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Original Article | Open Access | Int. J. Mat. Math. Sci., 2022; 4(4), 94-101. | doi: 10.34104/ijmms.022.0940101

Study of Properties of Local Polypropylene Compared to International Standard Properties

Yasmin Abd Elrazeg* Mail Img ,
Muhammed Rukshanul Kabir Mail Img ,
Mohammad Zahirul Haque Mail Img ,
Seedahmed Ahmed I. Mail Img

Abstract

This study was conducted in the Khartoum refinery in Algylee to study the properties of polypropylene (grade 113 &114) which are produced by the addition technique; they used refined propylene from Liquefied Petroleum Gas and Ziegler-Natta catalyst. The samples were taken from samples which are produced in (1-15)/08/2010 in three features (powder, granulates, and specimens). Both grades are homopolymer and isotactic polypropylene. They checked the component of liquefied petroleum gas by using a gas chromatography instrument and determination of thermal, mechanical, and physical properties. From the result, both grades differed in their properties according to molecular weight. Grade 113 has a large molecular weight which is suitable for the extrusion process while grade 114 has a small molecular weight which is suitable for the injection molding process. Each grade of polypropylene is within the standard range but they contain a slight amount (˂0.5ppm) of sulfur and moisture (49.1ppm)  which are affecting product quality. However, if there is no separation unit the product will become yellowish and toxic. 

INTRODUCTION

As early as 1969 propylene was polymerized by Bert-helot which did not exhibit interesting properties for industrial application? In 1955 polypropylene was first polymerized by G. Natta following the work of K. Zeigler which resulted semi-crystalline with  has strong mechanical properties (Karian, 2003; Gowariker, 1986). Polypropylene is linear hydrocarbon polymer, the steric arrangement of the methyl group attached to every second carbon atom in the chain may vary produce three different kinds of polypropylene; isotactic poly-pro-pylene (methyl group on the same side), syndiotactic polypropylene (pendant methyl group in alternating manner), atactic polypropylene (pendant methyl group in a random manner). Polypropylene is produced two commercially types depending on the properties desi-red; polypropylene homopolymer contains propylene monomer and polypropylene copolymer contains two or more different types monomer (Karger-Kocsis, 1995; Tripathi, 2002). Polypropylene was prepared from propylene monomer which produced by cracking of petroleum product by using fractional distillation and Ziegler-Natta catalyst. A typical catalyst system prepared by reacting titanium trichloride (TiCl3) with aluminum triethyl, aluminum tributyl or diethyl mono-chloride in naphtha under nitrogen form slurry. There is new catalyst system which contained magnesium compound will give appreciable improvement in the yield of isotactic material. Both those system were including liquid and gas phases which must need sepa-ration unit to remove catalyst residues and atactic material (Brydson, 1999; Cowie, 2007; Lahcene, 2021). 

The mechanical and thermal properties of polypro-pylene dependant on the isotacticity, molecular weight and its distribution, crystallinity. Good balances of properties can be tailored to large fabrication methods and application and low cost make it useful in various1 industries such as automotive, medical application appliance application, textile and nonwovens, package-ing, construction (3, 4). Polypropylene is already recy-cled from a numbers of commercial sources; crates, trays, battery case etc. The recovered material is reused within the automotive industry and for a proprietary rang of furniture (Brydson, 1999; Maier, 1998; Ahmad et al., 2018). In this study the material is was poly-propylene which was produced in Sudan by Khartoum Petrochemical Company (KPC). 

They were used Ziegler-Natta catalyst and propylene as monomer which was obtained from refining lique-fied petroleum gas (LPG) by using fractional distil-lation. There are four units are used to produce poly-propylene in (KPC). 

1) Gas distillation unit contained four distillation columns, firstly components above C4 were removed, secondly C3, thirdly propane and pro-pylene and fourthly refined propylene and sulfur and moisture are removed. 

2) Polymerization unit includes (1) raw material refinery process where propylene refined and removed non hydrocarbon impurities such as water, sulfur and oxygen. All refinery processes are involved alkali dehydration, desulfurization, re dehydration, gas phase de carbon monoxide, de oxygenation and deep dehydration. (2) pro-pylene polymerization in which refinery propy-lene is transferred via two different ways to polymerization kettle, one from the activator pipe the other from catalyst feed. The reaction was occurred under temperature 74°, pressure 3.5 MPa for 3 - 4 hours till the kettle becomes dry then collected propylene no reacted. 

3) Flash vapourization and deactivation unit after the gas in the polymerization kettle is recycled by force of the remained pressure then refined nitrogen gas to displace the air in the flash vapourization kettle then feeding. To discharge the powder from the flash vapourization used rotary valve. 

4) Pressing and granulating unit stabilizer materials were added to polypropylene powder and the mixture was pressed into pelletization machine and cut in granulates form. Fourth packing and delivering unit where (poplypropylene granulates) is packed in certain weight and storage.

MATERIALS AND METHODS

Samples 

Liquefied petroleum gas, crude propylene gas, refinery propylene gas, two grades of local polypropylene (grade 113 & grade 114) in three forms (semi product (polypropylene powder), final product (polypropylene granulates) and specimens). 

The analysis Method 

For analysis was used ASTM standard method. 

Determination of liquefied petroleum gases 

This test used to determine the composition of lique-fied petroleum gases (LPG) and it is applicable to analysis of propane, propylene, butane and sulfur 

Apparatus 

Gas chromatography instrument with thermal conduc-tivity detector, a strip-chart recorder. 

Procedure 

The GC instrument was operated (used nitrogen gas as carrier gas LPG sample, crude and refiner propylene and argon gas to determine sulfur). Then the sample was injected and recorded the result (ASTM, D 2163-9) 

Melt flow rate of polypropylene 

This test measure the rate of extrusion of molten resins through a die of specific length and diameter under prescribed conditions of temperature, load and piston position in the barrel as timed measurement is made by using a manual cut off operation based on time used for materials having flow rates that fall. 

Apparatus 

Melt flow index device consist of a dead - weight piston plastometer consisting of a thermostatically con-trolled heated steel cylinder with a die at the lower end and a weighted piston, funnel, tool for cutting, sen-sitive balance and loading weight. 

Procedure 

6.0g of samples 2 (powder, granule) was weighed , 5 cm3 of heating stabilizing solution were added and the mixture was in oven at 100°C for 15 min. the cylinder was charge with the sample, reinsert the piston and add the appropriate weight. Few minutes waited until the material was soften and begin to melt then was purged to a position, the purge was completed at least 2 min prior then for material was started. For all tests collec-ting a time extrudate (t) was started when requirement for the position are met. Once the extrudate is cool, it was weighed (G). For final product (granule) applied the same procedure but without adding the heating stabilizing the melt flow rate was calculated in grams per 10 min 

MFR= (G×600)/t ……………………………….. (1)

Where 

MFR ≡ melt flow rate, G ≡ weigh of extrudate, t ≡ cutting interval time. (ASTM, D 1238-04c) 

Deflection temperature of polypropylene 

This test determined the temperature at which an arbit-rary deformation occurs when specimens are subjected to an arbitrary set of testing conditions. 

Apparatus 

Deflection Temperature Instrument which consists of specimen supports, immersion silicon oil bath, deflect-tion measurement device, weight, temperature measu-rement system. 

Procedure 

To2 determine the temperature at which an arbitrary deformation occurs when the specimens are subject to an arbitrary set of testing conditions. Specimens were prepared in plate form by injection molding with thickness 3.2mm, width 13mm and length 127mm. The apparatus was prepared which arranged to shut off the heat automatically with sound an alarm or record the temperature when the deflection has been reached. The test condition was checked; at room temperature, immersion medium silicon oil heating rate 2°C/ min temperature at the start of the test 35°C, preheating 300s. The test specimens edgewise were positioned in the apparatus and ensure that they are properly aligned on the supports. The road rod was applied to the specimen and lowers the assembly into the bath and the machine was stared. The temperature (heat-transfer medium) was recorded when the specimen has de-flected specified amount at the specified fiber stress. (ASTM, D648-98c) 

Density and specific gravity of polypropylene 

Apparatus 

Analytical balance is equipped with stationary support for the immersion vessel above it, sample holder and sinker. Procedure: The mass of specimen was weighed in air (m1). The immersion vessel was put on the support and completed by distilled water and the specimen was weight after immersed (m2) then the specific gravity was calculated 

Dg/dm3 = m1/m2 ×997.5 ……………………….. (2) 

Where D ≡ specific gravity, m1≡ weigh of specimen in air, m2 ≡ weigh of specimen completed immersion (ASTM, D792-08). 

