• 폴리머
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• 제38권2호
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• pp.129-137
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• 2014

본 연구에서는 재활용 폴리프로필렌을 첨가한 wood plastic composite(WPC)의 물성을 극대화하기 위해 먼저 용융혼합 조건을 최적화하였으며 재활용 폴리프로필렌의 함량이 WPC의 물성에 미치는 영향을 조사하였다. WPC의 기계적 특성을 측정하기 위해 만능재료시험기와 충격시험기를 사용하였고 열적 특성을 조사하기 위해 DSC, TGA, DMA를 사용하였다. SEM을 이용하여 WPC의 파단면을 관찰하였다. 전체 폴리프로필렌 함량의 50 wt%를 재활용 폴리프로필렌으로 함유한 WPC의 최적가공 조건은 $170^{\circ}C$, 15분, 60 rpm이었다. 재활용 폴리프로필렌의 함량증가는 WPC의 수분흡수성을 증가시켰고 열적, 기계적 특성을 저하시켰다. 그러나 모든 물성을 종합하여 분석한 결과 WPC의 두드러진 물성 감소 없이 전체 폴리프로필렌 함량의 50 wt%까지 재활용 폴리프로필렌을 첨가하는 것이 가능하였다.

• 지능정보연구
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• 제2권1호
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• pp.45-58
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• 1996

This paper describes an a, pp.oach to recognizing composite features of prismatic parts. AAG (Attribute Adjacency Graph) is adopted as the basis of describing basic feature, but it is extended to enhance the expressive power of AAG by adding face type, angles between faces and normal vectors. Our a, pp.oach is called Extended AAG (EAAG). To simplify the recognition procedure, feature classification tree is built using the graph types of EEA and the number of EAD's. Algorithms to find open faces and dimensions of features are exemplified and used in decomposing composite feature. The processing sequence of recognized features is automatically determined during the decomposition process of composite features.

• Transactions on Electrical and Electronic Materials
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• 제12권3호
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• pp.110-114
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• 2011

Polymeric films of high chemical stability and mechanical strength covered with a thin metallic film have been extensively used in various fields as electric and electronic materials. In this study, we have chosen polypropylene (PP) as the polymer due to its outstanding chemical resistance and good creep resistance. We coated thin nickel film on PP films by the electroless plating process. The surfaces of PP films were pre-treated and modified to increase the adhesion strength of metal layer on PP films, prior to the plating process, by an environment-friendly process with atmospheric plasma generated using dielectric barrier discharges in air. The surface morphologies of the PP films were observed before and after the surface modification process using a scanning electron microscope (SEM). The static contact angles were measured with deionized water droplets. The cross-sectional images of the PP films coated with thin metal film were taken with SEM to see the combined state between metallic and PP films. The adhesion strength of the metallic thin films on the PP films was confirmed by the thermal shock test and the cross-cutting and peel test. In conclusion, we made a composite material of metallic and polymeric films of high adhesion strength.

• Advances in nano research
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• 제16권2호
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• pp.127-140
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• 2024

