Steady-state conduction in linear low-density polyethylene with Poole-lowered trap depth

In this paper, an industrial linear low density polyethylene (LLDPE) production process including two serried fluidized bed reactors (FBR) and other process equipment was completely simulated in steady state mode. Both of FBRs were considered like two serried continuous stirred tank reactors (CSTR). In this simulation, a kinetic model that is based on a multiple active site heterogeneous Ziegler-Natta catalyst was used for simulation of reactions in two FBRs. Simulator by using this model is able to predict the important attributes of LLDPE like melt flow index (MFI), density (ρ), polydispersity (PDI), numerical and weight average molecular weight (Mn, Mw) and co-polymer molar fraction (SFRAC). On the other hand, this simulator can be applied in wide range of changing in inlet operating conditions. The results of the simulation are compared with industrial data of LLDPE plant. A good agreement is observed between the simulator predictions and actual plant data. Finally, by using of the simulator, the steady state operating conditions for producing different grades of polyethylene are obtained.

Download Full-text

Steady‐state bulk trap‐modulated hopping conduction in doped linear low‐density polyethylene

Journal of Applied Physics ◽

10.1063/1.343197 ◽

1989 ◽

Vol 65 (12) ◽

pp. 4854-4858 ◽

Cited By ~ 17

Author(s):

R. Nath ◽

M. M. Perlman

Keyword(s):

Steady State ◽

Low Density Polyethylene ◽

Low Density ◽

Hopping Conduction ◽

Linear Low Density Polyethylene

Download Full-text

Dynamic and steady-state rheological properties of linear-low-density polyethylene melt

Polymer Engineering & Science ◽

10.1002/pen.760241511 ◽

1984 ◽

Vol 24 (15) ◽

pp. 1215-1218 ◽

Cited By ~ 10

Author(s):

D. R. Saini ◽

A. V. Shenoy

Keyword(s):

Steady State ◽

Rheological Properties ◽

Low Density Polyethylene ◽

Low Density ◽

Linear Low Density Polyethylene ◽

Polyethylene Melt

Download Full-text

Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

Polymers ◽

10.3390/polym13101537 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1537

Author(s):

Luděk Hynčík ◽

Petra Kochová ◽

Jan Špička ◽

Tomasz Bońkowski ◽

Robert Cimrman ◽

...

Keyword(s):

Strain Rate ◽

Material Model ◽

Low Density Polyethylene ◽

Low Density ◽

Linear Low Density Polyethylene ◽

Stress Strain ◽

Rate Dependent ◽

Constitutive Material Model ◽

Principal Directions ◽

Constitutive Material

Current industrial trends bring new challenges in energy absorbing systems. Polymer materials as the traditional packaging materials seem to be promising due to their low weight, structure, and production price. Based on the review, the linear low-density polyethylene (LLDPE) material was identified as the most promising material for absorbing impact energy. The current paper addresses the identification of the material parameters and the development of a constitutive material model to be used in future designs by virtual prototyping. The paper deals with the experimental measurement of the stress-strain relations of linear low-density polyethylene under static and dynamic loading. The quasi-static measurement was realized in two perpendicular principal directions and was supplemented by a test measurement in the 45° direction, i.e., exactly between the principal directions. The quasi-static stress-strain curves were analyzed as an initial step for dynamic strain rate-dependent material behavior. The dynamic response was tested in a drop tower using a spherical impactor hitting a flat material multi-layered specimen at two different energy levels. The strain rate-dependent material model was identified by optimizing the static material response obtained in the dynamic experiments. The material model was validated by the virtual reconstruction of the experiments and by comparing the numerical results to the experimental ones.

Download Full-text