Thermal Simulation of Polymer Crystallization during Post-Filling

Abstract:

Crystallization from polymer melt is one of the most fundamental phenomena of material phase transformations. The possibility of controlling crystallization kinetics is essential to achieve the proper polymer microstructure and consequently obtain desired material properties, reducing undesired effects such excessive anisotropy of shrinkage, warping and insufficient dimensional stability. Due to the high transformation rate, the simulation of crystallization is fundamental to mimic this important physical phenomenon under several testing and processing conditions by using commercial software. User subroutines were developed and implemented into finite element-based model to simulate crystal growth in semicrystalline polymers with various crystal morphologies. These subroutines allowed the commercial program Abaqus to be customized for solving the Kolmogoroff-Avrami-Evans equation with Hoffmann-Lauritzen model in order to simulate the variation of the polymer crystallization degree. The micro-structural evolution in non-isothermal conditions and with different cooling rates was considered. The study was performed on isotactic PP (SABIC PP 505) for its simplicity to the measure polymer crystals. A tensile test specimen, produced by injection molding, was chosen as case study to evaluate the crystallization evolution. The paper reports the numerical and experimental results.

• Periodical: Key Engineering Materials (Volumes 554-557)
• Pages: 1699-1706
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.554-557.1699
• Online since: June 2013
• Authors: Roberto Spina, Marcel Spekowius, Klauss Küsters, Christian Hopmann
• Keywords: Injection Molding, Numerical Simulation, Polymer Crystallization

References

[1] Boyer S.A.E., Silva L., Gicquel M., Devisme S., Chenot J.-L., Haudin J.-M., How to determine the parameters of polymer crystallization for modeling the injection-molding process? Int. J. of Material Forming, 1 (2008) 599-602.

DOI: 10.1007/s12289-008-0327-2

[2] Chang R.Y., Chen C.H.. Su, K.S., Modifying the Tait equation with cooling-rate effects to predict the pressure-volume-temperature behaviors of amorphous polymers: modeling and experiments. Polymer Engineering & Science, 36 (1996) 1789-1795.

DOI: 10.1002/pen.10574

[3] Galera V.V., Marinelli A.L., Carvalho, B.de M., Determination of non-isothermal crystallization rate constant for pseudo-experimental calorimetric data. Materials Research, 12 (2009) 151-157.

DOI: 10.1590/s1516-14392009000200007

[4] Guo X., Isayev A. I., Guo, L., Crystallinity and microstructure in injection moldings of isotactic polypropylenes. Part 1: A new approach to modeling and model parameters. Polymer Engineering & Science, 39 (1999) 2096-2114.

DOI: 10.1002/pen.11601

[5] Koscher E., Fulchiron R., Influence of shear on polypropylene crystallization: morphology development and kinetics. Polymer, 43 (2002) 6931-6942.

DOI: 10.1016/s0032-3861(02)00628-6

[6] Lamberti G., A direct way to determine iPP density nucleation from DSC isothermal measurements. Polymer Bulletin, 52 (2004) 443-449.

DOI: 10.1007/s00289-004-0304-y

[7] Lamberti G., Isotactic polypropylene crystallization: Analysis and modeling. European Polymer Journal, 47 (2011) 1097-1112.

DOI: 10.1016/j.eurpolymj.2011.02.005

[8] Michaeli W., Hopmann C., Bobzin K., Arping T., Baranowski T., Heesel B., Laschet G., Schläfer, Oete M., Development of an integrative simulation method to predict the micro-structural influence on the mechanical behaviour of semi-crystalline thermoplastic parts. International Journal of Materials Research, 1 (2012) 120-130.

DOI: 10.3139/146.110628

[9] Rao I.J., Rajagopal, K.R., On the modeling of quiescent crystallization of polymer melts. Polymer Engineering & Science, 44 (2004) 123-130.

DOI: 10.1002/pen.20011

[10] Yamamoto T., Computer modeling of polymer crystallization - Toward computer-assisted materials' design. Polymer, 50 (2009) 1975-1985.

DOI: 10.1016/j.polymer.2009.02.038

[11] Zhao S., Xu N., Xin Z., Jiang C., A novel highly efficient β-nucleating agent for isotactic polypropylene. Journal of Applied Polymer Science, 123 (2012) 108-117.

DOI: 10.1002/app.34441

[12] Zinet M., El Otmani R., Boutaous M., Chantrenne P., Numerical modeling of non-isothermal polymer crystallization kinetics: Flow and thermal effects. Polymer Engineering & Science, 50 (2010) 2044-2059.

DOI: 10.1002/pen.21733