Woo T. Production of Polyurethane Nanocomposite (Master)

7/28/2019 Woo T. Production of Polyurethane Nanocomposite (Master)

1/41

DEPARTMENT OF CHEMICAL ENGINEERING

1E406 INDIVIDUAL

INQUIRY

Production of Polyurethane Nanocomposite

from Commercially Available Precursors

BY TIM WOO

Supervisors : Dr. Peter Halley

Dr. Darren Martin

Date Submitted: 27th October, 2000


2/41

- -

Abstract

This thesis will focus on the investigation on the morphology, properties and

chemorheology of novel rigid polyurethane nanocomposite prepared from commercially

available precursors.

Intercalated polyurethane nanocomposite has been synthesized from UC-30

polyurethane by Era and Cloisite 30B organoclay by Southern Clay Products. PPO 400

swelling agent has also been used. There was slight improvement in mechanical

properties such as tensile Youngs modulus and the flexural modulus. However, the

impact strength was reduced. This was because exfoliation of the clay was not achieved

as determined by the x-ray diffraction data. Hence not all the potential surface area of

the clay was utilized.

In one case however, an exfoliated nanocomposite was produced even though its

stoichiometry was not balanced. This proved that exfoliated nanocomposite was

possible, but this would require careful optimization of the amount of precursors added,

duration of shear, viscosity and amount and types of nanofillers added.

It is recommended that the chemical reaction between the polyurethane precursors and

the swelling agent should be monitored. This can be done by FTIR (Fourier Transform

Infrared Spectroscopy) so the chemistry between all reactants will be clearer. After

understanding the chemistry, the ideal stoichiometry for producing exfoliated, high

performance polyurethane nanocomposite can be deduced.


3/41

- -

Acknowledgment

Special thanks to Mr. Graham Ruhle and Mr. Lambert Bekessy for assisting in sampletestings, also thanks must go to my supervisors, Dr. Peter Halley and Dr. Darren Martin

for their continuous guidance and supports.


4/41

- -

Table of Content

Abstract ______________________________________________________________ ii

Acknowledgment ______________________________________________________ ii i

Table of Content ______________________________________________________ iv

Table of F igures _______________________________________________________ v

1.0 I ntroduction________________________________________________________ 1

2.0 L iterature Review ___________________________________________________2

2.1 Polyurethane __________________________________________________________ 2

2.1.1 Polyurethane Chemistry _______________________________________________ 2

2.1.2 Polyurethane Properties _______________________________________________ 4

2.2 Polymeric Nanocomposite________________________________________________ 4

2.2.1 Organoclay __________________________________________________________ 5

2.2.2 Nanocomposite Structure_______________________________________________ 6

2.2.3 Properties enhancement________________________________________________ 7

2.3 Preparation ___________________________________________________________ 7

2.4 Nanofillers in polyurethane ______________________________________________ 8

3.0 Experimental _______________________________________________________ 9

3.1 Plan of study___________________________________________________________ 9

3.2 Material ______________________________________________________________ 9

3.3 Apparatus_____________________________________________________________ 93.4 Methodology__________________________________________________________ 10

4.0 Resul ts and D iscussion ______________________________________________12

4.1 Rheological Effect Viscosity Profile _____________________________________ 12

4.2 Tensile Properties _____________________________________________________ 13

4.3 Charpy Impact Strength________________________________________________ 14

4.4 Flexural Properties ____________________________________________________ 15

4.5 X-Ray Diffraction (XRD) Result _________________________________________ 16

5.0 Future I nvestigation ________________________________________________ 196.0 Conclusion________________________________________________________ 20

7.0 Reference_________________________________________________________ 21

Appendix A-Equipment Photos __________________________________________22

Appendix B-Data and Equipment Detail s __________________________________25

Appendix C-XRD Plots _________________________________________________ 35


5/41

- -

Table of Figures

F igure 2.1 Major applications of polyurethane____________________________________________ 2

F igure 2.1 Urethane and urea linkage in polyurethane______________________________________ 3

F igure 2.2 The effect of molecular weight of polyurethanes on properties_______________________ 4

Figure 2.3 Three possible structur es when nanof il lers are added to polymeri c mater ials___________ 6

F igure 3.1 The basic process of making polyurethane nanocomposite samples in thi s project______ 10

F igure 4.1 Ef fect of clay on viscosity of polyurethane______________________________________ 12

Table 4.1 Tensile Properti es of the polyur ethane nanocomposite produced_____________________ 13

Table 4.2 Impact strength of the polyurethane nanocomposite produced_______________________ 14

Table 4.3 F lexur al Propert ies of the polyurethane nanocomposite produced____________________ 15

Table 4.4 XRD of the polyurethane nanocomposite produced________________________________ 16

Figure 4.2 The exfol iation of clay when PPO reacted with part A_____________________________ 17

Fi gure A-1: I nstron__________________________________________________________________ 23

F igure A-2: Charpy Impact Tester-300J_________________________________________________ 23

F igure A-3: X-Ray Dif fr actometer_____________ ________________________________________ 23

F igure A-4: RDSI I Rheometer ________________________________________________________ 23

F igure A-5: Charpy I mpact Tester-4J ___________________________________________________ 23

F igure A-6: M il kshake M ixer _________________________________________________________ 23

Figure A-7: Mechani cal Sample Mould _________________________________________________ 24

Figure A-8: Degasser_______________________________________________________________ 24

Figure A-9: I nstron (Tensile Testing Mode) _____________________________________________ 24

F igu re A-10: Vacuum Oven ___________________________________________________________24


6/41

- -

1.0 Introduction

Manufactures insert different fillers into polymers for various reasons. Some traditional

fillers are: calcium carbonate, glass, clays and various mineral fibres. The purposescould be improving mechanical properties such as stiffness and toughness of the

materials or enhancing resistance to fire and ignition. Another simple reason is just

reducing cost. However, addition of filler typically imparts drawbacks to resulting

composites such as brittleness or opacity.

