• 한국구조물진단유지관리공학회 논문집
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• 제10권2호
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• pp.83-90
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• 2006

고강도 콘크리트는 구조적인 장점에도 불구하고 화재 시 폭렬과 함께 취성적인 파괴를 나타내는 단점으로 인하여 내화설계 시 주의하여 사용하여야 한다. 고강도 콘크리트의 폭렬제어를 위하여 폴리프로필렌 섬유(PP섬유)의 혼입이 가장 효율적인 것으로 여러 연구결과를 통하여 보고 되었으나, 이들은 대부분 콘크리트 공시체를 대상으로 한 내화실험의 결과로서 최적의 PP섬유 혼입량에 대한 부재수준의 연구는 매우 부족한 실정이다. 본 연구에서는 고강도 콘크리트 기둥의 내화설계를 위한 최적의 PP섬유 혼입량을 제시하기 위하여 콘크리트 강도와 PP섬유의 혼입량을 변수로 하는 기둥부재의 내화실험 및 잔존강도 실험을 수행하였으며, 실험결과 콘크리트 강도가 증가 할수록 기둥 실험체의 잔존 축강도비는 증가하였으며, PP섬유 혼입량을 0%에서 0.2%까지 증가 시킬수록 기둥의 잔존 축강도비가 증가하는 것으로 나타났다. 따라서 최적의 PP섬유 혼입량으로서 0.2%가 적절할 것으로 판단된다.

• 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.

• 한국구조물진단유지관리공학회 논문집
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• 제11권2호
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• pp.155-163
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• 2007

고강도 콘크리트(HSC)는 화재 시 폭렬현상과 함께 부재가 취성적인 거동을 하게 되는 단점을 지니고 있다. 폭렬현상은 화재 시 $100{^{\circ}C}$이상에서 부재내부의 수분 증발로 인하여 발생한 수증기가 수밀한 콘크리트에 갇혀 발생한다. 따라서 콘크리트 강도가 증가 할수록 수밀성이 높아져 폭렬의 정도가 심해진다. 콘크리트의 폭렬을 제어할 수 있는 방안으로는 폴리프로필렌 섬유(PP섬유)를 혼입하는 방법이 가장 효율적인 것으로 보고 되었다. 본 연구에서는 콘크리트 강도와 PP섬유 함유량을 변수로 하는 기둥 실험체에 대한 내화실험과 잔존강도실험을 수행하여 폭렬현상을 관찰하고 잔존강도를 측정하였다. 그 결과 콘크리트 강도가 60MPa에서 85MPa로 증가할 때 기둥 실험체의 잔존 축 강도는 10%증가하였다. 또한, PP섬유 함유량이 0%에서 0.2%까지 증가 할수록 잔존 축강도비는 68%에서 85%까지 증가하였으나, PP섬유 함유량이 0.2%이상에서는 잔존강도의 증가가 거의 나타나지 않았다.

• 폴리머
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• 제27권5호
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• pp.458-463
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• 2003

표면처리된 몬모릴로나이트 (montmorillonite, MMT)가 PP 나노복합재료의 열안정성에 미 치는 영향을 조사하였다. $Na^{+}$-MMT는 dodecylammonium chloride를 이용하여 유기적으포 개질하였다. 비표면적 ( $S_{BET}$), 평형확산압력 ($\pi$$_{e}$ ), 그리고 비극성 요소 (${\gamma}$ $s^{L}$)를 포함하는 표면 특성은 $N_2$ 흡착을 이용하는 BET 방법을 이용하여 고찰하였다. 또한, 나노복합재료의 열안정성은 시차주사열량계 (DSC)와 열중량 분석기 (TGA)를 통해 알아보았다. 실험 결과, 오존처리된 dodecylammonium chloride (DA-MK ( $O_3$))의 $\pi$$_{e}$ 과 ${\gamma}$ $s^{L}$는 1.7과 3.5 mJ/ $m^2$로 증가하였는데, 이는 미세기공이 증가하기 때문으로 판단된다. DSC 결과로부터, PP/DA-MK와 PP/DA-MK ( $O_3$)의 용융 온도와 결정화 온도는 순수한 PP보다 더 높았는데, 이러한 결과는 나노크기의 DA-MK가 PP 결정화를 위한 핵생성 효과를 유도하기 때문으로 판단된다. 또한, PP/DA-MK ( $O_3$) 나노복합재료의 열안정성은 64 kJ/mol 향상되었는데, 이는 PP 매트릭스 내 DA-MK ( $O_3$)의 분산성 향상에 기인하는 것으로 판단된다.단된다.다.

• 한국식품저장유통학회지
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• 제30권4호
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• pp.562-572
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• 2023

In this study, we aimed to evaluate the quality of Aralia elata shoots according to different packaging methods during storage at 2℃. The highest level of dehydration and wilting incidences were observed in polypropylene containers with polyvinyl chloride wrap (PP+PVC), and these levels continually increased during the entire storage period, compared to other packaging methods. The overall marketability of A. elata shoot packaged in polyethylene terephthalate container (PET) and PP with the mineral-coted functional warp (PP+F) constantly declined during storage with a similar level of 38.6 and 36.0% at 15 days in storage, respectively. PP with PET cover packaging (PP+PET) showed the lowest decay and wilting rates during the entire storage, and the wilting score at 10th day was 51.9, 58.0, 51.8% suppressed, as compared to PET, PP+PVC, and PP+F, respectively. Consequently PP+PET packaging effectively decreased the deterioration of A. elata and maintained marketability for 10 days of storage at 2℃.

