• Title, Summary, Keyword: polypropylene

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Effect of Molecular Weight and Rheological Properties on the Cross-sectional Characteristics of Polypropylene Hollow Fiber (분자량 및 유변성질이 폴리프로필렌 중공섬유의 단면특성에 미치는 영향)

  • 박경수;김상용
    • Textile Science and Engineering
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    • v.37 no.6
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    • pp.309-315
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    • 2000
  • Extrudate swell from segmented arc type spinneret was investigated by studying the roundness as well as hollowness of polypropylene hollow fibers from different molecular weight polypropylene chips. Extrudate swell increases as the spinning temperature decreases and average molecular weight increases. Also, extrudata swell of polypropylene with higher first normal stress difference is larger. Hollowness of fibers is influenced by the extrudate swell and the fiber formation process along the spinline. Hollowness decreases as the spinning temperature increases and the rate of decrease in hollowness is greater for polypropylene with smaller activation energy. In the case of polypropylenes with similar first normal stress difference, hollowness of fibers increases as the weight average molecular weight increases. Roundness of the inner circle is more sensitive to spinning temperature and molecular weight than that of the outer circle.

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Effect of chain structure of polypropylenes on the melt flow behavior

  • Lee, Young-Jun;Sohn, Ho-Sang;Park, Seung-Ho
    • Korea-Australia Rheology Journal
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    • v.12 no.3_4
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    • pp.181-186
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    • 2000
  • Rheological Properties of polypropylenes having different molecular structures (linear polypropylene (PPL) and branched one (PPB)) were studied. Both the extensional flow and oscillatory shear flow properties were checked. Especially, the melt strength of polypropylenes having various shear history were investigated by using in-house-made Rheometer (called SMER). Compared to linear polypropylene, the branched polypropylene shows enhanced melt strength during extensional flow due to the retarded relaxation of molecules. When the slope of melt tension was plotted against take up speed of melt strand, the characteristic peak was observed in case of branched polypropylene, while the linear polypropylene shows only monotonously decreasing pattern. This entanglement was partially disrupted by physical forces such as shear during melt extrusion. However, the melt strength of PPB after multiple extrusion is still higher than PPL, implying the loss of elasticity during multiple extrusion is not so comprehensive. On dynamic experiments, PPB shows typical shear thinning behavior and the tangent delta of PPB is lower than PPL, reflecting high elasticity of PPB.

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Modification and Properties of Polypropylene Fibers Using Aluminosiloxane

  • Yoon, Cheol-Soo;Ji, Dong-Sun
    • Fibers and Polymers
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    • v.4 no.4
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    • pp.210-214
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    • 2003
  • Siloxylated polypropylene fibers composed of polypropylene (PP) and aluminosiloxane (AS) were prepared by melt blending followed by spinning. The effects of blend compositions on the thermal behaviors, surface and tensile properties of PP/AS blend fibers were investigated by DSC, WAXD, SEM, static honestometer, etc. The heat of fusion of PP/AS blends decreased with increasing AS contents. In addition, the peak intensity of PP/AS blends in X-ray diffraction patterns decreased with increasing AS contents. It was observed that the silicone molecules exist and well distribute on the surface of siloxylated polypropylene fibers. From the results of the half-life period measurements, the anti-static properties of PP fibers siloxylated with AS was found to be significantly modified.

A Study on the Strength and Drying Shrinkage Crack Control Properties of Polypropyl (폴리프로필렌 합성섬유보강 콘크리트의 강도 특성 및 건조수축균열제어 특성에 관한 연구)

  • 오병환;백상현
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.146-152
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    • 1996
  • Polypropylene fiber reinforced mortar and concrete as civil material or architectural material have been used in America and British etc, and have been researched. Polypropylene fibers have many advantages in many points ; in economical costs, chemical stability and durability. It has been reported that polypropylene fiber can control restrained tensile stresses and cracks and increase toughness, resistance to impact, corrosion, fatigue and durability. This study has been performed to obtain the properties of polypropylene fiber reinforced concrete such as compressive strength, flexural strength, toughness, slump, drying shrinkage crack and drying shrinkage characteristics. The test variables are fiber contents, fiber length, fiber types, and so on. From the results of this study, we can expect the effects of the admixtures of polypropylene fiber about strength and drying shrinkage properties in concrete and mortar.

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Gas Permeability and Blood Compatibility in Polydimethylsiloxane Polypropylene Combined Membrane (Polydimethylsiloxane 가공 Polypropylene막에서의 기체투과 및 혈액적합성)

  • Kim, K.B.;Lee, S.C.;Jheong, G.R.
    • Proceedings of the KOSOMBE Conference
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    • v.1998 no.11
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    • pp.233-234
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    • 1998
  • The purpose of this paper is the evaluation of a permeability and blood compatibility for silicone/polypropylene combined membrane. Despite the overall good performances of polypropylene membrane, its long-lasting usage for artificial lung has been limited by serum leakage. In order to overcome this problem, we have newly fabricated polydimethylsiloxane(silicone)/polypropylene combined membrane(SPCM). SPCM has been proved to be serum leakage free in hours experimental. It has shown good long-lasting gas transfer and durability features.