Nanocomposites are a new class of composites based on nanometer scale fillers. This

implies that at least one dimension of the dispersed filler particle must be in the

nanometer (10-9

m) range. From the many possible nanocomposite precursors, ones

based on clay and layered silicates are more widely investigated due to the fact that the

starting clay materials are easily available and also the intercalation chemistry of these

materials have been studied for a long time (Review by Alexandre and Dubolis 2000).

Clay platelets also have a high surface area and aspect ratio (200 1000

diameter/thickness ratio) which is attractive from a structural point of view.

Polyurethane is any polymer with large number of urethane linkages. A urethane

linkage is formed from the reaction between an isocyanate functional group and a

hydroxyl functional group. The polyurethane family has an enormous degree of

versatility in terms of mechanical and other properties available due to the great number

of possible precursors. With polyurethane nanocomposites, it is believed that properties

such as stiffness, tensile strength and heat distortion temperature can be improved and at

the same time the drawbacks on properties such as impact strength and clarity can be

minimized.

This thesis will focus on the investigation on the morphology, properties and

chemorheology of novel rigid polyurethane nanocomposite prepared from commercially

available precursors.


7/41

- -

2.0 Literature Review

2.1 Polyurethane

The first fibre-forming polyurethane was developed by Professor Otto Bayer in 1937 as

polymer fibre to complete with nylon. The invention ranks among the major

breakthroughs in polymer chemistry, but at that time the polymer was dismissed as

impractical. Today, polyurethanes are among the most important class of specialty

polymers. The following diagram illustrates the major applications for polyurethane

(Szycher 1999).

Figure 2.1 Major applications of polyurethane

2.1.1 Polyurethane Chemistry

Polyurethanes include all polymers with a plurality of urethane groups in the molecular

backbone, regardless of the chemical composition of the rest of the chain. Hence

polyurethanes are an enormous family of polymers, which show great diversity in the

properties between different members. The chemistry of urethanes makes use of the

reaction of organic isocyanates with compounds containing active hydrogens. An


8/41

- -

example would be the formation of urethane linkages from isocyanate groups reacting

with hydroxyl groups (Szycher 1999). The following diagram shows this example

graphically.

Figure 2.1 Urethane and urea linkage in polyurethane

The important building blocks for polyurethanes are the isocyanates, polyols, diamines

and polyamines.

Isocyanates with two or more NCO groups in the molecule are required for the

formation of polyurethanes. Aromatic as well as aliphatic and cycloaliphatic di and

poly-isocyanates are suitable for the polyurethane chemistry. However aromatic types

are more important in terms of volume and economics because they are significantly

more reactive than the aliphatic one (Oretel 1994).

Polyols are compounds with several hydroxyl functional groups. Besides the

isocyanates, they are the essential components for the formation of polyurethanes.

Lower molecular weight polyols act as chain extenders or as crosslinkers while the

higher molecular weight polyols are the actual basis for the formation of the

polyurethanes (Oretel 1994).

Di- and polyamines play an important role for the formation of polyurethanes in terms

of being starters for polyols and as chain extenders. Diamines are especially suited as

crosslinking agents or chain extenders because of the much higher reactivity of the


9/41

- -

amine function in comparison to the hydroxyl function towards isocyanates (Oretel

1994).

2.1.2 Polyurethane Properties

Depending on their structure, polyurethanes cover a broad range of properties. They

could range from rigid solid polyurethane to soft, elastic polyurethane foam. Besides the

different in composition, molecular weight of polyurethanes can also greatly affect the

physical properties of a polymer. The general trend is shown in the following diagram.

Figure 2.2 The eff ect of molecular weight of polyur ethanes on properti es

The polymer chains of polyurethanes have a spacial architecture. They may be linear,

branched, or networked. Polyurethanes display stereo microstructure. They exist as

homopolymers and copolymers. Also, polyurethanes can be crystalline solids,

segmented solids, amorphous glasses, or viscoelastic solids. Depending on what state

the polyurethane is in, it could show very different properties (Szycher 1999).

2.2 Polymeric Nanocomposite

The existing polymeric resins could be upgraded and diversified via the development of

novel nanofillers based on organophilic layered silicates. Novel polymeric

nanocomposites possess attractive properties such as flame retardant, barrier properties,


10/41

- -

improved optical and electrical properties and so forth. Mica, talc, kaolin and

wollastonite are the traditional layered silicates fillers in the plastics industry. For the

use in the plastics industry, layered silicates are rendered organophilic, they are

insoluble in water and capable of swelling in organic media by means of ion exchange.

They are then dispersed in the plastics matrix by applying shear during processing

(Dietsche et al. 1998).

Hydrophobic behavior and an increase of the spacing between sheets of layer-lattice

silicates are two of the most important factors for the silicates to be use as

nanocomposite fillers. Ions exchange in the intermediate layers is the usual method to

obtain hydrophobic behavior and an increase in spacing for layered- silicates. In water-

swollen layered silicates, Na+

ions are replaced with organic cations (e.g. alkyl

ammonium ions). The lengths of the alkyl chains in the alkyl ammonium ions affect the

extent of the increase in the spacing between layers. The distance between layers can be

further increase by the result of the shearing action during processing. For exfoliated

layered silicates (the term exfoliated will be discussed in the later section), ionic and

hydrogen bond interactions between layers, especially between edges, can lead to the

formation of skeletal network structures. These skeletal network structures are critical

for the rheological and mechanical properties of nanocomposites (Dietsche et al. 1998).

