shown in Figure 12-35c, diagram d and Figure 12-35a. In glassy state polymers can be classified as amorphous or crystalline with different properties (see Figure 12-35d). Most polymers are in either amorphous or semi-crystalline forms. Depending on temperature, they can also exist in rubbery and melt states (Figure 12-35d). Thermo-plastics do not undergo chemical change in their composition when heated and can be moulded repeatedly. Thermosets type plastics can melt and take shape once; they stay solid after solidification. Mass of common thermoplastics range from 20,000 to 500000 amu (atomic mass unit = 1.6x10 -24 gm), while thermosets are assumed to have infinite molecular weight. Table 12-07b (in Microsoft Word 97-2003 Document Format) lists the four families of plastics in declining quality from top row to bottom. Detail of some examples can be accessed by doing a ctrl-click on the subject. Micelles, Vesicles, and Emulsions - Micelle is an aggregate of surfactant molecules dispersed in liquid. Surfactant is a class of organic chemicals call amphiphiles, which has a hydrophilic (water loving) head and a hydrophobic (water hating) tail (see surfactant for more detail). Vesicle is a double layers sphere made from surfactant molecules with the hydrophilic heads facing the aqueous solutions on the outside and inside (Figure 12-35i). Most vesicles have specialized functions depending on what materials they contain. For example, the living cell contains vesicles called Endoplasmic reticulum, Golgi complex, and Lysosomes for processing foods and removing wastes. The cell membrane is also a form of vesicle. Emulsion is