Thermal and rheological properties of mLLDPE/LDPE blends

Abstract

Abstract The thermal and rheological properties of two types of metallocene‐catalyzed linear low‐density PEs (mLLDPEs) and two LDPEs, as well as their blends, were studied using differential scanning calorimeter (DSC) measurements and rheometry. The DSC results showed that the mLLDPE‐1 based on the hexene comonomer is immiscible with both LDPEs in crystalline states, whereas the mLLDPE‐2 based on the octene comonomer is miscible with the LDPEs. This suggests that increasing the length of short chains in mLLDPEs can promote the miscibility of mLLDPE/LDPE blends. The linear viscoelastic properties confirmed the immiscibility of the mLLDPE‐1 with the LDPEs in the molten state, and the miscibility of mLLDPE‐2 with LDPEs. In addition, the Palierne [1] emulsion model provided good predictions of the linear viscoelastic data for both miscible and immiscible PE blends. However, as expected, the low‐frequency data showed a clear influence of the interfacial tension on the elastic modulus of the blends for the immiscible blends. POLYM. ENG. SCI., 45:1254–1264, 2005. © 2005 Society of Plastics Engineers