Viscous and Failure Mechanisms in Polymer Networks: A Theoretical Micromechanical Approach

Abstract

Polymeric materials typically present a complex response to mechanical actions; in fact, their behavior is often characterized by viscous time-dependent phenomena due to the network rearrangement and damage induced by chains’ bond scission, chains sliding, chains uncoiling, etc. A simple yet reliable model—possibly formulated on the basis of few physically-based parameters—accounting for the main micro-scale micromechanisms taking place in such a class of materials is required to properly describe their response. In the present paper, we propose a theoretical micromechanical approach rooted in the network’s chains statistics which allows us to account for the time-dependent response and for the chains failure of polymer networks through a micromechanics formulation. The model is up-scaled to the mesoscale level by integrating the main field quantities over the so-called ‘chains configuration space’. After presenting the relevant theory, its reliability is verified through the analysis of some representative tests, and some final considerations are drawn.

Morphological properties, rheological behaviors, and phase interaction of nylon 11/polypropylene blends by in situ reactive compatibilization and dispersion through polyhydroxybutyrate

“…This indicates that the PP chain is more susceptible to lower the viscosity, and the same behavior can be anticipated in the PP rich blends. Whereas for high molecular weight component (PA11 and PHB), the chains start to entangle with an increase in frequency because of which the shear thinning behavior was restricted 77–79 . Aberuee et al used the Taylor theory for evaluation of the melt miscibility of the polymers blend.…”

“…Whereas for high molecular weight component (PA11 and PHB), the chains start to entangle with an increase in frequency because of which the shear thinning behavior was restricted. [77][78][79] Aberuee et al used the Taylor theory for evaluation of the melt miscibility of the polymers blend. They have explained that if the viscosity ratio is <4, then the particle breakup mechanism helps in the compatibilization of the blends.…”

Laser-based additively manufactured polymers: a review on processes and mechanical models

“…This could imply that the knowledge of the achieved degree of cure alone is not enough to correctly predict the mechanical behaviour of the AM component. Mechanical models describing the polymer network according to physically based mesoscale parameters may be helpful [181]. Accordingly, to achieve the same degree of cure, high curing rates (i.e.…”

“…) of a component and in the ultimate stress (whose amount depends on the monomer atoms bonding energy, [182]), since both aspects depend on the so-called mean square length of the chain end-to-end vector r 0 ¼ b ffiffiffiffiffiffi N S p in the undeformed configuration (being b the Kuhn's segment length, see [181] for more details). With respect to this point, the mechanical model presented in [152] does not take into account the length of a single chain in terms of Kuhn's segments, since it evaluates the degree of cure which is related only to the evolution of the number of chains per unit volume, irrespectively of their length.…”