Eco-friendly conductive polymer nanocomposites (CPC) for solar absorbers design

To reduce both the cost and the environmental impact of copper-based thermal solar absorbers, we have investigated their possible substitution by bio-based conductive polymer nanocomposite (CPC) elements. Our results show that carbon nanotubes (CNT) have no significant influence on polymers' calorimetric properties such as Tm and Tg but lead to a strong increase in crystallinity of poly(lactic acid) (PLA) and to a lesser extent of poly(amide 12) poly(amide 12) (PA12) for 2 and 3 CNT wt % respectively. Percolation thresholds as low as 0.5 and 0.58 were obtained for PA12 and PLA, respectively, and visco-elastic properties such as *, G' and G were found to increase exponentially with CNT content confirming the formation of a CNT network within the matrix. All CPC are absorbing more energy in the visible and infrared than in the ultraviolet wavelength ranges. Finally, the thermal conductivity k of PLA-CNT and PA12-CNT were increased, respectively, of 85% and 24%, to reach 0.28W.m-1.K-1 and 0.26W.m-1.K-1, for only 5wt% CNT. The figure of merit suggests that PA12 is the polymer which satisfies at best all criteria, particularly combining a lower viscosity at almost equivalent thermal conductivity and absorptivity. Copyright (c) 2013 John Wiley & Sons, Ltd.