• Polymer(Korea)
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• v.32 no.1
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• pp.7-12
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• 2008

We confirmed that poly (ethylene terephthalate) (PET) fiber had the possibility to improve the mechanical properties of polypropylene (PP) by fabricating PP/PET fiber composites because PET enhanced mechanical properties and higher melting temperature than PP. But lower compatibility of between PP and PET fibers induced poor mechanical properties of PP/PET fiber composites in spite of incorporating PP-g-MAH as compatibilizer. To solve these problems of PP/PET fiber composites, we carried out a surface treatment on PET fiber using NaOH solution and Prepared PP/PET fiber composites with good mechanical properties by adding PP-g-MAH as a compatibilizer Then the behavior of the mechanical properties was correlated with the results obtained from SEM and IR spectroscopy.

• Journal of the Society of Disaster Information
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• v.11 no.4
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• pp.607-614
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• 2015

This study evaluated the flexural performance of steel and PP fiber reinfroced shotcrete using round panel test according to ASTM that can consider the actual stress of fiber reinforced shotcrete in tunnel and under ground structures. The results of round panel test are converted to the square panel test results according to the EFNARC. The energy absorptions of each fiber reinforced shotcrete were classified according to the EFNARC toughness classification. Test results show that the PP fiber reinforced shotcrete has better flexural performance compared with the steel fiber reinforced shotcrete.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.424-432
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• 1996

The fiber reinforced thermoplastic composites(FRTP) were prepared with polypropylene fiber(PPF) as matrix and vinylon(VF), Aramid(KF) or nylon fiber(PAF) as reinforcing materials using the integrated fiber mixing apparatus. The composite sheets were prepared by compression molding and their impact and morphological properties were characterized. VF/PP system showed the maximum value in Izod impact strength, while KF/PP system showed the maximum value in high rate impact properties. Ductility Index(DI) order was VF/PP>KF/PP>PAF/PP. A maximum DI for VF/PP, 2.43, was obtained when the weight fraction of VF was 20%. The optimum amount of the reinforcing organic fiber was found to be 20~30%. As a result, it is concluded that VF/PP system has better interfacial adhesion properties than either KF/PP or PAF/PP.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.391-398
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• 2010

The fire performance of RC slabs with half-depth precast panel after exposure to the ISO-834 fire standard without loading has been experimentally investigated. During heating, according to the ISO 834 fire curve, concrete spalling was observed for concrete without PP(polypropylene) fibers. No spalling occurred when heating concrete containing PP fibers. The maximum temperature of RC slabs with PP fibers with half-depth precast panel was lower than that of concrete without PP fibers. The ultimate load after cooling of the RC slabs that were not loaded during the furnace tests was evaluated by means of 3 points bending tests. The ultimate load of the RC slabs without PP fibers showed a considerable reduction (around 32.5%) of the ultimate load after cooling if compared with of RC slabs with PP fibers. The ultimate load of the RC slabs with half-depth precast panel with PP fibers is higher than that of a full-depth RC slabs with PP fibers. Also, the addition of PP fibers and the use of half-depth precast panel improve fire resistance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2A
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• pp.137-143
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• 2011

This study evaluated the effects of maleic anhydride grafted polypropylene powder (mPP) contents on the bond properties of cement mortar and nonpolar macro synthetic fibers (macro synthetic fiber). Dog-bone bond tests were performed to evaluate the bond performance of macro synthetic fiber in cement mortar with varying amounts of mPP (0%, 5%, 10%, 15%, 20%, 25%, 30% of cement weight). The bond properties (pullout behavior, pullout load and interface toughness) of macro synthetic fiber in cement mortar increased as the mPP contents was increased. The bond properties increased with the mPP contents. The microstructure of macro synthetic fiber surface was examined after the pullout test to analyze the frictional resistant force according to mPP contents during the pullout process of macro synthetic fiber in cement mortar. The scratched of macro synthetic fiber increased with the mPP contents.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.2
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• pp.83-90
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• 2006