2.2.1 Organoclay

Clays have been recognized as potentially useful filler materials in polymer matrix

composites. Purity level, cation exchange capacity and aspect ratio are the clay

characteristics of great importance. For example, purity of the clay can affect

mechanical properties of the polymer composite and optimum clarity in packaging (Lan

et al. 1999).

To make the clays compatible to polymers, inorganic cations are replaced by organic

onium ions via ions exchange. This will also increase the spacing between the silicate

layers which in turns promote the penetration of polymer chains or precursors into the

space between silicate layers. The length of the surfactant chain length and the charge


11/41

- -

density will determine how far apart the silicate layers will be forces. The longer the

chain length and the larger the charge density, the further apart the silicate layers will be

forced (LeBaron, Pinnavaia and Wang 1998).

2.2.2 Nanocomposite Structure

Depending on how does the polymer interact with the layered silicate, three types of

structure can be identified. If the polymer is not capable to intercalate between the

silicate sheets, a phase separated composite is obtained. The filler material forms a

tactoid structure in the polymer matrix. In this case, the properties of the composite

remain in the same range as traditional microcomposite. For true nanocomposite, there

are two classes. They are the intercalated structure and the exfoliated or delaminated

structure. Intercalated structure occurs when a single (and sometimes more than one)

extended polymer chain is intercalated between the silicate layers resulting in a well

ordered multiplayer morphology built up with alternating polymeric and inorganic

layers. For the case in which the silicate layers are completely and uniformly dispersed

in a continuous polymer matrix, it is called an exfoliated or delaminated structure. The

following is a graphical illustration of the three different types of structure arise when

nanofillers are added to polymer (Review by Alexandre and Dubolis 2000).

Figure 2.3 Three possible structur es when nanof il lers are added to polymeri c materi als


12/41

- -

2.2.3 Properties enhancement

Layered silicate nanofillers have drawn a lot of attention because of the tremendous

improvement in mechanical properties, thermal stability, fire retardancy, superior barrier

properties and so on. Pioneering work at Toyota research developed nylon 6

nanocomposites laboratory for underbonnet applications. Researchers reported an

increase in tensile strength (107 from 69 MPa), tensile modulus (2.1 from 1.1 GPa) and

heat distortion temperature (152 from 65C) of their nanocomposite when compared to

pristine nylon-6 (Kaviratna, Pinnavaia and Lan 1995). Successful nanocomposites of

polyethylene, polyester, polystyrene and epoxy resins have also been reported (Review

by Alexandre and Dubolis 2000). The property profile enhancement for these different

systems is different in each individual case.

2.3 Preparation

There are four major preparation methods for nanocomposite, they are: (Review by

Alexandre and Dubolis 2000)

Exfoliation-adsorption: A solvent in which the polymer is soluble is applied for the

layered silicate to be exfoliated into.

In situ intercalative polymerization: In this technique, the layered silicate is swollen

within the liquid monomer (or a monomer solution) so as the polymer formation can

occur in between the intercalated sheets.

Melt intercalation: The polymer is first melted and then the silicate is mixed into the

melt. If the layer surfaces are sufficiently compatible with the polymer melt, the

polymer can fit into the interlayer space to form either an intercalated or an exfoliated

nanocomposite. Using this method, no solvent is required.

Template synthesis: This method requires the silicates to be formed in an aqueous

solution containing the polymer and the building blocks for the silicate.

In this thesis, the nanocomposite is formed using an exfoliation-adsorption technique.

The details of the method will be listed in the methodology section.


13/41

- -

2.4 Nanofillers in polyurethane

Polyurethane is a very versatile family of polymers which are capable to perform an

enormous range of applications. However the stiffness, strength and heat distortion

temperature of rigid grades polyurethanes are generally below that expected from a

true engineering (structural) plastic. In this thesis, ways to enhance the mechanical

properties of commercially available polyurethane via the addition of nanofillers is

investigated. Some papers on synthesis and characterization of novel segmented

polyurethane/clay nanocomposites include the one by T.K Chen, Y.I Tien, and K.H Wei

1999 and also the one by J. Finter et al. 1999.


14/41

- -

3.0 Experimental

3.1 Plan of study

The key point in this project is to produce an intercalated or exfoliated polyurethane

nanocomposite from commercially available organoclay and polyurethane. To

determine if the polyurethane composite is a nanocomposite or microcomposite, XRD

data will be required. Once a polyurethane nanocomposite is established, the mechanical

and rheological properties will be analysis to see if any improvement exists.

3.2 Material

Cloisite 30B was produced by Southern Clays Product and was the most hydrophilic in

their Cloisite range organoclays. This was the nanofillers used in this experiment. It had

an aspect ratio range from 200 to 1000, surface are of 750 m2

per gram and a cation

exchange capacity of 100 milli-equivalents per 100 grams of clay. The polyurethane

used in this experiment was UC-30, a two parts, castable rigid polyurethane by Era. A

swelling agent was also used. This was PPO 400 which was a polyether macrodiol (HO

OH) with a molecular weight of 400 grams per mole.

3.3 Apparatus

The apparatus used in the experiment included; milkshake mixer which was the

primitive mixer first used to disperse filler into the polymer matrix. High shear mixer

(homogeniser) was used to provide a high shear so the clay can be evenly distributed

into the polyurethane precursor. Rheological properties are tested via Rheometrics

RDSII rheometer. Charpy impact tester was applied to measure the unnotched charpy

impact strengths of samples. Instron was used to determined mechanical properties of

samples such as flexural modulus, tensile strength and so on. WAXD (wide-angle x-ray

diffractometer) was employed for detecting the clay basal spacing (Detailed description

of x-ray diffraction included in Appendix B-1). The samples for mechanical testing

were produced by a silicone mechanical sample mould and polyurethane was poured

into this mould when it is a liquid. Degasser created a vacuum so gases trapped in the


15/41

- -

polyurethane were removed. This was very important because trapped air bubbles in

polyurethane were stressors and created weak spots in the sample hence reducing the

mechanical properties. Vacuum oven was used to dry the organoclays and other

components before making the nanocomposite. It was also utilized for curing of the

polyurethane nanocomposite upon the removal from the mould.

