Heat capacities of cis-1,4-polyisoprene from 2 to 360 K

Hea t c apac it ies o f amo rph o us s yn th e ti c cis-l ,4-polyi sop re ne have been d e te rmin e d for th e qu e nc he d a nd a nn ea led g:la sse;; fro m 2 to T" (aro und 200 K) a nd for th e li q uid from T" to 360 K , with a prec is io n of be lle r than 0.05 perce nt a bove 15 K. Til' a s d ete rmin ed fro m H ve rs us T plots , is 203 K fo r th e q ue nc hed glass a nd 198 K for th e a nn ea le d g lass.For th e glasses th e hea l. capa c it y va lu es from thi s resea rc h a re a bo ut 1 pe rce nt hi ghe r th a n th at re ported in 1935 for n atura l rubbe r h yd roca rbo n.Fo r th e li quid th e res ult fro m thi s resea rc h ag rees be tt e r (with in 1 pe rce nt ) w ith rece ntl y (1967) proposed va lu es than th ose from th e ea rli e r ex pe rim e nt c ite d.E ff ec ts of c rys ta ll izatio n a nd me ltin g, st a rk rubbe r c rystal s, a nd add iti ves (antiox id a nts a nd s ta b ili ze rs) we re a lso s tudi ed.Key wo rd s : A nn ea led a nd q ue nc hed glass; ca lo rim e try ; glass tra nsfo rm a tion; hea t ca pa c it y; na tura l rubber ; no rm a l a nd s upe rcoo led liquid ; cis-l ,4-po lyisop re ne; rubbe r, natura l; th e r ma l diffu s ivit y; th e rm ody na mi c pro pe rti es.* Prese nt a ddress: O(ft{'(• of S peci al S tud ies .Na ti on al O('e a ll o~ra phi c and Atm osp he ric Admi n is trat iull .60 10 Exec utive Blvd., Hockv ill e. J\'ld .20852.f Fi g:ur('s ill brac ke ts indi ca te til(> li teratu re I•efere nces a t th e e nd of thi s pape r.