A three-phase micromechanical model for the elastic
properties of semicrystalline polymers
Citation for published version (APA):
Sedighiamiri, A., Erp, van, T. B., Peters, G. W. M., Govaert, L. E., & Dommelen, van, J. A. W. (2009). A three-phase micromechanical model for the elastic properties of semicrystalline polymers. Poster session presented at Mate Poster Award 2009 : 14th Annual Poster Contest.
Document status and date: Published: 01/01/2009 Document Version:
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A three-phase micromechanical model for the
elastic properties of semicrystalline polymers
A. Sedighiamiri, T.B. van Erp, G.W.M. Peters, L.E. Govaert, J.A.W. van Dommelen
Materials technology institute, Eindhoven University of Technology
Polymer Technology
Introduction
The mechanical performance of semicrystalline materials is strongly dependent on their underlying microstructure, consisting of amorphous layers and crystallographic lamellae (figure 1). To better design products, it is important to accurately predict their properties as a function of the morphology and crystallinity.
Aggregate Model
hybrid interaction model based on interface orientation
- Inclusion model
Experimental
The degree of crystallinity and lamellar thickness of HDPE samples were measured by WAXS and SAXS (figure 2). Tensile tests were also performed to obtain the elastic modulus.
Composite Inclusion Model
Application
The spherulitic structure of HDPE is presented by an aggregate of 2000 randomly generated inclusions (figure 4). Confrontation of the two-phase and three-phase model predictions with experimental data and the influence of the rigid-amorphous layer properties on the overall behavior can be seen in figures (5) and (6).
Figure 1. Morphology of a spherulitic semicrystalline polymer.
Figure 2. WAXS profile (left), SAXS profile (middle) and variation of lamellar thickness versus crystallinity of HDPE samples (right).
Auxiliary unknowns
- Inclusion model
Figure 4. Equal area projection pole figures of random orientations of crystallographic lattice directions and interface normals.
Gr = 0.5
/ Department of Mechanical Engineering
Composite Inclusion Model
The behavior of microscopically heterogeneous semicrystalline material has been modeled by an aggregate of layered two-phase composite inclusions [1]. Here a three-phase composite model is
used, which includes the lamellar thickness and allows
interlamellar properties to vary with crystallinity.
Reference
[1] B.J. Lee et al., journal of the mechanics and physics of solids, 1993, 41: 1651 – 1687.
x1 I x2 I nI interface crystalline lamella amorphous layer f c f a x1I x2I nI interface crystalline lamella amorphous layer f c rigid-amorphous layer δ ,c f r δ ,r f a δ ,a 1 2 f r δ ,r1 2 Interface orientation: Interface conditions:
Figure 3. A two-phase (left) and three-phase (right) composite inclusion
Constitutive behavior: ,
Gr = 0.5 GPa
δr* = 1.5 nm
Figure 5. Predicted Young’s modulus of HDPE samples using the two-phase (left) and the three-phase (right) models.
Figure 6. Effect of different shear and bulk moduli (left) and layer thickness (right) of rigid-amorphous phase on the prediction of the model.
