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Reversible melting process exists at the fold-end surfaces of polymer lamellar crystals [1].This process has been evidenced by both experiments [2] and molecular simulations [3].However, the expected association between this process and the chain mobility requires further evidence.Here we performed dynamic Monte Carlo simulations of a polymer lamellar crystal in 3D lattice box with periodic boundary conditions.By using saw-tooth-type temperature modulation upon the quasi-isothermal annealing, the internal energy of the crystal appears as a periodic response corresponding to the modulated temperatures, as shown in Fig 1.We chose the data analysis method without Fourier transformation, which was proposed by Hu et al.[4], to calculate the reversing heat capacity from the internal energy data.We observed that the reversing heat capacity originates from the reversible melting process at the fold-end surfaces.For lower chain-sliding mobility in the lamellar crystal, the reversing heat capacity decreases, as shown in Fig 2a.This result evidences the association between the reversible melting and the chain mobility.In addition, with the increase of the modulated frequency, the reversing heat capacity exhibits a declining tendency, as shown in Fig 2b.This result implies a competition between chain relaxation and temperature modulation.