Tg/Tm for unsubstituted polymers

Polymers under discussion can be represented by [CH2)nR]p where R is CH2, CF2, O, S or CH = CH; and where n can vary from 0 to ∞. The copolymer, P(ethylene‐alt‐TFE) is also included. These polymers tend to be highly crystalline with resultant confusion about their Tg and hence their Tg/Tm values and a clarification scheme is proposed in which it is considered that each such polymer has a double glass transition, Tg(L)/f(χc), Tg(U) = F(χc); and a sub‐glass T c. T c, is also a linear function of Tm. It is suggested that the scheme outlined above should help to resolve uncertainties in assigning transition temperatures for unsubstituted polymers. The low Tg/Tm values for these polymers is discussed in terms of their small da/dc ratios and small crosssectional areas per chain.