Upon direct/indirect exposure to flame or heat, composite structures may burn or thermally buckle. This issue becomes more important in the natural fiber-based composite structures with higher flammability and lower mechanical properties. The main goal of the present study was to obtain an optimal eco-friendly composite system with low flammability and high thermal buckling resistance. The studied composite consisted of polypropylene (PP) and short abaca fiber (AF) with eggshell powder (ESP) and halloysite clay nanotubes (HNTs) additives. An optimal base composite, consisting of 30 wt.% AF and 70 wt.% PP, abbreviated as OAP, was initially introduced based on burning rate (BR) and the Young's modulus determined by horizontal burning test (HBT) and tensile test, respectively. The effects of adding ESP to the base composite were then investigated with the same experimental tests. The results indicated that though the BR significantly decreased with the increase of ESP content up to 6 wt.%, it had a very destructive influence on the stiffness of the composite. To compensate for the damaging effect of ESP, small amount of HNT was used. The performance of OAP composite with 6 wt.% ESP and 3 wt.% HNT (OAPEH) was explored by conducting HBT, cone calorimeter test (CCT) and tensile test. The experimental results indicated a 9~23 % reduction in almost all flammability parameters such as heat release rate (HRR), total heat released (THR), maximum average rate of heat emission (MARHE), total smoke released (TSR), total smoke production (TSP), and mass loss (ML) during combustion. Furthermore, the combination of 6 wt.% ESP and 3 wt.% HNT reduced the stiffness of OAP to an insignificant amount by maximum 3%. Moreover, the char residue analysis revealed the distinct differences in the formation of char between AF/PP and AF/PP/ESP/HNT composites. Afterward, dilatometry test was carried out to examine the coefficient of thermal expansion (CTE) of OAP and OAPEH samples. The obtained results showed that the CTE of OAPEH composite was about 18% less than that of OAP. Finally, a theoretical model was used based on first-order shear deformation theory (FSDT) to predict the critical bucking temperatures of the OAP and OAPEH composite plates. It was shown that in the absence of mechanical load, the critical buckling temperatures of OAPEH composite plates were higher than those of OAP composites, such that the difference between the buckling temperatures increased with the increase of thickness. On the contrary, the positive effect of CTE reduction on the buckling temperature decreased by raising the axial compressive mechanical load on the composite plates which can be assigned to the reduction of stiffness after the incorporation of ESP. The results of present study generally stated that a suitable combination of AF, PP, ESP, and HNT can result in a relatively optimal and environmentally friendly composite with proper flame and thermal buckling resistance with no significant decline in the stiffness.

• Elastomers and Composites
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• 제44권2호
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• pp.164-174
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• 2009

모듈라 치합형 동방향 이축 스크류식 압출기(modular intermeshing co-rotating twin screw extruder)를 이용하여 저온 내 충격성 향상을 위해 PA66/EPDM/PP-g-MA 및 PA66/EPDM-g-MA/PP-g-MA 복합체를 각 성분 wt%를 변화하여 제조하였다. 그 결과 이들 복합체 중에서 PA66/EPDM-g-MA/PP-g-MA의 wt%가 90/8/2인 복합체가 다른 복합체들 보다 열적, 기계적으로 우수한 결과를 나타내었다. 그리고 열중량분석기(Thermogravimetric Analysis), 시차주사열량계(Differential Scanning Calorimeter)를 이용하여 열적 특성, 주사 전자현미경(Scanning Electron Microcsopy)을 이용하여 형태학적 변화를 분석하였다. 본연구를 통하여 기존 PA66/EPDM composite의 단점인 낮은 계면력과 저온 내충격성을 향상 시켰으며, 최적의 mixing효과를 위한 screw configuration에 따른 압출 공정 확립과 PA66/EPDM composite 생산 공정 국산화 및 원가절감의 효과를 가져왔다.

• Composites Research
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• 제26권1호
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• pp.1-6
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• 2013

용액 분산법을 이용하여 CNT를 균질하게 분산시켰고, CNT-폴리프로필렌 복합재료 제조를 위해 압출기와 사출기를 사용하였다. CNT 고유의 전도성을 기반으로 CNT-PP 복합재료의 내부 손상을 감지하기 위해 전기저항 측정법을 이용하였다. CNT-PP의 기계적 및 계면 물성을 확인하고 일반 PP와 비교하였다. CNT의 강화 효과로 인하여 CNT를 함유함으로서, PP 기지의 기계적 물성은 더 증가되는 경향을 확인하였다. CNT-PP 복합재료의 내부 손상을 평가하기 위해 파괴 및 굴곡실험을 진행하며, 동시에 발생되는 전기저항 변화도를 감지하여 미세손상을 평가하였다. CNT 강화제의 첨가는 좋은감지능을 보여주었다. 낮은 CNT 함유율임에도 CNT-PP 복합재료의 감지가 가능했으며, 반복 하중 실험 중 최대 임계 응력을 확인하여, 내부에 발생된 미세 파괴를 찾아 낼 수 있었다.

