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Ultrasonic Effects on PP/PS/Clay Nanocomposites during Continuous Melt Compounding Process
Kim, Kyung Yl,Ju, Dong Uk,Nam, Gi Joon,Lee, Jae Wook WILEY-VCH Verlag 2007 Macromolecular symposia Vol.249 No.1
<P>Polymer blend/clay nanocomposites were prepared by ultrasonic-assisted continuous extrusion process. This process was employed to enhance the compatibility between two polymers, and nano-scale dispersion between the polymer blend and organically modified clay. Materials were linear polypropylene and polystyrene with 3 phr loading of organophilic montmorillonite clay. The effectiveness of the proposed ultrasonic-assisted process on the polypropylene/polystyrene/clay nanocomposites was confirmed by rheological property measurements and structural analysis by scanning electron microscope and X-ray diffraction. The sonication during extrusion was effective in improving the compatibility between polypropylene and polystyrene. Also, it led to enhanced breakup of the clay agglomerates. The observed clay was in the exfoliated state from the X-ray diffraction analysis.</P>
그래핀과 실세스키옥세인을 포함한 팔라듐 나노입자와의 나노복합체 제조
임정혁(Jung Hyurk Lim),고일웅(Yl Woong Ko),김기영(Ki Young Kim),김경민(Kyung Min Kim) 한국고분자학회 2012 폴리머 Vol.36 No.5
케이지 구조의 POSS-NH3 +를 이용하여 팔라듐 입자들의 자기 조직화로 인한 구조가 제어된 Pd-POSS 나노입자를 제조하였다. 또한 흑연을 강산과 산화제를 이용하여 산화된 그래핀 옥사이드(GO)를 합성한 후 얻어진 GO와 NaBH4와의 반응을 통하여 그래핀을 제조하였다. 합성된 그래핀과 acrylic acid와 라디칼 중합 반응을 통하여 그래핀 표면에 poly(acrylic acid)(PAA)가 결합된 PAA-grafted graphene을 얻었다. Pd-POSS와 PAA-grafted graphene을 이용한 나노복합체는 POSS-NH3 +로 인하여 양전하를 띠는 Pd-POSS 나노입자와 PAA로 인하여 음전하를 띠는 PAAgrafted graphene와의 정전기적 인력을 이용하여 제조하였다. Pd-POSS 나노입자가 PAA로 치환된 그래핀 표면에 정전기적 인력으로 결합되어 있고, 나노복합체의 열적 안정성은 PAA와 PAA-grafted graphene 보다 우수한 것을 확인 할 수 있었다. 제조된 Pd-POSS/PAA-grafted graphene 나노복합체의 구조 및 형태와 열적 안정성은 FE-SEM, AFM, TEM, EDX, FTIR과 TGA를 통하여 분석하였다. The palladium nanoparticles were self-assembled to make Pd-POSS using POSS-NH3 + (polyhedral oligomeric silsesquioxane) as a crosslinker. Graphene oxide (GO) was produced by the reaction of graphite under a strong acid and oxidizer and poly(acrylic acid) (PAA) was covalently grafted on the surface of graphene to make PAA-grafted graphene through the radical polymerization of acrylic acid and GO along with a reduction process under NaBH4. The nanocomposites of Pd-POSS and PAA-grafted graphene were fabricated via ionic interactions between positively charged Pd- POSS and negatively charged PAA-grafted graphene. Pd-POSS nanoparticles were attached to the surface of PAA-grafted graphene through ionic interactions. The thermal stability of Pd-POSS/PAA-grafted graphene was higher than that of PAA and PAA-grafted graphene. The composition, structure, surface morphology, and thermal stability of the Pd-POSS/ PAA-grafted graphene were studied by FE-SEM, AFM, TEM, FTIR, and TGA.
High-pressure rheology of polymer melts containing supercritical carbon dioxide
Lee Sang-Myung,Han Jae-Ro,Kim Kyung-Yl,Ahn Young-Joon,Lee Jae-Wook The Korean Society of Rheology 2006 Korea-Australia rheology journal Vol.18 No.2
Supercritical carbon dioxide ($scCO_2$) has advantages of being incorporated in polymer with high solubility and of being recovered easily by depressurizing. $scCO_2$ reduces the viscosity of polymer melt and it is expected to be use as a plasticizing agent. In this work, we studied on the effect of $scCO_2$ on the rheological properties of polymer melts during extrusion process. Slit die attached to twin screw extruder was used to measure the viscosity of polymer melts plasticized by supercritical $CO_2$. A gas injection system was devised to accurately meter the supercritical $CO_2$ into the extruder barrel. Measurements of pressure drop within the die, confirmed the presence of a one phase mixture and a fully developed flow during the measurements. The viscosity measurement of polypropylene was performed at experimental conditions of various temperatures, pressures and $CO_2$ concentrations. We observed that melt viscosity of polymer was dramatically reduced by $CO_2$ addition.