Influence of the concentration of copper nanoparticles on the thermo-mechanical and antibacterial properties of nanocomposites based on poly(butylene adipate-co-terephthalate)

Abstract

Poly(butylene adipate-co-terephthalate) (PBAT) was mixed with copper nanoparticles (Cu-NPs) in concentrations of 1%, 3%, and 5% with particle size between 100 nm and 200 nm by the melting method. A morphological, thermal, and structural characterization of the nanocomposites (NCs-PBAT/Cu) was performed to analyze the effect of the Cu-NPs on the polymer chains, as well as to explain the influence on their crystallinity, and its influence on the thermomechanical and antibacterial properties. The percentage of crystallinity (X-c) increased 6.7% to 9.5% with the amount of Cu-NPs in the matrix. E-modulus was slightly improved from 84.04 to 87.7 MPa, in the same way the degradation temperature (T-d) of the PBTA was improved from 420.7 degrees C to 427.2 degrees C for 5% loading of Cu-NPs. In contrast, Delta H-m decreased from 12.50 to 6.96 J/g, indicating that there was no significant modification of the PBAT chain, mainly by heterogeneous nucleation in the presence of Cu-NPs, which act as a heat barrier. No blue or red shifts we observed in the nanocomposites Fourier transform infrared (FTIR) spectra, indicating there is no effective interaction between PBAT and Cu-NPs. The nanocomposites showed excellent antibacterial properties inhibiting 100% of the strains Enterococcus faecalis, Streptococcus mutans, and Staphylococcus aureus, at 2 hours of treatment. For more resistant strains such as Acinetobacter baumannii, the NCs-PBAT/Cu did not show antibacterial activity at any time of treatment. POLYM. COMPOS., 40:1870-1882, 2019. (c) 2018 Society of Plastics Engineers