X - ray crystallographic studies of polymeric materials
نویسنده
چکیده
X-ray diffraction (XRD) studies are very usefu l for distinguishing crystalline and non-crystalline states. Highl y crystal line substances give patterns with sharp diffraction peaks or spots, whereas liquids or amorphous material s lie between these two extremes, because their chain length is large and it is difficult to attain three-dimensional regularity. However, XRD stud ies of polymers yield interesting results. A large number of polymeric materials such as po lyeth ylene, polypropylene, nylon, polyethylene terephthalate (PET), polyvinylidine tluoride etc. as well as natural polymers like, cotton and silk have been studied. The diffraction pattern usually consists of some sharp peaks together with broad halos. A carefu l analysis of the diffraction pattern allows us to find out the crystallite shapes , sizes and percentage crysta llinity. The diffraction pattern is very sensiti ve to thermal hi story, chemical processing and other fac tors. In the present paper, the results of XRD of PET when subjected to thermal , chemical and plasma treatments have been presented . The results show that the percentage cryst allinity can be varied from 17 to 50 %.
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