ENGINEERING TEAM PROJECT

GROUP 24

Project: Polymer Solution Preparation Kit

Team leader:

LUVENRAJ A/L C SATHASIVAM (EE) 13108

Members:

AMIR HAZWAN BIN ABD GAFAR (ME) 13029

ABDUL AFIF BIN AHMAD (CE) 12997

FAZIANA ZARITH BINTI ZAMBERI (CE) 13068

ZULHAZMI BIN MOHD ZULKIFLI (CV) 15191

SITI HAJAR AISYAH BINTI MAT SOH (PE) 13379

KABILAN A/L MUTHUSAMY (ME) 13093

Supervisor:

MR. MOHD ZAMRI ABDULLAH

1

Chapter 1: Introduction

1.1 ABSTRACT

The basis of this research is to design a device to facilitate the movement of solutions

in the pipeline in order to maintain a proper flow rate of polymer and tap water solution. We

have done a review on previous studies carried out and have chosen the study done by Al-

Wahaibi et al. (2007) and Ngan et al. (2007) as our reference. Our project does however have

some variation in terms of design and function. A brief description of our design includes the

use of an aluminium filter funnel as the feed tank of the polymer, a centrifugal pump to draw

water molecules into the feed tank, PVC pipes to channel water into the feed tank and also an

orifice tube to create a pressure variation in the tank. Special effort should be expended to

ensure complete, homogeneous dissolution. Once formed, various tests will also be carried

out to determine the quality of homogenous solution obtained. Our overall approach is to

form a suitable concentration of polymer solution which is homogenous through our design.

Looking at a larger scale, our findings may be useful for the Oil & Gas Industry as it may

provide a platform for them to facilitate movement of fluids in Oil Rigs.

2

1.2 PROBLEM STATEMENT

We must first understand the problem in order to come up with an effective solution.

Previously, there were several ideas came up in order to prepare the polymer solution and

there were also problems occurred during the experiment. The problems that we want to

overcome are:

The problem that occurs is that huge amount of polymer gel is observed at the

centre of the tank when the polymer powder is sprinkled onto the surface of

water during the stirring. At the certain parts of the solution the polymer may

agglomerates and produces gel or lumps. The gel sticks at the impeller shaft

produced a heterogeneous solution. This is also might be due to the small

vortex that is only produced further at the centre during stirring and unable to

mix the long chain polymer consistently throughout the solution.

The strange outcomes of the drag reduction study are observed since the

solution 'concentration' is not consistent. This is due to the polymer composed

of long carbon chains; therefore the behaviour of the solution prepared would

not be the same as the solution made up by small molecules. This might pose a

problem since the polymer solution is hardly being a homogeneous, and even

clearly visualized through the naked eye.

The polymer solution should be rested in order to reduce shear degradation

due to mixing. After being left, the viscosity reduction phenomena of diluted

polyacrylamide occurred in water. Besides, they found out the solution

became cloudy and sometimes a small amount of precipitates could be

observed after storing in a long time.

Most of the process are using human effort to sprinkles the polymer powder

into the solvent or reactor. This will lead us to random error such as the

measurement of polymer powder; the time of sprinkles and the area of sprinkle

3

itself. This error will reduce the quality of polymer solution and the basic

problem in producing the drag-reducing additives.

1.3 OBJECTIVES

As we all know, the addition of the drag-reducing additives influence the reduction of

wall friction especially during the liquid flow and the drag-reducing additives use in this

project is the polymer solution. Our team starts evaluating the idea and did some research in

investigating the concept of the idea. The main purpose for this project is to design a device

that will be used to prepare a homogeneous polymer solution.

There are several objectives need to fulfil in order to ensure that the idea of the device

can be achieves:

To avoid agglomerates or lumps during the process of addition of the drag-

reducing additives especially at the stirrer of the reactor.

The basic idea is we will prepare and use the homogeneous polymer solution

instead of the polymer powder as the drag-reducing additives.

To produce high quality of the polymer solution especially in terms of

concentration of the solution in the solvent.

In order to get a consistent concentration, we will need to analyse whether the

solution produce is homogeneous in term of polymer powder and water by

using the suitable water pressure and flow rate. We also will be ensuring that

there are no large particles of polymer powder pass through the end of our

device which can lead to the long chain of carbon in our solvent.