A spalling is defined as the damages of concrete exposed to high temperature during the fire by causing cracks and localized bursting of small pieces of concrete. It is reported that spalling is caused by the vapor pressure and polypropylene(PP) fiber has an important role in protecting from spalling. The characteristics of fire resistance of high-strength reinforced concrete columns with various concrete strength and various contents of PP fiber were investigated in this study. In results, the ratio of unstressed residual strength of columns increases as the concrete strength increases and the ratio of unstressed residual strength of columns exposed to fire decreases as the content of PP fiber increases from 0% to 0.2%.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.113-119
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• 2009

This study is to investigate the fundamental and fireproof qualities of high strength concrete corresponding to changes in the curing factors and the PP fiber ratio. The results were as follows. For the fundamental characteristics of concrete, the fluidity was reduced in proportion to the increase in the PP fiber ratio. The compressive strength was somewhat reduced according to an increase in the PP fiber ratio. However, it had the high strength scope of more than 60 MPa at 7 days and of more than 90 MPa at 28 days. On the spalling mechanism followed by changes of the water content ratio, spalling was prevented in all combinations, except the specimen without PP fiber and subjected to 3.0% of moisture contents. When spalling was prevented at that time, the residual compressive strength ratio was 22%~41% and the mass reduction ratio was 5%~7%, which was relatively favorable. As the spalling mechanism corresponds to changes in the curing method, spalling was prevented in concrete with a PP fiber mixing ratio of more than 0.05% in the event of standard curing, and in concrete with a PP fiber mixing ratio of more than 0.10% in the case of steam curing and autoclave curing. In these cases, when spalling was prevented, the residual compressive strength ratio was 23~42% and the mass reduction ratio was 7~11%. In these results, the ease of spalling prevention in high strength concrete was inversely proportional to the water content ratio. Depending on the curing method, spalling was prevented in concrete with over 0.05% PP fiber with standard curing and in concrete with over 0.1% PP fiber with steam curing and autoclave curing.

• Composites Research
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• v.33 no.6
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• pp.346-352
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• 2020

In mobility industries, the use of thermoplastic composites increased dynamically. In this study, the mechanical and impregnation properties of continuous glass fiber (GF)/polypropylene (PP) composite were evaluated with different GF contents. The GF/PP commingled fiber was manufactured with different GF contents and continuous GF/PP composite was manufactured using continuous compression molding process. Tensile, flexural, and impact test of specimens were evaluated with different GF contents. The fracture behavior of specimens was proved using field emission-scanning electron microscope images of fracture area and impregnation property was evaluated using dynamic mechanical analyzer and interlaminar shear strength. Finally, the GF/PP composite was the optimized mechanical and impregnation properties using 50 wt.% GF/PP commingled fiber.

• Polymer(Korea)
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• v.39 no.1
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• pp.99-106
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• 2015

The surface of nano-kenaf containing cellulose fibers was treated with alkali (NaOH) and their effects on the physical properties of the polypropylene (PP) composite were investigated. The treatment of alkali on the fibers increased the melt flow index (M.I.), elongation%, and impact strength, while it decreased the tensile strength, flexural modulus and heat deflection temperature (HDT) of the compound compared to the untreated one. It seemed the alkali treatment on the nano-kenaf fiber changed the character of the fiber due to removal of impurities and chemicals on the surface and resulted in decreased interfacial adhesion between the nano-fiber surface and the PP matrix and changed the character of the PP.

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.786-795
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• 1996

The fiber reinforced thermoplastics(FRTP) were prepared with polypropylene fiber(PP) as matrix and polyvinyl alchol(VF), aramid(KF) or polyamide fiber(PAF) as the reinforcing materials using the integrated fiber mixing apparatus. The reinforced thermoplastic sheets were prepared by com¬pression molding and their morphology, rheological and mechanical properties were characterized. In the morphological properties of composites, the wettability of the reinforced thermoplastics were decreased in proportion to the content of fibers. At low angular frequency, the viscosity of PAF /PP and VF/PP composite was increased with the content of reinforced fiber. However at high frequency the viscosity of composite reinforced with 5~20wt% fiber, was shown the reduced values which approaches that of the neat matrix. The mechanical properties of the composite were changed with the content of reinforecd fiber, and VF/PP and KF/PP composite had better properties than PAF/PP system.