engleski

Utjecaj ugljikovih nanocjevčica s više stijenki na svojstva polilaktida

Polylactide (PLA) is a biodegradable thermoplastic and compostable polymer, polyester derived from renewable sources. Since the lactides can be produced by microbial fermentation, it is considered as a sustainable alternative to petrochemical products. Of special interest are investigations of nanofillers addition, because of its high specific surface area achieve great contact with the matrix and thereby in small amount they can change the properties of the matrix. In this study the influence of multiwall carbon nanotubes in amount from 0.5 to 5% wt on structure, electrical properties, thermal properties and stability of polylactide was investigated. Samples were prepared by mixing in a Brabender plasticoder. Thermal properties were investigated by differential scanning calorimetry under non-isothermal conditions and with dynamic mechanical analysis. Thermal stability was determined by thermogravimetric analysis. Electrical properties were investigated using four point method. Structure investigation of PLA/MWCNT systems was carried out by wide-angle X-ray diffraction (WAXD). Study of the structure of nanocomposites showed that the PLA has an amorphous structure and crystallizes after the glass transition temperature by cold crystallization process. PLA has crystallizes in -form and crystal form of PLA does not change with addition MWCNT. Compared to pure PLA matrix the highest storage modulus at a temperature of 25 °C has system with 2 % of MWCNT. The obtained results indicate that after the initial stages of degradation, carbon nanotubes can effectively postpone degradation of PLA. Electrical conductivity is greatly increased by 11 orders of magnitude by the addition of only 0.5 % wt of MWCNTs, from which it can be concluded that by 0.5% MWCNTs in PLA conductivity threshold is reached. By further increase of MWCNTs up to 5% conductivity further increases by 3 orders of magnitude. All investigated nanocomposites have potential application for the removal of electrostatic charge and electrostatic painting. Thermal stability of PLA matrix is improved by carbon nanotubes, and the most effective increase of the thermal stability was achieved with the addition of 2 % of MWCNT.

polilaktid, ugljikove nanocjevčice, toplinska svojstva, toplinska stabilnost, električna svojstva

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