• Macromolecular Research
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• v.12 no.5
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• pp.466-473
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• 2004

We have used FT-IR spectra to explain the effects of hydrogen bonding between chitosan and polycaprolactam (PA6). A dynamic mechanical analysis study suggested that the optimum chitosan and PA6 miscibility under the conditions of this experiment were obtained at a blending ratio of 40:60. We studied the thermal degradation of chitosan blended with PA6 (chitosan/PA6) by thermogravimetric analysis and kinetic analysis (by the Ozawa method). Dry chitosan and PA6 exhibited a single stage of thermal degradation and chitosan/PA6 blends having> 20 wt% PA6 exhibited at least two stages of degradation. In chitosan/PA6 blends, chitosan underwent the first stage of thermal degradation; the second stage proceeded at a temperature lower than that of PA6, because the decomposition product of chitosan accelerated the degradation of PA6. The activation energies of the blends were between 130 and 165 kJ/mol, which are also lower than that of PA6.

• Textile Coloration and Finishing
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• v.34 no.1
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• pp.46-57
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• 2022

In this study, the relationship between fiber orientation and mechanical properties with the injection pressure of polyamide-6/glass fiber composite materials manufactured by the injection molding process was investigated. Also, an actual experimental data and finite element model-based simulation data were analyzed. Specimens were manufactured through the injection molding process setting the injection pressure differently to 700, 800, 900, and 1000 bar, respectively. A morphological analysis and orientation of the PA6/GF composite material were observed using Optical microscope. Through tensile and flexural strength tests, the mechanical properties of the PA6/GF composite materials with the injection pressure were studied. As a result, it was confirmed that the mechanical properties were the superior under the injection pressure of 900 bar molding conditions. In addition, the mechanical properties of the actually manufactured specimen (PA6/GF) and virtual engineering S/W((Digimat, Abaqus) were used to compare and analyze the analysis results for the mechanical properties, and based on the reliable DB, the physical properties of the PA6/GF composite characteristics were studied.

• Textile Coloration and Finishing
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• v.35 no.1
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• pp.29-41
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• 2023

This study is about a hybrid lightweight cowl crossbeam structure with high rigidity and ability to absorb collision energy to support the cockpit module, which is an automobile interior part, and to absorb energy during a collision. It is a manufacturing process in which composite material bracket parts are inserted and injected into existing steel bars. When considering the mounting condition of a vehicle, the optimization of the fastening condition of the two parts and the mechanical properties of the composite material is acting as an important factor. Therefore, this study is about a composite material having a volume content of Polyamide(PA) and Glass Fiber used as a composite material for a composite material-metal hybrid cowl crossbeam. As a result of analyzing the physical properties of the PA/GF composite material, experimental data were obtained that can further enhance tensile strength and flexural strength by using PA66 rather than PA6 used as a base material for the composite material. And based on this, it contributed to securing the advantage of lightening by using high-stiffness composite material by improving the high disadvantage of the weight of the cowl crossbeam material, which was made only of existing metal materials.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_3
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• pp.1297-1303
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• 2023

Research on enhancing the mechanical strength, lightweight properties, electrical conductivity, and thermal conductivity of composite materials by incorporating nano-materials is actively underway. Thermoplastic resins can change their form under heat, making them highly processable and recyclable. In this study, Polyamide-Nylon 6 (PA6), a thermoplastic resin, was utilized, and as reinforcing agents, fused carbon nano-materials (FCN) formed by structurally combining Carbon Nanotube(CNT) and Graphene were employed. Nano-materials often face challenges related to cohesion and dispersion. To address this issue, Silane functional groups were introduced to enhance the dispersion of FCN in PA6. The manufacturing conditions for the composite materials involved determining the use of a dispersant and varying FCN content at 0.05 wt%, 0.1 wt%, and 0.2 wt%. Tensile strength measurements were conducted, and FE-SEM analysis was performed on fracture surfaces. As a result of the tensile strength test, it was confirmed that compared to pure PA6, the strength of the polymer composite with a content of 0.05 wt% was improved by about 60%, for 0.1 wt%, about 65%, and for 0.2 wt%, the strength was improved by 50%. Also, when compared according to the content of FCN, the best strength value was shown when 0.1 wt% was added. The elastic modulus also showed an improvement of about 15% in the case of surface treatment compared to the case without surface treatment, and an improvement of about 70% compared to pure PA6. Through FE-SEM, it was confirmed that the matrix material and silane-modified nanomaterial improved the dispersibility and bonding strength of the interface, helping to support the load evenly and enabling effective stress transfer.

