• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.173-178
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• 2001

This study investigates the effect of fiber content on the fracture behavior of thermoplastic composites (glass fiber/polypropylene). The fiber contents used were 20%, 30%, and 40% by weight. Fracture tests were performed using compact tension (CT) specimens made of composite sheets of three fiber contents (20%, 30%, 40%). The results showed that compliance, fracture load, and fracture toughness were affected by the fiber content. The compliance decreased with fiber content while the fracture load increased as the fiber content increased. The fracture toughness also increased as fiber content increased. Specifically, the fracture toughness increased 14% as the fiber content increased from 20% to 40%.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.74-85
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• 2010

In order to formulate the compounded polypropylene(C-PP) which is suitable to an automotive door trim panel, 9 sorts of properties were measured after manufacturing the C-PP using an extruder and an injection machine with polypropylene(PP), ethylene-octene rubber(EOR) and talc. Mixture design, especially extreme vertices design, in DOE with MINITAB - commercial software was used to analyze the data. The relations between each property and each component, for example, $y=0.00907222x_1+0.00870556x_2+0.0155722x_3$ for specific gravity, were found out by the regression analysis and the variance analysis. The optimized formulation of the C-PP for an automotive door trim panel was acquired at PP(77.6962), EOR(11.0238) and talc(10.2800) by use of the response optimizer(mixture) in MINITAB.

• Composites Research
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• v.27 no.2
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• pp.42-46
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• 2014

In the present study, impact tests were carried out to investigate the crashworthy behaviour of the expanded polypropylene under the constant incident energy (100 J and 200 J) with five different combinations of striker mass and velocity. Also, preliminary quasi-static test was performed to obtain basic characteristics of the expanded polypropylene. MTS 858 and Instron dynatup 9250 HV were used for the quasi-static test and impact tests, respectively. In consequence, it was found that the impact energy absorption characteristics of the expanded polypropylene was more influenced by the striker mass instead of the velocity of the striker.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.791-796
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• 2013

In this study, the mechanical properties of a carbon fiber/polypropylene composite were evaluated according to the carbon fiber surface treatment. Carbon fiber surface treatments such as silane coupling agents and plasma treatment were performed to enhance the interfacial strength between carbon fibers and polypropylene. The treated carbon fiber surface was characterized by XPS, SEM, and single-filament tensile test. The interlaminar shear strength (ILSS) of the composite with respect to the surface treatment was determined by a short beam shear test. The test results showed that the ILSS of the plasma-treated specimen increased with the treatment time. The ILSS of the specimen treated with a silane coupling agent after plasma treatment increased by 48.7% compared to that of the untreated specimen.

• Composites Research
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• v.35 no.3
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• pp.127-133
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• 2022

Polypropylene (PP) has been received great attention as a next-generation high-voltage power cable insulation material that can replace cross-linked polyethylene (XLPE). However, the PP cannot be used alone as an insulation material because of its high elastic modulus and vulnerability to impact, and thus is mainly utilized as a form of a copolymer with rubber phases included in the polymerization step. In this paper, a soft PP-based blend was prepared through melt-mixing of impact PP, polyolefin elastomer, and propylene-ethylene random copolymer. The elastic modulus and impact strength of the blend could properly be decreased or increased, respectively, by introducing elastomeric phases. Furthermore, the blends showed a high storage modulus even at a temperature of 100℃ or higher at which the XLPE loses its mechanical properties. In addition, the blend was found to be effective in suppressing the space charge compared to the pristine PP as well as XLPE.

