• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.145-146
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• 2023

In this study, the effect of hybrid fiber reinforcement on the residual strength and impact resistance of high-strength cementitious composites exposed to high temperatures was investigated. A cementitious composites was manufactured in which 0.15 vol% of polypropylene fiber (PP) and 1.0 vol% of smooth steel fiber (SSF) were double-mixed, and a residual strength test was conducted while thermal stress was applied by heating test, and then a high-velocity impact test was performed. In the case of general cementitious composites, the rear surface is damaged due to explosion and low tensile strength during high temperature or impact, while hybrid fiber reinforced cementitious composites can repeatedly absorb and distribute stress until multiple fibers are damaged to suppress the propagation of impact and resistance to explosion. Therefore, this study analyzed the residual strength of cementitious composites exposed to high temperatures depending on whether hybrid fibers were mixed or not, and collected research data on fracture behavior through high-speed impact tests to evaluate impact resistance and mechanical properties.

• Fire Science and Engineering
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• v.33 no.1
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• pp.69-75
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• 2019

In this study, the combustibility of five types of plastic plates, fiber reinforced plastic (FRP), polystyrene (PS), polycarbonate (PC), polypropylene (PP), and polyvinyl chloride (PVC), were tested using a cone calorimeter (ISO 5660). The PVC plate showed a $44.65kW/m^2$ lower peak heat release rate (HRR) and a $30.97kW/m^2$ lower maximum average rate of heat emission than the other four types of plastics, whereas the PS plate showed a $773.44kW/m^2$ higher peak HRR and $399.14kW/m^2$ higher maximum average rate of heat emission. The PC plate and PS plate showed the highest HRR by a maximum of 3.88 times in $CO_{mean}$ yields, while the PS pate and PP plate showed the highest HRR by a maximum 4.88 times in $CO_{2mean}$ yields. In addition, the smoke performance index (SPI) of the PS plate decreased by 74.81%~95.99%; the smoke growth index (SGI) increased to 76%~300%; the smoke intensity (SI) also increased to 917.73% ~ 9607.57%, and the danger of smoke increased. The PS plate was found to have the highest risk of life damage due to smoke on the thermal and smoke sides.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.387-390
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• 2005

Recently, in order to reduce the spalling of high strength concrete under fire, the addition of organic fibres to high strength concrete has been investigated. In this study, the effect of organic fibre content on the spalling of high strength concrete was experimantally investigated. Two types of fibre, polypropylene(PP) and polyvinyl alcohol(PVA) fibres, were selected, and three water/binder ratios were selected, which were W/B $30\%,\;24.\%,\;and\;16\%$, respectively. As a result, it appears that as the concrete strength increases, the fiber content for prevention spalling increases. When W/B ratios are $30\%,\;24.9\%$, the additions of $0.1vol.\%$ and $0.2vol.\%$, respectively, appear to avoid the spalling in this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1671-1676
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• 2015

A unique crystallization behavior of poly(L-lactide)(PLLA)/poly(D-lactide)(PDLA) stereocomplex(SC) was observed when a PLLA/PDLA blend was subjected to the specific melting conditions. Therefore, we tried to blend PLLA and PDLA at overall composition to form PLA stereocomplexes. Moreover, impact modifier and reinforcement materials such as talc and glass fiber added to enhance the mechanical and thermal properties such as impact strength and heat distortion temperature(HDT). As a result, we got one representative result, one composite recipe with HDT $115^{\circ}C$. For more economic technology, we tried to blend PLLA and Polypropylene at overall composition and we got another representative result which could be applied to current PP/talc composites and ABS materials. The core technology of this might be the well dispersion of glass fibers into the matrix resin such as PP, PLLA and impact strength modifier.

• Composites Research
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• v.28 no.3
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• pp.112-117
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• 2015

Mechanical properties of nonwoven alfa fiber based reinforced biocomposite were evaluated to assess the possibility of using it as a new material in engineering applications such as orthopedic application. Samples were fabricated by needle punching, thermal bonding and Hydroentanglement, by blending alfa fibers with wool fibers or Polypropylene fibers. The mechanical properties were tested and showed that the nonwoven NW3 (alfa fiber/PP/PLA, with hydroentanglement) is the best. It has a value of stress at break of 1.94 MPa, a strain of 54.2% and a young's module of 7.95 MPa, in a production normal direction. A biocomposite has been made with NW3 mixed with PMMA matrix. The use of nonwoven based alfa fiber in reinforcing the composite material increases its rigidity and the tensile strength; the elongation was found to be 1.53%, the Young's Module of 1.79 GPa and the tensile at break of 15.06 MPa. Results indicated that alfa fibres are of interest for low-cost engineering applications and can compete with glass fibres in orthopedic application.

