• Polymer(Korea)
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• v.31 no.5
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• pp.428-435
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• 2007

The thermomechanical property, morphology, and gas permeability of nanocomposites of ultra high molecular weight polyethylene (UHMWPE) with two different organoclays are compared. Hexamethylene benzimidazole-mica ($C_{16}BIMD-Mica$) and Cloisite 25A were used as reinforcing fillers in the formation of UHMWPE hybrid films. Dispersions of organoclays with UHMWPE were carried out by using the solution intercalation method at different organoclay contents to produce nano-scale composites. Transmission electron microscopy (TEM) micrographs show that some of the clay layers are dispersed homogeneously within the polymer matrix on the nano-scale, although some clay particles are agglomerated. We also found that the addition of only a small amount of organoclay is enough to improve the thermomechanical property and gas barrier of the UHMWPE hybrid films. In general, Cloisite 25A is more effective than $C_{16}BIMD-Mica$ in increasing both the thermomechanical property and the gas barrier in a UHMWPE matrix.

• Journal of Biomedical Engineering Research
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• v.18 no.2
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• pp.107-112
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• 1997

The effect of gamma-irradiation sterilization on molecular structural changes in orthopaedic surgical-grade polyethylene was studied. The relative crystallinity ud. percent crosslinking of the substance increased as a result of the gamma irradiation and varied anisotropically as a function of depth. Samples from the articulating surfaces showed 5% Venter relative crystallinity than those from the mid-sections, whereas samples from the mid-sections exhibited 15% greater crosslinking than those from the surfaces. These anisotropic variations are discussed in assDciation with oxidation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.108-114
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• 2008

Uniaxial tension and compression test were conducted on conventional and crosslinked ultra-high molecular polyethylene (UHMWPE) all prepared from the same lot of medical grade GUR 1050. The conventional materials were unirradiated and gamma irradiated with $25kGy{\sim}200kGy$. Gamma irradiated processing was found to significantly impact the crystallinity, and hence the mechanical behavior, of the highly crosslinked UHMWPE. The crystallinity and radiation dose were key predictors of the uniaxial yielding, hardness, plastic flow, and failure properties of conventional and highly crosslinked UHMWPE. The correlation model from experiments would be the basic information to design the liner of artificial joint.

• Polymer(Korea)
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• v.33 no.2
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• pp.97-103
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• 2009

Ultra-high molecular weight polyethylene (UHMWPE)/functionalized-MWNT hybrid films were prepared by the solution intercalation method, using 4-cumylphenol-MWNT (CP-MWNT) as the functionalized-MWNT. The variation of the thermomechanical properties, morphology, gas permeability, and optical transparency of the hybrid films with CP-MWNT content in the range of 0$\sim$2.00 wt% were examined. The newly synthesized UHMWPE/functionalized-MWNT hybrid films were characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and a universal tensile machine (UTM). It was found that the addition of only a small amount of functionalized-MWNT was sufficient to improve the thermomechanical properties of the UHMWPE hybrid films, with maximum enhancement being observed in the CP-MWNT loading in the range 0.50 to 1.00 wt%. The maximum enhancement in the oxygen gas barrier was also found at the functionalized MWNT content of 1.00 wt%. In this work, the thermomechanical properties and gas permeability of the hybrid films were found to be better than those of pure UHMWPE.

• Textile Coloration and Finishing
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• v.27 no.1
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• pp.27-34
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• 2015

Novel super hydrophobic disazo red dyes were synthesized to improve light fastness of the primary monoazo red dye of previous study on polyolefin fibers such as polypropylene and ultra high molecular weight polyethylene fibers. 4-Alkylanilines were diazotized and then coupled to 2,5-dimethylaniline to produce dye intermediates which were then further used to synthesize final disazo red dyes by diazoization and coupling to ${\beta}$-naphthol. Considering both affinity of the dyes toward both polyolefin fibers and color fastnesses, the decyl-substituted dye was determined as the optimum dye. The decyl-substituted disazo red dye exhibited good dyeability on both polyolefin fibes and almost the same color values as the previous primary monoazo red dye. Light fastness on ultra high molecular weight polyethylene fibers was improved up to rating 3~4 compared to rating 2~3 of the previous primary monoazo red dye.

• Tribology and Lubricants
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• v.14 no.4
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• pp.1-6
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• 1998

인공관절 라이너에 널리 사용되는 대표적 생체재료인 초고분자량 폴리에틸렌(Ultra-High Molecular Weight Polyethylene)은 체내에 삽입되기 전에 멸균처리를 거쳐야 하며, 가장 보편적인 멸균방법은 감마선을 이용한 멸균처리이다. 그러나, 감마선은 폴리에틸렌의 화학분자 결합구조에 변화를 일으키며, 따라서 물리적, 기계적 물성치에 변화를 야기시킨다. 이는 인공관절 수명을 좌우하는 변형과 마모현상에도 결정적 영향을 줄 것으로 사려된다. 본 연구에서는 감마선 멸균처리가 UHMWPE의 크리프 변형 및 마모에 미치는 영향이 관찰되었고, 그 결과들은 감마선 멸균처리로 야기된 폴리에틸렌의 화학분자 결합구조의 변화(Crystallinity, Oxidation, Crosslinking)와 함께 분석되었다. 압축 제작된 초고분자량 폴리에틸렌 봉(extruded UHMWPE rod)으로부터 원통형의 시평을 제작하여 감마선 멸균처리를 행하고, 압축 크리프 실험과 마모 실험을 실시하여 멸균처리하지 않은 시편을 제작하여 감마선 멸균처리를 행하고, 압축 크리프 실험과 마모 실험을 실시하여 멸균처리하지 않은 시편 사이에는 크리프 복원정도를 제외하고 거의 차이가 없었으나, 반면에 마모의 경우, 감마선 멸균처리된 시편이 멸균처리하지 않은 시편보다 훨씬 적은 마모량을 보였다(p〈0.05). 이것은 crosslinking 증가에 따른 마모 저항력 향상으로 볼 수 있다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.227-233
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• 1998

