Phase-selective conductivity enhancement and cooperativity length in PLLA/TPU nanocomposite blends with carboxylated carbon nanotubes
| Autor: | Omid Yousefzade, Jordi Puiggalí, Sofia Valenti, Roberto Macovez |
|---|---|
| Přispěvatelé: | Universitat Politècnica de Catalunya. Doctorat en Polímers i Biopolímers, Universitat Politècnica de Catalunya. Departament d'Enginyeria Química, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. PSEP - Polimers Sintètics: Estructura i Propietats. Polimers Biodegradables, Universitat Politècnica de Catalunya. GCM - Grup de Caracterització de Materials |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Polymers and Plastics Polymers 02 engineering and technology Carbon nanotube 010402 general chemistry 01 natural sciences law.invention Thermoplastic polyurethane Differential scanning calorimetry Nanocompòsits (Materials) law Phase (matter) Materials Chemistry chemistry.chemical_classification Nanocomposites (Materials) Nanocomposite Física [Àrees temàtiques de la UPC] Organic Chemistry Polymer 021001 nanoscience & nanotechnology 0104 chemical sciences Dielectric spectroscopy Polímers chemistry Chemical engineering 0210 nano-technology Glass transition |
| Zdroj: | UPCommons. Portal del coneixement obert de la UPC Universitat Politècnica de Catalunya (UPC) |
| Popis: | Transmission electron microscopy, temperature-modulated differential scanning calorimetry, and broadband dielectric spectroscopy were employed to characterize ternary nanocomposites consisting of carboxylated carbon nanotubes (CNT) dispersed in a blend of two immiscible polymers, poly(L,lactide) (PLLA) and thermoplastic polyurethane (TPU). The nanocomposite blends were obtained by melt-compounding of PLLA and TPU in the presence of 0.2 wt-% CNT, either in the presence or absence of a Joncryl® ADR chain extender for PLLA, leading to reactive and non-reactive melt mixed samples. In both cases, the binary PLLA/TPU blend is characterized by phase separation into submicron TPU droplets dispersed in the PLLA matrix, and displays two separate glass transition temperatures. The carbon nanotubes are present either inside the TPU phase (samples obtained without chain extender), or at their boundaries (reactive-melt mixed samples). The effect of the sub-micron confinement of the TPU component is to decrease the cooperativity length of the primary segmental relaxation of this polymer, which is accentuated by the presence of the CNT fillers. Depending on the type of sample, five or six distinct relaxations are observed by means of dielectric spectroscopy, which we are able to assign to different dielectric phenomena. Our dielectric data show that the CNT fillers do not contribute directly to the long-range charge transport in the nanocomposite blends, consistent with the nanocomposites morphology, but rather result in a shift of the Maxwell-Wagner-Sillars space-charge frequency associated with charge accumulation at the PLLA/TPU boundary. Such shift testifies to a selective conductivity enhancement of the TPU phase due to the filler. |
| Databáze: | OpenAIRE |
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