To avoid precipitation and reduction of viscosity phenomenon during the

process of reduce shear degradation.

When we are using the device, the solution does not need to be rested in order

for it to be a homogeneous. Thus, the process of precipitation and reduction of

viscosity will not occur.

To decrease human effort on producing the drag-reducing additives.

4

The method of sprinkling the polymer powder is not practical. Thus, we are

using the suitable flow rate and the pressure of water inlet to produce the

polymer solution and directly stream the solution into the solvent.

1.4 BACKGROUND ANALYSIS

Research in the area of fluid dynamic drag reduction has received increased emphasis

in recent years. In 1949, Toms has discovered the phenomenon of turbulent drag reduction

by polymer additives. The addition of an amount of long-chain polymer molecules in water

or in organic solvents, the frictional drag of turbulent flow through pipes and channels can be

reduced dramatically. In pipe flows, for example, the drag can be reduced by up to 80 % by

adding just a few parts per million (ppm) of polymer. Toms discovered it by chance in the

summer of 1946, when he was actually investigating the mechanical degradation of polymer

molecules using a simple pipe flow apparatus. He observed it is really an outstanding thing

that a polymer solution clearly offered less resistance to flow, under constant pressure, than

the solvent itself.

The drag reduction effect is extremely interesting from a practical point of view.

Liquids are mostly transported through pipes, and a drag reduction by adding a small amount

of polymers can offer large economic advantages and a larger effectiveness of this

transportation. The most spectacular success in polymer applications for drag reduction has

been the use of oil-soluble polymers in the trans-Alaska pipeline system, where as a result the

flow rate has been increased by 32,000 m3/d. However, one of the complexities encountered

during polymer induced drag reduction is degradation of polymer chains which hamper their

effectiveness as a drag reducing agent. Another minus point is the difficulty to remove the

solvent from its’ final form, causing degradation of bulk properties. Besides that, polymer

induced drag reduction is also not environmental friendly as it causes environmental pollution

due to solvent release. Our goal leads to the rise of a new question, “How can we design an

effective device to prepare a homogeneous polymer solution?”

Our project focusses on ways how a homogeneous solution with suitable

concentration can be produced via appropriate conceptual design with reference to the study

done by Al-Wahaibi et al. (2007) and Ngan et al. (2007). ln their most recent study, the

polymer solution is prepared by mixing the polymer in powder form with deionized water in

a stirred tank. The additive used is a copolymer of acrylamide and sodium acrylate (HPAM,

5

Magnafloc 1011, Cibi Specialty Chemicals). The polymer solution was hardly being a

homogeneous, and could clearly be visualized through the naked eye. As a result, the

anomalous outcomes of the drag reduction study are observed since the

solution'concentration'is not consistent.

Chapter 2: Design Approach and Methodology

Main objective states that the purpose of this project is to design a device that will be

used to prepare a homogeneous polymer solution. Basically, the device is used to facilitate

the movement of solution in the pipeline in order to maintain a proper flow rate of polymer

and tap water solution.

2.1 PROCEDURE

Polymer powder

Pump Homogeneous solution

Tap water

1. At the inlet, the tap water is pumped through the device so to increase the velocity of

the water.

2. Then, polymer powder is poured into the hopper inlet which is installed on top of the

device.

3. Later, through contact between water and polymer powder that will ensure

homogeneous solution to occur.

6

Preparation Device

Start

Practicality

Successfully functioning

2.2 PLAN AND SCHEMATIC FLOW PROCESS OF THE PROJECT

7

Prototype design

Prototype fabrication

Testing

NO

YES

Presentation and Exhibition

Final report

NO

YES

Check the solubility of polymer

Design the casing of the device

Test the flow rate of water through orifice /venturi

Experiment

Check the homogeneity of the solution outlet

END

2.3 HARDWARE /TOOLS AND SOFTWARE

These are the hardware/tools and software needed in order to make the prototype model.

