Abstract
A series of blends of poly(ethylene glycol) (PEG) with different molecular weights with: (i) capric, (ii) lauric, (iii) myristic, (iv) palmitic or (v) stearic acid, as a thermal energy storage material, has been investigated by differential scanning calorimetry (DSC). Transition temperatures and latent heat of transition of PEG, fatty acids and their binary blends were determined since these properties are of primary importance in the design of phase change energy storage materials. The experimental results showed that it is possible to obtain homogeneous (as indicated by DSC data) polymer/fatty acid blends by mixing in the melt and subsequent solidification. The melting ranges of PEG/fatty acid systems were observed to be from 30 to 72βΒ°C while their heat of transition lies in the range of 168β208 JβΒ·βg^β1^. Synergistic action of the components was found for PEG 10β000/stearic acid blend β heat of transition was ca. 15 and 35% higher than for pure stearic acid and PEG, respectively. This phenomena may be explained in terms of strengthened specific interactions via hydrogen bonding leading to formation of more perfect crystalline lattice.
DSC melting and freezing curves of blends PEG/lauric acid. 1 β PEG 3β400/lauric acid, 2 β PEG 10β000/lauric acid, 3 β PEG 20β000/lauric acid, 4 β PEG 35β000/lauric acid (cooling β 10 KβΒ·βmin^β1^), 5 β PEG 3β400/lauric acid, 6 β PEG 10β000/lauric acid, 7 β PEG 20β000/lauric acid, 8 β PEG 35β000/lauric acid (heating β 10 KβΒ·βmin^β1^).
magnified imageDSC melting and freezing curves of blends PEG/lauric acid. 1 β PEG 3β400/lauric acid, 2 β PEG 10β000/lauric acid, 3 β PEG 20β000/lauric acid, 4 β PEG 35β000/lauric acid (cooling β 10 KβΒ·βmin^β1^), 5 β PEG 3β400/lauric acid, 6 β PEG 10β000/lauric acid, 7 β PEG 20β000/lauric acid, 8 β PEG 35β000/lauric acid (heating β 10 KβΒ·βmin^β1^).