중합체 매개 용융압출에 의한 참당귀 나노복합체의 제조

Md Obyedul Kalam Azad,조현종,임정대,강위수 한국약용작물학회 2018 한국약용작물학회지 Vol.26 No.5

Background: The objective of this study was to make colloidal dispersions of the active compounds of radix of Angelica gigas Nakai that could be charaterized as nano-composites using hot melt extrusion (HME). Food grade hydrophilic polymer matrices were used to disperse these compound in aqueous media. Methods and Results: Extrudate solid formulations (ESFs) mediated by various HPMCs (hydroxypropyl methylcelluloses) and Na-Alg polymers made from ultrafine powder of the radix of Angelica gigas Nakai were developed through a physical crosslink method (HME) using an ionization agent (treatment with acetic acid) and different food grade polymers [HPMCs, such as HP55, CN40H, AN6 and sodium alignate (Na-Alg)]. X-ray powder diffraction (XRD) analysis confirmed the amorphization of crystal compounds in the HP55-mediated extrudate solid formulation (HP55-ESF). Differential scanning calorimetry (DSC) analysis indicated a lower enthalpy (ΔH = 10.62 J/g) of glass transition temperature (Tg) in the HP55-ESF than in the other formulations. Infrared fourier transform spectroscopy (FT-IR) revealed that new functional groups were produced in the HP55-ESF. The content of phenolic compounds, flavonoid (including decursin and decursinol angelate) content, and antioxidant activity increased by 5, 10, and 2 times in the HP55-ESF, respectively. The production of water soluble (61.5%) nano-sized (323 ㎚) particles was achieved in the HP55-ESF. Conclusions: Nano-composites were developed herein utilizing melt-extruded solid dispersion technology, including food grade polymer enhanced nano dispersion (< 500 ㎚) of active compounds from the radix of Angelica gigas Nakai with enhanced solubility and bioavailability. These nano-composites of the radix of Angelica gigas Nakai can be developed and marketed as products with high therapeutic performance.

Properties of poly(ethylene terephthalate) containing epoxy-functionalized polyhedral oligomeric silsesquioxane

Yoon, Kwan Han,Polk, Malcolm B,Park, Jae Hong,Min, Byung G,Schiraldi, David A John Wiley Sons, Ltd. 2005 Polymer international Vol.54 No.1

<P>Poly(ethylene terephthalate) (PET) containing epoxy-functionalized polyhedral oligomeric silsesquioxane (POSS) was prepared by melt-mixing and in situ polymerization methods. The melt-mixed composite showed phase separation while the in situ polymerized composite did not, based on SEM characterization. During melt mixing, the reaction between the epoxy groups of POSS and hydroxyl groups of PET occurred, based on DSC results. DSC results on the in situ polymerization product showed formation of a lower-melting component compared with PET. The tensile strength and modulus of the melt-mixed composite fiber decreased compared with those properties of PET, whereas those of the in situ polymerized composite showed slightly higher values than PET despite the relatively small amounts (1 wt%) of POSS used. Dynamic mechanical analysis results showed an increase in storage modulus for the in situ polymerized composite of POSS and PET compared with PET over the temperature range of 40 °C to 140 °C. Copyright © 2004 Society of Chemical Industry</P>

Numerical investigation of cold-start behavior of polymer-electrolyte fuel-cells from subzero to normal operating temperatures - Effects of cell boundary and operating conditions

Gwak, G.,Ko, J.,Ju, H. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.36

In this study, we performed transient cold-start simulations of polymer-electrolyte fuel-cells (PEFCs) under a wide range of PEFC operating temperatures, from subzero (-20 <SUP>o</SUP>C) to normal operating temperatures (80 <SUP>o</SUP>C). For these wide temperature range transient simulations, the cold-start model developed in a previous study is enhanced by including ice-melting phenomena and additional constitutive relationships. The model successfully predicts various stages of PEFC cold-starts, i.e., ice formation/growth, constant ice accumulation with undersaturated vapor, ice melting/membrane hydration, and membrane dehydration. In addition, the results for simulations performed under various cold-start operating conditions clearly address the effects of key cold-start factors such as cathode stoichiometry, external thermal boundary condition, inlet relative humidity, startup temperature, and co- and counter-flow configurations on PEFC cold-start behavior, especially ice freezing/melting and membrane hydration/dehydration processes. This numerical investigation attempts to develop effective cold-start strategies that can simultaneously suppress both ice formation/growth and anode dry-out, thereby ensuring rapid and stable startup of a PEFC from subzero temperatures.

