Izvorni znanstveni članak
https://doi.org/10.15255/KUI.2016.044
Influence of Multiwalled Carbon Nanotube Modification on the Polyurethane Properties: I. Morphology and Thermal Properties
Sanja Lučić Blagojević
orcid.org/0000-0002-4414-2727
; Fakultet kemijskog inženjerstva i tehnologije Sveučilišta u Zagrebu, Marulićev trg 19, 10 000 Zagreb
Martina Zeljko
; Fakultet kemijskog inženjerstva i tehnologije Sveučilišta u Zagrebu, Marulićev trg 19, 10 000 Zagreb
Anđela Pustak
; Institut Ruđer Bošković, Bijenička cesta 54, 10 000 Zagreb
Sažetak
In this work, the influence of multiwalled carbon nanotubes (MWCNT) and carbon nanotubes modified with COOH groups (MWCNT-COOH) on the structure and properties of thermoplastic polyurethane (PU) were investigated. The samples of nanocomposite were prepared from a mixture of polyurethane and MWCNT in acetone by slow drying at room temperature. The effect of the addition of nanofillers on the spherulite structure of polyurethane and the distribution of the nanofillers in the PU matrix were analysed with optical polarization microscopy. Thermal properties in non-isothermal and isothermal conditions were investigated by differential scanning calorimetry (DSC).
The results of contact angle measurement imply that modification of MWCNT surface with COOH groups changes its surface from hydrophobic to hydrophilic (Fig. 2 and Table 1).
Optical polarization microscopy showed that the addition of both nanofillers disrupts the coarse spherulite morphology of the polyurethane matrix (Fig. 4 and Fig. 5). It was observed that, at the macro level, the modified MWCNT-COOH filler is better distributed in the PU matrix than is the MWCNT filler (Fig. 5).
The DSC results showed that, in non-isothermal conditions, up to a certain amount, both nanofillers accelerate the crystallization of the soft segments of polyurethane. This effect is more pronounced in systems with MWCNT filler (Fig. 9). The results of the crystallization enthalpy during cooling showed that MWCNT filler, despite its worse distribution in the PU matrix, more significantly enhances crystallization of PU’s soft segment than does the MWCNT-COOH filler (Fig. 10). This conclusion can be ascribed to better compatibility between the nonpolar MWCNT filler and the nonpolar soft phase of the PU matrix, as well as to the previous scientific finding that functional groups at MWCNT surface decrease the nucleation effect of MWCNT. By analysing the melting peaks, it can be concluded that the PU systems with MWCNT compared to systems with MWCNT-COOH contain a higher proportion of less ordered crystalline soft phase (Fig. 11).
In isothermal conditions, the MWCNT filler accelerates crystallization more significantly than does the MWCNT-COOH filler (Fig. 16).
This work is licensed under a Creative Commons Attribution 4.0 International License.
Ključne riječi
polyurethane; carbon nanotubes; nanocomposites; morphology; crystallinity; thermal properties
Hrčak ID:
177614
URI
Datum izdavanja:
1.4.2017.
Posjeta: 1.349 *