Problem

Molecular weight data for some polymer are tabulated here. Compute (a) the numberaverage m...

Molecular weight data for some polymer are tabulated here. Compute (a) the numberaverage molecular weight and (b) the weightaverage molecular weight. (c) If it is known that this material’s degree of polymerization is 710, which one of the polymers listed in Table 4.3 is this polymer? Why?

Molecular Weight Range (g/mol)	xi	wi
15,000–30,000	0.04	0.01
30,000–45,000	0.07	0.04
45,000–60,000	0.16	0.11
60,000–75,000	0.26	0.24
75,000–90,000	0.24	0.27
90,000–105,000	0.12	0.16
105,000–120,000	0.08	0.12
120,000–135,000	0.03	0.05

Table 4.3 Repeat Units for 10 of the More Common Polymeric Materials

Polymer	Repeat Unit
Polyethylene (PE)
Poly(vinyl chloride) (PVC)
Polytetrafluoroethylene (PTFE)
Polypropylene (PP)
Polystyrene (PS)
Poly(methyl methacrylate) (PMMA)
Phenol-formaldehyde (Bakelite)
Poly(hexamethylene adipamide) (nylon 6,6)
Poly(ethylene terephthalate) (PET, a polyester)
Polycarbonate (PC)