Samples of polyethylene containing lamellae of thickness 30nm and 15nm are found to melt at T1=131.2C and T2=121.2C, respectively. Assuming the density of the crystallites c=1.004g/cm3; the increase in enthalpy per unit mass, h, on melting is 2.540(105)J/kg for an infinitely thick crystal, determine the equilibrium melting temperature and the surface free energy of the crystallites fold surface (use GibbsThomson equation)