Accessible Requires Authentication Published by De Gruyter July 7, 2021

Micro-Injection Molding of Polymer Nanocomposites Composition-Process-Properties Relationship

Z. Dekel and S. Kenig

Abstract

The mechanical, electrical, thermal, and rheological properties of micro injection molded nanocomposites comprising 2% and 5% carbon nanotubes (CNTs) incorporated in polycarbonate (PC), and polyamide 66 (PA) were studied. The design of experiments method was used to investigate the composition-process – properties relationship. Results indicated that the process variables significantly affected the flow patterns and resulting morphology during the filling stage of the microinjection molding (lIM) process, using 0.45 mm diameter lIM samples. Two distinct flow regimes have been identified in lIM using the low cross-section samples. The first was a conventional “fountain flow,” which resulted in a skin/core structure and reduced volume resistivity up to 10 X cm in the case of 5% CNTs and up to 100 X cm in 2% CNTs, in both polymers, respectively. In addition, inferior mechanical properties were obtained, attributed to polymer degradation under high shear rate conditions, when practicing high injection speeds, high mold temperatures, and high screw rotation velocities. The second was a “plug flow” due to wall slippage, obtained under low injection speeds, low mold temperatures, and low rotation velocities, leading to a substantial increase in modulus of elasticity (60%) with increased electrical resistivity up to 103 X cm for 5% CNTs and 105 X cm for 2% CNTs, respectively. The rheological percolation threshold was obtained at 2% CNTs while the electrical threshold was attained at 0.4% CNTs, in both polymers. It was concluded that in lIM, the process conditions should be closely monitored. In the case of high viscous heating, degradation of mechanical properties was obtained, while skin- core morphology formation enhanced electrical conductivity.


Sam Kenig, Dept. of Polymer Materials Engineering, Shenkar College of Engineering & Design,10 Anna Frank St., Ramat Gan, Israel, 52526

References

Abbasi, S., Carreau, P. J. and Derdouri, A.,“Flow Induced Orientation of Multiwalled Carbon Nanotubes in Polycarbonate Nanocomposites: Rheology, Conductivity and Mechanical Properties”, Polymer, 51, 922–935 (2010), DOI:10.1016/j.polymer.2009.12.041 Search in Google Scholar

Abbasi, S., Derdouri, A. and Carreau, P. J., “Properties of Microinjection Molding of Polymer Multiwalled Carbon Nanotube Conducting Composites”, Polym. Eng. Sci., 51, 992–1003 (2011), DOI:10.1002/pen.21904 Search in Google Scholar

Anass, B., Boutaous, M., El Otmani, R., El Hakimi, A., Touache, A., Musa, K. R., Derdouri, S., Refaa, Z. and Siginer, D. A., “Simulation of Crystallization Evolution of Polyoxymethylene during Microinjection Molding Cycle”, Polym. Adv. Technol., 31, 838–852 (2020), DOI:10.1002/pat.4819 Search in Google Scholar

Bauer, H.-D., Ehrfeld, W., Hossfeld, J. and Paatzsch, T., “Manufacturing Microcomponents for Optical Information Technology Using the LIGA Technique”, Optical Fabrication and Testing, 3739, 224–229 (1999), DOI:10.1117/12.360148 Search in Google Scholar

Black, W. B., Graham, M. D., “Effect of Wall Slip on the Stability of Viscoelastic Plane Shear Flow”, Physics of Fluids, 11, 1949–1956 (1999), DOI:10.1063/1.870040 Search in Google Scholar

Chien, R.-D., Jong, W.-R. and Chen, S.-C., “Study on Rheological Behavior of Polymer Melt Flowing through Micro-Channels Considering the Wall-Slip Effect”, J. Micromech. Microeng., 15, 1389 – 1396 (2005), DOI:10.1088/0960-1317/15/8/003 Search in Google Scholar

El Otmani, R., Kandoussi, K., Kamal, M. R., Derdouri, S. and Boutaous, M., “Morphology and Flow Effect of Microinjection-Molded Plastic Microgears”, Polym. Adv. Technol., 28, 511–515 (2017), DOI:10.1002/pat.3946 Search in Google Scholar

Hu, G.-J., Zhao, C.-G., Zhang, S.-M., Yang, M.-S. and Wang, Z.-G., “Low Percolation Thresholds of Electrical Conductivity and Rheology in Poly(ethylene terephthalate) through the Networks of Multi-Walled Carbon Nanotubes”, Polymer, 47, 480–488 (2006), DOI:10.1016/j.polymer.2005.11.028 Search in Google Scholar

Joshi, Y. M., Lele, A. K. and Mashelkar, R. A., “A Unified Wall Slip Model”, J. Non-Newtonian Fluid Mech., 94, 135–149 (2000), DOI:10.1016/S0377-0257(00)00160-9 Search in Google Scholar

