• Fibers and Polymers
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• 제4권4호
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• pp.145-150
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• 2003

Polypropylene nonwoven fabrics were exposed to He/$O_2$ atmospheric pressure glow discharge plasma. Surface chemical analysis and contact angle measurement revealed the surface oxidation by formation of new functional groups after plasma treatment. Weight loss (%) measurement and scanning electron microscopy analysis showed a significant plasma etching effect. It was investigated in low-stress mechanical properties of the fabrics using Kawabata Evaluation System (KES-FB). The surface morphology change by plasma treatment increased surface friction due to an enhancement of fiber-to-fiber friction, resulting in change of other low-stress mechanical properties of fabric.

• Structural Engineering and Mechanics
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• 제43권5호
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• pp.623-636
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• 2012

The aim of the current work is to describe the flexural behaviour of simply supported concrete beams with tension reinforcement spliced at mid-span. The parameters included in the study were the type of the concrete, the splice length and the configuration of the hooked splice. Fifteen beams were cast using an ordinary concrete mix and two fiber reinforced concrete mixes incorporating steel and polypropylene fibers. Each concrete mix was used to cast five beams with continuous, spliced and hooked spliced tension steel bars. A test beam was reinforced on the tension side with two 12 mm bars and the splice length was 20 and 40 times the bar diameter. The hooked bars were spliced along 20 times the bar diameter and provided with 45-degree and 90-degree hooks. The test results in terms of cracking and ultimate loads, cracking patterns, ductility, and failure modes are reported. The results demonstrated the consequences due to short splices and the improvement in the structural behaviour due to the use of hooks and the confinement provided by the steel and polypropylene fibers.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.278-283
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• 2000

This study is performed to evaluate the strength and permeable properties of soil-concrete. The results show that the highest compressive strength and bending strength of soil-concrete is achieved by 20% gravel, 20% excellent soil compound and 0.1% polypropylene fiber filled soil concrete. The coefficient of permeability is decreased with increase of the content of gravel and excellent soil compound, and increased with increase of the content of polypropylene fiber. Accordingly, soil concrete with polypropylene fiber will be improve the physical and mechanical properties of concrete.

• 한국세라믹학회지
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• 제31권5호
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• pp.491-498
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• 1994

A fiber reinforced grouts were made using ordinary cement mortar and high effective water reducing agent (naphthalene sulfonate) were made by addition polypropylene fiber and carbon fiber. The physical properties of the grouts were investigated through the observation of the microstructure and the application of fracture mechanics. When the polypropylene fiber and carbon fiber were added respectively with 0.03 wt% to the grouts the compressive strength, flexural strength and Young's modulus were about 60∼63 MPa, 12.2∼12.4 MPa, 4.2∼4.8 GPa and 63∼68 MPa, 12.2∼12.6 MPa, 4.8∼5.1 GPa, and critical stress intensity were about 0.77∼0.82 MNm-1.5, and 0.80∼0.87 MNm-1.5 respectively, It can be considered that the strength improvement of fiber reinforced grouts (FRG) may be due to the removal of macropores and the increase of various fracture toughness, polymer fibril bridging and fiber bridging.

• 한국세라믹학회지
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• 제55권5호
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• pp.446-451
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• 2018

In this study, different formulations of magnesium oxide and various modifiers (phosphoric acid, ferrous sulfate, pure acrylic emulsion, silicone acrylic emulsion, glass fiber, and polypropylene fiber) were used to prepare magnesium oxychloride cement composites. The compressive strength of the magnesium oxychloride cement was tested, and the softening coefficients of the composites after soaking in water were also calculated. The results showed that a magnesium oxychloride cement sample could not be coagulated when the MgO activity was 24.3%, but the coagulation effect of the magnesium oxide cement sample was excellent when the MgO activity was 69.5%. While pure acrylic emulsion, silicon-acrylic emulsion, and glass fiber showed insignificant modification effects on the magnesium oxychloride cement, ferrous sulfate heptahydrate, phosphoric acid, and polypropylene fiber could effectively improve its water resistance and compressive strength. When the phosphoric acid, ferrous sulfate heptahydrate, and polypropylene fiber contents were 0.47%, 0.73%, and 0.25%, respectively, the softening coefficient of a composite soaked in water reached 0.93 after 7 days, and the compressive strength reached 64.3 MPa.