Design, Analytical and Experimental Evaluations of Additive Manufacturing for Laser Melting of Polymer-Metal Colloids

Chunliang Kuo,Tingyu Chang,Jhihjie Liu,Chunhui Chung 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.6

This paper presents a novel additive manufacturing process, namely the laser melting of polymer-metal colloids (LMC), which is advantageous for repairing features and reducing contamination sources. The developed polymer-metal colloids are conveyed via the designed spindle-driven dispensing system to demonstrate consolidations of the metallic phase onto heterogeneous substrate materials via laser melting. Modelling of the flow rate, velocity and pressure fields is linked to the geometric design of the mechanical devices in the spindle-driven process. The equilibriums of the heat transfer equations in the colloid element were initiated and presented for the estimations of input laser energy. When the input heat was absorbed by the colloid element, the average energy density could be obtained by the ratio of the overall energy density and the engaged laser scanning volume. In the experimental work of the validation tests, the polymer-metal colloid was consolidated on the substrate material with three different results: unconsolidated, partially consolidated and consolidated. The consolidation and bonding of metallic fractions on the heterogeneous substrate materials in the laser melting actions were evaluated and reported.

Controlling the Properties of OPEFB/PLA Polymer Composite by Using Fe2O3 for Microwave Applications

Daw Mohammad Abdalhadi,Zulkifly Abbas,Ahmad Fahad Ahmad,Khamirul Amin Matori,Fahmiruddin Esa 한국섬유공학회 2018 Fibers and polymers Vol.19 No.7

Microwave-absorptive polymer composite materials provide protection against interference to communication systems caused by microwave-inducing devices. Microwave-absorptive polymer composites were prepared from polylactic acid (PLA) biocomposite blended with oil palm empty fruit bunch (OPEFB) fiber and commercial Iron oxide (Fe2O3) as filler using the melt-blending method. The composites characterization was carried out using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The coefficient of reflection S11 and coefficient of transmission S21 of the composites for various Fe2O3 filler percentages were determined using a rectangular waveguide in connection with microwave vector network analyser (HP/Agilent model PNA N5227). These coefficients were then used to calculate microwave-absorption properties (in decibels). XRD analysis showed that increasing amounts of reinforced material (Fe2O3) reduces the crystallinity of the composites. SEM data indicated that Fe2O3 filler ratio increased in the composites, and adhesion to the cellulose fiber grew gradually until the highest percentage of filler was added. The complex relative permittivity and relative permeability were obtained within the broad frequency range of 8-12 GHz at room temperature for various percentages of filler and were measured by the transmission/reflection method using a vector network analyser. Fe2O3 embedment in OPEFB/PLA was observed to have resulted in enhancing the dielectric and magnetic properties. The values of permittivity and permeability increased with increasing Fe2O3 filler content. Theoretical simulation studied the relation between ε' and ε" of the relative complex permittivity in terms of Cole-Cole dispersion law. The result indicated that the processes of Debye relaxation in Fe2O3/OPEFB/PLA, the unique dielectric characteristics of Fe2O3 cannot be accounted for by both the Debye dipolar relaxation and natural resonance. Results further showed that the material transmission, reflection, and absorption properties could be controlled by changing the percentage of Fe2O3 filler in the composites.

데이터 기반 Styrene-Acrylonitrile 중합 공정의 Melt Index 예측

송민준,조필성,이종민 제어로봇시스템학회 2021 제어로봇시스템학회 국내학술대회 논문집 Vol.2021 No.6

Melt index (MI) is one of the important variables that determine the quality and grade of a polymer. Therefore, it is necessary to keep the MI value between an acceptable range during the polymerization process. However, MI and other quality variables cannot be measured in real-time, which makes it difficult to control polymerization processes. This study applies 6 data-based modeling methods to build soft sensor models for predicting the MI of a styrene-acrylonitrile polymerization process and compares the prediction performances between them. The linear regression model and the partial least squares (PLS) model had poor prediction performances because of their inabilities to model the nonlinearity of the styrene-acrylonitrile polymerization process. On the other hand, the artificial neural network (ANN) model showed the best prediction performance among all models. In particular, the ANN model predicted the MI accurately even when grade change occurred.

