Homogeneous nucleation in polyethylene: Molecular weight dependence

Th e drop let tec hniqu e wa s used to o btain es tim a tes of th e isoth e rm a l ra te of hom oge neo us cr yst al nu c leation in hi ghl y s upe rc oo led m e lts of 8 c ha racte rize d fraction s of lin ear po lye th yle ne (we ight a ve rage molec ular weights from 3,100 to 249 ,000). Th e da ta obta in e d from th ese e xpe rim e nt s we re a na lyzed in acco rd with c urre nt th eori es of hom oge neou s nu cl eatio n of c ha in folded c r ys ta ls . Valu es fo r th e quantity a 2 a ", wh e re U a nd U e are th e la tc ra l a nd e nd s urfa ce free e ne rgies of th e c rys ta l, were es tim a ted a s a fun c ti o n of mo lec ular we ig ht.