L. Kouchachvili and M. Ikura (Canada)
Pyroelectric, Waste heat, Poling, Resistivity, P(VDF TrFE).
Pyroelectric conversion can produce high voltage DC from low-grade waste heat. Our pyroelectric converter uses 60%/40% P(VDF-TrFE) copolymer. Previously we encountered substantial power losses due to internal leakage at high temperature and voltage. In order to increase the power output, we examined the polymer purification using solvent extraction. After copolymer purification, we compared the electrical properties of the purified copolymer with these of the unpurified. Although we removed only 0.4 wt % of the copolymer impurities by solvent extraction, the electrical resistivity of purified copolymer was 35% higher than that of unpurified copolymer. We also observed that thin films produced using purified copolymer were able to withstand 50% higher electric field before they were ruined by electrical short-circuit. Subsequently, we conducted pyroelectric conversion using single 25 :m thick 60%-40% P(VF2 TrFE) copolymer films. Copolymer purification resulted in a three-fold increase in net power output. Net power output per unit volume of unpurified copolymer was 95 J/L but increased to 279 J/L for purified copolymer.
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