• 소성∙가공
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• 제32권6호
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• pp.367-375
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• 2023

Composite materials, known for their excellent mechanical properties and lightweight characteristics, are applied in various engineering fields. Recently, efforts have been made to develop an automotive battery protection panel using a plain-woven composite composed of glass fiber and polypropylene to reduce the weight of automobiles. However, excessive warpage occurs during the GF/PP compression molding process, which makes car assembly challenging. This study aims to develop a model that predicts the warpage during the compression molding process. Obtaining out-of-plane properties such as elastic or shear modulus, essential for predicting warpages, is tricky. Existing mechanical methods also have limitations in calculating these properties for woven composite materials. To address this issue, finite element analysis is conducted using representative volume elements (RVE) for woven composite materials. A warpage prediction model is developed based on the estimated physical properties of GF/PP composite materials obtained through representative volume elements. This model is expected to be used for reducing warpages in the compression molding process.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.95-98
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• 2007

This study investigates the mechanical properties of the high strength concrete in the region of 80MPa corresponding to the temperature and fiber content change. For the properties of the fresh, slump flow is $600{\pm}100mm$, and air content is $3.0{\pm}1.0%$. They satisfy each targets, and there was no difference for the each fiber types. As the propertied of the hardened concrete, the compressive strength at 28 days is indicated over 80MPa, and they are similar to the change of the fiber types. The residual compressive strength in response to the temperature change of the NY, PP, and NY+PP fiber at $200^{\circ}C$ are increased by 115, 114, and 110% on the standard condition, and it is suddenly decreased at $400^{\circ}C$. They are decreased by 33, 19, and 16% on the standard condition at $800^{\circ}C$.

• 한국농공학회논문집
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• 제55권1호
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• pp.1-8
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• 2013

This study will not only prove experimental dynamic properties which are classified to slump, compressive strength, tensile strength, flexure strength and toughness granite soil concrete with a fine aggregate of granite soil and blast-furnace cement and polypropylene fiber over 45 mm, but also establish a basic data in order to use environment-friendly pavement through prove useful pavement mixed with granite and polypropylene (PP) fiber which is a kind of material to prevent a dry shrinkage clack, a partial destruction and useful and light. The value of slump test was gradually increased by PP fiber volume 3 $kgf/m^3$, but compressive strength took a sudden turn for the worse from 5 $kgf/m^3$. The compressive strength indicated a range of 13.72~18.35 MPa. On the contrary to compressive strength, the tensile strength showed to decrease with rising PP fiber volume, and the tensile strength indicated a range of 1.43~1.64 MPa. The tensile strength was stronger about 2~15 % in case of mixing with PP fiber volume than normal concrete. The flexural strength indicated a range of 2.76~3.41 MPa. The flexural strength was stronger about 20 % in case of PP fiber volume 0 $kg/m^3$ than PP fiber volume 9 $kg/m^3$. The toughness indicated a range of 0~25.46 $N{\cdot}mm$ and increased proportionally with PP fiber volume. The toughness was stronger about 8.3 times in case of PP fiber volume 9 $kg/m^3$ than PP fiber volume 1 $kg/m^3$. The pavement with PP fiber volume over such a fixed quantity in the park roads and walkways can have a effect to prevent not only resistance against clack but also rip off failures.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.119-120
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• 2011

Recently, the effects of high temperature and fiber content on the residual mechnical properties of high-strength concrete were experimentally investigated. In this paper, residual mechanical properties of concrete with water to cement (w/c) ratios of 55%, 42% and 32% exposed to high temperature are compared with those obtained in fiber reinforced concretes of similar characteristics with the ranging of 0,05% to 0,20% polypropylene (PP) fibers by volume of concrete, and considered factors include pre-load levels (20% and 40% of the maximum load at room temperature). Outbreak time and water contents were tested and were determined the compressive strength. In the result, it is showed that to prevent the explosive spalling of 50MPa grade concretes exposed to high temperature need more than 0.05Vol.% PP fibers. Also, the cross-sectional area of PP fiber can influence on the residual mechanical properties and the spalling tendency of fiber reinforced concrete exposed to high temperature. Especially, the external loading increases not only the residual mechanical properties of concrete but also the risk of spalling and the brittle tendency.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.422-425
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• 2003

Investigated whether fiber orientation distribution of twisted yarn composites and the fiber content are 0$^{\circ}$ and 90$^{\circ}$ direction tensile strength and some correlation. Tensile strength of 0$^{\circ}$ directions of twisted yarn composites increased changelessly being proportional the fiber content and fiber orientation function get into anisotropic in isotropic. But, tensile strength ratio by separation of fiber filament of 90$^{\circ}$ directions tensile strength decreased when tensile load is imposed for width direction of reinforcement fiber. 0$^{\circ}$ and 90$^{\circ}$ direction tensile strength ratio value of a twisted yarn composites not receive almost effect of the fiber content of fiber orientation function J = 0.4 lows. Although do, 20 wt% of the fiber content is high about 0$^{\circ}$ and 90$^{\circ}$ direction tensile strength ratio about 1.6~2 than 10 wt% from J = 0.4. Therefore. could know that effect of the fiber content is dominate.

