Original scientific paper

https://doi.org/10.15255/KUI.2016.045

Influence of Multiwalled Carbon Nanotube Modification on Polyurethane Properties: II. Mechanical Properties, Electrical Conductivity and Thermal Stability

Sanja Lučić Blagojević orcid.org/0000-0002-4414-2727 ; University of Zagreb, Faculty of Chemical Engineering and Technology, Marulićev trg 19, 10 000 Zagreb, Croatia
Martina Zeljko ; University of Zagreb, Faculty of Chemical Engineering and Technology, Marulićev trg 19, 10 000 Zagreb, Croatia
Marijana Kraljić Roković ; University of Zagreb, Faculty of Chemical Engineering and Technology, Marulićev trg 19, 10 000 Zagreb, Croatia

Abstract

In this paper, the influence of multiwalled carbon nanotubes (MWCNT) and carbon nanotubes modified with COOH groups (MWCNT-COOH) on the mechanical and electrical properties as well as on thermal stability of polyurethane (PU) were investigated. The samples of nanocomposite were prepared by dispersion of the nanofiller in a solution of polyurethane in acetone, followed by slow evaporation of the solvent at room temperature. The effect of the fillers on the mechanical properties of PU nanocomposites was examined by the uniaxial deformation test, and electrical properties of the samples were determined by the four probe method. Thermal stability was investigated by thermogravimetric analysis (TGA).
The addition of both types of MWCNTs fillers increases modulus (Fig. 1), due to higher modulus of the nanofillers. Due to the better distribution in PU matrix and stronger interactions between COOH groups and carbonyl group in PU matrix, nanocomposites with MWCNT-COOH have higher modulus than nanocomposites with MWCNT filler. Most of the composites have lower strength and elongation at break than PU (Figs. 2 and 3). Smaller MWCNT-COOH aggregates and stronger interactions between this filler and the PU matrix cause less pronounced decreasing of strength at break.
Compared to the pure PU, with conductivity of the order of 10–13 S cm–1, the conductivity of the nanocomposite with mass fraction of MWCNT nanofiller 0.2 % substantially increases up to the value of the order 10–6 S cm–1 (Fig. 4). A further increase up to 4 % for both types of MWCNTs, resulted in a further increase in conductivity up to values exceeding 10–2 S cm–1. Due to the better distribution in PU matrix and stronger interactions between COOH groups and carbonyl groups in PU matrix, the conductivity increase effect in systems with MWCNTs-COOH is slightly more pronounced. All investigated nanocomposites have potential applications as electric discharge materials and for electrostatic painting.
The results of the thermogravimetric analysis indicate that the addition of both types of MWCNTs significantly improves the thermal stability (Figs. 6 and 7). The maximal degradation rate temperature of polyurethane increased by about 45 °C, thereby this effect is slightly more pronounced for systems with MWCNTs (Fig. 7).


This work is licensed under a Creative Commons Attribution 4.0 International License.

Keywords

polyurethane; carbon nanotubes; nanocomposites; mechanical properties; electrical conductivity; thermal stability

Hrčak ID:

181497

URI

https://hrcak.srce.hr/181497

Publication date:

2.6.2017.

Article data in other languages: croatian

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