Melting and crystallization behaviour of poly(ethylene glycol) (PEG) with different molecular weights (from 1000 to 35 000) and chosen blends of PEG is investigated by means of differential scanning calorimetry (DSC) operating in dynamic mode at different heating rates. The influence of the molecular weight of PEG on its melting point and enthalpy of fusion is evaluated; from the DSC data the degree of crystallinity is calculated–it is found that there is an increased tendency of higher‐molecular‐weight PEGs towards the formation of crystalline phase owing to their lower segmental mobility and more convenient geometrical alignment. During the freezing cycle, an increase in the molecular weight of PEG causes an increase in the solidification temperature and heat of crystallization. Thermal transition data are supplemented by optical microscopy–numerous small sphere‐shaped crystalline structures are observed to join together and impinge on their neighbours, forming eventually a multilayered lamellar texture. By implementing second polymeric component the polydispersity of the system increases, thus lowering the crystallization degree during preparation phase. It influences also the course of solidification by lowering the crystallization temperature, Tc. An additional effect observed in the case of the blend's freezing is associated with larger supercooling, probably due to morphological constraints and entanglements in interlamellar regions. The possible advantage of using PEG blends to replace pure components is connected with the possibility of changing the temperature range and heat associated with melting/freezing. Copyright © 2003 John Wiley & Sons, Ltd.

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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 72 °C while their heat of transition lies in the range of 168–208 J · g−1. Synergistic action of the components was found for PEG 10 000/stearic acid blend – 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 ‐ PEG 3 400/lauric acid, 2 ‐ PEG 10 000/lauric acid, 3 ‐ PEG 20 000/lauric acid, 4 ‐ PEG 35 000/lauric acid (cooling ‐ 10 K · min−1), 5 ‐ PEG 3 400/lauric acid, 6 ‐ PEG 10 000/lauric acid, 7 ‐ PEG 20 000/lauric acid, 8 ‐ PEG 35 000/lauric acid (heating ‐ 10 K · min−1).magnified imageDSC melting and freezing curves of blends PEG/lauric acid. 1 ‐ PEG 3 400/lauric acid, 2 ‐ PEG 10 000/lauric acid, 3 ‐ PEG 20 000/lauric acid, 4 ‐ PEG 35 000/lauric acid (cooling ‐ 10 K · min−1), 5 ‐ PEG 3 400/lauric acid, 6 ‐ PEG 10 000/lauric acid, 7 ‐ PEG 20 000/lauric acid, 8 ‐ PEG 35 000/lauric acid (heating ‐ 10 K · min−1).

The thermal behavior of a series of poly(ethylene oxide) (PEO)/stearic acid blends was investigated by means of differential scanning calorimetry (DSC), modulated temperature DSC, Fourier transform infrared spectroscopy (FT‐IR) and scanning electron microscopy (SEM) for application as thermal energy storage materials. It has been found that PEO/stearic acid blends are efficient polymer‐based phase change materials that can be applied in the temperature range 55.7–75.2°C with the enthalpy of phase transition values in the range of 202.8–252.3 J/g. The PEO/stearic acid blend (1:3 w/w) exhibits a senergistic effect—its value of enthalpy of melting and crystallization is higher than those of pure components. The origin of this promising effect was investigated by FT‐IR and SEM techniques to ascertain the influence of hydrogen bonds on the sample's supramolecular morphology. Copyright © 2005 John Wiley & Sons, Ltd.

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