• Restorative Dentistry and Endodontics
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• v.39 no.1
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• pp.12-16
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• 2014

Objectives: Extensively destroyed teeth are commonly restored with composite resin before cavity preparation for indirect restorations. The longevity of the restoration can be related to the proper bonding of the resin cement to the composite. This study aimed to evaluate the microshear bond strength of two self-adhesive resin cements to composite resin. Material and Methods: Composite discs were subject to one of six different surface pretreatments: none (control), 35% phosphoric acid etching for 30 seconds (PA), application of silane (silane), PA + silane, PA + adhesive, or PA + silane + adhesive (n = 6). A silicone mold containing a cylindrical orifice ($1mm^2$ diameter) was placed over the composite resin. RelyX Unicem (3M ESPE) or BisCem (Bisco Inc.) self-adhesive resin cement was inserted into the orifices and light-cured. Self-adhesive cement cylinders were submitted to shear loading. Data were analyzed by two-way ANOVA and Tukey's test (p < 0.05). Results: Independent of the cement used, the PA + Silane + Adhesive group showed higher microshear bond strength than those of the PA and PA + Silane groups. There was no difference among the other treatments. Unicem presented higher bond strength than BisCem for all experimental conditions. Conclusions: Pretreatments of the composite resin surface might have an effect on the bond strength of self-adhesive resin cements to this substrate.

• Composites Research
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• v.37 no.2
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• pp.59-67
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• 2024

Research was conducted on a PA material-based composite material manufacturing method for application to engine mount brackets. Engine mount brackets must have heat resistance, impact resistance, and damping performance. PA66 resin was used as the base material for the composite material. The glass fiber was used as the reinforcement material. The composite material was manufactured using the injection molding method. The thermal, mechanical, and morphological characteristics were analyzed depending on the content of glass fiber. 3D model was created using the property evaluation database of composite materials(input data). The damping performance of the generated 3D model was extracted as out-put data. The reason for evaluating the characteristics of PA-based composite materials and conducting simulations on the damping performance of 3D models of engine brackets is because product performance can be predicted without manufacturing actual automobile parts and conducting damping performance tests. As a result of the damping simulation, damping performance tended to increase proportionally as the mass fraction of the reinforcement increased. But above a certain level, it no longer increased and slightly decreased. As a result of comparing the actual experimental values a nd the simulated values, the approximate value was within ±5%.

• Composites Research
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• v.36 no.5
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• pp.355-360
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• 2023

