Abstract
A general model for all kinds of sizeโdependent melting points, free of any adjustable parameter, is extended to illustrate the sizeโdependence of the melting temperature of polyethylene (PE). The model prediction for the depression of the melting temperature of PE is consistent with the calorimetric experimental results as shown in the Figure where the melting temperature of lamellae PE crystals as a function of the thickness of the crystals is presented.
The T~m~(D) function of PE shown as a solid line in terms of Equation (4). The necessary parameters for use of Equation (4) are shown in Table 1. The symbols โ and โข denote the experimental evidence of T~m~(D) of linear alkanes14b and cyclic alkanes,14c respectively. The values of D are determined by Dโ=โ0.1273__n__6 with 0.1273 nm being the orthorhombic C๏ฃฟC lattice distance in the cโdirection.5 The symbol โก denotes the experimental evidence of chainโextended PE.6
imageThe T~m~(D) function of PE shown as a solid line in terms of Equation (4). The necessary parameters for use of Equation (4) are shown in Table 1. The symbols โ and โข denote the experimental evidence of T~m~(D) of linear alkanes14b and cyclic alkanes,14c respectively. The values of D are determined by Dโ=โ0.1273__n__6 with 0.1273 nm being the orthorhombic C๏ฃฟC lattice distance in the cโdirection.5 The symbol โก denotes the experimental evidence of chainโextended PE.6