Heat capacities of polyethylene. IV. High molecular weight linear polyethylene

Abstract

A high mo le cu lar weight lin ear polyet hyl en e samp le has been studi ed by ad iaba ti c c a lorim e try from 10 to 380 K. Two broad tem pe rature regions of unus ua l spo ntaneo us temperature drift have be e n observed. Th e phenomena occ urrin g around 240 K are simil ar to th a t observe d in other poly· e thyl e ne s amp les st. udi ed in t.hi s se rie s, a nd a re pres um e d to be ca used by t.he re laxa ti onal process e s in the amorphous phase. The weak exo th er mi c be hav ior occ urrin g around 160 K is pres um ed to be ca used by th e s tabi li zation of th e qu e nc hed sa mpl e. Ke y word s : C las s tran s itio n; hea t capacity; hi gh molecu lar weight lin ear polye thyl e ne; polyethylene; temperature drift ; th ermodynam ic properties .