• Composites Research
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• v.19 no.3
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• pp.15-22
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• 2006

In this study, we prepared glass fiber reinforced polypropylene composites using Brabender twin-screw extruder. Compatibilizer, polypropylene-based maleic anhydride (PP-g-MAH), was used to increase the molecular interaction between polypropylene matrix and glass fiber and to enhance melt processability. We also measured the shear and uniaxial elongational behaviors of glass-fiber reinforced composites in the absence or presence of compatibilizer. The effects of compatibilizer and fiber loading on the viscoelastic behaviors were examined. It was fuund that the PP-g-MAH compatibilizer improved the fluidity and increased the molecular bonding of composite melts in shear flow. Transient elongational viscosity was increased with fiber loadings in uniaxial elongational flow However, it was decreased with increasing elongational rates because of microscale shear flow between fibers.

• Composites Research
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• v.23 no.6
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• pp.55-60
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• 2010

In this paper, tensile and bending tests of glass/polypropylene composite (Twintex) specimens fabricated by various forming conditions were carried out and the results were compared according to the forming conditions to find the appropriate condition for the forming composite bone plates. From the tests it was found that the most appropriate forming conditions were $230^{\circ}C$, 3MPa. Composite bone plates were formed using this condition by two different fabricating methods for screw holes: one was a net shape molding and the other was drilling. The forming and bending tests revealed that the drilling process provided much better bending stiffness of bone plates. This paper provided the most appropriate condition for forming composite bone plates and this result was also expected to offer informative data on forming of other Twintex structures.

• Polymer(Korea)
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• v.27 no.4
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• pp.299-306
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• 2003

It is well known that the interaction and adhesion between the glass fiber (GF) and polymer matrix has a significant effect in determining the properties of fiber-reinforced materials. Therefore, it is one of important considerations to modify the surface of glass fiber with an appropriate sizing. We investigated the treatment method of glass fiber with coupling agent to improve the interaction of the interfacial region. The correlation between interfacial property and interphase microstructure was also examined in an attempt to realize a proper morphology at the glass fiber surfaces.

• Composites Research
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• v.26 no.5
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• pp.328-333
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• 2013

In this study, bone plate made of glass/polypropylene composite material which was applied to an artificial bone was tested to check the service ability under fatigue loading. To check serviceability of composite bone plates fatigue test was carried out considering changes in the moisture absorption rate, locking position of screws and loading condition. Test results showed that all the tested specimens had the fatigue life more than one million cycles which was much higher fatigue life than the expected value of 650,000 cycles. Screw position was not critical impact on the deformation of the fracture site. In this paper, the mechanical performance of the glass/polypropylene composite was verified by fatigue test under various water absorption conditions, and this result may give useful information on the design of composite bone plate.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.88-95
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• 1996

유리섬유가 강화된 열가소성 복합재료 판재의 성형성에 대한 이해를 돕기 위해 이론적 고찰과 실험적 고찰이 행해졌다. 성형시험에서 사용된 형상은 임의의 방향으로 위치한 유리섬유를 중량비로 30% 함유한 폴리프로필렌 재료가 사용되었고, 시험된 형상은 판재의 굽힘성이나 인장성을 측정하는데 널리 사용되는 스위프트컵(Swift flat-bottomed cup)모양이다. 성형시험과 재료시험은 플리프로필렌 Matrix의 유리성 천이온도(Glass transition temperature)와 용융온도 사이에서 행해졌다. 본 연구의 이론과 고찰을 위해서 재료의 평면 방향으로는 동질성을 그리고 그 직각 방향으로는 이질성을 가진 연속체 물질로 가정하여 유도하였다. 이러한 이론적 결과는 실험 결과와 비교되어졌고,이를 통해 시험된 재료의 최적의 성형조건을 제시하였다.

• 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.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.5.2-8
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• 1999

• Journal of the Korean Society for Precision Engineering
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• v.15 no.3
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• pp.119-126
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• 1998

유리섬유 강화 열가소성 복합재료는 고상성형법에 의해 저렴한 가격으로 큰 부피의 제품의 제조에 널리 사용될 수 있어 아주 좋은 전망을 가지고 있다. 그러나 이러한 재료의 성형성이나 재료거동의 특성은 아직 잘 파악되지 않았다. 본 연구의 주안점은 이러한 재료의 단순 굽힘에서의 굽힘성형성을 연구하는데 두었다. 실험에 사용된 재료는 임의의 방향으로 위치한 유리섬유를 중량비로 20 %, 35 %, 40 % 함유한 폴리프로필렌이다 굽힘시험은 75 $^{\circ}C$에서 150 $^{\circ}C$ 사이의 온도에서 25 $^{\circ}C$ 씩 증가하면서 행했고, 편치속도는 2.54 mm/sec와 0.0254 mm/sec에서 행했다. 단순 굽힘시험에서 측정된 굽힘성형성은 해석적 모델로 예측한 결과와 비교하였다. 실험결과와 예측결과가 비교적 잘 일치함을 보였으며, 굽힘성 map으로써 성형 온도와 펀치반경의 좌굴에 대한 효과를 가시화 함은 물론 좋은 성형조건을 선정할 수 있는 좋은 도구로써 나타내었다.

• Composites Research
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• v.12 no.6
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• pp.8-14
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• 1999

This research is focused on the investigation of impact strength and the microscopic observation of material behavior of glass fiber reinforced polypropylene in solid phase forming. The fiber weight per-centage of the composite materials was 20%, 30% and 40%. The solid-phase formed specimens were pre-strained to 10%,20%. and 30% strain levels. The forming temperatures of specimens were $100^{\circ}C$, $125^{\circ}C$ and $150^{\circ}C$. Izod impact test was performed with unnotched specimens. With increasing the glass fiber content ; the impact strength was increased.

• Composites Research
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• v.35 no.2
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• pp.75-79
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• 2022

In this study, the effect of mechanical and chemical properties of glass fiber reinforced thermoplastic (GFRTPs) according to the number of recycling was confirmed. The composite materials were manufactured through a hot press compression molding process using an E-glass chopped strand mat and a polypropylene film. Four specimens were named according to the number of recycled test repeat: First manufacture, 1st Recycle, 2nd Recycle, and 3rd Recycle. To investigate the mechanical properties of the prepared specimen, tensile test, flexural test, drop-weight impact test, differential scanning calorimetry (DSC), and field emission electron gun-scanning electron microscope (FE-SEM) was performed. As a result, as the number of recycling steps repeat, the degree of crystallization, tensile strength, elastic modulus, and flexural strength were increased, but the impact properties were greatly reduced.