Polyphthalamide (PPA) is an engineering polymer with high temperature resistance. a) Knowing that PPA belongs to the group of semi-crystalline thermoplastics, please decide which of the following designations for PPA are correct. Write your answer as follows. af) correct, ag) wrong, etc. [Caution: Wrong answers are counted - 1 -> better skip if you are not sure, minimum total points = 0]. (5P) PPA.. aa) has a melting temperature ab) in the liquid state is transparent ac) upon heating forms crosslinks ad) has its preferred service temperature between T, and Tm ae) is not suitable for injection moulding mm ... W... www.wo * b) For the production of PPA 6T by polycondensation, hexamethylenediamine (HMDA) and terephthalic acid are used: monomers NH2 OH HN HO NH2 OH HON HO HMDA Terephthalic acid Please draw the chemical structure of the repeating unit of PPA 6T and highlight the amide-bond. (4 P) c) In PPA OT, T stands for terephthalic acid. What does the 6 stand for? (1 P)