LDPE与HDPE和LLDPE共混体系的流变和热性能研究OA

In this paper,the differences in rheological and crystallization behavior between HDPE/LDPE and LLDPE/LDPE binary blend systems were compared systematically.Rheological results show that the viscosity of HDPE/LDPE blends follows the logarithmic additivity rule,whereas LLDPE/LDPE blends exhibit significant positive deviation behav-ior(PDB).The high degree of branching in LLDPE reduces the interfacial tension,leading to the formation of smaller"emulsion-type"dispersed domains under shear.The interfacial viscosity induced by such domains is responsible for the PDB phenomenon,while the prerequisite for this phenomenon is that the viscosities between the matrix and the dispersed phase are comparable.Col-Cole plots confirm that neither blend system undergoes phase separation at the macroscopic level;however,at the microscopic scale,both systems exhibit"emulsion-type"dispersed structures.Compared with HDPE/LDPE,the LLDPE/LDPE blends have smaller dispersed domains,longer relaxation time,and a greater in-crease in viscosity.DSC results reveal significant differences in crystallization behavior between the two blend systems.The addition of LDPE suppresses the crystallization ability of the matrix phase in both cases.With the increasing content of LDPE,the cocrystallinity of the blends shows an initial rise followed by a decline.At low LDPE contents,LDPE acts as a dispersed phase and serves as nucleation sites,thereby increasing the cocrystallization ratio.