• 폴리머
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• 제26권2호
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• pp.153-159
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• 2002

본 연구에서는 지하수 중의 NO$_{3}^{-}$ 이온을 선택적으로 흡착 제거시키기 위하여 E-beam 전조사법에 의해 GMA 단량체를 폴리프로필렌 섬유 기재에 그라프트 반응시켜 PP-g-GMA 공중합체를 제조한 후 아민화 반응을 통하여 강염기성 APP-g-GMA 음이온교환수지를 합성하였다. 공중합체의 그라프트율 및 TMA에 의한 아민화율은 반응온도가 증가할수록 증가하였으며, $60^{\circ}C$일 때 각각 133%, 88% 최대치를 나타내었고, 이때의 팽윤율과 이온교환용량은 각각 86%, 2.5 meq/g으로 IMAC HP555, Amberlite IRA 400와 같은 상용 이온교환수지 보다 높게 나타났다. $NO_3;^-$ 이온흡착의 최적 조건은 pH 5~6이었으며, trimethylammonium 기를 갖는 -Cl형의 APP-g-GMA 이온교환체가 가장 높은 선택 흡착성을 나타냈다.

• 한국농공학회논문집
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• 제57권4호
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• pp.11-19
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• 2015

The important properties of EVA (ethylene vinyl acetate) redispersible polymer was waterproof, densification of internal pore space of concrete and ball bearing and micro filler. Also, the significant role of polypropylene(PP) fiber was crack control and blockade of movement for deterioration factors. The most studies for EVA were limited in the field of mortar and PP fiber reinforced concrete had been studied in the state of being restricted unit water content, rich mix and mixing much of the fiber without considering construction site. Therefore, the control mix design were applied in ready mixed concrete using 10 % fly ash of total cement weight used in batch plant. On the basis of control mix design, EVA contents ranging from 0 % to 10 % of total cement weight and PP fiber contents ranging from 0 % to 0.5 % of EVA concrete volume were used in the mix designs. The results showed the maximum compressive strength value was measured at EVA 5.0 % and PP fiber 0.1 %, the minimum water absorption ratio was at EVA 10 % and PP fiber 0 %, the durability factor for freezing and thawing resistance was at EVA 5.0 % and PP fiber 0.3 % and the minimum weight reduction ratio of resistance to sulfuric acid attack was at EVA 10 % and PP fiber 0.5 % after curing age 42days. Meanwhile, From these results, PP fiber reinforced EVA concrete would be very benefit, if each optimal mix types were used in hydraulic structures, underground utilities and agricultural structures.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.125-128
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• 2005

The dispersion of carbon nanofiber (CNF) was carried out by solution blending, mechanical mixing, and sonication. CNFs at levels of 5-50% fiber weight content were mixed with polypropylene (PP) powder, and then were melt-mixed using a twin-screw extruder. For the further alignment of fibers, extruded rods were stacked uni-directionally in the mold cavity for the compression molding. For the evaluation of mechanical properties of nanocomposites, tension, in-plane shear, and flexural tests were conducted. CNF/PP composites clearly showed reinforcing effect in the longitudinal direction. The tensile modulus and strength have improved by 100% and 40%, respectively for 50 % fiber weight content, and the flexural modulus and strength have increased by 120% and 25%, respectively for the same fiber weight content. The shear modulus showed 65% increase, but the strength dropped sharply by 40%. However, the property enhancement was not significant due to the poor adhesion between fiber and matrix. In the transverse direction, the tensile, flexural, and shear strength decreased as more fibers were added.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.187-191
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• 2008

It is necessary to develop a technology for effectively controling explosive spalling of high strength concrete caused increasing construction of high rise building and putting up the fireproof standard of high strength concrete by MLTM (Ministry of Land, Transport and Maritime Affairs). Accordingly, it was investigated basic properties such as slump, air content and compressive strength, and fire resistance properties of high strength concrete using polypropylene fiber for field application as a countermeasure for explosive spalling of concrete on fire in this study, As a test result, it was confirmed that PP fiber is available as fire resistance method of high strength concrete.

• 한국화재소방학회논문지
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• 제25권5호
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• pp.85-92
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• 2011

최근 고강도 콘크리트의 내화성능이 사회적 이슈로 부각되고 국토해양부에서 고강도 콘크리트의 내화성능 관리기준이 고시되면서 국내에서도 고강도 콘크리트의 내화성능을 향상시키기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 유기질 섬유인 폴리프로필렌 섬유(PP섬유)와 강섬유를 하이브리드한 Fiber Cocktail를 혼입한 고강도 내화콘크리트 개발을 위한 연구를 수행하였다. 100 MPa 고강도 콘크리트의 내화실험을 실시하여 최적단면 조건을 도출하기 위해 철근온도를 분석한 결과, 단면이 커질수록 철근온도는 점차 낮아지는 경향이 나타났으며 $600{\times}600mm$, $800{\times}800mm$ 단면에서 내화성능을 확보할 수 있는 것으로 나타났으며, 이중 경제성을 고려할 경우 $600{\times}600mm$ 단면이 최적단면으로 도출되었다. 또한 도출된 $600{\times}600mm$ 단면에 대해서 철근의 온도를 분석한 결과 PP섬유 $1.5kg/m^3$와 강섬유 $40kg/m^3$를 배합비의 실험체가 내화성능이 더 확보되었다.