Polymer Composites for Electrical Engineering. Группа авторов

1096 Poly(hexadecyl acrylate)/cellulose/graphene[94] Atom transfer radical polymerization (ATRP) and injection molding 9 wt% 78 1.32 560 PEG/biological porous carbon[16] Vacuum impregnation 14.6 wt% 158.8 4.489 953 PEG/cellulose‐graphene aerogel[68] Vacuum impregnation 5.3 wt% 156.1 1.35 463 PEG/microcrystalline cellulose‐GNP aerogel[95] Vacuum impregnation 1.51 wt% 182.6 1.03 232 PEG/GO‐GNP aerogel[55] Vacuum impregnation 2.23 wt% 181.5 1.43 361 PEG/cellulose nanofiber‐GNP hybrid‐coated melamine foam[96] Vacuum impregnation 0.65 wt% 178.9 0.26 189 PEG/Si₃N₄ nanowires[97] Solution blending 10 wt% 152.3 0.362 89 PEG/SiO₂/Al₂O₃[99] Ultrasound‐assisted sol–gel and in‐situ doping method 12.6 wt% 123.8 0.435 21 PEG/EVM/SiC nanowires[100] Physical blending and impregnation 3.29 wt% 64.93 0.53 96 PEG/epoxy/BN[101] Melt blending and curing 40 wt% 60.7 2.962 ~887 PEG/GO/BN[17] Solution blending 34 wt% 107.4 3.00 900 PEG/crosslinked cellulose ‐chitosan/BN[102] Interfacial polyelectrolyte complex spinning 47.4 wt% 48.3 4.005 2256 PEG/chitosan‐BN scaffold[103] Nondirectional freezing and vacuum impregnation 27 wt% 136.9 2.77 ~794 PEG/cellulose‐BN nanosheet scaffold[69] Vacuum impregnation 10 vol% 136.8 4.764 ~1344 PEG/GO‐BN scaffold[104] Nondirectional freezing and vacuum impregnation 19.2 wt% 145.9 1.84 479 PEG/aligned GO‐BN scaffold[66] Unidirectional freezing and vacuum impregnation 28.7 wt% 143.6 3.18 864 PEG/silver‐graphene[57] Solution blending 8 wt% 166.1 0.414 95 PEG/BN‐GNP[106] Solution blending 31 wt% 122.2 1.33 329

(2.2)

      where m is the mass, 𝛥H is the phase change enthalpy determined by differential scanning calorimeter (DSC), U and I, respectively, represent the applied voltage and current, and t is phase change time.

      The majorities of the systems used to conduct electro‐to‐heat conversion are organic non‐polymeric solid–liquid PCMs. Leakage‐proof phase change composites composed of microcrystalline cellulose/GNPs aerogel and PEG have been reported. The conductive composites have the ability of electrical energy transition and release (Figure 2.7a).[95] When an electrical field is applied, electrical energy can be inverted into thermal energy by generating Joule heat. Once the accumulated heat reaches the phase transition temperature of working substance, phase change and heat storage behaviors occur. Likewise, shape‐stabilized PW‐based composites containing commercial melamine foam incorporated by GO and GNPs exhibited high electrical conductivity (2.787 S cm⁻¹) at a filler loading of 4.89 wt% and efficient electro‐to‐heat conversion capacity with an efficiency of 62.5%.[113] In addition, Chen et al.[114] employed solid–solid PCMs to realize electro‐to‐thermal energy conversion. PEG was introduced into graphite foam and then in‐situ polymerized, giving rise to the formation of PU‐based solid–solid phase change composites. When a relatively low voltage of 1.2 or 1.4 V is applied, the phase change composites can complete the electro‐to‐heat conversion, and the estimated conversion efficiency is above 80%. Also, an efficient electro‐to‐heat conversion for PU‐based solid–solid phase change composites has been achieved after introducing electrically conductive graphene aerogel.[115, 116]

      2.4.2 Light‐to‐Heat Conversion

Not only can electricity be converted into thermal energy, but also solar energy can be transformed into heat and stored in PCMs. Solar energy, a renewable and clean energy source, is considered to be one of the most effective methods to solve the energy shortage issue. However, there are still technical challenges in the effective utilization of solar energy owing to the intermittence and discontinuity of solar radiation in time and space, which can be exactly solved with the assistance of PCMs storing and releasing heat during the phase transition process. The weak photoabsorption capacity of PCMs makes them unable to convert solar energy into heat