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| Untersuchte Arbeit: Seite: 15, Zeilen: 4-22 |
Quelle: Bhattacharya et al. 2008 Seite(n): 25, Zeilen: 6-26 |
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| The two major types of polyamides are polyamide 6 and polyamide 66. PA 6 is prepared by the polymerization of caprolactam. PA 66 is derived from the polycondensation of hexamethyelene diamine with adipic acid. Polyamides are crystalline polymers. The key features include a high degree of solvent resistance, thoughness, and fatigue resistance. Polyamides do exhibit a tendency to creep under applied load. Glass fibers and mineral fillers are often used to enhance the properties of polyamides. In addition, the properties of polyamides are greatly affected by moisture. The largest area of application for polyamide is in fiber and engineering plastic. Molded applications include automotive component, related machine parts (gear, cams, pulleys, rollers, etc.), and electrical insulation.
Earlier studies [79] have illustrated that the addition of clay to PA has improved the strength, stiffness, barrier, and heat resistance properties of polyamide 6. The barrier resins exhibit reduced moisture absorption and increased melt stability. Toyota researchers (1989) have shown that, similar to other nanocomposites, PA nanocomposites are able to achieve a lot of improved characteristics compared to pure PA. Thus, it has been reported that PA6 nanocomposites show higher tensile strength, higher tensile modulus, higher heat distortion temperature, increased solvent resistance, decreased thermal expansion coefficient, reduced gas permeability and increased flame retardancy. With these enhanced properties, PA nanocomposites have found increased application in the automobile and textile industries, where stronger yarn could be produced, with better extensional characteristics [88-90]. |
The two major types of polyamides are nylon 6 and nylon 66. Nylon 6, or polycaprolactam, is prepared by the polymerization of caprolactam. Poly (hexamethylene adipamide), or nylon 66, is derived from the condensation polymerization of hexamethylene diamine with adipic acid. Polyamides are crystalline polymers. Their key features include a high degree of solvent resistance, toughness, and fatigue resistance. Nylons do exhibit a tendency to creep under applied load. Glass fibers or mineral fillers are often used to enhance the properties of polyamides. In addition, the properties of nylon are gready affected by moisture. The largest area of application for nylons is in fibers. Molded applications include automotive components, related machine parts (gears, cams, pulleys, rollers, boat propellers, etc.), appliance parts, and electrical insulation.
Earlier studies have illustrated that the addition of clay to PA has improved the strength, stiffness, barrier, and heat resistance properties of nylon 6. The barrier resins exhibit reduced moisture absorption and increased melt stability. Toyota researchers (1989) have shown that, similar to other nanocomposites, PA nanocomposites are able to achieve much improved characteristics compared to neat PA. It has been reported that PA6 nanocomposites show approximately 40 % higher tensile strength, 68 % higher tensile modulus, 60 % higher flexural strength, 126 % higher flexural modulus, higher heat distortion temperatures, increased solvent resistance, decreased thermal expansion coefficient, reduced gas permeability, and increased flame retardancy. With these enhanced properties, PA nanocomposites have found increased application in the automobile and textile industries, where stronger yarns could be produced, with better extensional characteristics. |
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