Micromechanical modeling of the deformation kinetics of semicrystalline polymers

Abstract

The mechanical behavior of semicrystalline polymers is strongly dependent on their crystallinity level, the initial underlying microstructure, and the evolution of this structure during deformation. A previously developed micromechanical constitutive model is used to capture the elasto‐viscoplastic deformation and texture evolution in semicrystalline polymers. The model represents the material as an aggregate of two‐phase layered composite inclusions, consisting of crystalline lamellae and amorphous layers. This work focuses on adding quantitative abilities to the multiscale constitutive model, in particular for the stress‐dependence of the rate of plastic deformation, referred to as the slip kinetics. To do that, the previously used viscoplastic power law relation is replaced with an Eyring flow rule. The slip kinetics are then re‐evaluated and characterized using a hybrid numerical/experimental procedure, and the results are validated for uniaxial compression data of HDPE, at various strain rates. A double yield phenomenon is observed in the model prediction. Texture analysis shows that the double yield point in the model is due to morphological changes during deformation, that induce a change of deformation mechanism. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1297–1310, 2011

Role of the Amorphous Morphology in Physical Properties of Ultra High Molecular Weight Polyethylene

“…As was reported, the elastic deformation is just mainly affected by the amorphous layer [6][7][8][9] .…”

“…As depicted by the ''switchboard model'' [13] , semicrystalline polymers consists of amorphous layers and crystalline regions. Normally, the amorphous layer is in rubbery state, for the glass transition temperature of the amorphous layer is below room temperature [6] . So when the polymer was deformed, it would make a certain strain in the amorphous layer prior to the lamellas.…”

“…(7) [17] , where the thickness of lamellas (lc) and crystallinity (W c ) was detected by XRD as shown in Table 2, the density of the amorphous layer q a was calculated using Eq. (6).…”

Structural mechanics of semicrystalline polymers prior to the yield point: a review

“…However, structural properties are treated implicitly in this approach. Another group of papers [108][109][110][111][112][113][114][115][116][117][118][119][120][121] uses conception of two-phase continuum containing rigid and soft components (crystalline and amorphous phases) with essentially different mechanical properties. The main distinction of semicrystalline polymers from the particulate composites is their peculiar self-organized structure containing stacks of crystal lamellae alternating with thin amorphous layers.…”

Time‐dependent response of polypropylene/clay nanocomposites under tension and retraction

“…In the past 5 years, multiphase constitutive models have been proposed in [10–13] for semicrystalline polymers and in [14–17] for polymer/clay nanocomposites, see also reviews [18, 19]. The main obstacle for development of multiphase models is a pronounced growth of the number of adjustable parameters in stress–strain relations.…”