• Composites Research
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• v.31 no.6
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• pp.317-322
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• 2018

In various industry, the composite is tried to be applied to products and thermoplastic based composite is in the spotlight because this composite can be recycled. The use of continuous fiber thermoplastic (CFT) method increased gradually than long fiber thermoplastic (LFT). In this study, tensile, flexural, and impact test of different array types of glass fiber (GF)/thermoplastic composites were performed to compare with GF array. Impregnation property between GF mat and thermoplastic was determined using computed tomography (CT). At CFT method, thermoplastic film is not wet into GF roving and many voids are appeared into composite. This phenomenon affects to decrease mechanical properties. Plain pattern GF mat was the best mechanical and impregnation properties that distance between two roving was set closely to $100{\mu}m$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.25-30
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• 2017

Carbon-fiber-reinforced plastic (CFRP) composite materials have been widely used in various industrial fields because the design variables can be adjusted according to the application of the required structure. Thermosetting and thermoplastic resins are used as the base materials of CFRP composites for the lightweight construction of automotive components. Thermoplastics have several advantages such as no curing and recyclability compared to thermosetting resin. In this study, CFRP composites were made using the Long-Fiber Thermoplastic-Direct (LFT-D) process. The LFT-D process includes an in-line production system that directly impregnates a thermoplastic resin, extrudes the composite material, and molds it. This process increases the strength and decreases the molding time. The tensile strength characteristics on the mechanical properties of CFRP were analyzed according to the parameters of LFT-D based on thermoplastics. To analyze the properties of CFRP, the specimens were prepared based on the tensile test standard ASTM 3039 of composite materials.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.261-264
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• 2000

The objective of this work was to characterize mechanical properties of thermoplastic composites for various forming condition in compression molding. Randomly oriented long glass fiber reinforced polypropylene(PP) was used in the work. The composite materials contained 20%, 30%, and 40% glass fiber by weight. Compression molding was conducted to make the test specimen. Dimensional stability was measured on each forming condition with the spring-forward angle. Tensile test was conducted to characterize mechanical properties of formed parts in various forming conditions.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.29-32
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• 2001

The objective of this work was to optimize processing parameters of hybrid thermoplastic composites in compression molding. The mechanical properties of the composites manufactured with various forming conditions were measured to characterize processing parameters. Polypropylene(PP) composites containing randomly oriented long carbon fiber and carbon black were used in this work. The composite materials contained 5%, 10%, 15%, and 20% carbon fiber and 5%, 10%, 15%, 20%, and 25% carbon black by weight. Compression molding was conducted at various mold temperatures. The temperature of the material in the mid-plain was monitored during the forming. Crystallinity was also measured by using XRD. The tensile modulus of the composites increase, with increasing the mold temperature. However, the impact strength of the composites decreases as mold temperature increases.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.67-70
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• 2000

This study was performed to investigate the material behavior of hybrid thermoplastic composites contained glass fiber and calcium carbonate. The composite was prepared with each combination ratio of calcium carbonate, and the content of glass fiber was fixed with 10% by weight. In order to investigate the material behavior for various combination ratio, tension test, flexural test, and impact test were performed. Microscopic observation were conducted to examine the fractured surface of specimen for tension test. And the material behavior of the hybrid thermoplastic composite immersed in salt water with definite time was investigated.

• Composites Research
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• v.37 no.2
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• pp.68-75
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• 2024

Polypropylene (PP), a thermoplastic resin with excellent mechanical, thermal, chemical, and water resistance properties, has been attracting attention due to its economic efficiency and recyclability. However, repeated processing of thermoplastic resins can lead to property degradation, and the point at which quality degradation occurs varies depending on the processing conditions. In this study, we evaluated the performance changes of composite materials with repeated processing by blending PP resin with various additives and conducting extrusion and injection processes repeatedly. In addition, we evaluated the mechanical properties of composite materials to evaluate the effect of MFI value change during repeated processing on fiber impregnation in composite material processing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.513-517
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• 1997

Glass fiber reinforced thermoplastic composite materials have considerable promise for increased use in low cost high volum applications because of the potential for processing by solid phase forming. However, the forming characteristics of these materials have not been well known. The primary focus of this research is the investigation of the bendability of these composites and spring-back phenomena in pure bending. The materials tested contained 10, 35, and 40 percent by weight of randomly oriented glass fiber in a polypropylene matrix. The bending tests were performed at temperatures ranging form 75 ".deg. c" to 150 ".deg. c" and at punch speeds of 2.54 mm/sec and 0.0254 mm/sec. The measured bendability and spring back angle in pure bending werw compared with the predictions based on the simple analyical models. Goog agreement between experimental and analytical results was observed.esults was observed.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.91-94
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• 1999

• Design & Manufacturing
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• v.15 no.3
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• pp.39-44
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• 2021

In molding of continuous fiber-reinforced thermoplastic composites, it is very difficult to impregnate between the reinforcements and the matrix since the matrix has a high melting temperature and high viscosity. Therefore, most of composite molding processes are divided in the manufacturing processes of intermediate materials called prepreg and the forming of products from intermediate materials. The divided process requires additional facilities and thermoforming, and they increase the cycle time and cost of composite products. These problems can be resolved by combining the continuous fiber-reinforced composite molding process with injection molding. However, when a composite material is manufactured by inserting woven fabric into the injection mold, poor impregnation occurs on the surface of the molded product. It affects the properties of the composites. In this paper, through an impregnation experiment using cores with different heat transfer rates and pore densities, the reason for the poor impregnation was confirmed, and molding experiments were conducted to produce composite with improved surface impregnation by inserting the mesh. And also, the surface impregnation and deformation of composites molded using different types of mesh were compared with each other.

• Composites Research
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• v.33 no.6
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• pp.383-389
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• 2020

Thermoplastic composite is introduced to design an automotive door impact beam, and the manufacturing process is demonstrated. The safety regulation for vehicles has been steadily tightened, and weight-reduction has become a mandatory factor in the automotive industry. Hence, both high-performance and lightweight are demanded for automotive components. The aim of the present study is to develop an automotive door impact beam using fiber-reinforced thermoplastic composites to reduce the weight of the impact beam while increasing its mechanical performance. A new production method which combines continuous fiber-reinforced composite and LFT(Long Fiber-reinforced Thermoplastic) is implemented by using insert injection molding process. The mechanical performance of the composite impact beam was evaluated using 3-point bending tests. Thermoplastic composite will expand its application range to various automotive components due to its light-weight design capability and high productivity.