• Journal of Adhesion and Interface
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• v.9 no.4
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• pp.24-29
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• 2008

Polypropylene-natural fiber composites have been prepared and their rheological properties during mixing and thermal properties were investigated. Two types of natural fibers (cotton fiber and wood fiber) were compared. On increasing fiber contents, the torque values of composites were increased, where the cotton fiber exhibited higher increase in torques. The torque values of composites were higher as the MI of PP decreased. X-ray diffraction and differential scanning calorimetry results showed an increase in the crystallization temperature but a decrease of crystallinity of the PP/natural fiber composites on increasing fiber contents.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.46-54
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• 2005

To make the composite panels of wood particles and recycled plastics, the recycled polypropylene was used. In the composite panels the sizes of wood particles were 1/32", 1/4" and 1/2" mesh, and the composition ratios of the recycled plastics were 10%, 30%, 50% and 70%. The physical and mechanical properties of the composite panels were investigated. As the composition ratio of wood particle increases, the density increases, while it decreases at the same composition ratio because the size of wood particle increases. As the composition ratio of recycled polypropylene increases from 10% to 30%, both thickness swelling and water adsorption significantly decrease. As the composition ratio of recycled polypropylene increases, the modulus of rupture in bending strength increases, but the modulus of elasticity in bending strength decreases. SEM shows that the dissolved recycled polypropylene penetrates into tracheid and pit, and bonds mechanically to other wood particle and matrix to increase the bonding strength and improve the physical and mechanical properties of composite panel.

• Elastomers and Composites
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• v.46 no.3
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• pp.204-210
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• 2011

In this study, Jute fibers reinforced polypropylene (JFRP) composites were manufactured by injection molding technique. In order to improve the affinity and adhesion between fibers and thermoplastic matrices during manufacturing, Maleic anhydride (MA) as a coupling agent have been employed. Untreated and treated surfaces of jute fibers were characterized using SEM and Fourier transform infrared (FTIR). Physical properties like water absorption rate were studied. Tensile and flexural tests were carried out to evaluate the composite mechanical properties. Tensile test and bending test indicated that JFRP composites show higher strength and modulus than pure PP. In addition, strength and modulus were found to be influenced by the variation of MAPP content (1%, 2%, and 3%). Tensile fracture surfaces were examined using scanning electron microscope. It ensures better interfacial adhesion between fibers and matrix by increasing the percentage of MAPP.

• Composites Research
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• v.26 no.3
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• pp.201-206
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• 2013

The electrical resistance measurement was investigated as a damage monitoring method. In this study, 0.5 wt% Carbon nanotube reinforced polypropylene (CNT/PP) composites were evaluated under compressive fatigue loading. The shape of specimens was $20^{\circ}$ curved round type. Compression strength and electrical resistance were measured at different sections of specimen during compression. The microcracks of CNT/PP composites were detected based on the changing ratio of electrical resistance. Micro-damage during compressive fatigue test could be detected by electrical resistance measurements. The reason is that the contact points of CNTs in composites decreased under fatigue loading. During compressive fatigue test, larger change of electrical resistance was detected at the microcrack sections. It was proved that microcracks could be detected by electrical resistance measurement under compression test, whereas the real delamination parts were consistent with the predicted results by electrical resistance measurement.

• Resources Recycling
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• v.16 no.4
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• pp.17-26
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• 2007

Inorganic shell powder waste was added to recycled polypropylene(COPP), and its effect on the mechanical properties and flammability was investigated. Compatibilizer(Polytail H) was added to improve mechanical properties of COPP/shell composites. Also three different flame retardants($Al_2O_3$, DBDPO, $Sb_2O_3$) were added to improve flammability. Experimental results indicated that addition of compatibilizer resulted in an improved mechanical properties, and especially impact strength approached that of 100 wt% COPP. Addition of flame retardant did not result in decreased mechanical properties. UL-94 flammability test indicated that COPP/shell composite did not show good flame retardancy, however, in the case of COPP/shell composites containing flame retardant showed good flammability. flammability was found $Sb_2O_3>Al_2O_3>DBDPO$ in this order. Finally, UL-94 V-0 grade was found in COPP/shell composite with $Al_2O_3$, compatibilizer, and 40 wt% shell, and COPP/shell composites with $Sb_2O_3$.