Pictures of some of the above equipment are included in this report attached in

Appendix A. Accuracy of equipment is included in appendix B.

3.4 Methodology

The following are the basic procedures of the experiments for this project:

Figure 3.1 The basic process of making polyurethane nanocomposite samples in this project

Preparation of materials: The Cloisite 30B organoclays and the PPO 400 swelling agent

(if required) have to be dried in the vacuum oven overnight before used. The

organoclays are dried at 110C and the PPO 400 at 80C. The reason of this is to reduce

as much moisture content as possible because water can cause foam formation in

polyurethane. This is especially important for the clays because they generally absorbed

a lot of moisture from the atmosphere due their large surface area.

Preparation of materials

Shearing clay into polymer precursor

Mixing together the polyurethane

precursors

Rheological testingManufacturing mechanical testingsamples

Curing of samples Samples testing


16/41

- -

Shearing clay into polymer precursor: For the first several experiments, the clays were

sheared into part A precursor of the UC-30 polyurethane after drying. However, there

was no major improvement in properties and the XRD data indicated that the clays were

only partially intercalated. A swelling agent was then applied (PPO 400). In that case,

the clay was first sheared into the PPO first at a concentration of 30%. After that, the

mixture was sheared into part A or part B precursor depended on the experiment. Then,

the resulting mixture was degassed.

Mixing together the polyurethane precursors: In this step, the other precursor of the

polyurethane was added and the two were mixed by hand using a spatula. If rheological

testing were required, samples would be taken from this point. After that, the reacting

polyurethane was degassed to minimize the amount of air bubbles in the resulting

nanocomposite.

Manufacturing mechanical testing samples: This is done by pouring the liquid

polyurethane nanocomposite mixture into the mechanical testing sample mould (photo

of this is included in appendix A). The polyurethane would take a few hours before

solidifying.

Curing of samples: After the samples solidified in the mould, they have to be taken out

and cured at 80C for 16 hours. This was done using the vacuum oven.

Samples testing: The standards followed in testing the samples are:

Tensile properties of plastics, D 638 97

Flexural properties, D 790 96a

Method for impact tests on plastics, AS 1146.2 1990


17/41

- -

4.0 Results and Discussion

4.1 Rheological Effect Viscosity Profile

The following is a comparison of the viscosity profiles between 1% clay polyurethane

and the 0% clay polyurethane.

Figure 4.1 Eff ect of clay on viscosity of polyurethane

Figure 4.1 shows that there is no significant different in the viscosity profile between the

samples. This is expected since the clay containing sample only had 1% in it. Hence,

low loading of clay in polyurethane nanocomposite will not affect the viscosity

characteristic of the original polyurethane.

Viscosity profile of UC-30 polyurethane

nanocomposite with respect to time

0

100

200

300

400

500

600

0 500 1000 1500 2000 2500 3000 3500 4000 4500

Time (s)

Viscosity(Pa.s

)0% clay

1% clay


18/41

- -

4.2 Tensile Properties

Table 4.1 Tensile Properties of the polyurethane nanocomposite produced

SampleStress at peak

(MPa)

% Strain at

break

Youngs

Modulus (MPa)

0% clay polyurethane * 42.6 15.56 616

1% clay polyurethane 38.3 18.36 659

4% clay polyurethane 32.7 9.03 691

5% clay polyurethane * 37.1 10.92 487

5% clay polyurethane *^ 32.2 8.07 555

5% clay polyurethane *# 34.5 9.68 593

* The Cloisite 30B organoclay is not presheared into the PPO 400 swelling agent.

# Milkshake mixer was used instead of the high shear mixer.^ The PPO and clay mixture was sheared into the part B precursor first then mixed into the part A

precursor.

According to the literature, the stress at peak (yield stress) may vary strongly depending

on the nature of the interactions between the matrix and the filler. Hence the trends are

different between polymers (Review by Alexandre and Dubolis 2000). In this case, the

yield stress of the material decreases as the loading of clay increases are observed.

The elongation of the nanocomposite shows an interesting behavior. At low level of clay

addition (1%), there is an increase but at higher loading (e.g. 4%), the elongation of the

nanocomposite is reduced. This agrees with the result of the works done by Chen, Tien

and Wei on similar polyurethane material (Chen, Tien and Wei 1998). The cause of this

phenomenon is suspected to be how the microstructure of the nanocomposite changes

with respect to the level of nanofillers addition. At a low level, the filler materials are

distributed in the hard domain and have little effect on the polyurethane nanocomposite.

At higher loading, the fillers begin to distribute into both the soft and hard domain and

the elongation begins to reduce because the soft domain, which is responsible in

determining the elongation, is changing.

Regarding the Youngs modulus, there is an increase with the addition of clays

(Samples with PPO). With 4% clay, an increase of about 12% in Youngs modulus was


19/41

- -

achieved. This is not similar to the increase of 200% recorded in Youngs modulus by

Toyotas researcher in their pioneering work with nylon 6 nanocomposite.