• Advances in materials Research
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• 제4권2호
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• pp.97-111
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• 2015

Polypropylene short fiber (PP)-clay particulate-epoxy ternary composites were prepared by reinforcing PP short fiber and clay particles in the range of 0.1 phr to 0.7 phr into epoxy resin. Prepared hybrid composites were characterized for their mechanical, thermal and flame retardant properties. The obtained results indicated an increase in impact resistance, tensile strength, flexural strength and Young's modulus to an extent (up to 0.5 phr clay and 0.5 phr PP short fiber) and then decreases as the reinforcing phases are further increased. The thermal stability of these materials are found to increase up to 0.2 phr clay and 0.2 phr PP addition, beyond which it is decreased. Addition of clay is found to have the negative effect on epoxy-PP short fiber composites, which is evident from the comparison of mechanical and thermal properties of epoxy-0.5 phr PP short fiber composite and epoxy-0.5 phr PP short fiber-0.5 phr clay composite hybrid. UL-94 tests conducted on the composite hybrids have showed a reduction in the burning rate. Morphological observations indicated a greater fiber pull with the addition of clay. The performed tests in the present study indicated that materials under investigation have promising applications in construction, agriculture and decorative purposes.

• Elastomers and Composites
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• 제38권2호
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• pp.122-127
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• 2003

환경에 유해한 PVC 재질의 바닥재나 시트를 대체하기 위하여 styrene-ethylene-butadiene-styrene(SEBS)과 같은 열가소성고무를 사용하고 polypropylene(PP) 등의 폴리머와 오일, 무기물 및 안정제 등을 혼합하여 내충격성 또는 탄성이 우수한 새로운 소재를 개발하기 위한 컴파운딩 연구를 진행하였다. SEBS와 오일의 혼합물에서 경도는 오일의 함량이 증가함에 따라서 선형적으로 감소하였고, SEBS/oil/PP의 조성물에서는 PP의 함량이 증가하면 인장강도는 선형적으로 증가하는 반면, 신율은 PP가 50phr상에서는 거의 영향이 없었다. PVC 소재의 바닥재나 시트를 대체 사용하기 위한 실질적인 SEBS 혼합물의 조성물에서도 인장 및 인열강도, 그리고 경도는 PP 함량에 비례하여 증가하는 것으로 나타났으나, 용융지수는 PP 함량이 증가하면 감소하는 것으로 나타났다.

• Carbon letters
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• 제11권4호
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• pp.311-315
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• 2010

In this work, the effect of glycidyl methacrylate grafted multi-walled carbon nanotubes (GMA-MWCNTs) on the viscoelastic behaviors of polypropylene (PP) based nanocomposites was studied. The GMA-MWCNTs/PP was prepared using a bravender at $200^{\circ}C$ by melt mixing as a function of GMA-MWCNT content. The viscoelastic behaviors of GMA-MWCNTs/PP nanocomposites were measured by a rheometer. It was found that the GMA-MWCNTs were homogeneously dispersed in the PP matrix. The GMA-MWCNTs/PP nanocomposites showed higher storage modulus, loss modulus, and shear viscosity compared to pure PP nanocomposites and the maximum value was shown at 2.0 wt% GMA-MWCNTs loading. These results were probably attributed to the strong interfacial interaction between the GMA-MWCNT and the PP matrix.

• Elastomers and Composites
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• 제55권1호
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• pp.1-5
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• 2020

This study examined the effects of the addition of maleic anhydride-grafted polypropylene (PP-g-MA) and polyolefin elastomer (POE) on polyamide 66 (PA66) and polypropylene (PP) blends. The blends of PA66/PP with PP-g-MA and POE were prepared using a twin screw extruder. Mechanical testing results revealed that the tensile, flexural, and izod impact strengths of the blends were maximized at a PP-g-MA content of 2 phr. The increased mechanical strength of the blends with PP-g-MA was attributed to the compatibilizing effect of the PA66 and PP blends. In addition, as the POE content increased, the impact strength of the blends increased. However, at a high POE content, the tensile and flexural strengths decreased, seemingly because of the lower mechanical properties of POE.

• Computers and Concrete
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• 제26권2호
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• pp.115-125
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• 2020

To reduce the damage of concrete in fire, a new type of lightweight cinder aggregate concrete was developed due to the excellent fire resistance of cinder. To further enhance its fire resistance, Polypropylene (PP) Fibers which can enhance the fire resistance of concrete were also used in this type of concrete. However, the bond behavior of this new type of concrete after fire exposure is still unknown. To investigate its bond behavior, 185 specimens were heated up to 22, 200, 400, 600 or 800℃ for 2 h duration respectively, which is followed by subsequent compressive and tensile tests at room temperature. The concrete-rebar bond strength of C30 PP fiber-reinforced cinder concrete was subsequently investigated through pull-out tests after fire exposure. The microstructures of the PP fiber-reinforced cinder concrete and the status of the PP fibre at different temperature were inspected using an advanced scanning electron microscopy, aiming to understand the mechanism of the bonding deterioration under high temperature. The effects of rebar diameter and bond length on the bond strength of PP fiber-reinforced cinder concrete were investigated based on the test results. The bond-slip relation of PP fiber-reinforced cinder concrete after exposure at different temperature was derived based on the test results.