Influence of the dispersion characteristics for producing thermoregulating nano phase change slurries

Abstract

Phase Change Dispersions (PCDs) of large colloidal stability were produced by sonication at an energy per liquid volume of ∼ 800 kJ/L, using gum arabic (GA) and sodium dodecyl sulfate (SDS) mixtures as dispersant agent and varying their mass ratios from 0 to 100 (GA/SDS). An important interplay between the PCD base properties and the final phase change slurry (PCS) characteristics was observed, finding that the PCD with the minimum breaking ratio, promotes the PCS with the largest colloidal stability. PCSs from GA/SDS mass ratios of 70/30 and 40/60 were homogeneous, whereas those ones from mass ratios 20/80 or 0/100 generated two phase products. The PCS prepared with a 40/60 of GA/SDS mass ratio was the unique slurry that satisfied the European classification as nanomaterial with a dn0.5 of 94.7 ± 15.0 nm. This homogenous nano-slurry (NPCS) had a solid concentration of 28.1 wt% and large latent heat (32.8 J g−1), exhibiting thermal reversibility, long-term colloidal stability (|ζ| =53.4 ± 1.8 mV freshly and |ζ| =55.86.3 ± 6.3 mV after two years) and Newtonian behavior with low viscosity (10.7 ± 0.3 mPa·s). Besides, observing the encapsulation efficiency, the best reaction was performed producing this nano-slurry with a particle yield of 72.3 % and a PCM content in the capsules close to 50 %.