Thermal analysis of paraffins as model compounds for polyethylene

The n‐paraffins C₅₀H₁₀₂, C₄₄H₉₀, and C₂₆H₅₄ were analyzed with standard and temperature‐modulated differential scanning calorimetry. Crystallization and ordering from the melt to the condis phase showed practically no supercooling. These observations were confirmed with hot‐stage microscopy and a melting‐point apparatus. Only the organization of the C₂₆H₅₄ condis crystals to fully ordered crystals showed a supercooling of 4.0 K. The measurement of the apparent reversing heat capacity with a 0.05‐K modulation amplitude revealed that the melting of C₅₀H₁₀₂ was completed within 1.0 K and the isotropization of C₂₆H₅₄ was completed within less than 0.6 K, but 62–78% of the total transitions occurred over a much narrower temperature range of 0.1 K or less. The link to polyethylene was made with fractions of the masses 15,520, 2150, and 560 Da. The 560‐Da sample corresponded to C₄₀H₈₂ and showed also almost no supercooling, whereas the others, with folded and extended‐chain crystals, supercooled by about 10 K. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2810–2822, 2000