Abstract
AbstractThis article describes work with model polymers to explore the effects of long branches on polyethylene melt rheology. Dynamic moduli were measured at two or more temperatures on melts, blends, and solutions of linear (L) and star (B) hydrogenated polybutadiene (HPB). Enhancement factor Γ and temperature coefficient (flow activation energy Ea) were determined from viscosity data and correlated with arm molecular weight Mb and volume fraction of the star component Φ. As in other species, Γ for a given branch point functionality is roughly an exponential function of Φ11/6Mb in entangled melts and solutions. In contrast with other species, however, (Ea)B and (Ea)L are different; (Ea)B – (Ea)L is directly proportional to ΦMb, and the degree of thermorheological complexity varies primarily with (Ea)B – (Ea)L. In blends with linear HPB of comparable viscosity, Γ for the star component remains essentially constant, and (Ea)B – (Ea)L is directly proportional to the volume fraction of the star component.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
