SAXS INVESTIGATION OF THE STRUCTURE OF HIGH-PRESSURE CRYSTALLIZED POLY(ETHYLENE-TEREPHTHALATE) - A NEW NANOSTRUCTURED MATERIAL

The common crystallization conditions of poly(ethylene terephthalate) (PET) were replaced by an anabaric high-pressure crystallization at 32 0 degrees C. The PET samples were characterized by differential scanni ng calorimetry, density and microhardness. The resulting two-phase mic rostructure was studied by means of absolute small-angle X-ray scatter ing (SAXS). A complete SAXS analysis utilizing the interface distribut ion function (IDF) method was carried out. The resulting structure exh ibited the presence of stacks of 10 nm thick crystalline lamellae whic h were separated by amorphous layers of about 1.3 nm thickness. Simila r structures have been found after annealing of amorphous metals and h ave been termed nanocrystalline. Microhardness and structure have been discussed in analogy with the notions from the field of nanostructure d materials. Theoretically, a multi-component lamellar two-phase struc ture has been discussed. The equations derived allow the computation o f volume fractions and specific surfaces of the components (different kinds of stacks).