Reversible Giant\nBarocaloric Effect with Broad Working\nTemperature Range in an Amorphous Ethylene Propylene Diene Monomer

The barocaloric effect of a solid material is an intense\nresearch\ntopic due to its potential application in solid-state refrigeration.\nAmong the proposed candidates, elastic polymers are distinctive because\ntheir barocaloric responses are independent from a pressure-induced\nphase transition which makes it possible to realize a broad working\ntemperature range in principle. However, the barocaloric performance\nof most elastic polymers diminishes significantly as temperature decreases.\nIn this work, giant and reversible barocaloric effects were observed\nin a broad working temperature range from 252 to 345 K in an amorphous\npolymer of ethylene propylene diene monomer, which are much higher\nthan the investigated crystalline and partially crystallized ones.\nIt is demonstrated that the degree of crystallinity can be a key factor\nresponsible for the mobility of polymer chains and the corresponding\nbarocaloric performance at low temperatures. The reversible giant\nbarocaloric effects, broad working temperature regions, low cost,\nand absence of pressure-transmitting fluid make the ethylene propylene\ndiene monomer attractive for solid-state barocaloric refrigeration.