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Characteristics of compaction and strength for synthetic fiber reinforcement soils (섬유 보강토의 다짐 및 강도 특성)

  • 송창섭;장병욱;이용범;임성윤
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.444-448
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    • 1998
  • This paper presents the results of an experimental investigation on the compaction and compressive strength of polypropylene fiber reinforced soils. This study has been performed to obtain the physical properties of PFRS(polypropylene fiber reinforced soil) such as strain-stress relationships, OMC(optimum moisture contents) and ${\gamma}$$_{dmax}$ (maximum dry unit weight), with four different concentrations(i.e., 0.1%, 0.3%, 0.5% and 1.0% weights) of mono-filament and fibrillated polypropylene fibers. The test results indicate an appreciable increase in strength due to addition of fibers. OMC is increased with the concentration ratio of fiber, but ${\gamma}$$_{dmax}$ is decreased. From the viewpoint of strength, the fibrillated polypropylene fiber soil is more effective than the mono-filament polypropylene fiber soil.oil.

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On the Pyrolysis of Polymers IV. Pyrolysis of Polythylene and Polypropylene (高分子物質의 熱分解에 關한 硏究 (第4報) Polyethylene 및 Polypropylene의 熱分解에 關하여)

  • Chwa-Kyung Sung;Icksam Noh;Jung Yup Kim;Sung Bong Chang
    • Journal of the Korean Chemical Society
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    • v.7 no.2
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    • pp.122-127
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    • 1963
  • Pyrolysis fo polyethylene and polypropylene has been studied in order to clarify the mechanism of chain scission and effect of oxygen on degradation. Rate of weight decrease was measured under nitrogen and air atmosphere at constant temperature for the samples of high density polyethylene, low density polyethylene and isotactic polypropylene, and then gaseous hydrocarbons produced from pyrolysis were analysed by gas chromatography. Although there is little substantial difference between composition of hydrocarbon gases from pyrolysis of high density polyethylene and low density polyethylene except some difference in quantity of total gas produced, gas composition from polypropylene pyrolysis differs from that of polyethylene pyrolysis. Gases from pyrolysis under air contain much more unsaturated hydrocarbons than those from pyrolysis under inert gas.

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Mechanical and Hygroscopic Behaviour of Teak Wood Sawdust Filled Recycled Polypropylene Composites

  • Yadav, Anil Kumar;Srivastava, Rajeev
    • Composites Research
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    • v.31 no.5
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    • pp.202-208
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    • 2018
  • In this paper, mechanical and hygroscopic properties of teak sawdust and recycled polypropylene (RPP) composites are evaluated and compared with virgin polypropylene (VPP) matrix based composites. Verities of composites are prepared by variation in the plastic types, wood plastic ratio and the addition of coupling agent in the formulations. Mixing of wood sawdust and polypropylene is done by a twin screw extruder, and then sheets of wood plastic composites (WPCs) are produced by using the compression molding method. The results show that recycled matrix composites exhibit better tensile, flexural strength with low impact strength than virgin matrix based composites. Recycled composites show low water absorption and thickness of swelling than virgin matrix based composites. The results confirm that wood content in the polymer matrix affects the performance of composites while presence maleated polypropylene (MAPP) improves the properties of the composites significantly. Developed RPP matrix composites are as useful as VPP matrix composites and have the potential to replace the wood and plastics products without any adverse effect of the plastics on the environment.

Physical and Mechanical Properties of Eco-concrete with Polypropylene Fiber (폴리프로필렌 섬유를 혼입한 에코콘크리트의 물리.역학적 특성)

  • 성찬용;리신호;송창섭
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.43 no.1
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    • pp.116-121
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    • 2001
  • This study is performed to examine the physical and mechanical properties of eco-concrete with polypropylene fiber. Test results show that the strengths are increased with increase of the content of natural gravel, excellent soil compound and polypropylene fiber. The coefficient of permeability is increased with increase of the content of the polypropylene fiber but it is decreased with increase of the content of natural gravel and excellent soil compound. The lowest coefficient of permeability is achieved by eco-concrete which it is 100 times lower than that of the control. The durability factor is increased with increase of the content of natural gravel and excellent soil compound, and decreased with increase of the content of polypropylene fiber.

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Properties of Fire Resistance of Concrete with Contents of Polypropylene Fiber and Specimens Size (폴리프로필렌 섬유의 혼입률 및 부재크기 변화에 따른 콘크리트의 내화 특성)

  • 전선천;황인성;이병열;양성환;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.463-468
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    • 2001
  • A lot of considerations on the spatting by fire of high performance concrete should be taken into for fire resistance of the concrete structures. In this paper, fire resistance of high performance concrete is described using polypropylene fiber, which is known to be contributed to fire resistance. Strength level and member size are varied with. According to test results, spatting by fire takes place more easily, as W/C increases and member size decreases. It shows that concrete containing polypropylene fiber has good effects on preventing spatting by fire. In case high performance concrete does not contain polypropylene fiber, residual strength shows to be decreased remarkably compared :o that of normal concrete. Whereas, in case 0.1% of polypropylene fiber contents, high performance concrete shows higher residual strength than that of normal concrete. As member size is smaller, residual strength shows to be decreased.

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