• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.146-147
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• 2006

Polyamides have been widely used in the various industrial fields on account of their excellent properties. Especially the largest market with more than 40% of the total demand is in automobiles and transportation equipment. In this lecture, we would like to introduce several new functional materials (new polyamide elastomer UBESTA XPA, UBESTA gas pipe system and new polyamide terpolymer TERPALEX) based on polyamides developed by UBE. Here UBESTA is the trademark for UBE's polyamide12.

• Elastomers and Composites
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• v.51 no.4
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• pp.317-341
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• 2016

Polyamide (PA) is one of five engineering plastic materials which has good mechanical properties and competitive price compared to other engineering plastics and it has various applications including in the areas of automotives, electronics and aerospace industry. Even though PA market grows fast compared to other engineering plastics, it has few organized literatures regarding researches and applications. In this paper, we review overall background, characteristics, formulation, current market trends and technology development of PA resins and their composites.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.73-74
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• 2018

In this study, it evaluate the tensile properties of polyamide fiber reinforced cementitious composite and hooked steel fiber reinforced cementitious Composites by strain rate. Polyamide fiber reinforced cement composites (PAFRCC) and Hooked Steel Fiber Reinforced Cement Composite(HSFRCC) were fabricated. Each specimen was reinforced with 1.0 and 2.0vol% fiber. The length of the reinforced fiber was 30 mm for both fibers, and the tensile test specimen was made in dumbbell shape. As a result, the tensile strength of fiber in polyamide fiber and the mechanical bonding between fiber and matrix in hooked steel fiber are considered to be the main factors affecting tensile behavior of fiber reinforced cement composite.

• The Journal of Advanced Prosthodontics
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• v.8 no.6
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• pp.504-510
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• 2016

PURPOSE. Polyamide polymers do not provide sufficient bond strength to auto-polymerized resins for repairing fractured denture or replacing dislodged denture teeth. Limited treatment methods have been developed to improve the bond strength between auto-polymerized reline resins and polyamide denture base materials. The objective of the present study was to evaluate the effect of surface modification by acetic acid on surface characteristics and bond strength of reline resin to polyamide denture base. MATERIALS AND METHODS. 84 polyamide specimens were divided into three surface treatment groups (n=28): control (N), silica-coated (S), and acid-treated (A). Two different auto-polymerized reline resins GC and Triplex resins were bonded to the samples (subgroups T and G, respectively, n=14). The specimens were subjected to shear bond strength test after they were stored in distilled water for 1 week and thermo-cycled for 5000 cycles. Data were analyzed with independent t-test, two-way analysis of variance (ANOVA), and Tukey's post hoc multiple comparison test (${\alpha}=.05$). RESULTS. The bond strength values of A and S were significantly higher than those of N (P<.001 for both). However, statistically significant difference was not observed between group A and group S. According to the independent Student's t-test, the shear bond strength values of AT were significantly higher than those of AG (P<.001). CONCLUSION. The surface treatment of polyamide denture base materials with acetic acid may be an efficient and cost-effective method for increasing the shear bond strength to auto-polymerized reline resin.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.756-765
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• 2015

Background: Fibers have been used in cement mixture to improve its toughness, ductility, and tensile strength, and to enhance the cracking and deformation characteristics of concrete structural members. The addition of fibers into conventional reinforced concrete can enhance the structural and functional performances of safety-related concrete structures in nuclear power plants. Methods: The effects of steel and polyamide fibers on the shear resisting capacity of a prestressed concrete containment vessel (PCCV) were investigated in this study. For a comparative evaluation between the shear performances of structural walls constructed with conventional concrete, steel fiber reinforced concrete, and polyamide fiber reinforced concrete, cyclic tests for wall specimens were conducted and hysteretic models were derived. Results: The shear resisting capacity of a PCCV constructed with fiber reinforced concrete can be improved considerably. When steel fiber reinforced concrete contains hooked steel fibers in a volume fraction of 1.0%, the maximum lateral displacement of a PCCV can be improved by > 50%, in comparison with that of a conventional PCCV. When polyamide fiber reinforced concrete contains polyamide fibers in a volume fraction of 1.5%, the maximum lateral displacement of a PCCV can be enhanced by ~40%. In particular, the energy dissipation capacity in a fiber reinforced PCCV can be enhanced by > 200%. Conclusion: The addition of fibers into conventional concrete increases the ductility and energy dissipation of wall structures significantly. Fibers can be effectively used to improve the structural performance of a PCCV subjected to strong ground motions. Steel fibers are more effective in enhancing the shear performance of a PCCV than polyamide fibers.

