“…A number of studies have shown the effectiveness of using wollastonite (calcium monosilicate Ca 6 Si 6 O 18 with a theoretical composition, wt.%: CaO—48.3, SiO 2 —51.7 [ 25 , 26 , 27 , 28 , 29 ]) to increase the strength and durability of PCM [ 30 , 31 , 32 , 33 , 34 ]. Wollastonite is used in various high-tech fields including the ceramics and polymer industry [ 35 , 36 , 37 , 38 ]. The use of wollastonite as a filler in PCM is associated with its reinforcing effect on the polymer matrix, chemical inertness, high melting point, and environmental friendliness [ 38 ].…”