Krause, B., Boldt, R., Häußler, L. and Pötschke, P., “Ultralow Percolation Threshold in Polyamide 6.6/MWCNT Composites”, Compos. Sci. Technol., 114, 119–125 (2015), DOI:10.1016/j.compscitech.2015.03.014 Search in Google Scholar

Lin, S.-Y., Chen,E.-C., Liu, K.-Y. and Wu, T.M., “Isothermal Crystallization Behavior of Polyamide 6,6/Multiwalled Carbon Nanotube Nanocomposites”, Polym. Eng. Sci., 49, 2447–2453 (2009), DOI:10.1002/pen.21495 Search in Google Scholar

Liu, Z., Chen, Y.-H., Ding, W.-W. and Zhang, C.-H., “Filling Behavior, Morphology Evolution and Crystallization Behavior of Micro-injection Molded Poly(lactic acid)/Hydroxyapatite Nanocomposites”, Composites, Part A, 72, 85–95 (2015), DOI:10.1016/j.compositesa.2015.02.002 Search in Google Scholar

Martins, J. N., Bassani, T. S., Barra, G. M. O. and Oliveira, R. V. B., “Electrical and Rheological Percolation in Poly(vinylidene fluoride)/Multi-Walled Carbon Nanotube Nanocomposites”, Polym. Int., 60, 430–435 (2011), DOI:10.1002/pi.2965 Search in Google Scholar

McNally, T., Potschke, P.: Polymer-Carbon Nanotube Composites: Preparation, Properties and Applications, Woodhead Publishing Limited, Cambridge (2011) Search in Google Scholar

Niggemann, M., Ehrfeld, W. and Weber, L., “Fabrication of Miniaturized Biotechnical Devices”, Proceeding SPIE 3511, Micromachining and Microfabrication Process Technology IV, 204–213 (1998), DOI:10.1117/12.324303 Search in Google Scholar

Pan, Y.-Z., Li, L., “Percolation and Gel-Like Behavior of Multiwalled Carbon Nanotube/Polypropylene Composites Influenced by Nanotube Aspect Ratio”, Polymer (United Kingdom), 54, 1218–1226 (2013), DOI:10.1016/j.polymer.2012.12.058 Search in Google Scholar

Pantani, R., Coccorullo, I., Speranza, V. and Titomanlio, G., “Modeling of Morphology Evolution in the Injection Molding Process of Thermoplastic Polymers”, Prog. Polym. Sci., 30, 1185–1222 (2005), DOI:10.1016/j.progpolymsci.2005.09.001 Search in Google Scholar

Penu, C., Hu, G.-H., Fernandez, A., Marchal, P. and Choplin, L., “Rheological and Electrical Percolation Thresholds of Carbon Nanotube/Polymer Nanocomposites”, Polym. Eng. Sci., 52, 2173 – 2181 (2012), DOI:10.1002/pen.23162 Search in Google Scholar

Ribeiro, B., Pipes, R., Costa, M. and Botelho, E., “Electrical and Rheological Percolation Behavior of Multiwalled Carbon Nanotube-Reinforced Poly(phenylene sulfide) Composites”, J. Compos. Mater., 51, 199–208 (2016), DOI:10.1177/0021998316644848 Search in Google Scholar

Rosenbaum, E. E., Hatzikiriakos, S. G., “Wall Slip in the Capillary Flow of Molten Polymers Subject to Viscous Heating” AIChE J., 43, 598–608 (1997);, DOI:10.1002/aic.690430305 Search in Google Scholar

Tadmor, Z., “Molecular Orientation in Injection Molding”, J. Appl. Polym. Sci., 18, 1753–1772 (1974), DOI:10.1002/app.1974.070180614 Search in Google Scholar

Tiusanen, J., Vlasveld, D. and Vuorinen, J., “Review on the Effects of Injection Moulding Parameters on the Electrical Resistivity of Carbon Nanotube Filled Polymer Parts”, Compos. Sci. Technol., 72, 1741–1752 (2012), DOI:10.1016/j.compscitech.2012.07.009 Search in Google Scholar

Zhao, D.-Y., Jin, Y.-F. and Wang, M.-J., “Study on Viscosity of Polymer Melt Flowing through Microchannels Considering the Wall-Slip Effect”, Polym. Eng. Sci., 52, 1806–1814 (2012), DOI:10.1002/pen.23113 Search in Google Scholar

Zhou, S.-T., Hrymak, A. and Kamal, M. R., “Electrical and Morphological Properties of Microinjection Molded Polypropylene/Carbon Nanocomposites”, J. Appl. Polym. Sci., 134, 45462 (2017), DOI:10.1002/app.45462 Search in Google Scholar

Received: 2020-11-14
Accepted: 2021-01-21
Published Online: 2021-07-07
Published in Print: 2021-07-27

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