인공관절 라이너에 널리 사용되는 대표적 생체재료인 초고분자량 폴리에틸렌 (Ultra-High Molecular Weight Polyethylene)은 체내에 삽입되기 전에 멸균처리를 거쳐야 하며, 가장 보편적인 멸균 방법은 감마선을 이용한 멸균처리이다. 그러나, 감마선은 폴리에틸렌의 화학분자 결합구조에 변화를 일으키며, 따라서 물리적, 기계적 물성치에 변화를 야기 사려된다. 이는 인공관절 수명을 좌우하는 변형과 마모현상에도 결정적 영향을 줄 것으로 사려된다. 본 연구에서는 감마선 멸균처리가 UHMWPE의 크리프 변형 및 마모에 미치는 영향이 관찰되었고, 그 결과들은 감마선 멸균처리로 야기된 폴리에틸렌의 화학분자 결합구조의 변화(Crystallinity, Oxidation, Crosslinking)와 함께 분석되었다. 압출 제작된 초고분자량 폴리에틸렌 봉(extruded UHMWPE rod)으로부터 원통형의 시편을 제작하여 감마선 멸균처리를 행하고, 압축 크리프 실험과 마모 실험을 실시하여 멸균처리 하지 않은 시편의 결과와 비교하였다. 크리프 변형의 경우, 감마선 멸균처리 된 시편과 멸균처리 하지 않는 시편 사이에는 크리프 복원정도를 제외하고 거의 차이가 없었으나, 반면에 마모의 경우, 감마선 멸균처리 된 시편이 멸균처리 하지 않은 시편보다 훨씬 적은 마모량을 보였다 (p<0.05). 이것은 crosslinking 증가에 따른 마모 저항력 향상으로 볼 수 있다.

• Textile Coloration and Finishing
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• v.23 no.2
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• pp.76-82
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• 2011

Ultra High molecular weight polyethylene(UHMWPE) films were photooxidized by UV/ozone irradiation. Reflectance of the irradiated films decreased in the low wavelength regions of visible light, indicating destructive interference of visible light due to roughened surface. The UV treatment developed the nano-scale roughness on the UHMWPE films surface, which increased by two-fold from 82.6 to 156.6nm in terms of peak-valley roughness. The UV irradiation caused the oxygen content of the UHMWPE film surface to increase. Water contact angle decreased from $83.2^{\circ}$ to $72.9^{\circ}$ and surface energy increased from 37.8 to 42.6mJ/$m^2$ with increasing UV energy. The surface energy change was attributed to significant contribution of polar component rather than nonpolar component indicating surface photooxidation of UHMWPE films. The increased dyeability to cationic dyes may be due to the photochemically introduced anionic and dipolar dyeing sites on the film surfaces.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.37-44
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• 1999

Because of bone resorption, wear of ultra-high molecular weight polyethylene(UHMWPE) in total knee arthroplasty has been recognized as a major factor in long-term failure of knee implant. The surface damage and the following harmful wear debris of UHMWPE is largely related to contact stress. Most of the previous studies focused on the contact condition only at the articulating surface of UHMWPE. Recently, contact stress at the metal-backing interface has been implicated as one of major factors in UHMWPE wear. Therefore, the purpose of the is study is to investigate the effect of the contact stress for different thickness, conformity friction coefficient, and flexion degree of the UHMWPE component in total knee system, considering the contact conditions at both interfaces. In this study, a two-dimensional non-linear plane strain finite element model was developed. The results showed that the maximum value of von-Mises stress occurred below the articulating surface and the contact stress was lower for the more conforming models. All-polyethylene component showed lower stress distribution than the metal-backed component. With increased friction coefficient on the tibiofemoral contact surface, the maximum shear stress increased about twofold.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.365-366
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• 2002

The sliding wear behavior of ultra high molecular weight polyethylene (UHMWPE) was examined on a novel low temperature degradation-free zirconia/alumina composite material and conventional alumina and zirconia ceramics used for femoral head in total hip joint replacement. The wear of UHMWPE pins against these ceramic disks was evaluated by performing linear reciprocal sliding and repeat pass rotational sliding tests for one million cycles in bovine serum. The weight loss of polyethylene against the novel low temperature degradation-free zirconia/alumina composite disks was much less than those against conventional ceramics for all tests. The mean weight loss of the polyethylene pins was more io the linear reciprocal sliding test than in the repeal pass rotational sliding lest for all kinds of disk materials. Neither the coherent transfer film nor the surface damage was observed on the surface of the novel zirconia/alumina composite disks during the test. The observed r,'stilts indicated that the wear of the polyethylene was closely related to contacting materials and kinematic motions. In conclusion, the novel zirconia/alumina composite leads the least wear of polyethylene among the tested ceramics and demonstrates the potential as lhe alternative materials for femoral head in total hip joint replacement.