Effects of grafted chain length on mechanical and electrical properties of nanocomposites containing polylactide-grafted carbon nanotubes

We herein report the effects of interfacial reinforcement on mechanical and electrical properties of nanocomposites based on polylactide (PLA) and multi-walled carbon nanotube (MWCNT). For this purpose, a series of MWCNTs grafted with PLA chains of various lengths (MWCNT- g-PLAs) were prepared by ri...

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Veröffentlicht in:Composites science and technology 2010-05, Vol.70 (5), p.776-782
Hauptverfasser: Yoon, Jin Tae, Lee, Sang Cheol, Jeong, Young Gyu
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Sprache:eng
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Zusammenfassung:We herein report the effects of interfacial reinforcement on mechanical and electrical properties of nanocomposites based on polylactide (PLA) and multi-walled carbon nanotube (MWCNT). For this purpose, a series of MWCNTs grafted with PLA chains of various lengths (MWCNT- g-PLAs) were prepared by ring-opening polymerization of l-lactide with carboxylic acid-functionalized MWCNT (MWCNT-COOH). MWCNT- g-PLAs were then mixed with commercial PLA to obtain PLA/MWCNT- g-PLA nanocomposites with 1.0 wt.% MWCNT content. It was revealed that morphological, mechanical, and electrical properties of PLA/MWCNT- g-PLA nanocomposites were strongly dependent on the PLA chain length of MWCNT- g-PLAs. FE-SEM images exhibited that the nanocomposites containing MWCNT- g-PLA with longer PLA chain length exhibited better dispersion of MWCNTs in the PLA matrix. Initial moduli and tensile strengths of PLA/MWCNT- g-PLA composites increased with the increment of chain length of PLA grafted on MWCNTs, which attributes to the improved interfacial adhesion between the grafted PLA chains of MWCNT- g-PLA and the PLA matrix. As a result, the experimental initial modulus (2775 ± 193 MPa) of the nanocomposite including MWCNT- g-PLA with PLA chains of average molecular weight of 530 g/mol was quite close to the theoretical value (2911 MPa) predicted for the nanocomposite with perfect interfacial adhesion. Unexpectedly, electrical resistivities of PLA/MWCNT- g-PLA nanocomposites were found to increase from ∼10 4 to ∼10 12 Ω/sq with increasing the PLA chain length of MWCNT- g-PLA, which is due to the fact that the PLA chains grafted on MWCNTs prevent the formation of the electrical conduction path of MWCNTs in the PLA matrix.
ISSN:0266-3538
1879-1050
DOI:10.1016/j.compscitech.2010.01.011