1. The relations derived in this and other chapters normally assume that the polymer sample has a unique molar mass. 2. The extent of sample crystallinity can influence the behaviour of a polymer sample greatly. 3. The occurrence of significant crystallinity in a polymer sample is of considerable consequence to a materials scientist. 4. However, a polymer sample is rarely completely crystalline and the properties also depend on the amount of crystalline order. 5. Chain symmetry and flexibility both affect the crystallinity of a polymer sample. 6. The first attempts to explain the crystalline structure of a polymer sample produced a model called the fringe-micelle structure. 7. The polymer sample is placed in the bulb of a dilatometer, degassed, and a confining liquid such as mercury added. 8. The polymer sample is described as an ensemble of co-operative regions, or subsystems, each containing monomeric segments. 9. The onset of molecular motion in a polymer sample is reflected in the behaviour of E and E. |