Impact resistance of polypropylene 

This test determined the impact resistance which based on the polymer to standardized pendulum-type ham-mers, mounted in standardized machines in breaking standard specimens with one pendulum swing 

Apparatus 

Cantilever beam (Izod-type) impact machine, engine lathe and a notch-depth micrometer. 

Procedure 

The molded specimens were prepared using injection molding with width between 3.0 – 12.7 mm, thickness is between 3.0 – 12.7 mm, and length is 62 mm. The specimens were notched by using engine lathe. The included angle of notch should be 45° with a radius of curvature at the apex of 0.25 mm, the depth of speci-men under the notch should be 10.20 mm. The test condition was checked; temperature 23°C, and pendu-lum hammer energy is 0.5 J. The specimen positioned precisely clamped in the vise, operated the machine and selected a pendulum of suitable energy. The pen-dulum was released and recorded the excess energy remaining in the pendulum after breaking the specimen (E), and the average Izod impact resistance (I) of the group of the specimens was calculated 

I = (E J ×1000)/w ……………………………….. (3) 

Where 

I ≡ impact resistance J/mm, E ≡ break energy J, W ≡ width of specimen mm. (ASTM, D256 – 97) 

Tensile property of polypropylene 

This test determined the tensile properties in form stan-dard dumbbell shaped test specimen under condition pretreatment, temperature, humidity and testing machine speed. 

Apparatus 

Testing machine of constant rate of cross head move-ment type comprising fixed member, movable mem-ber, grips, drive machine, load indicator, crosshead extension indicator. 

Procedure 

Specimen were prepared in plate form by injection molding with thickness 3.2mm, width of narrow section 13mm, length of narrow section 27mm. width over all 19 mm, length over all165 mm. the test condition checked; at room temperature, load range 2000 N gauge length 50 mm, test speed 50 mm/min. the specimen was place in the grips of the test machine and the test machine was started then the result was recorded. (ASTM, D 638 – 08) 

Flexural property of polypropylene 

This test determined the flexural properties in form standard dumbbell shaped test specimen under condi-tion pretreatment, temperature, humidity and testing machine speed 

Apparatus 

Testing machine of constant rate of cross head move-ment type comprising fixed member, movable member, grips, drive machine, load indicator, crosshead exten-sion indicator. 

Procedure 

Specimen were prepared in plate from injection mold-ing with thickness 3.2 mm, width 13 mm and length 127 mm. the test condition was checked ; at room tem-perature, load range 100 N, extension range 10% and test speed 1.3 mm/min, span 50 mm and end point 9 mm. the specimen was placed in the grips of the machine 

RESULTS AND DISCUSSION

Liquefied petroleum gas

Table 1: Components of Liquefied Petroleum Gas Sample.

From the Table 1 it was found that LPG contains per-centage of 8.95% propane, 37.57% propylene, 26.68% butane, 28.04% isobutylene which may be monomers for manufacture of polymer.

Table 2: Components of Sample Outlet Firstly Distillation Column

Table 3: Components of Sample Outlet Secondly Distillation Column.

Table 4: Components of Sample Outlet Thirdly Distillation Column.

Table 5: Components of Sample Outlet Fourthly Distillation Column.

From Table (2, 3, 4, 5) it is noticed the sample con-tained 42.74% butane and 56.46 isobutylene which are isolated in the first column and recycled. The likely amount of isobutylene may be used to prepare poly-isobutylene that importance formanufacture of inner tubes for truck and bicycles. 

Table 6: Components of Crude Propylene.

Table 7: Components of Refined Propylene.

From Table 7 the amount of propyne in crude pro-pylene and the refined propylene is over the rate but didnt effect because is very reactive and can be convert to propylene in the reactor when present of hydrogen gas. 

Table (8, 9) showed that refined propylene contained ˂ 0.5ppm of sulfur and 49.1ppm moisture content that effect on polypropylene properties such as melt flow rate, strength and on life time of the specimens.

Table 8: Sulfur Content.

Table 9: Moisture Content.

Properties of Polypropylene 

Melt Flow Rate  

Table 10: Malt Flow Rate of Polypropylene Grade (113&114).