Effect of the Monomer Ratio on the Properties of Melt-Polymerized Polycarbonate

임병훈,이진우,박오옥 한국고분자학회 2019 Macromolecular Research Vol.27 No.12

In this study, the effects of bisphenol A (BPA) and diphenyl carbonate (DPC) molar ratio, on the properties of melt-polymerized polycarbonate (PC) were investigated. The molecular size distribution theory proposed by Flory was applied, to melt polymerization of PC to predict physical properties, affected by the molar ratio of BPA and DPC. A terminal OH group affected the viscosity of PC at high temperatures, leading to instability during processing. With increase in the DPC/BPA molar ratio, terminal OH content decreased, albeit different from the theoretical predicted value, because of the volatilization of DPC. Additionally, BPA residual amount was affected by BPA and DPC molar ratio. BPA is regulated in countries because of its similarity to estrogen, and BPA residues can be predicted and managed by using the Flory equation.

Synthesis of Poly(D-lactide) with Different Molecular Weight via Melt-Polymerization

김수현,Purba Purnama,정영미,홍채환,한도석 한국고분자학회 2012 Macromolecular Research Vol.20 No.5

Polylactide is considered as “Green Polymer” due to its sustainability. Poly(D-lactide) is absolutely required in order to make stereocomplex polylactide. But, there is no report about D-lactide polymerization. Various molecular weight of poly(D-lactide) were successfully polymerized from D-lactide in the melt stage using various catalysts. Stannous octoate, aluminum isopropoxide and lanthanum isopropoxide has better solubility in the molten monomer compared to yttrium isopropoxide oxide. We obtained high conversion (99.17%) and high molecular weight (Mn=384,992) using stannous octoate. We also obtained high conversion (94.46%) and medium molecular weight (Mn=78,634) using aluminum isopropoxide. This data is suitable for industrial applications. In the kinetic study, stannous octoate has higher polymerization rate (kp=10.8×10-2 min-1) compared to the aluminum isopropoxide (kp=7.3×10-2 min-1).

Effects of Annealing on Structure and Properties of TLCP/PEN/PET Ternary Blend Fibers

김준영,EunSuSeo,김성훈,TakeshiKikutani 한국고분자학회 2003 Macromolecular Research Vol.11 No.1

Thermotropic liquid crystalline polymer (TLCP)/poly(ethylene 2,6-naphthalate) (PEN)/poly(ethylene terephthalate) (PET) ternary blends were prepared by melt blending, and were melt-spun to fibers at various spinning speeds in an effort to improve fiber performance and processability. Structure and property relationship of TLCP/ PEN/PET ternary blend fibers and effects of annealing on those were investigated. The mechanical properties of ternary blend fibers could be significantly improved by annealing, which were attributed to the development of more ordered crystallites and the formation of more perfect crystalline structures. TLCP/PEN/PET ternary blend fibers that annealed at 180 oC for 2 h, exhibited the highest values of tensile strength and modulus. The double melting behaviors observed in the annealed ternary blend fibers depended on annealing temperature and time, which might be caused by different lamellae thickness distribution as a result of the melting-reorganization process during the DSC scans.

Tailoring thermal and moisture absorption properties of Nylon 4,6 copolymers by incorporating ε-caprolactam

김남철,조홍찬,백배현,안태환,김영준 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1

At the meeting thermal and moisture absorption properties of Nylon 4,6 copolymer via melt polymerization will be discussed. Nylon 4,6 is obtained from Nylon 4,6 salt via melt polymerization, and is sold under trade name of “Stanyl”. It has excellent physical properties such as high stiffness, good toughness, and high thermal stability. However, it has poor melt processability due to its high melting point (~290 oC). Monomer of nylon 6, ε-caprolactam, was incorporated to tailor melting point and moisture absorption of nylon 4,6. Nylon 4,6/6 copolymerization with various mole ratios were carried out in a Parr reactor by melt polymerization. Their thermal and moisture absorption properties were interpreted in terms of physicochemical characteristics nylon 4,6/6 copolymers.