Microcellular injection molding process for producing lightweight thermoplastic polyurethane with customizable properties
Tóm tắt
A three-stage molding process involving microcellular injection molding with core retraction and an “out-of-mold” expansion was developed to manufacture thermoplastic polyurethane into lightweight foams of varying local densities, microstructures, and mechanical properties in the same microcellular injection molded part. Two stages of cavity expansion through sequential core retractions and a third expansion in a separate mold at an elevated temperature were carried out. The densities varied from 0.25 to 0.42 g/cm3 (77% to 62% weight reduction). The mechanical properties varied as well. Cyclic compressive strengths and hysteresis loss ratios, together with the microstructures, were characterized and reported.
Tài liệu tham khảo
Colton J S, Suh N P. The nucleation of microcellular thermoplastic foam with additives: Part I: Theoretical considerations. Polymer Engineering and Science, 1987, 27(7): 485–492
Ames K A. Elastomers for shoe applications. Rubber Chemistry and Technology, 2004, 77(3): 413–475
Colton J S, Suh N P. Nucleation of microcellular foam: Theory and practice. Polymer Engineering and Science, 1987, 27(7): 500–503
Lakes R S. Viscoelastic Materials. Cambridge: Cambridge University Press, 2009, 359–360
Engels H W, Pirkl H G, Albers R, et al. Polyurethanes: Versatile materials and sustainable problem solvers for today’s challenges. Angewandte Chemie International Edition, 2013, 52(36): 9422–9441
Okamoto K T. Microcellular Processing. Cincinnati: Hanser Publication, 2003
Anson M, Ko J M, Lam E S S. Advances in Building Technology. Amsterdam: Elsevier, 2002
Xu J. Microcellular Injection Molding. Hoboken: Wiley, 2011
Kharbas H A. Developments in microcellular injection molding technology. Dissertation for the Doctoral Degree. Madison: University of Wisconsin-Madison, 2003
Sun X, Turng L S. Novel injection molding foaming approaches using gas-laden pellets with N2, CO2, and N2 + CO2 as the blowing agents. Polymer Engineering and Science, 2014, 54(4): 899–913
Shaayegan V, Mark L H, Park C B, et al. Identification of cellnucleation mechanism in foam injection molding with gas-counter pressure via mold visualization. American Institute of Chemical Engineers, 2016, 62(11): 4035–4046
Rizvi S J, Alaei M, Yadav A, et al. Quantitative analysis of cell distribution in injection molded microcellular foam. Journal of Cellular Plastics, 2014, 50(3): 199–219
Moon Y, Cha S W, Seo J. Bubble nucleation and growth in microcellular injection molding processes. Polymer-Plastics Technology and Engineering, 2008, 47(4): 420–426
Nellis G, Klein S. Heat Transfer. Cambridge: Cambridge University Press, 2009, 137
Sun X, Turng L. Foam injection molding using nitrogen and carbon dioxide as co-blowing agents. Society of Plastics Engineers: Plastics Research Online, 2013, 2–4
Sun X, Kharbas H, Peng J, et al. A novel method of producing lightweight microcellular injection molded parts with improved ductility and toughness. Polymer, 2015, 56: 102–110
Sun X, Kharbas H, Turng L S. Fabrication of highly expanded thermoplastic polyurethane foams using microcellular injection molding and gas-laden pellets. Polymer Engineering and Science, 2015, 55(11): 2643–2652
Kharbas H A. Manufacturing highly expanded thermoplastic polyurethane foams using novel injection molding foaming technologies. Dissertation for the Doctoral Degree. Madison: University of Wisconsin-Madison, 2016
Qi H J J, Boyce M C C. Stress-strain behavior of thermoplastic polyurethanes. Mechanics of Materials, 2005, 37(8): 817–839
Gong L, Kyriakides S, Triantafyllidis N. On the stability of Kelvin cell foams under compressive loads. Journal of the Mechanics and Physics of Solids, 2005, 53(4): 771–794