From the above table, the difference in properties due to the preshearing of clay in PPO

is also shown. The tensile properties of samples without PPO were not as good as the

one with the organoclays first sheared into the swelling agent. Also the shearing of the

clay into which precursor (part A and part B) of the polyurethane first appeared to have

no significant effect in the tensile properties of the polyurethane nanocomposite.

However, the ratio of part A to part B precursor is 2:1 and part A precursor has a lower

viscosity, in term simplicity for processing, it is easier to shear the clay into the part A

precursor first. Differences in properties depend on the extent of intercalation or

exfoliated of the nanocomposite will be analyzed further in the X-ray diffraction (XRD)

data section.

4.3 Charpy Impact Strength

Table 4.2 Impact strength of the polyurethane nanocomposite produced

Sample

Unnotched Charpy

Impact Strength

(KJ/m2)

Level of Variance

0% clay polyurethane * 49.7 Medium

1% clay polyurethane *# 32.8 Medium

1% clay polyurethane 40.0 Low

3% clay polyurethane *# 20.8 Medium

4% clay polyurethane 34.4 Low

5% clay polyurethane *# 15.8 High

5% clay polyurethane * 12.0 Medium

5% clay polyurethane *^ 19.8 High

* The Cloisite 30B organoclay is not presheared into the PPO 400 swelling agent.# Milkshake mixer was used instead of the high shear mixer.

^ The PPO and clay mixture was sheared into the part B precursor first then mixed into the part A

precursor.

It is clear that the impact strength reduces as the filler content increases. This behavior is

commonly observed in all the traditional fillers such as glass, calcium carbonate and so


20/41

- -

on. According to the literature, one feature of nanocomposite is that the reduction of

impact strength due to the filler is minimal. This is certainly not the case in this

experiment. The reason behind this is the fact that exfoliated nanocomposite is not

produced in this experiment. In the x-ray diffraction result section, this will be

investigated further.

The reduction in impact strength of samples with the addition of PPO is less than those

without. The level of variance also lowered. This is because the PPO swelled up the clay

and caused the nanocomposite to be more intercalated. Definition of level of variance

and raw data will be included in Appendix B.

4.4 Flexural Properties

Table 4.3 F lexur al Properties of the polyurethane nanocomposite produced

Sample Flexural Modulus (MPa)

0% clay polyurethane * 1641

1% clay polyurethane 1752

4% clay polyurethane 1853

5% clay polyurethane * 1605

5% clay polyurethane *^ 1708

5% clay polyurethane *# 1777


# Milkshake mixer was used instead of the high shear mixer.


precursor.

The flexural modulus followed the similar trend as the Youngs tensile modulus. Filler

content goes up, the modulus goes up. Once again, the addition of PPO as a swelling

agent induces positive effect to the flexural modulus. With PPO, 4% clay loading

facilitated a 13% increase in flexural modulus.


21/41

- -

4.5 X-Ray Diffraction (XRD) Result

In this experiment, the main objective is to see if intercalated or exfoliated

nanocomposite are produced. If the layer spacing of the nanocomposite is larger than the

original clay, the nanocomposite is intercalated. If there is no diffraction peak related to

clay, the nanocomposite is totally exfoliated. The diffraction peak related to the clay

should be located between equal to 0 and equal to 10. The following table will

summarize the XRD data measured during the experiment, the actual XRD plots will be

attached in Appendix C.

Table 4.4 XRD of the polyurethane nanocomposite produced

Sample Silicate Layer Spacing (

A )

Types of

Nanocomposite

Cloisite 30B organoclay * 18.87 ____________

PPO + 30% clay 31.98, 27.94 Intercalated

1% clay polyurethane *# 43.27, 19.03 Partially intercalated

1% clay polyurethane 49.04 Intercalated


4% clay polyurethane 43.06,19.62 Partially intercalated


5% clay polyurethane * 40.12, 19.03 Partially intercalated

5% clay polyurethane *^ 40.87, 19.71 Partially intercalated

PPO + 8%clay +Part A _____________ Exfoliated


# Milkshake mixer was used instead of the high shear mixer.


precursor.

This table illustrated clearly why only minor improvements are observed in mechanical

properties. The two values for silicate layer spacing in some nanocomposite correspond

to two intensity peaks on the XRD plot related to the clay. If the silicate layer spacing of

the clay in the nanocomposite is bigger than the original clay in the powder form. The

nanocomposite is intercalated. If there is no intensity peak relates to the clay in the XRD


22/41

- -

plot, then the nanocomposite is exfoliated. With the exception of the last case, all the

nanocomposite produced are only intercalated. Most are evenly partially intercalated.

This is due to not enough shear being impart on the clay during processing because of

the part A precursor low viscosity. To maximize the potential of the organoclay, all

potential surface area of the clay need to be exposed to the polymer matrix. Hence,

exfoliation of the clay is necessary. Clearly the introduction of swelling agent further

intercalated the clays. The 1% clay polyurethane nanocomposite with PPO is fully

intercalated. However, at 4%, there is still of a portion of clays not intercalated.

