• Transactions on Electrical and Electronic Materials
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• 제15권5호
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• pp.235-240
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• 2014

Nanocomposites made of linear low density polyethylene (LLDPE) and organo-modified montmorillonite (O-MMT) were processed by melt compounding from a commercially available premixed LLDPE/nanoclay masterbatch, at different nanoclay loadings, by co-rotating twin-screw extruder. The morphological and dielectric properties of LLDPE/O-MMT nanocomposites were investigated to understand the structure-dielectric properties relationship in the nanocomposites. The microstructures of the materials were characterized by wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Initial findings by FTIR spectroscopy characterization indicated the absence of any chemical interaction between LLDPE and nanoclay during the extrusion process, while DSC showed that a 1% wt loading of nanoclay particles increased the degree of crystallinity of the nanocomposites samples. On the other hand, XRD, SEM, TEM and AFM indicated that nanoclay layers were intercalated or exfoliated in the LLDPE matrix. A correlation between the structure and dielectric properties of LLDPE/O-MMT nanocomposites was found and discussed.

• Fire Science and Engineering
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• 제26권1호
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• pp.89-95
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• 2012

In this study, we were manufactured wood flour-HDPE composites by modular co-rotating twin screw extruder with L/D ratio of 42. We was measured cone calorimeter test and thermogravimetric analysis (TGA) to find the combustion characteristics and thermal properties for wood flour-HDPE composites. We then evaluated the effect of three additive-type flame retardants on fire resistance performance. The cone calorimeter test showed that the heat release rate (HRR) of untreated composites was the highest Peak HRR ($446.6kW/m^2$) as well as Mean HRR ($185.5kW/m^2$). From the TGA, it was shown that composites added flame retardants began early thermal decomposition and improved thermal stability.

• Elastomers and Composites
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• 제52권3호
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• pp.201-210
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• 2017

We studied the antibacterial effect and mechanical properties of PLA composites with in organic porous zeolite-type bacteriocides. The specimens were prepared by an intermeshing co-rotating twin screw extruder using different contents of inorganic bacteriocide. The degree of dispersion of the in organic bacteriocide in the PLA composite was confirmed by FE-SEM. The contents of Ag and Zn in the composite were also investigated by energy dispersive spectroscopy at different concentrations of the inorganic bacteriocide. The antibacterial effects were analyzed by turbidity analysis, shaking culture, and drop-test. The mechanical properties, such as the tensile and flexural properties, impact strength, and physical properties, were also investigated. As the content of inorganic bacteriocide increased, the antibacterial activity was increased, especially against Staphylococcus aureus. Mechanical properties, namely, tensile strength, elongation, flexural strength, and impact strength, tended to decrease with an increase in inorganic bacteriocide content, but the tensile and flexural modulus increased.

• Transactions of the Korean Society of Automotive Engineers
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• 제18권1호
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• pp.74-85
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• 2010

In order to formulate the compounded polypropylene(C-PP) which is suitable to an automotive door trim panel, 9 sorts of properties were measured after manufacturing the C-PP using an extruder and an injection machine with polypropylene(PP), ethylene-octene rubber(EOR) and talc. Mixture design, especially extreme vertices design, in DOE with MINITAB - commercial software was used to analyze the data. The relations between each property and each component, for example, $y=0.00907222x_1+0.00870556x_2+0.0155722x_3$ for specific gravity, were found out by the regression analysis and the variance analysis. The optimized formulation of the C-PP for an automotive door trim panel was acquired at PP(77.6962), EOR(11.0238) and talc(10.2800) by use of the response optimizer(mixture) in MINITAB.

• International Journal of Automotive Technology
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• 제6권6호
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• pp.665-670
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• 2005

Nanocomposites of polypropylene with organically modified clays were compounded on a twin-screw extruder by two-step melt compounding of three components, i.e., polypropylene, maleic anhydride grafted polypropylene (PP-g-MA), and organically modified clay. The effect of PP-g-MA compatibilizers, including PH-200, Epolene-43, Polybond-3002, Polybond-3200, with a wide range of maleic anhydride (MA) content and molecular weight was examined. Morphologies of nanocomposites and their mechanical properties such as stiffness, strength, and impact resistance were investigated. X-ray diffraction patterns showed that the dispersion morphology of clay particles seemed to be determined in the first compounding step and the further dispersion of clays didn't occur in the second compounding step. As the ratio of PP-g-MA to clay increased, the clay particles were dispersed more uniformly in the matrix resin. As the dispersibility of clays was enhanced, the reinforcement effect of the clays increased, however impact resistance decreased.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1284-1284
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• 2001

The transesterification of molten ethylene/vinylacetate (EVA) copolymers by octanol as a reagent and sodium methoxide as a catalyst in an extruder has been monitored by on-line near infrared (NIR) spectroscopy. A total of 60 NIR spectra were acquired for 37 minutes with the last spectrum recorded 31 minutes after the addition of octanol and catalyst was stopped. The experimental spectra show strong baseline fluctuations which are corrected for by multiplicative scatter correction (MSC). The chemometric methods of orthogonal projection approach (OPA) and multivariate curve resolution (MCR) were used to resolve the spectra and to derive concentration profiles of the species. The detailed analysis reveals the absence of completely pure variables that leads to small errors in the calculation of pure spectra. The initial estimation of a concentration that is necessary as an input parameter for MCR also presents a non-trivial task. We obtained results that were not ideal but applicable for practical concentration control. They enable a fast monitoring of the process in real-time and resolve the spectra of the EVA copolymer and the ethylene/vinyl alcohol (EVAL) copolymer to be very close to the reference spectra. The chemometric methods used and the decomposed spectra are discussed in detail.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제22권11호
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• pp.935-940
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• 2009

