Dynamic-mechanical response of carbon fiber laminates with a reactive thermoplastic resin containing phase change microc
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Dynamic-mechanical response of carbon fiber laminates with a reactive thermoplastic resin containing phase change microcapsules Giulia Fredi1 · Andrea Dorigato1 · Alessandro Pegoretti1
Received: 31 January 2019 / Accepted: 10 September 2019 © Springer Nature B.V. 2019
Abstract Dynamic-mechanical analysis (DMA) was performed to investigate the viscoelastic response of multifunctional laminates for thermal energy storage (TES). The laminates were constituted by a microencapsulated paraffinic phase change material (PCM), a carbon fiber fabric, and an innovative reactive acrylic resin (Elium® ). In the Elium® /PCM systems, the PCM fraction affected neither the glass transition temperature (Tg ) of the resin, found at 100–120 ◦ C, nor the activation energy of the glass transition, determined with multifrequency scans from the position of the tan δ peaks. On the other hand, the low-temperature (0–40 ◦ C) transition detected on the neat resin was hidden by the PCM melting, evidenced by a step in E and peaks in E and tan δ. In the laminates, the amplitude of the E step and the intensity of the tan δ peak associated to the PCM melting presented a linear correlation with the PCM content and the melting enthalpy. Cyclic heating/cooling DMA tests showed that the decrease in E due to PCM melting was almost completely recovered (90–95%) upon crystallization. The difference between the tan δ peak positions on heating and on cooling decreased from 30 to 12 ◦ C when the heating/cooling rate changes from 3 to 1 ◦ C/min. Multifrequency tests highlighted that the activation energy of the glass transition of the laminates was lower than that of the matrices, and it did not follow a trend with the PCM fraction. Interestingly, also the E and tan δ peaks related to PCM melting depended on the testing frequency, and their asymmetric shape could be interpreted by considering a progressive melting of the PCM in the microcapsules during heating. Keywords Phase change materials · Thermal energy storage · Paraffin · Dynamic-mechanical analysis · Thermoplastic composites
B G. Fredi
[email protected]
B A. Pegoretti
[email protected]
1
Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy
Mech Time-Depend Mater
1 Introduction Thermal energy storage (TES) is one of the key technologies for a more efficient and rational use of energy resources, as it allows the temporary conservation of excess heat that can be released when the demand for thermal energy overcomes its availability. Such techniques are especially useful to manage intermittent energy sources (e.g., solar) and to recover waste industrial heat (Pielichowska and Pielichowski 2014; Pereira da Cunha and Eames 2016; Zhang et al. 2016). Among the most promising materials for TES are the organic solid– liquid phase change materials (PCMs), which accumulate heat when they melt and release it upon crystallization (Zalba et al. 2003; Sharma et al. 2015). As they can store a high amount of latent heat at a nearly con
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