Preparation and Crystallization Behavior of Poly(lactic acid)/Polyamide 11/Silica Composites
| Autor: | Kuan-Yu Lee, 李冠宇 |
|---|---|
| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 Poly(lactic acid) (PLA), nylon 11, and silica nanoparticles were mixed using twin-screw extruder to fabricate the PLA/nylon 11/SiO2 composites with different nylon 11 mixing ratios (0~3.0 wt%). The tensile properties of the PLA/nylon 11/SiO2 compositeswere estimated. The ultimate tensile strength (UTS) of the PLA/nylon 11 blends decreased with increasing nylon 11 amount. However, Young’s modulus (E) and the elongation at break (εb) increased significantly with increasing nylon 11 amounts. Furthermore, the addition of silica nanoparticles into the PLA/nylon 11 blends lowered the values of UTS and E of the PLA/nylon 11/SiO2 composites.However, the value of elongation at break of the composites increased significantly. It can be observed that the ligands on the fracture surface of the PLA/nylon 11 blends were higher than those of the neat PLA fracture surface, indicating that the incorporationof nylon 11 made the PLA matrix more ductile. Moreover, the blending PLA with small amount (less than 3 wt%) could considerably increase the Izod impact strength of the PLA polymer, increasing the value of Izod impact strengthto 6.42 kJ/m2 for the PLA/nylon 11 (31% increment).Moreover, it is surprise that the addition of silica nanoparticles increased the value to as high as 8.72 kJ/m2.Accordingly, the additions of nylon 11 and silica nanoparticles couldeffectively toughen the PLA polymer. Regarding the isothermal crystallization behavior of the PLA/nylon 11/SiO2 composites, the additions nylon 11 and silica nanoparticles increased the absolute crystallinity of the resulting PLA composites. Under higher isothermal crystallization temperatures, the addition of nylon 11 could increase the crystallization rate of the PLA matrix. However, the addition silica nanoparticles increased the crystallization rate of thePLA/nylon 11/SiO2 composites while the addition amount of the nylon 11 was lower. Regarding the nonisothermal crystallization behavior of the PLA/nylon 11/SiO2 composites,the addition nylon 11 could also increase the absolute crystallinity of the PLA/nylon 11 blends. Otherwise,for the PLA/nylon 11/SiO2 composites,the absolute crystallinity of the composites decreased when the mixing amount of nylon 11 was higher than 1.5 wt%. The combined Avrami-Ozawa equation could well describe the nonisothermal crystallization behavior of the PLA/nylon 11/SiO2 composites. The additions of nylon 11 and silica nanoparticles increased the necessary temperature gradient of the PLA/nylon 11 blends and PLA/nylon 11/SiO2 composites, respectively, under a given relative crystallinity. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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