• Computers and Concrete
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• 제17권3호
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• pp.323-336
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• 2016

Although the self-compacting concrete (SCC) offers several practical and economic benefits and quality improvement in concrete constructions, in comparison with conventionally vibrated concretes confronts with autogenously chemical and drying shrinkage which causes the formation of different cracks and creates different problems in concrete structures. Using different fibers in the mix design and implementation of fibrous concrete, the problem can be solved by connecting cracks and micro cracks together and postponing the propagation of them. In this study an experimental investigation using response surface methodology (RSM) based on full factorial design has been undertaken in order to model and evaluate the polypropylene fiber effect on the fibrous self-compacting concrete and curing time, fiber percentage and fiber amount have been considered as input variables. Compressive strength has been measured and calculated as the output response to achieve a mathematical relationship between input variables. To evaluate the proposed model analysis of variance at a confidence level of 95% has been applied and finally optimum compressive strength predicted. After analyzing the data, it was found that the presented mathematical model is in very good agreement with experimental results. The overall results of the experiments confirm the validity of the proposed model and this model can be used to predict the compressive strength of fibrous self-compacting concrete.

• 멤브레인
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• 제15권3호
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• pp.233-240
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• 2005

유용하고 중요한 의료기기인 폐 보조 장치(LAD)의 혈액 접촉 표면과 인공 폐 막에 사용하기 위한 혈액 적합성 생체 재료를 개발하기 위해 폴리프로필렌 중공사 막의 표면 개질을 수행하였다. 재료의 혈액적합성은 항응고 처리된 혈액을 사용하였고 플라스마 응고 형성, 혈소판 접착 및 플라스마 응고 활성화, 그들의 표면 혈전 형성을 평가하여 결정하였다. 실험 결과는 실리콘 코팅 중공사들에 부착한 혈소판 수가 우수한 혈액 적합성을 나타내는 폴리프로필렌에 부착한 혈소판 수보다도 상당히 더 낮았음이 확인되었다. 또한, 상대적으로 플라스마 표면 처리한 폴리프로필렌 중공사 막이 혈액 적합성 평가에서 보체 활성화 억제를 보였음이 확인되었다.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2007년도 추계학술발표회
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• pp.47-48
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• 2007

• 콘크리트학회논문집
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• 제14권1호
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• pp.76-82
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• 2002

초속경 시멘트 콘크리트는 양생 시 초기재령에서 높은 수화열과 건조수축으로 인해 균열이 발생하기 쉽다. 이러한 문제점을 해결하기 위해 각종 소재를 적극 활용하려는 노력의 일환으로 섬유보강 콘크리트를 사용하게 된다 합성섬유보강 콘크리트는 건조수축에 대한 저항성과 내구성을 증진시키는 것으로 보고되고 있는데 대부분이 일반콘크리트에 대한 연구가 수행되었을 뿐 초속경 시멘트콘크리트에 관한 건조수축의 영향에 대해 정량적 및 정성적 연구가 미미한 상태이다. 따라서, 본 연구에서는 합성섬유보강 콘크리트의 건조수축 저감효과와 초속경 시멘트 콘크리트에서 수축에 대한 구속효과를 평가하기 위하여 콘크리트종류, 섬유보강 여부, 물-시멘트비, 구속여부를 주요 실험변수로 하여 건조수축실험을 수행하였다. 그 결과 일반 콘크리트에 비해 초속경 시멘트 콘크리트의 건조수축의 진행이 상당히 작음을 알 수 있었다. 이는 속경성 콘크리트의 수화반응이 빠르게 진행되어 건조에 의한 중량감소율이 다소 작은 점과 수화생성물과의 관계에 기인되는 것으로 판단된다. 또한 1축으로 구속된 건조수축의 구속으로 인한 초속경 시멘트 콘크리트의 건조수축을 예측할 수 있었고 초속경 시멘트 콘크리트에 섬유보강으로 인한 건조수축 제어는 일반콘크리트에 비해 효과가 매우 큰 것으로 나타났다.

• Advanced Composite Materials
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• 제16권4호
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• pp.315-334
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• 2007

In the present study, chopped henequen natural fibers without and with surface modification by electron beam (E-beam) treatment were incorporated into a polypropylene matrix. Prior to composite fabrication, a bundle of raw henequen fibers were treated at various E-beam intensities from 10 kGy to 500 kGy. The effect of E-beam intensity on the interfacial, mechanical and thermal properties of randomly oriented henequen/polypropylene composites with the fiber contents of 40 vol% was investigated focusing on the interfacial shear strength, flexural and tensile properties, dynamic mechanical properties, thermal stability, and fracture behavior. Each characteristic of the material strongly depended on the E-beam intensity irradiated, showing an increasing or decreasing effect. The present study demonstrates that henequen fiber surfaces can be modified successfully with an appropriate dosage of electron beam and use of a low E-beam intensity of 10 kGy results in the improvement of the interfacial properties, flexural properties, tensile properties, dynamic mechanical properties and thermal stability of henequen/polypropylene composites.