In this research, the composites (100-x)LCP-xBNT (x = 0, 10, 20, 30, 40 vol.%) were fabricated with thermoplastic LCP(Liquid Crystal Polymer) and BNT($BaNd_2Ti_4O_{12}$) which is a high frequency dielectric material. Their dielectric properties, mechanical strength and microstructure were investigated by Impedance analyser, Instron and SEM. In order to fabricate LCP-BNT composites, LCP resin was put into the twin screw type mixer($310^{\circ}C$), melted by keeping for 10 min. After that, BNT filler was dispersed with melted LCP resin for 15 min. in the mixer. For measuring the dielectric properties and mechanical strength, Composite specimens were made by pressing composite granule (LCP-BNT) with 7 ton in the mold at $310^{\circ}C$. With increasing the BNT content (0~40 vol.%) of the composite, Its dielectric constant increased, dielectric loss and flexural strength decreased. The dielectric constant and flexural strength of composites with 20~30 vol.% of BNT filler are 4.1~6.0 and 35~55 MPa respectively. BNT/LCP composite is the potential substrate material for the high frequency application.

• The Korean Journal of Rheology
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• 제10권4호
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• pp.247-255
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• 1998

The morphological changes during melt compounding of ternary blends containing various combinations of acrylonitrile-butadiene-styrene(ABS), methyl methacrylate-butadiene-ethyl acrylate(MBE), styrene-acrylonitrile(SAM) copolymers, and poly(methyl methacrylate)(PMMA) as dispersed components in a fixed matrix of polycarbonate(PC) have been investigated. Depending on the composition of the blend, MBE particles and PMMA phase appear to locate at the PC-SAN interface under the influence of interfacial tensions and motion induced coalescence. The interfacial viscosity is found to be a critical factor that affects the amount of coalescence.

• The Korean Journal of Rheology
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• 제8권1호
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• pp.11-29
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• 1996

스크류 채널 내에 주기적을 배리어를 설치함으로써 단축 스크류 압출 공정에서의 혼합 성능이 높여질수 있음이 S.J. Kim과 T.H. Kwom에 의해 밝혀진 바있다. 그들은 이새 로운 스크류를 통한 혼합이 카오틱하는 점으로부터 이 새로운 스크류를 카오스 스크류라고 명명했다. 우리는 카오스 스크류가 장착된 단축 압출공정에서 역학계 이론과 혼합운동학을 연계하여 연구를 수행하였다. 포인카레 단면을 통한 연구로부터 우리는 배리어의 배열이 islan의 크기에 대단히 밀접하게 관련되어 있음을 발견하였다. 연속적인 쉘 변형은 카오틱 유동에서 유체 요소를 지수 함수 형태로 늘이는 늘임과 접힘으로 이루어진 카오틱 혼합 메 카니즘을보여준다. 유체요소의 국부 늘임은 원리상으로는 계산되어질수 있으나 수치 해석상 의 어려운 점이 있다. 정규 유동에서와 달리 카오틱 유동에서는 입자 추적이 Runge-Kutta 적분중의 시간간격에 대단히 민감하다. 그래서 실제 사용될수 있는 시간 간격에 의해 계산 된 국부 늘임율 및 혼합효율의 정확도가 보장되어지지 않는다. 이러한 점들을 고려하여 우 리는 새로운 혼합 척도로 $\sigma$z를 제안하는데 이값은 비교적 긴 유체선분이 채널방향을 따라 늘어나는 비에 관련된 값이다. 배리어 영역의 길이가 짧을수록 $\sigma$z는 큰값으로 나타나지만 포인카레 단면에 의한 연구에 따르면 배리어의 주기가 너무 짧다면 두 개의 거대한 island 가 존재하는 것으로 밝혀졌다. 그리고 이러한 사실은 유체요소의 늘임비가 크다는 것이 항 상 좋은 혼합성능을 뜻하는 것은 아니라는 점을 보여준다. 이러한 관점에서 볼 때 혼합 스 크류를 설계하는데 있어서는 포인카레 단면을 병행하여 ${\sigma}_z$의 값을 사용하는 것이 바람직할 것이다.

• Journal of the Korean Society of Safety
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• 제27권1호
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• pp.26-31
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• 2012

Wood-plastic composites represents a growing class of materials used by the residential construction industry and furniture industry. In this study, the effect of flame retardants on the flammability and mechanical properties of wood flour-high density polyethylene(HDPE) composites were studied. we were manufactured wood flour-HDPE composites by modular intermeshing co-rotating twin screw extruder with L/D ratio of 42. The flame retardant properties were used limiting oxygen index(LOI) and mechanical properties were measured by universal testing machine(UTM). The Morphological analysis of composites were analyzed by Scanning electron microscope(SEM). It was found that Ammonium polyphosphate can effectively reduce the flammability of the wood flour-HDPE composites. Marginal reduction in the mechanical properties of the composites was found with addition of flame retardants. SEM images showed that the coupling agent improved wood flour-HDPE interfacial bonding.