Epoxy-based carbon fibers reinforced plastic (CFRP) exhibit limitations in their suitability for industrial applications due to high brittleness characteristics. To address this challenge, extensive investigations are underway to enhance their toughness properties. This research focuses on evaluating the toughening mechanisms achieved by Polyamide 6 particles(p-PA6) and Carboxyl-Terminated Butadiene-Acrylonitrile (CTBN) elastomer, with a specific emphasis on utilizing minimal additive quantities. The study explores the impact of varying concentrations of p-PA6 and CTBN additives, namely 0.5, 1, 2.5, and 5 phr, through comprehensive Mode I fracture toughness and tensile strength analyses. The inclusion of p-PA6 demonstrated improvements in toughness when introduced at a relatively low content of 1phr. This improvement manifested as a sustained fracture behavior, contributing to enhanced toughness, while simultaneously maintaining the material's tensile strength. Furthermore, the investigation revealed that the incorporation of p-PA6 affected in particle aggregation, thus influencing the overall toughening mechanism. Incorporation of CTBN, an elastomeric modifier, exhibited a pronounced increase in fracture toughness at higher concentrations of 2.5 phr and beyond. However, this increase in toughness was accompanied by a reduction in tensile strength, resulting in fracture behavior similar to conventional CFRP exhibiting brittleness. The synergy between pPA6, CTBN and CFRP appeared to marginally enhance tensile strength under specific content conditions. As a result of this study, optimized conditions for the application of the p-PA6, CTBN toughening technology have been identified and established.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.877-887
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• 2015

We have proposed a new method for estimating the viscosity of the composite. In this paper, we have developed a device for measuring the injection mold cavity pressure. This makes it possible to verify the accuracy of the viscosity in CAE D/B in real time by measuring the melt pressure in the mold, and comparing this with the simulated pressure from the CAE analysis. Materials used in this study is a PP(Polypropylene), PP/LGF30%(Polypropylene/long glass fiber 50% composite) and PA66/LGF50%(Polyamide 6,6/long glass fiber 50% composite). The viscosity data for PP and PP long fiber composite have already been built, but the one for PA66 long-fiber composite does not exist because it is a newly developed material. Thus we obtained the viscosity curve of PA66/LGF50% by this system. Then, the viscosity curves from conventional viscometer were also compared with the viscosity obtained by the our method. And, we proved the accuracy of the CAE data of PP. In case of PP/LGF50% which is highly viscous and complex material, we improved the existing CAE data.because there was a difference between the measuring data and the CAE data.

• Membrane and Water Treatment
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• v.10 no.6
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• pp.431-440
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• 2019

A novel composite membrane was synthesized using crosslinked polyamide and fly ash ceramic substrate for phenol removal. Glutaraldehyde was used as crosslinker. Characterization shows that synthesized membrane possesses good permeability ($0.184l.m^{-2}.h^{-1}.kPa^{-1}$), MWCO (1.7 kDa), average pore size (1.08 nm) and good chemical stability. RSM was adopted for phenol removal studies. Box-Behnken-Design using quadratic model was chosen for three operating parameters (feed phenol concentration, pH and applied pressure) against two responses (phenol removal, flux). ANOVA shows that model is statistically valid with high coefficient of determination ($R^2$)value for flux (0.9897) and phenol removal (0.9302). The optimum conditions are obtained as pH 2, $46mg.l^{-1}$ (feed phenol concentration) and 483 kPa (applied pressure) with 92.3% phenol removal and $9.2l.m^{-2}.h^{-1}$ flux. Data validation with deviation of 4% confirms the suitability of model. Obtained results reveal that prepared composite membrane can efficiently separate phenol from aqueous solution.

• Polymer(Korea)
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• v.28 no.5
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• pp.433-443
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• 2004

The membranes of the blends of chitosan and polycaprolactarn (PA6) were prepared in formic acid. FT-IR data revealed that hydrogen bonding between amide and hydroxyl groups of chitosan and PA6, respectively, was formed. Thermogravimetric analysis demonstrated that the blend samples contain water. DMA results showed that the dissipation of water in the samples significantly reduced the storage modulus (E'). The mechanical loss tangent (tan $\delta$) data of the blend samples showed the $\beta$d loss peak around $0^{\circ}C$. The blend samples were completely dried in a vacuum and then exposed to high moisture to absorb water which would cause, so called, w-bridges between the molecules. The E' data of these regained samples increased abnormally and additional loss peak appeared on the shoulder of the peak around $50^{\circ}C$. Under dry condition, the samples with a blend ratio of 40/60 for chitosan/PA6 displayed a better miscibility between two components.