• Journal of the Korean Geosynthetics Society
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• v.16 no.1
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• pp.19-29
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• 2017

The effects of synthetic fibers, cement content, and sand content on the flexural performance of cement-clay-sand mixtures has been evaluated through a flexural performance test with a third-point loading. Beam specimens for the flexural performance test were fabricated with a various amount of cement, sand, and synthetic fibers. Two types of fibers, PVA (Polyvinyl alcohol) and PP (Polypropylene) fibers, were employed in the test. The test results have exhibited that the factors considered in the test have significant effects on the flexural performance of the mixtures in several aspects. The flexural performance of the mixtures has been improved if the mixtures were reinforced with synthetic fibers. The flexural strength and the flexural toughness of the mixtures has been increased as the fiber content was increased. A multiple linear regression analysis has been performed to evaluate the effect of fiber content, cement dosage, and sand content on the flexural performance of the mixtures in terms of flexural strength and flexural toughness. Cement content and sand content were estimated as important factors to have an influence on the first-crack strength and the peak strength whereas the fiber content has the most significant influence on the post-crack behavior. The first-crack strength and the ultimate strength were increased as the cement content and the sand content were increased. As the fiber content was increased, the flexural toughness was increased.

• Macromolecular Research
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• v.16 no.1
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• pp.21-30
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• 2008

Based on the sheath-core bicomponent composite fibers with modified polystyrene (PS) and the modified polypropylene (PP), composite fibers obtained were further cross-linked and sulphonated with chlorosulphonic acid to produce strong acidic cation ion exchange fibers. The structures of the fibers obtained were characterized using Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) etc. The optimal technology of the fibers obtained is discussed. The static absorption capacity of the sheath-core bicomponent composite cation exchange fibers for $Zn^{2+}$, $Cu^{2+}$ was determined. The absorption kinetics and major factors affecting the absorption capacities of $Zn^{2+}$, $Cu^{2+}$ were studied, and its chemical stability and regenerating properties were probed. The results suggest that cation exchange fibers with better mechanical properties and higher exchange capability were obtained. Moreover, this type of ion exchange fiber has good absorption properties and working stability to various metal ions. Hence, they have higher practicability.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.9-13
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• 2014

Glass fiber reinforced thermoplastics(GFRTP) is made by adding chemical additive to glass fabric which is strong at a high temperate, incorrodible, and good at intensity and specific gravity. Although we focused on the weight lightening, the intensity of GFRTP is also important. To remedy thermoplastic resin's inferior property of matter to thermo-hardening resin, we formed several specimen, differing the chemical additive as Homo PP, MAPP 3%, Rubber 5%, and mixed. We put pressure of 5 type on the specimens. The analyses result for the different pressure, the resin spreads evenly, then the coherence is increased. Eventually, the mechanical properties are changed. When high intensity is needed, it is good idea to use polypropylene(PP) which has good coherence with glass fabric as chemical additive. We can get better intensity when we form the resin at the optimum pressure depending on mixing of chemical additive and glass fabric than when we increase the pressure.

• Carbon letters
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• v.20
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• pp.39-46
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• 2016

In this work, the effects of maleic anhydride (MA) content on mechanical properties of chopped carbon fibers (CFs)-reinforced MA-grafted-polypropylene (MAPP) matrix composites. A direct oxyfluorination on CF surfaces was applied to increase the interfacial strength between the CFs and MAPP matrix. The mechanical properties of the CFs/MAPP composites are likely to be different in terms of MA content. Surface characteristics were observed by scanning electron microscope, Fourier transform infrared spectroscopy, and single fiber contact angle method. The mechanical properties of the composites were also measured by a critical stress intensity factor (K_IC). From the K_IC test results, the K_IC values were increased to a maximum value of 3.4 MPa with the 0.1 % of MA in the PP, and then decreased with higher MA content.

• Journal of the Society of Disaster Information
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• v.8 no.3
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• pp.223-233
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• 2012

Steel fiber is high stiffness and large weight. So, Pumping hose to rupture of the safety management is difficult. Steel fiber caused by corrosion of the deterioration of durability and high-rebound losses are needed for the improvements. Thus, the revised regulations in 2009 by a steel fiber to reinforce other materials is possible. Variety of fiber reinforcement material for concrete review of applicability is needed. Steel fiber strength than the other fibers is large and by the geometry of the fibers are attached to improve performance. However, compared to steel fiber organic fibers and low modulus of elasticity and tensile strength of fiber and agglomeration occurs in the concrete to be used as reinforcement material is difficult. In this regard, the present study as a single object in the micro-fiber bouquet sharp entanglement through make muck attach surface area, distributed fibers from surfactant of the surface enhanced polyamide fibers, steel fiber and PP fiber reinforced concrete by comparing the scene to provide a basis for the use.