Perpustakaan Digital ITB

Both physical treatment, like heating or annealing, and mechanical treatment, like stretching to some extent, will influence the material structure. Structure is one of the aspects that influence polymer's properties. Structure could be characterized by the degree of crystallinity and the degree of orientation. In this research polyethylene terephtalate (PET) plates were made at its melting point temperature. Stretching with various extentions at 90°C and heating at various temperatures were carried out to see the effect on the polymer structure, i.e, based upon the degree of the crystallinity and the degree of orientation. Structure analysis and characterization were carried out by X-Ray Diffraction techniques. The results showed that PET was semicrystalline. The degree of crystallinity and the degree of orientation tended to increase with increasing extention of stretching. Increasing temperature made an increase in the degree of crystallinity, but a decrease in the degree of orientation. It might be due to the formation of bigger and more perfect crystals, which however is not followed by a regular crystal molecule chain arrangement with increasing the temperature of heating.