Poly(ethyleneterephthalate)(PET), which has a Tg and Tm of 85 and 276 oC, respectively, can exist in a number of different states depending upon temperature and thermal history. Thus it is possible to prepare materials that are semicrystalline with amorphous regions that are either glassy or rubbery. Consider a sample of PET cooled rapidly from 300 oC(state I) to room temperature. The resulting material is rigid and perfectly transparent (state II). The sample is then heated to 100 oC and maintained at this temperature, during which time it gradually becomes translucent (state III). It is then cooled to room temperature, where it is again observed to be translucent (state IV). a. Identify each of the states. b. In state IV PET has a higher modulus and is less flexible than in state III. Why is this? c. Why is PET transparent in state II, yet translucent in state IV?