No. Name Description

1 PVC Pipe To channel the tap water throughout the device process

2 Perspex Used as the basic building structure

3 Centrifugal Pump To create pressure and allow smooth movement of water

4 Orifice tube To determine the flow rate of the device

5 Pipe Hose To connect the tap water into the device

6 Aluminium Filter

Funnel

Used as the feed tank of the polymer into the device

7 Electronic Components Used for circuit completion.

Table 1: List of hardware used

No. Name Description

1 Electric Drill To create hole or passage for pipeline

2 Hot Glue Gun To join some of the parts of the device

3 Hand Tools Used to build prototype model.

Table 2: List of tools used

No. Name Description

1 AutoCAD Used for drawing of model in 2D and 3D mode

8

2 Microsoft Office Used for documentation; proposal, progress report and final

report

Table 3: List of software used

Chapter 3: Project Planning

Week Number

Activities

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Seminar I (ETP Briefing)

Mid

Sem

este

r Bre

ak 8

– 1

1 M

arch

201

2

Group Organization & Brainstorming

Consult Supervisor

Data Collection for Proposal

Project proposal due

Cost Analysis for The System Design

Purchase Required Tools & Material

Designing The Process & Prototype

Implement The Process of The Project

Construction of The Prototype

Progress Report due

Prototype Testing

Submission of FORM 03

Evaluation on Fabrication

Poster & Demonstrations

Consult Supervisor

Final Check On The Prototype

Preparing & Presenting Slides

Oral Presentations

9

EDX TBA

Return of FORM 03

Submission Peer Evaluation

Submission of Claim Form

Submission of Final Report

3.1 GANTT CHART

3.2 TASK ALLOCATION & ACTIVITIES

10

PROJECT DIRECTOR

LUVENRAJ A/L CSATHASIVAM (EE)

Plans for weekly meetings. Chairs all meetings. Coordinates project progress. Involves in the studies of

mechanical part of the project.

ASSISTANT PROJECT DIRECTOR

FAZIANA ZARITH BINTI ZAMBERI (CHE)

Assists the project director and other members in task.

Involves in the studies of mechanical part of the project.

SECRETARY

SITI HAJAR AISYAH BINTI MAT SOH (PE)

Writes the minutes of meeting.

Keeps record of all group activities.

Helps in the obtaining strength of the materials used.

Prepares the poster for presentation.

TREASURER

ZUL HAZMI BIN MOHD ZULKIFLI (CVE)

Manages the project account flow.

Estimates the project budgets.

Research the strength of materials used.

RESEARCH & DEVELOPMENT

ABDUL AFIF BIN AHMAD (CE)

Leads the research activities. Ensures research is in

accordance with project flow.

Dealing with electrical and

DESIGN & ANALYSIS

AMIR HAZWAN BIN ABD GAFAR & KABILAN A/L

MUTHUSAMY (ME)

Designs the layout and process of the system.

Research and select

RESEARCH

CIVIL ENGINEERINGMECHANICAL ENGINEERINGELECTRICAL & ELECTRONIC ENGINEERINGCHEMICAL & PETROLEUM ENGINEERING

Do research on pipe flow for the polymer mixtureDo research on existing device mechanism.Do research on the circuit of the device.Do research on homogenous of polymer.

3.3 PROJECT FLOW

11

RESEARCH & DEVELOPMENT

ABDUL AFIF BIN AHMAD (CE)

Leads the research activities. Ensures research is in

accordance with project flow.

Dealing with electrical and

DESIGN & ANALYSIS

AMIR HAZWAN BIN ABD GAFAR & KABILAN A/L

MUTHUSAMY (ME)

Designs the layout and process of the system.

Research and select

CONCEPTUAL DESIGN

Brainstorming on design alternatives. Combining features and concept from all engineering

field. Select the best design solution. Sketch and draw design schematically.

FUNDAMENTAL ENGINEERING

CIVIL ENGINEERING

Determine the fluid mechanic of the pipe flow and accurate viscosity for the polymer mixture.

MECHANICAL ENGINEERING

-Design the structure of the system.

-Dealing with the pulley system and flipping system.

CHEMICAL & PETROLEUM ENGINEERING

-Determine the composition of chemical in materials used and end product of the polymer solution.

ELECTRICAL & ELECTRONIC ENGINEERING

Determine the efficient electrical properties for the device.

3.4 CONCLUSION

Since its discovery more than 60 years ago, the drag reduction phenomenon has

achieved many notable energy saving effects. These achievements have encouraged

researchers to study drag reduction further and further so that it can be utilized better. Sooner,

the phenomenon of turbulent drag reduction by polymer additives which the drag can be

reduced by up to 80 % then discovered by Toms in 1949.

But due to the complex characteristics of some flow, for an instance a turbulent flow,

recent theories cannot explain all the phenomena of this polymer as drag reduction addictive.

To give an overview, our group has summarizes the main advancement of polymer drag

reduction by designing a device to prepare a homogeneous polymer solution.

Since drag reduction has a close relation to energy conservation. It has received more

and more attention as more and more potential applications become practical. The application

of drag reducing additives is greatly reducing pipe diameter, or increasing flow rate. The first

famous application of drag reduction addictive was in transport of crude oil in the trans-

Alaska (TAPS or Alyeska) Pipeline in 1979. The pipeline is 800 miles long with 48-inch

diameter. After injecting a concentrated solution of a high molecular weight polymer

downstream of pumping stations at homogeneous concentrations as low as 1 ppm, crude

throughput was increased by up to 30%.

Polymer drag reduction addictives were also successfully applied in other crude oil

pipelines such as Iraq-Turkey, Bass Strait in Australia, Mumbai Offshore and North Sea

Offshore, and in finished hydrocarbon product lines. In each case, the polymer composition

had to be designed for the particular hydrocarbon to be transported.

12

CREATE PROTOTYPE

TEST PROTOTYPE

FINISH

Polymer drag reduction addictives have also been proposed for the following

applications: oil field operations, slurry or hydraulic capsule pipeline transportation,

suppression of atherosclerosis, prevention of lethality from hemorrhagic shock, increased

water flow and water jet focusing in fire fighting equipment, prevention of overflows of

water in sewage systems after heavy rains, increase of volumetric flow rate of water in

hydropower and irrigation systems, and as anti-misting agents in jet fuel.

Chapter 4: Data gathering and analysis

4.1 PRELIMINARY INFORMATION

Methods in Preparing Polymer Solutions.

The reduction of wall friction during the liquid flow depends on the addition of the drag-

reducing additives, and in this project is the polymer solution. The additives could be injected

via slots or small tube into the channel (heterogeneous drag reduction) or dissolved at certain

concentration in the pool of solvent (homogeneous drag reduction). The concentration in

either case is usually given in term of the weight of the polymer, e.g-weight parts per million

of polymer (wppm, or just ppm) or weight percentage (wt%). Since the concentration

depends on the nature of the solvent, preparation of polymer solution plays a crucial role in

ensuring the drag reduction result is reproducible. Polymer composed of long carbon chains;

therefore the behaviour of the solution prepared would not be the same as the solution made

up by small molecules such as salts. This might pose a problem since the polymer may

agglomerates and produces gel or lumps at certain parts of the solution. The method of

preparation is therefore vital so that polymer solution achieved is as homogeneous as

possible, or at least the gel formation is minimized to a large extent.

Over the years, the ways of how the polymer solutions were prepared in the drag reduction

studies are vast, but brief. In addition the quality of the solution produced in term of rheology

wise, is not widely reported. In a recent study by Al-Wahaibi et al. (2007) and Ngan et al.

(2007), in which this research is based on, the polymer solution is prepared by mixing the

polymer in powder form with deionized water ih a stirred tank. The additive used is a

13

copolymer of acrylamide and sodium acrylate (HPAM, Magnafloc 1011, Cibi Specialty

Chemicals). The polymer solution is hardly being a homogeneous, and even clearly

visualized through the naked eye. As a result, the anomalous outcomes of the drag reduction

study are observed since the solution' concentration is not consistent.

