Description:
<jats:title>Abstract</jats:title><jats:p>A differential scanning calorimeter has been used to measure the heat capacity of a 75% crystalline sample of syndiotactic polypropylene from 180 to 460°K. An estimate has been made of heat capacity values below 180°K. Values of the heat capacity, entropy, enthalpy, and free energy have been estimated for the 100% crystalline polymer and are listed at 10° intervals. A glass transition (270°K), a first order transition of unknown origin (395°K) and a melting transition (410°K) were observed. The thermal properties of isotactic, atactic and syndiotactic polypropylene are compared. The entropy of polymerisation of gaseous propylene at 1 atmosphere pressure and 298.16°K to crystalline, syndiotactic polypropylene, ΔS<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-stack-1.gif" xlink:title="urn:x-wiley:0025116X:media:MACP021160112:tex2gif-stack-1" />, has been calculated as −45.7 ± 0.3 cal·deg<jats:sup>−1</jats:sup>·mole<jats:sup>−1</jats:sup>.</jats:p>