Modeling of Spherulite Microstructures in Semicrystalline Polymers

Oktay, Hasan Emre
Gürses, Ercan
Polymers constitute an important class of materials with a wide range of application areas in modern life. Among these, semicrystalline polymers (SCP), such as high-density polyethylene (HDPE), Nylon-6, poly(ethylene terephthalate) (PET), isotactic polypropylene (iPP) and ultra high molecular weight polyethylene (UHMWPE), form a sub-set with a significant technological interest. Owing to remarkable deformability and toughness, good impact strength, very low gas-permeability, superior wear resistance and biocompatibility, semicrystalline polymers are of ever increasing technological importance [1]. They have been used in applications such as ballistic plates, model aircraft, liquid and gas containers, plastic bags, piping systems, electrical insulation systems, substrates for flexible electronic devices and joint implants. Owing to crystalline structures and amorphous polymer chain networks, they exhibit both deformation mechanisms of crystalline materials and amorphous polymers. To this end, semicrystlline polymers can be considered as two-phase materials consisting of a soft amorph phase and a hard crystalline phase. One of the most common microstructures that are observed in melt crystallized semicrystalline polymers is the spherulite microstructure. In a spherulite microstructure ribbon-like crystalline lamellae are embedded in a matrix of amorphous material, that the lamellae grow out from a common central nucleus. The crystalline lamellae are 3 to 20 nm thick, whereas spherulite diameters are normally in the range of 2 to 20 microns [2]. Due to this complicated and hierarchical microstructure of semicrystalline polymers, the deformation mechanisms are complex and multistage processes. Therefore, a complete quantitative description of semicrystalline polymers requires different approaches at different scales of their microstructure [2]. In this work the large deformation mechanical behavior of semicrystalline polymers is studied by direct finite element modeling of the spherulite microstructure. Finite element meshes of spherulite microstructures are generated where different constitutive models are assigned to radially grown crystalline phase and amorphous polymer phase. A crystal plasticity model, which takes into account geometric constraints induced by inextensible polymer chains, is used for the crystalline phase, while an elastic microsphere model [3] is employed for the amorphous phase. The effects of several parameters, such as spherulite size and crystallinity, on the mechanical behavior are studied under different loading scenarios. Furthermore, it is shown that the model captured the evolution of inhomogeneous plastic deformation activity in spherulite microstructure reported in the literature.
IUTAM Symposium on Innovative Numerical Approaches for Materials and Structures in Multi-Field and Multi-Scale Problems (2014)


Versatility of biodegradable biopolymers: degradability and an in vivo application
Hasırcı, Vasıf Nejat; Gresser, JD; Wise, DL; Trantolo, DJ (2001-03-30)
Biodegradable materials have various important applications in the biomedical field. There are basically two groups of polyesters which have significant importance in this field. These are polylactides and polyhydroxybutyrates. Both groups degrade via hydrolysis with the rates of degradation depending on medium properties such as pH, temperature, solvent and presence of biocatalysts, as well as on chemical compositions. In order for these biomaterials to be suitable for use in load bearing applications with...
Investigations on the biodegradable polymeric and inorganic substrates for controlled drug delivery and bone and cartilage repair
Günay, Aycan; Bayramlı, Erdal; Department of Polymer Science and Technology (2008)
Tissue engineering is an interdisciplinary field that seeks to address the needs by applying the principles of chemistry, biology and engineering for the development of viable substitutes that restore and maintain the function of human bone and cartilage tissues. In tissue engineering, scaffolds play an important role as temporary supports for the transplantation of specific cells and tissues. In this study, poly(ester-urethane)urea (PEUU) and poly(caprolactone) (PCL) scaffolds were fabricated. Scaffolds we...
Study of physically transient insulating materials as a potential platform for transient electronics and bioelectronics
ACAR, Handan; Çınar, Simge; Thunga, Mahendra; KESSLER, Michael R.; HASHEMI, Nastaran; MONTAZAMI, Reza (Wiley, 2014-07-09)
Controlled degradation and transiency of materials is of significant importance in the design and fabrication of degradable and transient biomedical and electronic devices and platforms. Here, the synthesis of programmable biodegradable and transient insulating polymer films is reported, which have sufficient physical and chemical properties to be used as substrates for the construction of transient electronics. The composite structure can be used as a means to control the dissolution and transiency rate of...
Synthesis of acrylic based high internal phase emulsion polymers and their application in chromatography
Tunç, Yeliz; Hasırcı, Nesrin; Department of Polymer Science and Technology (2009)
High internal phase emulsion polymers (PolyHIPEs) are new generation materials with their high porosity and interconnected open-cell structures and finds applications in areas such as supports for catalytic systems, separation media and tissue engineering scaffolds. Styrene based PolyHIPEs are currently the most popular choice, but solvent compatibility and poor mechanical properties of these materials prevent their applications. Therefore development of new polyHIPEs with desired mechanical and cellular pr...
Investigations on the permeability of acrylic powder structures
Ağırtopçu, Yasin; Bayramlı, Erdal; Department of Polymer Science and Technology (2003)
There are many examples where creation and usage of porous substrates play important roles in various fields of application in material science and technology. In the manufacture of ceramic products, as an alternative to the plaster molds, porous resin molds are used İn order to resolve the drawbacks that result from plaster mold cementation. A porous substrate can be produced by various ways. In this study, porous polymeric matrices of pofy(methyl methacrylate) (PMMA) and poh/(methyl methacrylate-co-2-hydr...
Citation Formats
H. E. Oktay and E. Gürses, “Modeling of Spherulite Microstructures in Semicrystalline Polymers,” presented at the IUTAM Symposium on Innovative Numerical Approaches for Materials and Structures in Multi-Field and Multi-Scale Problems (2014), Siegen, Almanya, 2014, Accessed: 00, 2021. [Online]. Available: