Optimization studies of low-density polyethylene process: effect of different interval numbers

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ashraf Azmi ◽  
Suhairi Abdul Sata ◽  
Fakhrony Sholahudin Rohman ◽  
Norashid Aziz
Keyword(s):  
Dynamic Optimization ◽  
Monomer Conversion ◽  
Polymerization Process ◽  
Low Density Polyethylene ◽  
Quadratic Program ◽  
Flow Index ◽  
Low Density ◽  
Orthogonal Collocation ◽  
Interval Numbers ◽  
Optimization Study

AbstractThe highly exothermic nature of the low-density polyethylene (LDPE) polymerization process and the heating-cooling prerequisite in tubular reactor can lead to various problems particularly safety and economic. These issues complicate the monomer conversion maximization approaches. Consequently, the dynamic optimization study to obtain maximum conversion of the LDPE is carried out. A mathematical model has been developed and validated using industrial data. In the dynamic optimization study, maximum monomer conversion (XM) is considered as the objective function, whereas the constraint and bound consists of maximum reaction temperature and product melt flow index (MFI). The orthogonal collocation (OC) on finite elements is used to convert the original optimization problems into Nonlinear Programming (NLP) problems, which are then solved using sequential quadratic program (SQP) methods. The result shows that five interval numbers produce better optimization result compared to one and two intervals.

scholarly journals Dynamic optimization of low-density polyethylene production in tubular reactor under thermal safety constraint

2020 ◽  
pp. 27-27
Author(s):  
A. Azmi ◽  
S.A. Sata ◽  
F.S. Rohman ◽  
N. Aziz
Keyword(s):  
Dynamic Optimization ◽  
Critical Condition ◽  
Reference Model ◽  
Tubular Reactor ◽  
Monomer Conversion ◽  
Polymerization Process ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Thermal Safety ◽  
Orthogonal Collocation

A commercial low-density polyethylene (LDPE) which is produced by the polymerization process of ethylene in the presence of initiators in a long tubular reactor is the most widely used in polymer industry. The highly exothermic nature of the LDPE polymerization process and the heating-cooling prerequisite in tubular reactor can lead to various problems particularly safety in term of thermal runaway and productivity, i.e. decreasing monomer conversion. Therefore, model based optimization of an industrial LDPE tubular reactor under thermal safety consideration is required to be implemented. A first principle model for this process is developed and validated using industrial data. Mass and energy balances have been derived from kinetics of LDPE polymerization. Thereafter, an expression of reactor temperature under critical condition is developed and incorporated in the reference model for the thermal safety study. In order to ensure the process is thermally safe and meet the desired product grade, the constrained dynamic optimization is proposed to maximize the conversion of monomer using orthogonal collocation (OC). The dynamic optimization result shows that the maximum reaction temperature under critical condition constraint can be satisfied by optimizing reactor jacket. Moreover, it is achieved without jeopardizing the monomer conversion and the product grade.

Cable and Wire Application: Adoption of Nanomagnesium Hydroxide Blended with LDPE/EVA for Mechanical and Physical Properties

2013 ◽  
Vol 701 ◽  
pp. 202-206
Author(s):  
Ahmad Aroziki Abdul Aziz ◽  
Sakinah Mohd Alauddin ◽  
Ruzitah Mohd Salleh ◽  
Mohammed Iqbal Shueb
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Melt Flow Index ◽  
Low Density Polyethylene ◽  
Flow Index ◽  
Low Density ◽  
Elongation At Break ◽  
Mechanical And Physical Properties ◽  
Poly Ethylene ◽  
Loading Amount

Effect of nanoMagnesium Hydroxide (MH) nloading amount to the mechanical and physical properties of Low Density Polyethylene (LDPE)/ Poly (ethylene-co vinyl acetate)(EVA) nanocomposite has been described and investigated in this paper. The tensile strength results show that increased amount of nanofiller will decrease and deteriorate the mechanical properties. The elongation at break decreased continuously with increasing loading of nanofiller. Generally, mechanical properties become poorer as loading amount increase. Melt Flow Index values for physical properties also provide same trend as mechanical properties results. Increase filler amount reduced MFI values whereby increased resistance to the flow.

Simulation of an Industrial Linear Low Density Polyethylene Plant

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Ali Farhangiyan Kashani ◽  
Hossein Abedini ◽  
Mohammad Reza Kalaee
Keyword(s):  
Steady State ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Operating Conditions ◽  
Low Density Polyethylene ◽  
Process Equipment ◽  
Flow Index ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Wide Range

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.

scholarly journals Effects of Flame Retardants Additives on the Properties of Low-Density Polyethylene

2018 ◽  
Vol 5 (3) ◽  
pp. 57-65
Author(s):  
Raed Ma'ali
Keyword(s):  
Magnesium Hydroxide ◽  
Flame Retardants ◽  
Diphenyl Ether ◽  
Melt Flow Index ◽  
Degree Of Crystallinity ◽  
Low Density Polyethylene ◽  
Flow Index ◽  
Low Density ◽  
Melt Flow ◽  
Flame Resistance

Low-density polyethylene (LDPE) has many unique properties such as lightweight and high chemical resistance. Unfortunately, it burns rapidly when it is exposed to a flame which limits its applications especially when flame resistance is to be considered. Different percentages of magnesium hydroxide and decabromide diphenyl ether (3.0, 5.0, 7.0, and 9.0 wt.%) were mixed with LDPE using a two-roll mill machine at 1600C for 2 minutes. Then, the tensile and flame retardancy tests samples were prepared by an injection molding process using an industrial plastic machine at 1600C. Flammability, rheological, tensile and thermal properties of the produced samples were tested using a flammability test apparatus, a melt flow index machine, a universal testing machine, and a differential scanning calorimeter, respectively. It was observed that the flame resistance of LDPE was improved with the addition of both flame retardants up to 7.0 wt.%, then it was reduced when 9.0 wt.% of flame retardants were used. This may be attributed to the poor mixing due to the increase in the polymer melt viscosity as observed from the melt flow index results. An increase in elastic modulus and a reduction in ductility of LDPE were observed with the increasing of flame-retardant contents while the ultimate tensile strength of LDPE was increased from 5.7 to 7.6 and 7.5 MPa when 9.0 wt.% and 7.0wt.% decabromide diphenyl ether and magnesium hydroxide were added. This is due to the fact that the additives act as a load carried and/or their effects on the degree of crystallinity of LDPE.

Effects of different starch types on the physico-mechanical and morphological properties of low density polyethylene composites

2015 ◽  
Vol 35 (8) ◽  
pp. 793-804 ◽  
Author(s):  
Md. Dalour Hossen Beg ◽  
Shaharuddin Bin Kormin ◽  
Mohd Bijarimi ◽  
Haydar U. Zaman
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Water Absorption ◽  
Starch Content ◽  
Flexural Modulus ◽  
Morphological Properties ◽  
Low Density Polyethylene ◽  
Flow Index ◽  
Low Density ◽  
Sago Starch

Abstract The aim of this research is to investigate the effects of different thermoplastic starches and starch contents on the physico-mechanical and morphological properties of new polymeric-based composites from low density polyethylene (LDPE) and thermoplastic starches. Different compositions of thermoplastic starches (5–40 wt%) and LDPE were melt blended by extrusion and injection molding. The resultant materials were characterized with respect to the following parameters, i.e., melt flow index (MFI), mechanical properties (tensile, flexural, stiffness and impact strength) and water absorption. Scanning electron microscopy (SEM) was also used in this study for evaluating blend miscibility. MFI values of all blends decreased as the starch content increased, while the sago starch formulation showed a higher MFI value than others. The incorporation of fillers into LDPE matrix resulted in an increased in tensile modulus, flexural strength, flexural modulus and slightly decreased tensile strength and impact strength. However, sago starch filled composites exhibited better mechanical properties as compared to other starches. The SEM results revealed that the miscibility of such blends is dependent on the type of starch used. The water absorption increased with immersion time and the thermoplastic sago starch samples showed the lowest percentage of water absorption compared with other thermoplastic starches.

