Mechanical and optical properties of everyday products

Several disposable plastic products are considered, to illustrate mechanical and optical properties. 

Continue the loading until the body fractures. Although the ink tube will trap the broken pieces of the body, it is likely that a small piece(s) of PS might detach (Fig. 1.8b). Do not do the experiment without the ink tube, as pieces can fly off at speed. The strain energy released by the fracture is enough to create more than one fracture surface. 

Low-density polyethylene (LDPE) strapping, cut from 0.42 mm thick film, is used to hold four packs of drink cans together. If pulled slowly with the hands, parts of the strapping undergo tensile necking followed by cold drawing of the thin region (Fig. 1.9). Mark parallel lines at 5 mm intervals 

This requires a laser pointer and a CD. Observe safety precautions do not aim the laser beam at anyone s eyes. Aim it, at approximately normal incidence, at the side of the CD that appears silvered. When the beam hits the tracks near the centre of the disc, a diffraction pattern is created (Fig. 1.10). This pattern is a two-dimensional analogue of X-ray diffraction from a three-dimensional crystal. 

If the laser beam hits the main part of the disc, there are just two diffraction peaks, in addition to the directly reflected beam. These are caused by the 

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