The morphological structures of slowly cooled blends of deuterated metallocene-catalyzed octene linear low-density polyethylene (O-mLLDPE(D)) and hydrogenous low-density polyethylene (LDPE(H)) were studied by using small angle neutron scattering in combination with complementary small angle X-ray scattering and differential scanning calorimetry The phase segregation which is more nanoscale than macroscale and cocrystallization behaviors were found to vary with the blend composition Phase-segregated O-mLLDPE(D) lamellae are predominantly formed in LDPE(H)-rich compositions In contrast few segregated O-mLLDPE(D) lamellae form in O-mLLDPE(D)-rich compositions and instead O-mLLDPE(D) lamellar stacks are extensively cocrystallized with LDPE(H) mostly in the interlamellar amorphous region (C) 2010 Elsevier Ltd All rights reserved