Table 10 shows that melt flow rate each powder and granules of polypropylene grade 114 shows greater than polypropylene grade 113. The lower melt flow rate is indicated greater viscosity and higher molecular weight which effect on the processes thus extrusion processes which required high molecular weight must be used polypropylene grade 113 and injection proc-esses which required low molecular weight must be used polypropylene grade 114.

Table 11: Heat Deflection Temperature of Polypropylene Grade (113 &114).

However heat deflection temperature dependent on the molding process thus from Table 11 it can be seen that heat deflection temperature for two grades of polypro-pylene are less than standard value due to injection molding specimens. This test is suited to control and development work.

Table 12: Specific Gravity of Polypropylene Grade (113 &114).

Specific gravity is property useful to identify material, to follow physical changes in the sample, to indicate the degree of uniformity among different sampling units and calculating strength weight and cost weight ratios. Table 12 shows the different values of specific gravity for two grades of polypropylene due to the difference in crystallinity properties of the polymer.

Table 13: Impact Resistance of Polypropylene Grade (113 &114).

Table 13 shows that polypropylene grade 113 has higher impact resistance 

than polypropylene grade 114 due to the increase in molecular weight.

Table 14: Tensile Property of Polypropylene Grade (113 &114).

Table 15: Flexural Modulus of Polypropylene Grade (113 & 114).

Table (14, 15) show that polypropylene grade 113 has higher value of tensile property and flexural modulus  than polypropylene grade 114 due the different in molecular weight, crystallinity and orientation.

Table 16: Comparison Polypropylene Grade (113 &114) with other Polymers (3).

It can see from the table above polypropylene in both grades (113, 114) advantages as higher strength than high density polyethylene (HDPE) and low density polyethylene but lower than poly vinyl chloride (PVC) also they offer resistance to higher temperature and low impact resistance thus polypropylene is good tough-ness and is referred to use in many application such as transfer liquids, furniture, domestic appliance and auto-motive (Mostari et al., 2020; Awadala et al., 2020). 

CONCLUSION AND RECOMMENDATIONS

Polypropylene was produced in Sudan is homopolymer as recycling process of petroleum waste. They are product two grades of polypropylene grade 113 and grade 114, they are different in length of polymer chain; molecular weight. LPG contains enough amounts of gases which can be used as monomers to produce various polymers such as polypropylene, polyethylene and poly-isobutylene. Also it contains a large percent-age of propylene but contain sulfur and moisture which affect in production quality. Both grade of polypro-pylene (113 & 114) offer good thermal, mechanical and physical properties from the result of MFR of both grades concluded that grade 113 has higher molecular weight than grade 114. Both grades may be oriented either in the melt phase or by stretching when it is solid due to high tensile strength also low impact resis-tance leads to brittle failure. They have low density so are light therefore offer the advantage of being able to manufacture more items for a given weight of poly-mer. They are good thermal resistance (high heat deflection temperature) then they are useful application which needs high temperature as microwave. Since there is no separation unit (to separate the catalyst resi-due and byproduct "atactic polypropylene") so it may be toxic. Constructor many factor to produce the poly-mer from refinery of LPG, constructor unit to treat a large amount of propane in the refined propylene, increased activity of column to remove sulfur and moisture to improve quality of product and added sep-aration unit. 

ACKNOWLEDGEMENT

I thank Dr. Ahmed Ibrahim Ahmed Sid Ahmed for fruitful guidance, unlimited assistance encouragement, the staff of Gezira University, engineer Abd Allah Almalik and Khartoum Petroleum Company.   

CONFLICTS OF INTEREST

The authors declare that they have no conflict of interests.

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Article Info:

Academic Editor

Dr. Toansakul Tony Santiboon, Professor, Curtin University of Technology, Bentley, Australia.

Received

July 19, 2022

Accepted

August 22, 2022

Published

August 30, 2022

Article DOI: 10.34104/ijmms.022.0940101

Corresponding author

Yasmin Abd Elrazeg*

Graduate Collage, Sudan University of Science and Technology, Khartoum, Sudan

Cite this article

Elrazeg YA, Kabir MR, Haque MZ, and Ahmed SI. (2022). Study of properties of local polypropylene compared to international standard properties, Int. J. Mat. Math. Sci., 4(4), 94-101. https://doi.org/10.34104/ijmms.022.0940101 

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