• Polymer(Korea)
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• v.33 no.4
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• pp.284-289
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• 2009

The morphology and mechanical properties of epoxy/polyamide/MPD reactive blends with various amount of polyamide were investigated. The cure behaviors, mechanical strengths, and morphological changes of the epoxy blend systems were analyzed by using DSC, UTM, and SEM, respectively. The amount of high soluble polyamide in epoxy ranged from 0 to 30 phr, and the cure reaction occurred at $170^{\circ}$ for 30 min. The start and maximum exothermic temperature in heat flows during cure reactions appeared at almost same temperature, indicating that soluble polyamide could rarely hinder the cure reactions. From the SEM images, it was found that the size of separated-phase was very fine about 100-300 nm, and at 20 phr of polyamide the boundary of separated-phase was unclear and the phase revealed co-continuous. By AP plasma treatment of specimen surface, the adhesion strength was increased by 20% due to enhanced surface free energy. By blending 20 phr of polyamide with epoxy, the adhesion strength was increased by 50% due to co-continuous phase in morphology. By considering the surface treatment of specimen and morphological tuning of the blends, it can be expected that the improvement in toughness and excellent adhesion strength can be achieved in structural adhesive systems.

• Proceedings of the Korean Fiber Society Conference
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• 2001.04a
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• pp.99-102
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• 2001

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.136-142
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• 2018

Additive manufacturing process technology, known as the 3D printing process, is expanding its utilization from simple model realization to commercialized part production based on continuous material development. Recently, research and development have been actively carried out to fabricate lightweight and high-strength parts using polymers, such as polyamide (polyamide), which is a high-strength engineering plastic material. In this study, the Izod impact characteristics were analyzed for polyamide 12 (PA12) materials. For the specimen production, selective laser sintering process technology, which has excellent mechanical properties of finished products, was applied. In addition, PA12 and glass bead reinforced PA12 materials were produced. The specimens were classified according to the production direction on the production platform, and each specimen was subjected to an Izod test at test temperatures of $-25^{\circ}C$, $25^{\circ}C$, and $60^{\circ}C$. As a result, the impact strength of PA12 and glass bead-reinforced PA12 of vertical direction specimens were 48.8% and 16.3% lower than those of the parallel specimens at a $25^{\circ}C$ test temperature and the impact strength of parallel specimens was improved by 46.5% and 20.4% at a test temperature of $60^{\circ}C$ compared to that at $-25^{\circ}C$.

• Macromolecular Research
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• v.17 no.10
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• pp.797-806
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• 2009

The mechanical and thermal behaviors of polyamide-6/clay nanocomposites were studied using the continuum-based, micromechanical models such as Mori-Tanaka, Halpin-Tsai and shear lag. Mechanic-based model prediction provides a better understanding regarding the dependence of the nanocomposites' reinforcement efficiency on conventional filler structural parameters such as filler aspect ratio ($\alpha$), filler orientation (S), filler weight fraction (${\Psi}_f$), and filler/matrix stiffness ratio ($E_f/E_m$). For an intercalated and exfoliated nanocomposite, an effective, filler-based, micromechanical model that includes effective filler structural parameters, the number of platelets per stack (n) and the silicate inter-layer spacing ($d_{001}$), is proposed to describe the mesoscopic intercalated filler and the nanoscopic exfoliated filler. The proposed model nicely captures the experimental modulus behaviors for both intercalated and exfoliated nanocomposites. In addition, the model prediction of the heat distortion temperature is examined for nanocomposites with different filler aspect ratio. The predicted heat distortion temperature appears to be reasonable compared to the heat distortion temperature obtained by experimental tests. Based on both the experimental results and model prediction, the reinforcement efficiency and heat resistance of the polyamide-6/clay nanocomposites definitely depend on both conventional (${\alpha},\;S,\;{\Psi}_f,\;E_f/E_m$) and effective (n, $d_{001}$) filler structural parameters.

• Journal of the Korean Applied Science and Technology
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• v.19 no.4
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• pp.291-296
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• 2002

Fatty polyamide that gives softness, lubrication and bulky property and alkyl imidazoline that gives durable softness and antistatic property were synthesized. then, an O/W-type durable softener (DSN) was prepared by the emulsion of the synthesized fatty polyamide and alkyl imidazoline. Emulsion stability of the DSN was good, and the mixed HLB value was 11.2. From the measurement of softness, lubrication, antistatic property, bending resistance, and color fastness, it was proved that the prepared DSN was a good durable softener for nylon.