Solid-State 13C NMR Analyses of the Crystalline−Noncrystalline Structure for Metallocene-Catalyzed Linear Low-Density Polyethylene

Abstract

Solid-state 13C NMR analyses have been performed to obtain information about the crystalline−noncrystalline structure for metallocene-catalyzed linear low-density polyethylene (MLLDPE) isothermally crystallized from the melt. 13C spin−lattice relaxation time (T1C) and 13C spin−spin relaxation time (T2C) analyses have revealed that three components with different T1C and T2C values exist for MLLDPE, which are assignable to the crystalline, crystalline−amorphous interfacial, and rubbery amorphous components. Using such differences in T2C, we have separately recorded the spectra of interfacial and amorphous components and then resolved the fully relaxed DD/MAS spectrum of MLLDPE into the three components. As a result, it has been found that the thickness of the interfacial region is about 3 nm, in good accord with the previous result for bulk-crystallized high-density polyethylene (HDPE). T1ρH and T2C analyses have also revealed that butyl branches are excluded out from the crystalline region and are almost ...