• 폴리머
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• 제39권1호
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• pp.99-106
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• 2015

나노케냐프 섬유가 포함된 셀룰로스 섬유를 알카리(NaOH)로 처리 후 PP 수지에 첨가하여 물성에 미치는 영향에 대하여 조사하였다. 알카리를 섬유에 처리한 효과로는 M.I., 신장율, 충격강도가 증가하는 반면 인장강도, 휨모듈러스, 열변형온도가 처리하지 않은 섬유에 비해 감소하였다. 알카리를 나노섬유에 처리하였을 때 섬유표면의 불순물과 화학물질을 제거하여 섬유표면의 특성을 변화시켜서 나노섬유와 PP 수지간의 계면간 접착력을 감소시키고 PP의 특성을 변화시키는 것으로 보인다.

• Elastomers and Composites
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• 제46권2호
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• pp.125-131
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• 2011

일정한 길이로 분쇄한 케냐프섬유를 일정한 비율로 PP수지에 복합화하여 섬유의 함량에 따른 기계적특성을 조사하였다. 케냐프 섬유의 함량이 증가할수록 인장강도, 굴곡탄성률, 충격강도, 비중, 열변형온도가 증가하는 경향을 나타내었으나 신장률, 굴곡강도, 용융유동지수는 감소하는 경향을 나타내었다. 기계적물성증가의 원인은 섬유와 PP간의 계면접촉면적의 증가와 섬유간의 연결간섭으로 고찰되었다. 케냐프섬유내에 존재하는 증발성추출물질이 PP와 의 계면접착에 있어서 감소에 영향을 미치는 것으로 고려된다.

• Advanced Composite Materials
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• 제17권3호
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• pp.191-214
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• 2008

Polypropylene/layered silicate nanocomposites containing maleic anhydride grafted polypropylene were prepared by melt compounding and their rheological behavior was investigated in shear flow. Transient and steady shear flows were simulated numerically by using the K-BKZ integral constitutive equation along with experimentally determined damping functions under dynamic oscillatory and step strain shear flows. Nonlinear shear responses were predicted with the K-BKZ constitutive equation using two different damping functions such as the Wagner and PSM models. It was observed that PP-g-MAH compatibilized PP/layered silicate nanocomposites have stronger and earlier shear thinning and higher steady shear viscosity than pure PP resin or uncompatibilized nanocomposites at low shear rate regions. Strong damping behavior of the PP/layered silicate nanocomposite was predicted under large step shear strain and considered as a result of the strain-induced orientation of the organoclay in the shear flow. Steady shear viscosity of the pure PP and uncompatibilized nanocomposite predicted by the K-BKZ model was in good agreement with the experimental results at all shear rate regions. However, the model was inadequate to predict the steady shear viscosity of PP-g-MAH compatibilized nanocomposites quantitatively because the K-BKZ model overestimates strain-softening damping behavior for PP/layered silicate nanocomposites.

• 멤브레인
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• 제20권4호
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• pp.297-303
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• 2010

폴리올레핀 중합공정에서 발생되는 미반응 올레핀 모노머를 회수하기 위한 분리막/냉각응축 공정에 적용할 복합막을 용액 코팅공정과 플라즈마 중합공정의 두가지 방법으로 제조하였다. Polysulfone (PSF) 지지체 위에 poly(dimethylsiloxane) (PDMS) 용액을 코팅하였고 코팅 용액에서 prepolymer의 함량이 높을수록 올레핀 모노머의 선택도는 증가하였으나 막이 치밀하여지는 관계로 절대 투과량은 감소하는 경향을 보였다. 유기물의 복합막 투과는 용액확산 메커니즘에 의한 것으로서 임계온도가 높을수록 분리효율은 향상되고 molar volume이 증가할수록 투과도가 향상되었다. 또한 가교시간에 siloxane 계열의 물질을 plasma 종합하여 복합막을 제조하였는데 PSF 및 polypropylene (PP) 지지체를 사용하였다. 특히 지지체로 기존의 용액코팅 공정에서 사용되기 어렵던 PP 지지체 위에도 복합막을 코팅할 수 있었으며 용액코팅 공정으로 제조된 복합막과 유사한 성능을 나타내었다.