Hemp Fibers Waste and Linear Low Density Polyethylene Composite Properties

2016 ◽  
Vol 721 ◽  
pp. 33-37
Author(s):  
Zane Zelca ◽  
Silvija Kukle ◽  
Janis Kajaks ◽  
Marija Geikina-Geimana
Keyword(s):  
Water Resistance ◽  
Melt Flow Index ◽  
Lubricant Additive ◽  
Low Density Polyethylene ◽  
Flow Index ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Melt Flow ◽  
Hemp Fibers ◽  
Polyethylene Composite

Influence of the composite preparing technology and filler type (hemp waste and hemp fibres) on the performance characteristics (melt flow index and water resistance) of the composites based on a linear low density polyethylene (LLDPE) was investigated. The best melt flow index (MFI) results were achieved when as composites preparing method extrusion and two rolls mill with lubricant additive combination were used. It is established that usage of extrusion mixing method of the hemp fibers containing LLDPE composites significantly affects materials melts fluidity evaluated by values of MFI and quality of extruded profile. The lowest fluidity was observed for composite with hemp waste prepared by two rolls mill processing method. The best water resistance was observed for composites with lubricant and for their preparing two rolls mill and extrusion processing methods combination was used.

Numerical Simulation of the Polymerization Process in Turbulent Reacting Flows

2012 ◽  
Author(s):  
Anpeng He ◽  
Marie Bonvillain ◽  
Robert Bennett ◽  
Adam Duhon ◽  
Victor Lin ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Tubular Reactor ◽  
Decomposition Reaction ◽  
Polymerization Process ◽  
Polymerization Reaction ◽  
Low Density Polyethylene ◽  
Injection Velocity ◽  
Reacting Flow ◽  
Low Density ◽  
The Stability

The present research entails turbulent reacting flow being simulated inside a low-density polyethylene tubular reactor using computational fluid dynamics techniques. The effects of initiator mass fraction and initiator injection speed on the stability of the reactor have been studied. The reactor and injector should be designed such that the ethylene does not undergo the potential decomposition reaction; this reaction is exothermic and violent. The products of the decomposition must be vented as a safety measure. ANSYS FLUENT has been used to simulate this reacting flow problem. Both decomposition reaction and polymerization reaction are entered into the software along with their kinetic information. A high product yield of polymer without initiating the ethylene decomposition reaction is expected. Optimal mass fraction of initiator and optimal injection velocity were determined in order to maximize product and maintain the stability of the low-density polyethylene tubular reactor.

Physical and mechanical performance of bentonite and barite loaded low density polyethylene composites: Influence of surface silanization of minerals

2020 ◽  
Vol 54 (28) ◽  
pp. 4359-4368 ◽  
Author(s):  
Hesham Elkawash ◽  
Seha Tirkes ◽  
Firat Hacioglu ◽  
Umit Tayfun
Keyword(s):  
Mechanical Performance ◽  
Water Repellency ◽  
Surface Characteristics ◽  
Melt Flow Index ◽  
Low Density Polyethylene ◽  
Flow Index ◽  
Injection Molding Process ◽  
Low Density ◽  
Melt Flow ◽  
Molding Process

In this study, two kinds of mineral fillers, bentonite (BNT) and barite (BRT), were incorporated into low density polyethylene (LDPE) by extrusion process. Silane treatment was applied to BRT and BNT surfaces in order to increase their compatibility with LDPE matrix. Surface characteristics of fillers were examined by Fourier transformed infrared spectroscopy (FTIR). LDPE-based composites were prepared at a constant concentration of 10%wt for each additives. Test samples were shaped by injection molding process. Mechanical, thermo-mechanical, water repellency, melt-flow and morphological characterizations of LDPE and its composites were performed by tensile and impact tests, dynamic mechanical analysis (DMA), water absorption test, melt flow index (MFI) measurements and scanning electron microscopy (SEM) technique, respectively. Test results showed that surface treatments led to increase for final properties of composites since they promoted to stronger adhesion between minerals and LDPE matrix compared to untreated ones. Tensile and impact strength values, storage modulus and glass transition temperature of LDPE were improved by inclusion of silane treated minerals. BRT and BNT additions caused no remarkable changes with regard to MFI of LDPE. Additionally, silane modified mineral filled composites exhibited remarkable water resistance behavior. According to SEM analysis of composites, silane treated BNT and BRT containing samples displayed homogeneous dispersions into LDPE phase whereas debondings were observed for untreated BNT and BRT filled composites due to their weak adhesion to polymer matrix.

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