As mentioned before, one sample is exfoliated. This sample was initially planned to be

8% clay polyurethane nanocomposite. From the XRD, there is no peak in the =0 to

=10 region which implies the clay is exfoliated. During the process of shearing the

PPO and clay mixture into the part A precursor, something unexpected happened. Due

to the high content of clay, a longer shearing time was applied. Also the high level of

clay caused the mixture to raise to a higher temperature than usual. This started a

reaction between the part A precursor and the PPO swelling agent. Because of this, the

viscosity of the mixture began to rise which in turn enable the high shear mixture to

impart more shear on the organoclays and broke the layered structure of the clay. As

more and more PPO reacted with the part A, the mixture eventually solidified before the

addition of the part B precursor. So, the PPO swelling agent actually acted as a chain

extender for the part A precursor in this case. The follow diagram illustrated the

process:

Figure 4.2 The exfol iation of clay when PPO reacted with part A

HO

OH

HO

OH

HOOH

30% clay

~30A

Shear the PPO

& clay mixture

into the part Aprecursor

O=C=N N=C=O

**Exfoliated nanocomposite

(Skeletal structure)


23/41

- -

The resulting solid gives a very stiff, tough appearance, however the properties of this

sample were not optimized because the stoichiometry was out of balance. Due to the

scope of, no further testing has been undertaken. By controlling the shear, temperature

and stoichiometry, it is possible to produce exfoliated nanocomposite. Therefore with

careful optimization of the amount of precursors added, duration of shear, viscosity and

amount and types of nanofillers added, novel polyurethane nanocomposite with greatly

enhanced properties is likely to be manufactured.


24/41

- -

5.0 Future Investigation

Chemical reaction between the polyurethane precursors and the swelling agent should

be monitored because an exfoliated nanocomposite can be produced from them asdiscovered in the experiment. This can be done by FTIR (Fourier Transform Infrared

Spectroscopy) so the chemistry between all reactants will be clearer. After

understanding the chemistry, the ideal stoichiometry for producing high performance

polyurethane nanocomposite can be deduced.

Other possible future works include using clay with know composition, investigating

the effect of higher loading of clay (such as 20%) and so forth.


25/41

- -

6.0 Conclusion

Intercalated nanocomposite were successfully made. Most of the intercalated

nanocompostie were only partially intercalated due to not enough shear being impart onthe clay during processing.

PPO 400 was an effective swelling agent because of its low molecular weight. This

was evident by the XRD data. PPO 400 was also capable to be use as chain extenders

for the part A precursor. By doing this, it is possible to create an exfoliated

nanocomposite as illustrated in the experiment. However, the ideal stoichiometry is yet

to be found.

The nanocomposite with organoclay first sheared into the PPO intercalated to a

greater extent than those with the clay being presheared into the PPO.

Viscosity profile was not affected by the clay filler because only low concentration

was added. This might change as the level of clay increases.

There was only minor improvement in mechanical properties which was due to the

fact that only intercalated nanocomposite was made. This implied that not all the

potential surface area was utilized. Unless all the potential surface of the clay was used,

dramatic enhancement in properties would not occur.

There was still reduction in the impact strength upon the addition of filler.

One exfoliated nanocomposite is produced even though its stoichiometry is out of

balance. This proved that exfoliated nanocomposite is possible. However, this would

require careful optimization of the amount of precursors added, duration of shear,

viscosity and amount and types of nanofillers added.


26/41

- -

7.0 Reference

Books

1. Cullity B.D. 1978, Elements of X-Ray Diffraction, 2

nd

edition, Addison-WesleyPublishing Company, Candana

2. Metcalfe, C.H, J.E williams and F.E. Trink 1984, Modern Physics, Holt Rinehart

and Winston Publishers, Japan

3. Norton, G.M and G. Suryanarayana 1998, X-Ray Diffraction- A Practical

Approach, Plenum Press, America

4. Ohanian, H.C. 1989, Physics, 2nd edition, Penguin Books Canada Ltd., Canada

5. Oretel, G. 1993, Polyurethane handbook, 2nd edition, Hanser/Gardner Publications

Inc., Germany

6. Szycher, M. 1999, Szychers Handbook of Polyurethane, CRC Press LLC,

America

Journals

1. Alexandre M. and M. Dubois 2000, Polymer-Layered Silicate Nanocomposites:

Preparation, Properties and Uses of a New Class of Materials, Materials Science

and Engineering, volume 28 (2000), P.1-63

2. Chen T.K., Y.I. Tien and K.H. Wei 1998, Sythesis and Characterization of Novel

Segmented Polyurethane/Clay Nanocomposite via Poly(-caprolactone)/Clay,

Journal of Polymer Science, P.2225-2232

3. Finter .J, R. Mulhaupt, R. Thomann and C. Zilg 1999, Polyurethane

Nanocomposites Containing Laminated Anisotropiic Nanoparticles Derived from

Organophilic Layered Silicates, Advanced Materials, volume 11, P.49-52

4. Lan T., Y. Liang, G.W. Beall and K. Kamena 1999, Advances in Nanomer

Additives for Clay/Polymer Nanocomposites

5. LeBaron P.C., T.J. Pinnavaia and Z. Wang 1999, Polymer-Layered Silicate

Nanocomposites: An Overview, Applied Clay Science, volume 15 (1999), P.11-29


27/41

- -

Appendix A

Equipment Photos


28/41

- -

Figure A-1: I nstron F igure A-2: Charpy Impact Tester-300J

Figure A-3: X-Ray Diffractometer F igure A-4: RDSI I Rheometer

Figure A-5: Charpy I mpact Tester-4J F igure A-6: Milkshake M ixer


29/41

- -

Figure A-7: M echanical Sample M ould F igure A-8: Degasser

F igur e A-9: I nstr on (Tensile Testing Mode) F igur e A-10: Vacuum Oven


30/41

- -

Appendix B

Data and Equipment

Details


31/41

- -

Tensile PropertiesParameters

Crosshead speed: 5.0000 mm/min

Span: 100.00 mm Equipment toleranceLoad cell: 10 kN Load measurement accuracy: +/- 0.5% cell capacity

Standard followed: D 638 - 97 Strain measurement accuracy = +/- 0.5%

Equipment used: Instron 5584 Crosshead speed measurement accuracy = +/- 0.15

Sample

Stress at

peak (MPa)

