Rheological Properties of Polyethylene

In terms of the polyethylene industry Rheology is the science of investigating polyethylene in the molten state and more specifically the behavior of the molten polyethylene as it flows with an applied shear stress. 

Almost all polyethylene is conveyed during the fabrication process through an extruder, which is a machine that melts the polyethylene and conveys the polyethylene through the machine using a rotating screw. 

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H.-W. Shen, B.-H. Xie, W. Yang, M.-B. Yang, Thermal and rheological properties of polyethylene blends with bimodal molecular weight distribution. J. Appl. Polym. Sci. 129, 2145-2151 (2013)... 

Monasterio, F. Pita, V. R. Dias, M. L. Erdmann, E. Destefanis, H., Thermal and Rheological Properties of Polyethylene Composites Based on... 

Other subjects that will also be discussed that impact the polyethylene fabrication business are the wide array of additives that are blended into polyethylene to improve the performance of the end-use products and the rheological properties of polyethylene which explain the flow of molten polyethylene that takes place diuing the fabrication process. 

Valentino, O., Samo, M., Rainone, N.G., Nobile, M.R., CiambeUi, P., Neitzert, H.C., Simon, G.P., 2008. Influence of the polymer structure and nanotube concentration on the conductivity and rheological properties of polyethylene/CNT composites. Physica E Lowdimensional Systems and Nanostructures 40, 2440—2445. 

Horio, M., Fujii,T. and Onogi, S. (1964), Rheological properties of polyethylene melts - effects of temperature + blending. Journal of Physical Chemistry. 68(4) pp. 778-783. 

The rheological properties of polymeric materials vary with their chemical structures. Therefore, it is highly desirable to be able to relate the rheological properties of polymeric materials to their chemical structures. For instance, one may ask Why are the rheological properties of polystyrene so different from the rheological properties of polyethylene under an identical flow condition Unfortunately, at present there is no comprehensive molecular theory that can answer such a seemingly simple and fundamental question. 

Mederic P, VUle 1, Huitric 1, Moan M, Aubry T. Effect of processing procedures and conditions on structural, morphological, and rheological properties of polyethylene/polyamide/nanoclay blends. Polym Eng Sci 2011 51 969-78. 

Gabriel, C. Kaschta, J., Miinstedt, H. Influence of molecular structure on rheological properties of polyethylenes, 1 Creep recovery. Rheol Acta (1998) 37, pp. 7-20... 

The subject of this research is to study the influence of different coupling agents on the melt rheological properties of polyethylene-wood flour composites. The influence of molecular weight and molecular weight distribution (MWD) of the polymer matrix on the melt flow behavior of both unmodified and coupled wood-polyethylene composites is investigated in this work as well. 

Meissner, J. Modification of the Weissenberg rheogoniometer for measurement of transient rheological properties of molten polyethylene under shear. Comparison with tensile data. J. Appl. Polymer Sci. 16, 2877-2899 (1972). 

These experimental mixers enabled the study of the role of the rheological properties of the individual blend components on the mechanisms and rates of dispersive mixing. Three commercial polymers Dow Chemical Company polystyrene (PS686) and low density polyethylene (PE 132) and Chevron low density polyethylene (PE 1409) were used in the study. Figure 11.32 (a) shows the viscosities of the three polymers at 200°C (121). PS 685... 

For high density polyethylene the MWD represents one of the basic parameters which, together with average molecular weight, density, short and long chain branching content, determines the physical, mechanical and rheological properties of the polymer and therefore its end uses (Table 1). 

Rheology is defined as the science of the deformation and flow of matter. To enable polyethylene to be shaped into useful articles, the polymer must be melted and is typically heated to temperatures of -190 °C. Even at such temperatures, the molten polymer is very viscous. Hence, rheological properties of molten polyethylene are crucial to its end use and much study has been devoted to this subject. Strict mathematical treatment of polymer rheology can become quite complex and is outside the scope of this text. However, general discussions of polymer rheology (12) and specifically for polyolefins (13-15) are available. 

This standard covers measurement of the rheological properties of polymers with both stable and unstable melt viscosity parameters at various temperatures and shear rates. The test procedure lists typical test temperature conditions for polyethylene 190°C, for polypropylene 230°C, for poly(vinyl chloride) 170-205°C, however, this indicates that the most useful data are generally obtained at temperatures consistent with processing experience. The test method also prescribes using the Rabinowitsch shear rate correction (see above) and indicates that the basic rheology equations (17.10), (17.15) and (17.16) yield true shear rate and true viscosity for Newtonian fluids only for non-Newtonian fluids only the apparent shear rate and viscosity are obtained. 

N. Robledo, J.F. Vega, J. Nieto, J. Martinez-Salazar, Role of the interface in the melt-rheology properties of linear low-density polyethylene/low-density polyethylene blends Effect of the molecular architecture of the dispersed phase. J. Appl. Polym. Sci. 119, 3217-3226 (2011)... 

La Mantia, F. R, R. Scaffaro, G. Carianni, and P. Mariani. 2005. Rheological properties of different film blowing polyethylene samples under shear and elongational flow. Macromolecular Materials and Engineering 290 159-164. 

Yan, D., W. J. Wang, and S. Zhu. 1999. Effect of long chain branching on rheological properties of metallocene polyethylene. Polymer 40 1737-1744. 

Hyde, J. Licence, P. Carter, D. Poliakoff, M. (2001) Continuous Catalytic Reactions in Supercritical Fluids. Appl. Catal., A. Vol.222, No.1-2, pp.119-131 Jin, S. Kang, C Yoon, K Bang, D. Park, Y. (2009) Elect of compatibilizer on morphology, thermal, and rheological properties of polypropylene/functionalized multi-walled carbon nanotubes composite. /. Ayyl. Polym. Set. Vol.lll, No.2, pp.1028-1033 Joen, H Jung, H Lee, S. Hudson, S. (1998) Morphology of polymer/Silicate Nanocomposites Hieh Density Polyethylene and a Nitrile Copolymer. Polym. Bull. Vol.41, No.l, pp.107-111... 

Han MS, Lee YK, Lee HS, Yun CH, Kim WN. Electrical, morphological and rheological properties of carbon nanotube composites with polyethylene and poly(phenylene sulhde) by melt mixing. Chem Eng Sci 2009 64(22) 4649-56. 

Dong S, Sapieha S, Schfwber HP (1992) Rheological properties of corona modified cellulose/ polyethylene composites. Polym Eng Sci 32 1734-1739... 

S. Dong, S. Saphieha, and H.P. Schreiber, Rheological properties of corona modified cellu-lose/polyethylene composites. Polym. Eng. Sci. 32(22), 1734-1739 (1992). 

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