Regardless of whether the drag reduction studies are done in homogenous or heterogeneous,

the preparation of polymer solutions follows some main principle that include dispersion of

polymer in the solvent and followed by agitation. The approach, however, differs from one

researcher to another. Since the polymer must dissolves in the solvent, the property of the

solvent used will affect on the quality of the solution produced. For water-soluble polymers

such as PEO, PAM and HPAM, either tap or deionized water may be used. Depending on the

condition of water at site, tap water might contain dissolved metal ions such as lead from the

piping that would react with the solution. Den Toonder et al. (1995), for instance, used both

tap and demineralised water to prepare their PEO and PAMs solutions. They found out that

by using tap water, PEO refused to dissolve and gave less reduction. As a result, the authors

change the procedure by using demineralised water for their PAMs instead, and showed

higher drag reduction. Sun et al. (2005), also applied tap water, but it is filtered and

desecrated at 34-38'C. The choice of heating the solvent might be necessary since they are

using PAM and HPAM in granular form. Theoretically, by increasing the temperature,

solubility will increase. In addition, they study on the effect of adding small amounts of salt

to the water used to simulate unfiltered tap water, and also found out that drag reduction

decreased appreciably.

Polymer need to be in contact with the solvent as much as possible if a homogeneous solution

is to be achieved. Homogenous in this context means the clarity of the solution is observed,

gel or lumps formation is not visible and consistency in terms of the solution rheology is

achieved as possible. These can be attained on the way polymer is added to the solvent. In

current practice by Al-Wahaibi et al. (2007) and Ngan et al. (2007), the polymer in powder

form is sprinkled onto the surface of water during the stirring. Similar manner are also seen

from the study by McConaghy and Hanratty (L977) and McComb and Rabie (1982). The

problem that occurs is that huge amount of polymer gel is observed at the centre of the tank.

The gel sticks at the impeller shaft resulting a heterogeneous solution is therefore produced.

This might be due to the small vortex that is only produced further at the centre during

stirring and unable to mix the long chain polymer consistently throughout the solution. Bello

14

et al. (1982) addressed the problem of the vortex formation in their polymer solution

preparation technique. While impeller might produce higher vortex at high speed, the

polymer might degrade due to high shear. The authors therefore used a simple magnetic

stirrer in a tank to produce deep vortex while dispersing the polymer on the surface of water.

The practice may sound practical since the stirrer is located at the bottom of the tank as

compared to the impeller.

A better approach to induce contact between the polymer and the solvent is outlined by

Warholic et al. (1999), which is also pursued by Al-sarkhi and Hanratty (2001) and

Liberatore et al. (2004). Polymer powder was mixed with deionized water by injecting it into

the tank through a commercial mixing device (much like a carburettor) that covers wetting of

individual particles. The mixer has the shape of a tee. Water flows through one leg and is

directed out of the device through a constricted passage. This provides a vacuum that sucks

particles through the third leg into the flowing water. Agitation is employed to further

increase the bonding between the polymer and solvent. Al-Wahaibi et al. (2007) and Ngan et

al. (2007) stirred the solution at 40 RPM using a three-bladed propeller (marine propeller).

The choice to using the impel (ter \Nas atso mentioned by Warhotic etc (. (1999\, At-Sarkhi

and Hanratty (ZAAli and Lihe(ata(e et al. (200a). Their solution is agitated at 30 RPM with a

four-finned impeller that had a diameter of 0.6 m. On the other hand, magnetic stirrer was

also chosen as an alternative mechanism to mix the solution. IBello et al. (1996); Kiho et al.

(2000); Kim et al. (2001)]. A combination of magnetic stirrer and a roller was utilized by Sun

et al. (2005) in preparing their polymer solutions.

There are variations of agitation time reported in the literatures, from two-hour periods to up

to one week. Al- Wahaibi et al. (2007) and Ngan et al. (2007) stirred the solution for only two

hours, which is also practiced by Den Toonder et al. (1995). McConaghy and Hanratty (1977)

did 4 hours, while Ptasinki et al. (2001) mixed the solution for 10 hours. Brostow et al.

(2007) performed in a period of 6 to 24 hours, whereas Bello et al. (1996) done between 72 to

24 hours. The choice of 24 hours agitation was also reported by Kiho et al. (2000). Kim et al.

(2001), on the contrary, stirred their solution for one week. The time taken to agitate the

solution would depend on the speed employed for mixing, as well as the type of mixing

technique used. lf the solution is agitated for a long period using an impeller, there might be

chances that the polymer would degrade due to shearing effect. However, a shorter mixing

15

time would discourage a homogeneous solution to be achieved due to less bonding between

the polymers-solvent molecules.

ln order to reduce shear degradation due to mixing but promote molecules contact, the

polymer solution should be rested. ln literatures, the term that is used is hydration time.

