites have a mixed immiscible-intercalated structure and there is better intercalation when a compatibilizer is combined with the polymer and layered silicate to be melt blended. A very large increase in the LOI value was observed with hybrid filler addition and further enhancement in thermal stability and compatibility of blend was obtained for the compatibilized blend containing small amount of layered silicate.

• Korea-Australia Rheology Journal
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• 제17권2호
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• pp.71-77
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• 2005

We investigated thermal, rheological, morphological and mechanical properties of a binary blend of poly(lactic acid) (PLA) and poly(butylene succinate adipate) (PBSA). The blends were extruded and their molded properties were examined. DSC thermograms of blends indicated that the thermal properties of PLA did not change noticeably with the amount of PBSA, but thermogravimetric analysis showed that thermal stability of the blends was lower than that of pure PLA and PBSA. Immiscibility was checked with thermal data. The rheological properties of the blends changed remarkably with composition. The tensile strength and modulus of blends decreased with PBSA content. Interestingly, however, the impact strength of PLA/PBSA (80/20) blend was seriously increased higher than the rule of mixture. Morphology of the blends showed a typical sea and island structure of immiscible blend. The effect of the blend composition on the biodegradation was also investigated. In the early stage of the degradation test, the highest rate was observed for the blend containing $80wt\%$ PBSA.

• 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.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.41.2-41.2
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• 2009

Electrospinning of Polyvinylalcohol (PVA), Gelatin (GE), and PVA/GE blend solutions in acetic acid were investigated to fabricate biodegradable for tissue engineering. The morphology of the electrospun nanofibers was investigated with a field emission scanning electron microscope. The fibers have average diameters in the range 50-150 nm. The miscibility of PVA/GE blend fibers was examined by differential scanning calorimetry.The PVA and GE were immiscible in the as-spun nanofibrous structure. X-ray diffraction (XRD) determined the crystallinity of the membrane and tensile strength for evaluation physical properties. An in vitro study of PVA/GE blend nanofibers was conducted. To assay the cytocompatibility and cell behavior on the PVA/GE blend nanofibrous scaffolds, cell attachment and spreading of fibroblasts seeded on the scaffolds were studied. Our results indicate that thePVA/GE blend nanofibrous matrix, particularly the one that contained 20% PVA and 80% GE could be a good candidate for tissue engineering scaffolds, because it has an excellent cell attachment and spreading for fibroblast cell.

• Korea-Australia Rheology Journal
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• 제11권3호
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• pp.255-263
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• 1999

Blends of two thermotropic liquid crystalline polymers, HX2000 and Vectra A950, were prepared by melt blending. Effects of transesterification on these blends are investigated by comparing properties of the blends with and without the addition of an inhibitor, in terms of blend miscibility and rheology. Both the uninhibited and inhibited blends are found to be largely immiscible with very limited miscibility in HX2000-rich phase. No strong evidence indicates the occurrence of transesterification in the blends in the solid state. Dynamic rheological behaviour, such as shear storage modulus (G') and shear loss modulus (G") as a function of frequency, of the blends are interpreted by a three-zone model. HX2000 shows terminal-zone and plateau-zone behaviour, whilst Vectra A950 shows plateau-zone and transition-zone behaviour. The un- inhibited blends show plateau-zone behaviour up to 50% Vectra A950 content and the inhibited blends show plateau-zone behaviour up to 60% Vectra A950 content. Compositional dependence of the complex viscosities of the uninhibited and inhibited blends displayed positive deviations from additivity, which is a characteristic feature for the immiscible thermoplastic blends. When under steady shear, both the uninhibited and inhibited blends show shear thinning behaviour and their viscosities decrease monotonically with the addition of Vectra A950. Compositional dependence of the steady shear viscosities of the two sets of blends displayed negative deviations from additivity and the uninhibited blends were more viscous than the inhibited blends for the full composition range. Although limited agreement with the Cox-Merz rule is found for the inhibited blends, these two sets of blends, in general, do not follow the rule due to their liquid crystalline order and two-phase morphology. Despite being immiscible blends, transesterification, such as polymerization, in the blends might occur during the rheological characterization, supported by the facts that uninhibited blends show HX2000-dominant behaviour at lower Vectra A950 content and are more viscous than the inhibited blends. The addition of transesterification inhibitor in such blends is advised if only physical mixing is desired.ired.

• 폴리머
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• 제27권5호
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• pp.413-420
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• 2003

형광 현미경을 이용하여 4-클로로-7-니트로벤조퓨라잔이 표지된 폴리스티렌과 폴리부타디엔 블렌드 디옥틸프탈레이트 용액의 전단력하에서의 상평형 거동을 관찰하였다. 형광 현미경과 위상차 현미경을 동시에 사용하여 형광이미지가 실제 블렌드용액의 모폴로지와 같음을 알 수 있었다. 형광 현미경을 이용하여 각 도메인에서 형광의 세기를 측정함으로써 도메인상 (폴리스티렌 풍부상)과 연속 매트릭스상 (폴리부타디엔 풍부상)이 외부에서 가해준 전단력에 의하여 조성비가 변화하는 것을 관찰하였다. 이렇게 측정되어진 전단력의 변화에 따른 조성 차이의 변화로부터 상분리 곡선이 이동함을 알 수 있었다.

• 폴리머
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• 제33권6호
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• pp.588-595
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• 2009

본 연구의 목적은 기능성 단량체인 glycidyl methacrylate(GMA)와 전자선을 이용하여 비혼화성 poly (lactic acid) (PLA)/polycaprolactone (PCL) 블렌드의 상용성을 높이고자 하는 것이다. GMA를 포함하는 PLA/PCL 블렌드에 10, 50, 100 kGy의 전자선을 조사하여 시료를 제조한 후 모폴로지 및 유변학적 물성을 조사하였다. 50과 100 kGy로 조사된 블렌드는 크게 변화된 계면 형상을 보였고, 복합점도와 저장탄성률 또한 전자선을 조사하지 않은 블렌드에 비해 크게 증가하였다. 특히 100 kGy로 조사된 PLA/PCL(9/1) 블렌드의 복합점도는 순수 PLA보다 약 100배 가까운 증가를 보였다. 기능성 단량체 첨가와 적절한 전자선 조사로 비혼화성 PLA/PCL 블렌드의 상용성을 증가시킬 수 있었다.