Amorphous plastic scatter

As crystalline materials melt, their appearance transforms from opaque to transparent because the ordered structure is lost Highly amorphous polymers, including acryhcs, polycarbonate, and polystyrene do not form crystals, so are transparent (Figure 4.6). An exception is crystalline polyester poly (ethylene terephthalate) used in fizzy drinks botdes, which is transparent because its crystals are too small to interfere with hght waves. Fillers and additives usually decrease the light transmission of a plastic by scattering incident light. 

In Section 9.3 we present experimental studies of plastic deformation in two semi-crystalline polymers, HDPE and Nylon-6, both in tension and in plane-strain compression flow, from initial spherulitic morphologies to large plastic strains. In these studies, the evolving morphological alterations were monitored closely by a complementary array of techniques involving light microscopy and X-ray diffraction and scattering both in the crystalline and in the amorphous components. 

There are a few drawbacks of thermoplastics. Some thermoplastics do not fully crystallize below the glass hansition temperature (Tg) and retain some or all of then-amorphous characteristics. Amorphous and semiamorphous plastics are less resistant to chemical attack and environmental stress cracking because of the lack of crystalhne structure. Amorphous and semiamorphous plastics are typically used when there is high optical clarity because light is scattered strongly by crystallites larger than its wavelength [5]. 

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