About polymer crystallinity and melting temperature. Which of the following is not correct? (5 points) a) Melting is a phase transition from a crystalline phase to a solid amorphous phase b) Crystallinity does not affect the optical property of polymers. c) Crystallinity affects the mechanical property of polymers. d) Melting can be measured by differential scanning calorimetry (DSC). About polymer glass transition and glass transition temperature. Which of the following is not correct? (5 points) a) The glass transition temperature may be below 0C for some polymers. b) The glass transition is a transition from a glassy state to a rubbery state. c) A polymer becomes stiffer above the glass transition temperature. d) Glass transition can be measured by differential scanning calorimetry (DSC)