Hydration is to cause to take up or combine with water or elements of water. On top of two-

hours stirring, Al-Wahaibi et ol. (2007) and Ngan et al. 12007l. Further hydrated the solution

overnight to make the total time the solution prepared of 24 hours. Den Toonder et al. (1995)

chosen the hydration time to be 12 hours. Jun et al. (2004) did not stirred at all, but hydrated

the solution for a period of 4 to 5 days. McComb and Rabie (1-982) did not mention on the

stirring time employed, but reported that their polymer solutions were used in 2 to 3 days

period. A definite selection of hydration time varies based on studies. Sun et al. (2005)

however, reported that the time the solution is allowed to mix and hydrate has proven to be a

critical factor. This argument might be biased since the technique that they performed is by

using a roller, instead of an impeller. Nevertheless, the idea that they stated is that stirring

time of at least twelve hours was needed to yield adequate mixing and stable characteristics

in time. This is reflected in their drag reduction results of using PAM and HPAM. They

further added that visual inspection of the solution throughout the first eight hours of the

stirring period indicated that the solution was not fully mixed. lt is possible that the polymer

aggregates early on in the preparation process and the rolling time is not sufficient to affect

the mixing.

A long period of hydration time is also called 'aging' in some literatures. The expression

"aging" collects a number of ill-understood phenomena as aggregation, degradation, cross-

linking and, last but not least, slow dissolution of the polymer gel particles (Chmelir et al.,

1979). Chemlir et ol. (1,979) observed viscosity reduction phenomena of diluted

polyacrylamide in water after being left in a prolonged period of time (30 days). They found

out the solution became cloudy and sometimes a small amount of precipitates could be

observed after storing in a long time. The authors attributed the reduced in viscosity is due to

the presence of the microorganisms in the form of yeast and their breeding form in the

aqueous solution of polyacrylamide. Upon addition of small amount of sodium azide the

decrease in solution viscosity is lessened. Reduction in viscosity also observed by Narkis and

Rebhun (1966). They mentioned that for the prepared concentration of 0.284 g/100 mL

solution of polyacrylamide, the Ired decreases from 12.85 for 3-days storage time to 8.68 for

16

32-days storage time. However, they further concluded that the reduced viscosity effect due

to storage time only pronounced in low-molecular weight polymer and not seen in high-

molecular weight one. Furthermore they claimed that the effect of solution age on measured

values of viscosity and intrinsic viscosity, [r1] is to be explained not by degradation but

probably by disentanglement of the polymer molecules, which is an integral part of the

formation of a true polymer solution.

Kulicke et al. (1982) further clarified that aqueous solution of PAAm indeed shows a time

dependent viscosity. They use the term solution instability and discovereO itrat the viscosity

decrease of PAAm solution not only occurred in the industrially produced PAAm, but also

the laboratory-synthesized, high purity one too when the molecular weight exceed 1.5 x 106.

The authors deduced this observation to the possibility of hydrogen bonding existed in the

aqueous solution of PAAm and further clarified the hydrodynamic volume becomes smaller

with time as confirmed by the gel permeation chromatography (GPC) test. The molecular

weight of the polymer, however, is unchanged as proven by the light scattering method done

by the researchers. Even if the polymer solutions were hydrated, a period of too long would

eventually degrade the solution, either chemically or biologically. ln order to avoid any

chemical or biological degradation, additives shall be added. Alcohol such as ethanol has

been chosen as an effective anti-bacterial agent (Den Toonder et o1.., 1995), whereas

Chemlir et al.. (1979) and Belo et ol.. (19961used a small amount of sodium azide dissolved

in the polymer. Alcohol such as isopropanol could also prevent chemical degradation of the

polymer solution (Junetal..,2004). Kihoef o/.. (2OO2|, on the other hand used some kind of

antioxidant, in which type is not mentioned in their study, to avoid the peroxidation of their

PIB solution.

