Rheological Studies of Dynamically Vulcanized and Mechanical Blends of Polypropylene and Ethylene-Propylene Rubber

1995 ◽  
Vol 68 (5) ◽  
pp. 728-738 ◽  
Author(s):  
Peter K. Han ◽  
James L. White
Keyword(s):  
Shear Viscosity ◽  
Liquid Crystalline ◽  
Complex Viscosity ◽  
Normal Stresses ◽  
State Structure ◽  
Newtonian Viscosity ◽  
Zero Shear Viscosity ◽  
Flexible Chain ◽  
Ethylene Propylene ◽  
Yield Value

Abstract An experimental study is presented of the rheological properties of (i) polypropylene, (ii) a commercial polypropylene/ethylene-propylene terpolymer a dynamically vulcanized blend (PP/EDPM-TPE) and (iii) a mechanical blend of a polypropylene and an ethylene-propylene copolymer. The polypropylene behaves as a typical flexible chain thermoplastic exhibiting a zero shear viscosity and higher shear rate non-Newtonian viscosity, well defined normal stresses, an elongational viscosity three times the zero shear viscosity, and an equality of the shear viscosity and the complex viscosity (Cox-Merz Rule). The PP/EPM-TPE exhibits an apparent yield value in shear flow, unmeasurable normal stresses and a complex viscosity which is much greater than the shear viscosity. This is behavior similar to that of particle filled compounds, block copolymers and liquid crystalline thermoplastics and suggests a material with a rest state structure. The behavior of the PP/EPM mechanical blend is intermediate.

Prediction of Zero-Shear Viscosity of Linear Polybutadienes from the Crossover Point Using Doi-Edwards Theory

1988 ◽  
Vol 61 (5) ◽  
pp. 812-827 ◽  
Author(s):  
Ramesh R. Rahalkar ◽  
Henry Tang
Keyword(s):  
Shear Viscosity ◽  
Amorphous Polymers ◽  
Simple Expression ◽  
Crossover Frequency ◽  
Crossover Point ◽  
Zero Shear Viscosity ◽  
Plateau Modulus ◽  
Good Agreement

Abstract Based upon the Doi-Edwards theory, a simple expression has been obtained for zero-shear viscosity in terms of the plateau modulus and the crossover frequency. There are no adjustable parameters in the expression. The model is in very good agreement with the zero-shear viscosity values for linear polybutadienes, the typical discrepancy being ∼5–10%. If the model can be validated for other linear amorphous polymers, it may become possible to estimate the zero-shear viscosity by measuring a single Theological parameter (the crossover frequency).

scholarly journals Impact of Graphene Oxide on Zero Shear Viscosity, Fatigue Life and Low-Temperature Properties of Asphalt Binder

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3073
Author(s):  
Abbas Mukhtar Adnan ◽  
Chaofeng Lü ◽  
Xue Luo ◽  
Jinchang Wang
Keyword(s):  
Graphene Oxide ◽  
Fatigue Life ◽  
Low Temperature ◽  
Shear Viscosity ◽  
Storage Stability ◽  
Asphalt Binder ◽  
Asphalt Binders ◽  
Test Results ◽  
Zero Shear Viscosity ◽  
Modified Asphalt

This study has investigated the impact of graphene oxide (GO) in enhancing the performance properties of an asphalt binder. The control asphalt binder (60/70 PEN) was blended with GO in contents of 0%, 0.5%, 1%, 1.5%, 2%, and 2.5%. The permanent deformation behavior of the modified asphalt binders was evaluated based on the zero shear viscosity (ZSV) parameter through a steady shear test approach. Superpave fatigue test and the linear amplitude sweep (LAS) method were used to evaluate the fatigue behavior of the binders. A bending beam rheometer (BBR) test was conducted to evaluate the low-temperature cracking behavior. Furthermore, the storage stability of the binders was investigated using a separation test. The results of the ZSV test showed that GO considerably enhanced the steady shear viscosity and ZSV value, showing a significant contribution of the GO to the deformation resistance; moreover, GO modification changed the asphalt binder’s behavior from Newtonian to shear-thinning flow. A notable improvement in fatigue life was observed with the addition of GO to the binder based on the LAS test results and Superpave fatigue parameter. The BBR test results revealed that compared to the control asphalt, the GO-modified binders showed lower creep stiffness (S) and higher creep rate (m-value), indicating increased cracking resistance at low temperatures. Finally, the GO-modified asphalt binders exhibited good storage stability under high temperatures.

Rheological Behavior and Microstructure of Flame Retardant Polypropylene Composites

2010 ◽  
Author(s):  
Guo Jiang ◽  
Kai Liao ◽  
Juan-Juan Han ◽  
De-Xian Feng ◽  
Han-Xiong Huang
Keyword(s):  
Magnesium Hydroxide ◽  
Shear Viscosity ◽  
Flame Retardancy ◽  
Rheological Behavior ◽  
Oxygen Index ◽  
Complex Viscosity ◽  
Test Results ◽  
Screw Extruder ◽  
Polypropylene Composites ◽  
Twin Screw

Polypropylene (PP)/magnesium hydroxide (MDH) composite was melt-mixed using a twin-screw extruder. Two types of MDH were used, one with the modification of silane and another without. The rheological behavior was measured by capillary and dynamical rheometer. Microstructure of these composites was observed by SEM. Their flame retardancy was characterized by oxygen index and Horizontal/Vertical burning test. Results showed that shear viscosity and complex viscosity of PP with modified MDH were lower than that of PP with non-modified MDH. SEM results also showed a better dispersion of silane modified MDH in PP matrix. With the increase of MDH content, the oxygen index of composites was increased. When the content was increased to 60 wt%, the composite was UL94 HB and V-1.

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