Structure and Dynamics of Irregular Multiarm Star Polymers

Abstract

Melt properties of highly branched star polymers consisting of a 1,2-polybutadiene core and nearly 270 arms of 1,4-polybutadiene with varying sizes have been investigated using small angle X-ray scattering (SAXS) and dynamic rheological measurements in the linear viscoelastic limit. Despite their difference in internal structure compared to the regular stars with 128 arms and spherical dendritic core, these polymers exhibit the same features: a liquid-like ordering resulting from their specific intramolecular monomer density distribution. This leads to a dual terminal viscoelastic relaxation, consisting of a fast arm relaxation and a slow structural relaxation mechanisms. Both modes conform quantitatively to the generic behaviour of multiarm star polymers, suggesting a universality of the behaviour of highly branched macromolecular objects.

A pragmatic approach to analyze the ability of ethylene‐octene copolymer in the long chain branching of polypropylene in molten and solid state

“…The branched polymers exhibit enhanced values of G ′ at low frequencies and a broader transition between the terminal zone (low frequencies) and the plateau zone (high frequencies), indicating a new, well‐defined relaxation regime (Figure 7). This behavior suggests the presence of a distinct relaxation mechanism 72–74 …”

“…This behavior suggests the presence of a distinct relaxation mechanism. [72][73][74] The interfacial tension of PP/EOC blend was found to be significantly higher (five times higher than for the LCB-(PP/EOC) resulting in extremely lower adhesion between phases. It indicates lower bonding and a negligible role of the interphase in the properties of this material.…”