Lumley (1969) outlined some of the qualitative properties of the polymer solution that could

be examined through general observation such as the solution clarity, soapiness and filament

formation' clarity is determined by light scattering method. Dilute solutions of polymers

cater very little light and appear to the eye as clear. Apparent milkiness or cloudiness is

usually the result of incomplete solution in the case of synthetic polymers, or of impurities

producing relatively insoluble gel-like lumps in the case of natural polymers' in term of

soapiness, the author mentioned that polymer solutions are commonly observed to have a

slightly soapy feel. However, to what physical property this subjective response corresponds

is not clear; from the remarks above on simple-shear viscosity, it appears unlikely to be either

17

the somewhat higher viscosity or the shear thinning character. It seems more likely to be

some sort of lubrication phenomenon, taking place when the distance between the fingers is

of the order of the effective molecular diameter. Filament formation is the most striking

departure of these very water-like solutions from Newtonian behaviour under superficial

observation. lt is universally observed that when a finger is dipped In the liquid and

withdrawn, a very long, coherent, tenuous thread trails from the finger to the liquid. ln the

light of the remarks above under viscosity, it seems likely that this phenomenon is due to the

remarkable increase of intrinsic viscosity in a pure axisymmetric strain.

In this study the polyacrylamide based polymer is used. Polyacrylamide is obtained through

the free radical polymerisation reaction of acrylamide (Kulicke et ol., 19821. Further, an

alkaline hydrolysis can be used to introduce acrylate groups into the polyacrylamide. A

saponification reaction with aqueous sodium hydroxide, NaOH at room temperature (23'C)

leads to the sodium salts i.e. poly(acrylamide-co-sodium acrylate) which has the same degree

of polymerisation at the basic polyacrylamide.

Figure 1.8: Synthesis of HPAM from PAAm

Partially hydrolysed polyacrylamide (HPAM, or sometimes given acronym of PHPAAm) is a

copolymer of acrylamide and sodium acrylate. The degree of hydrolysis is defined as the

number of carboxyl residues (COO-), Y, replacing the amide groups (CONH2), X, over the

total number of the macromolecular residues, as given by the equation:

Partially hydrolysed polyacrylamide molecules contain randomly distributed polar carboxyl

groups and behave as a polyelectrolyte in aqueous solution. The carboxyl groups carry

18

negative charges and polymer solution becomes an anionic polyelectrolyte. Polyelectrolyte

properties originate from the combination of macromolecular and electrolyte behaviour.

Because of the repulsion forces between ionised carboxyl groups, polymer chain extends and

uncoils in the solution. Therefore the effective size or volume of the polymer molecules

increases which leads to larger hydrodynamic interactions between polymer chains and water

molecules. This influences the transport properties of polyelectrolyte and increases its

intrinsic viscosity (Zeynali et al., 2004) Acrylamide based homo- and copolymers have been

used as flocculants, dispersants, retention aids, steric stabilizers, mineral flotation and paper

making (Lewandowska, 2006). Partially hydrolysed polyacrylamide, specifically is widely

used as associate thickeners in areas as diverse as municipal and industrial waste water

treatment, in drilling mud as a viscofier and shale stabilizer and in enhanced oil recovery\

(EOR). ln EOR a dilute aqueous solution of HPAM is used as a pushing fluid in the injection

wells to sweep oil in the reservoir into the production well. Thus the mobility of HPAM

solution plays an important role in such applications (Zeynali et al., 2004).

4.2 REFERENCES

1. Chemical Engineering. 160/260 Polymer Science and Engineering. Retrieved

February 7, 2012 from

http://www.stanford.edu/class/cheme160/lectures/lecture13.pdf

2. Jacob Mainus den, T. (1995). Drag Reduction by Polymer Additives in a Turbulent

Pipe Flow: Laboratory and Numerical Experiments. Retrieved February 8, 2012 from

http://www.mate.tue.nl/~hulsen/papers_open/1733

3. Vanapalli. (2006, May 8). News from Peace Heaven, the professional DRA (Drag-

Reducing Agents) supplier. Retrieved February 8, 2012 from

http://www.vf18.org/news.aspx

4. Wilhjelm, A. (1993). Polymer Powder. Retrieved February 8,2012 from

http://www.niro.com/polymer-powder.html

19

20