% Strain at

Break

Young Modulus

(Mpa) Note

1 38.01 9.91 635 5% Closite 30B organoclay into

2 36.90 10.02 644 UC-30polyurethane (high shear mixer

3 36.57 10.42 463 and mix into part A)

4 37.61 12.70 352 Load cell 10kN

5 36.65 11.55 341

Average 37.15 10.92 487

S.D 0.63 1.19 147

Sample

Stress at

peak (MPa)

% Strain at

Break

Young Modulus

(MPa) Note


2 35.79 8.78 646 UC-30polyurethane (high shear mixer

3 31.53 7.22 684 and mix into part B)

4 25.41 6.96 367 Load cell 10kN

5 34.27 8.82 415

Average 32.23 8.07 555S.D 4.11 0.91 152

Sample

Stress at

peak (MPa)

% Strain at

Break

Young Modulus

(MPa) Note


2 34.08 10.58 362 UC-30polyurethane (milkshake mixer

3 35.44 9.44 711 and mix into part A)

4 33.96 8.89 686 Load cell 10kN

5 34.88 9.73 684

Average 34.46 9.68 593

S.D 0.68 0.61 149

Sample

Stress at

peak (MPa)

% Strain at

Break

Young Modulus

(MPa) Note


2 42.70 15.35 589 UC-30polyurethane (High shear mixer)

3 42.75 15.53 578

4 42.17 15.47 645 Load cell 10kN

5 43.17 16.84

Average 42.61 15.56 616

S.D 0.41 0.81 37


32/41

- -

Tensile PropertiesParameters


Span: 100.00 mm Equipment tolerance

Load cell: 10 kN Load measurement accuracy: +/- 0.5% cell capacity

Standard followed: D 638 - 97 Strain measurement accuracy = +/- 0.5%

Equipment used: Instron 5584 Crosshead speed measurement accuracy = +/- 0.15

Sample

Stress at

peak (MPa)

% Strain at

Break

Young Modulus

(MPa) Note


2 38.22 17.02 677 UC-30polyurethane (High shear mixer

3 38.26 18.17 707 and mix into part A with PPO)

4 38.34 17.40 702 Load cell 10kN

Average 38.32 18.36 659S.D 0.11 1.72 74

Sample

Stress at

peak (MPa)

% Strain at

Break

Young Modulus

(MPa) Note


2 31.87 8.99 713 UC-30polyurethane (High shear mixer

3 34.09 8.54 765 and mix into part A with PPO)

4 32.08 9.66 651 Load cell 10kN

5 32.83 8.76 621

Average 32.74 9.03 691

S.D 0.87 0.43 56

RheologicalEquipmen Rheometrics RDSII

Geometry:50 mm parallel plates

Test type: Dynamic time sweep test

Temperat 23C

Strain: 10%

Frequency10 rad/s

Transduc 200 g.cm

XRDEquipmen Phillips generator

Equipmen Full width half maximum of 0.025

Waveleng 1.54 e-10 m

Speed: 0.5 to 1 per min

Range: 0 to 35


33/41

- -

Flexural PropertiesParameters


Span: 40.00 mm

Load cell: 10 kN

Standard followed: D 790 - 96a

Equipment used: Instron 5584Equipment tolerance

Load measurement accuracy: +/- 0.5% cell capacity

Strain measurement accuracy = +/- 0.5%

Crosshead speed measurement accuracy = +/- 0.15

Sample

Flexural

Modulus (MPa) Note

1 1578.0 5% Closite 30B organoclay into

2 1507.0 UC-30polyurethane (high shear mixer

3 1557.0 and mix into part A)

4 1777.0 Load cell 10kNAverage 1604.8 S.D 118.6

Sample

Flexural

Modulus (MPa) Note


2 1616.0 UC-30polyurethane (high shear mixer

3 1529.0 and mix into part B)

4 1699.0 Load cell 10kN

Average 1707.5 S.D 198.2

Sample

Flexural

Modulus (MPa) Note


2 1864.0 UC-30polyurethane (milkshake mixer

3 1735.0 and mix into part A)


5 1740.0

Average 1777.4 S.D 51.9

Sample

Flexural

Modulus (MPa) Note


2 1696.0 UC-30polyurethane (High shear mixer)

3 1620.0


5 1596.0

Average 1640.8 S.D 78.0


34/41

- -

Flexural PropertiesParameters


Span: 40.00 mm

Load cell: 10 kN

Standard followed: D 790 - 96a

Equipment used: Instron 5584Equipment tolerance

Load measurement accuracy: +/- 0.5% cell capacity

Strain measurement accuracy = +/- 0.5%

Crosshead speed measurement accuracy = +/- 0.15

Sample

Flexural

Modulus (MPa) Note


2 1806.0 UC-30polyurethane (High shear mixer

3 1752.0 and mix into part A with PPO)4 1791.0 Load cell 10kN

5 1757.0

Average 1751.8 S.D 59.7

Sample

Flexural

Modulus (MPa) Note


2 1834.0 UC-30polyurethane (High shear mixer

3 1900.0 and mix into part A with PPO)


Average 1852.5 S.D 43.2


35/41

- -

Charpy Impact StrengthParameters

Pendulum used: 4 J, 300J

Length: 125 mm

Test Method: Unnotched Charpy Impact Test

Standard followed: AS 1146.2 - 1990

Equipment used: ZwickEquipment tolerance: 0.01J for 4J pendulum and 0.25J for 300J pendulum

Level of Variance: 0 to 0.1 = low

Level of Variance: 0.1 to 0.3 = medium

Level of Variance: >0.3 = high

Note: Milkshalker mix, 5% closite 30B organoclay in uc-30 polyurethane

Sample

arpy mpact strengt o

unnotched speciemens (kJ/m2) width (mm)

thickness

(mm) A (Joules)

