Comparative Study for Melt Flow Index of High Density Polyethylene, Low Density Polyethylene and Linear Low Density Polyethylene

Raza Muhammad Khan, Asim Mushtaq, Amina Israr, Asra Nafees


This study focus on the rheological behaviour of polyethylene polymer. The effect of molecular weight for three different types of polyethylene were study; high density polyethylene (HDPE), linear low density polyethylene (LLDPE) and low density polyethylene (LDPE). To find the rheological behaviour of the polymer, melt flow indexer and capillary rheometer was used. The shear stress and shear viscosity obtained from these three different polyethylene polymers were compared with the shear rate. It was observed that with the increase in shear rate, shear stress also increases. The behaviour of viscosity for HDPE, LLDPE and LDPE also discussed at the varying amount of shear rate. It was also found that viscosity of HDPE, LLDPE and LDPE decreases with increasing shear rate. The value of log shear stress of HDPE increases with an increase in log shear rate. The value of extension viscosity decreases from 8.295 to 1.606 KPa.s with a very high increase in extension rate of 23.5 s-1 to 721 s-1. Molecular mass and its distribution have a significant effect on the rheological behaviour of polymers.

Full Text:



Reynolds, C., Thompson, R., & McLeish, T. (2018). Pressure and shear rate dependence of the viscosity and stress relaxation of polymer melts. Journal of Rheology, 62(2), 631-642. doi: 10.1122/1.5012969

Yousfi, M., Alix, S., Lebeau, M., Soulestin, J., Lacrampe, M.-F., & Krawczak, P. (2014). Evaluation of rheological properties of non-Newtonian fluids in micro rheology compounder: Experimental procedures for a reliable polymer melt viscosity measurement. Polymer Testing, 40, 207-217. doi: 10.1016/j.polymertesting.2014.09.010

Ansari, M., Zisis, T., Hatzikiriakos, S. G., & Mitsoulis, E. (2012). Capillary flow of low-density polyethylene. Polymer Engineering & Science, 52(3), 649-662. doi: 10.1002/pen.22130

Drozdov, A. D. (2010). Cyclic thermo-viscoplasticity of high density polyethylene. International Journal of Solids and Structures, 47(11-12), 1592-1602. doi: 10.1016/j.ijsolstr.2010.02.021

Mnekbi, C., Vincent, M., & Agassant, J. F. (2010). Polymer rheology at high shear rate for microinjection moulding. International Journal of Material Forming, 3(S1), 539-542. doi: 10.1007/s12289-010-0826-9

Musil, J., & Zatloukal, M. (2011). Experimental investigation of flow induced molecular weight fractionation during extrusion of HDPE polymer melts. Chemical Engineering Science, 66(20), 4814-4823. doi: 10.1016/j.ces.2011.06.047

Peres, A. M., Pires, R. R., & Orefice, R. L. (2016). Evaluation of the effect of reprocessing on the structure and properties of low density polyethylene/thermoplastic starch blends. Carbohydr Polym, 136, 210-215. doi: 10.1016/j.carbpol.2015.09.047

Djellali, S., Sadoun, T., Haddaoui, N., & Bergeret, A. (2015). Viscosity and viscoelasticity measurements of low density polyethylene/poly(lactic acid) blends. Polymer Bulletin, 72(5), 1177-1195. doi: 10.1007/s00289-015-1331-6

Huang, Q., Mangnus, M., Alvarez, N. J., Koopmans, R., & Hassager, O. (2016). A new look at extensional rheology of low-density polyethylene. Rheologica Acta, 55(5), 343-350. doi: 10.1007/s00397-016-0921-z

Khanoonkon, N., Yoksan, R., & Ogale, A. A. (2016). Effect of stearic acid-grafted starch compatibilizer on properties of linear low density polyethylene/thermoplastic starch blown film. Carbohydr Polym, 137, 165-173. doi: 10.1016/j.carbpol.2015.10.038

Ansari, M., Derakhshandeh, M., Doufas, A. A., Tomkovic, T., & Hatzikiriakos, S. G. (2018). The role of microstructure on melt fracture of linear low density polyethylenes. Polymer Testing, 67, 266-274. doi: 10.1016/j.polymertesting.2018.03.015

Chen, A.-F., Huang, H.-X., & Guan, W.-S. (2015). Comparison of superimposed effects in high-shear-rate capillary rheology of polystyrene, polypropylene, and linear low-density polyethylene melts. Polymer Engineering & Science, 55(3), 506-512. doi: 10.1002/pen.23915

Wingstrand, S. L., van Drongelen, M., Mortensen, K., Graham, R. S., Huang, Q., & Hassager, O. (2017). Influence of Extensional Stress Overshoot on Crystallization of LDPE. Macromolecules, 50(3), 1134-1140. doi: 10.1021/acs.macromol.6b02543

Vera-Sorroche, J., Kelly, A. L., Brown, E. C., Gough, T., Abeykoon, C., Coates, P. D., Price, M. (2014). The effect of melt viscosity on thermal efficiency for single screw extrusion of HDPE. Chemical Engineering Research and Design, 92(11), 2404-2412. doi: 10.1016/j.cherd.2013.12.025

Burghelea, T. I., Starý, Z., & Münstedt, H. (2011). On the “viscosity overshoot” during the uniaxial extension of a low density polyethylene. Journal of Non-Newtonian Fluid Mechanics, 166(19-20), 1198-1209. doi: 10.1016/j.jnnfm.2011.07.007

Ebrahimi, M., Tomkovic, T., Liu, G., Doufas, A. A., & Hatzikiriakos, S. G. (2018). Melt fracture of linear low-density polyethylenes: Die geometry and molecular weight characteristics. Physics of Fluids, 30(5), 1-11. doi: 10.1063/1.5029380

Weon, J.-I. (2010). Effects of thermal ageing on mechanical and thermal behaviors of linear low density polyethylene pipe. Polymer Degradation and Stability, 95(1), 14-20. doi: 10.1016/j.polymdegradstab.2009.10.016

Rasmussen, H. K., & Fasano, A. (2018). Flow and breakup in extension of low-density polyethylene. Rheologica Acta, 57(4), 317-325. doi: 10.1007/s00397-018-1081-0

Ansari, M., Hatzikiriakos, S. G., & Mitsoulis, E. (2011). Slip effects in HDPE flows. Journal of Non-Newtonian Fluid Mechanics, 167, 18-29. doi: 10.1016/j.jnnfm.2011.09.007

Li, K., & Matsuba, G. (2017). Effects of relaxation time and zero shear viscosity on structural evolution of linear low-density polyethylene in shear flow. Journal of Applied Polymer Science, 135(13), 1-9. doi: 10.1002/app.46053

Zatloukal, M. (2016). Measurements and modeling of temperature-strain rate dependent uniaxial and planar extensional viscosities for branched LDPE polymer melt. Polymer, 104, 258-267. doi: 10.1016/j.polymer.2016.04.053

Copyright (c) 2019 Pakistan Journal of Engineering and Applied Sciences

Powered By KICS