With the increase of the deformation rate of polyethylene, LDPE shows an amazing increase in viscosity, which is caused by molecular chain entanglement. This phenomenon cannot be observed in LLDPE, because the lack of long branched chains in LLDPE makes the polymer not entangled. This property is very important for thin film applications. LLDPE films are easier to make thinner films while maintaining high strength and toughness.

Both LDPE and LLDPE have excellent rheology or melt fluidity. LLDPE has less shear sensitivity because of its narrow molecular weight distribution and short branched chains. LLDPE maintains a higher viscosity during shearing, so it is more difficult to process than LDPE with the same melt index. In extrusion, the lower shear sensitivity of LLDPE makes the stress relaxation of polymer molecular chain faster, and thus the sensitivity of physical properties to the change of blow up ratio decreases. In melt elongation, LLDPE usually has lower viscosity at various strain rates. That is to say, it will not produce strain hardening in tension like LDPE.