1 9.37 12.38 7.93 0.92

2 12.48 12.34 7.86 1.21

3 9.53 12.42 8.28 0.98

4 19.88 12.42 8.10 2.005 27.98 12.43 7.82 2.72

Average 15.85

S.D 8.01eve o

Variance 0.51


Sample



thickness

(mm) A (Joules)

1 26.84 12.50 7.51 2.52

2 22.68 12.42 7.74 2.18

3 18.63 12.45 7.76 1.80

4 19.42 12.38 7.82 1.88

5 16.26 12.41 7.83 1.58

Average 20.77

S.D 4.10Level of

Variance 0.20


Sample



thickness

(mm) A (Joules)

1 21.73 12.36 8.19 2.202 33.18 12.42 8.08 3.33

3 26.73 12.42 7.65 2.54

4 41.48 12.49 7.72 4.00

5 40.92 12.42 7.87 4.00

Average 32.81

S.D 8.67eve o

Variance 0.26


36/41

- -

Charpy Impact StrengthParameters

Pendulum used: 4 J, 300J

Length: 125 mm

Test Method: Unnotched Charpy Impact Test

Standard followed: AS 1146.2 - 1990

Equipment used: ZwickEquipment tolerance: 0.01J for 4J pendulum and 0.25J for 300J pendulum

Level of Variance: 0 to 0.1 = low

Level of Variance: 0.1 to 0.3 = medium

Level of Variance: >0.3 = high

Note: high shear mixer, 5% closite 30B organoclay in uc-30 polyurethane (mix into part a)

Sample



thickness

(mm) A (Joules)

1 7.90 12.34 8.21 0.80

2 31.41 12.32 8.45 3.27

3 24.67 12.41 8.10 2.48

4 25.45 12.32 8.10 2.545 9.39 12.35 8.11 0.94

Average 19.76

S.D 10.50eve o

Variance 0.53

Note: high shear mixer, 5% closite 30B organoclay in uc-30 polyurethane (mix into part b)

Sample



thickness

(mm) A (Joules)

1 9.39 12.38 8.43 0.98

2 12.10 12.45 8.50 1.28

3 17.22 12.35 8.65 1.84

4 8.95 12.34 8.78 0.97

5 12.28 12.37 8.82 1.34

Average 11.99

S.D 3.30Level of

Variance 0.27

Note: high shear mixer,ppo, 4% closite 30B organoclay in uc-30 polyurethane (mix into part a)

Sample



thickness

(mm) A (Joules)

1 26.47 12.44 8.32 2.742 31.72 12.39 8.60 3.38

3 38.49 12.49 8.32 4.00

4 38.16 12.42 8.44 4.00

5 36.92 12.46 8.50 3.91

Average 34.35

S.D 5.18eve o

Variance 0.15


37/41


38/41

- -

Appendix B-1

X-Ray Diffraction


39/41

- -

X-rays are high-energy electromagnetic radiation. They have energies ranging from

about 200 eV to 1 MeV, which puts them between -rays and ultraviolet (UV) radiation

in the electromagnetic spectrum (Norton and Suryanarayana, 1998). X-rays are

produced when any electrically charged particle of sufficient kinetic energy is rapidly

decelerated. Electrons are usually used, the radiation being produced in an x-ray tube,

which contains a source of electrons and two metal electrodes. The high voltage

maintained across these electrodes, some tens of thousands of volts, rapidly draws the

electrons to the anode, or target, which they strike with very high velocity. X-rays are

produced at the point of impact and radiate in all direction (Cullity 1978).

Diffraction

According to the wave theory, waves should bend around corners. As x-ray is an

electromagnetic wave, it should show this property. When waves encounter obstructions

with dimensions comparable with their wavelengths, the waves spread out and produce

spectral colors due to interference. Diffraction is defined as the spreading of light into a

region behind an obstruction (Metcalfe et al., 1984). It is due essentially to the existence

of certain phase relations between two or more waves. For the waves, the differences in

the length of the path traveled lead to differences in phase and the introduction of phase

differences produces a change in amplitude. A diffracted beam may be defined as a

beam composed of a large number of scattered rays mutually reinforcing one another.

At certain angles of incident (), diffraction will occur. This is described by the Bragg

law, which is formulated by W. L. Bragg. The formula is given below:

= 2dsin [1]

Experimentally, the Bragg law can be applied in two ways. By using x-rays of known

wavelength and measuring , this allows the determination of the spacing dof various

plane of a crystal. This is structural analysis and is the reason that x-rays diffraction

used in this experiment. The aim is to determine the spacing between the layers of clays

in the polyurethane nanocomposite. As mentioned earlier, how much the space between

the silicate layers of the clay increase relate directly to the enhancement of the

mechanical properties of the polyurethane nanocomposite. The second application is the

x-ray spectroscopy. In this case, a crystal with planes of known spacing d is used, is

measured in order to find out the wavelength of the radiation used (Cullity 1978).


40/41

- -

Appendix C

XRD Plots


41/41

- -

Listing of XRD plots:

Graph Sample

1 Cloisite 30B organoclay *

2 PPO + 30% clay

3 1% clay polyurethane *#

4 1% clay polyurethane


6 4% clay polyurethane


8 5% clay polyurethane *9 5% clay polyurethane *^

10 PPO + 8%clay +Part A

* The Cloisite 30B organoclay is not presheared into the PPO 400 swelling agent.# Milkshake mixer was used instead of the high shear mixer.

^ The PPO and clay mixture was sheared into the part B precursor first then mixed into the part Aprecursor.

Woo T. Production of Polyurethane Nanocomposite (Master)

Documents

Transcript of Woo T. Production of Polyurethane Nanocomposite (Master)