Summary: Last week

• Solid state of polymers– Crystalline state– Amorphous state

• Thermal transitions– Glass transition

temperature– Melting temperature

• Effect on properties– Mechanical– Thermal– Optical

• Processing and operating temperature range

Characterization methods

• Thermoanalytical techniques– DSC– TGA– DMA

• Spectroscopy– FTIR– Raman – NMR

Thermoanalytical methods

Introduction to Thermoanalytics

• Definition (ICTAC):

Thermal analysis (TA) is a group of techniques in which changes of physical or chemical properties of the sample are monitored against time or temperature, while the temperature of the sample is programmed

• Most methods are fast and easy to perform

Main Methods of Thermal Analysis

Differential scanning calorimetry (DSC)

Differential Scanning Calorimetry (DSC)

• A technique for determining the quantity of heat that is either absorbed or released by a sample undergoing a physical or a chemical change

• Measuring principles– Heat flux DSC: The temperature difference caused by the difference in the heat

flow of the sample and reference is measured– Power compensation DSC: The electric heating power required to compensate

the difference in heat flow is measured

dQ/dt = Total heat flow (W/g = J/g*s)

Cp = Specific heat capacity (J/g*oC)

dT/dt = Heating rate (oC/s)

f(t,T) = Time dependent (kinetic) response

e.g. melting, crystallization, curing etc.

Specific heat (Cp) represents the quantity of energy needed to raise the temperature of a unit of mass of sample by 1 °C

Ttfdt

dTC

dt

dQp ,

Heat flux DSC

• Aluminium pans are the most commonly used DSC pans

• It is important to ensure that the contact between the sample and the pan is very good– Large contact area is

desirable, in order to have uniform heat transfer

• Usually, the reference is an empty pan covered with a lid and sealed with a press

Applications of DSC

• Melting temperatures• Glass transition temperature• Degree of crystallinity• Crystallization temperatures• Specific heat capacity• Reaction kinetics

– Cross-linking reactions• Oxidative stability

– Oxidative induction time (OIT)

• Transition enthalpies• Phase transformations, phase diagrams• Polymorphism• Decomposition effects• Purity determinations• Compatibility

– Polymer blends– Co-polymers

DSC Thermogram

The Measuring Procedure

• Thermal history of the sample– Two heating cycles are used with

polymers:• The first run reveals the material

properties and unknown thermal history

• The second run also reveals material properties, but the thermal history is known

• The sample size (1-20 mg)– low mass improves resolution – high mass increases sensitivity

• The heating rate– Molecular motion associated with

Tg, Tcrys, Tm is time dependent. Therefore the heating rate affects the results

The Measuring Procedure

Analysis results depend on the following parameters:• Rate of heating and cooling• Size of the sample• Atmosphere used in the

oven– Inert or oxygen

• Thermal history of the sample

• As a rule of thumb:– Melting/crystallizaton:

• Sample 1 – 10 mg• 10 oC/min

– Glass transition:• Sample 10 – 20 mg• 20 oC/min

Thermal transitions in amorphous and semi-crystalline polymers

• For many amorphous polymers: CpTg 115 J/g

• Both the glass transition and melting temperatures are comparable to the regularity of the polymer structure

• Melting is endothermic. The width of the melting transition is due to different lamellar crystallites melting at slightly different temperatures

Determination of crystallinity

• Semi-crystalline polymers can be cooled down so quickly that crystallization is incomplete– The cold crystallization (exothermic reaction) can be observed

after the glass transition and before the melting transition temperature

• The crystallinity of the polymer sample can be calculated from the enthalpy values with the following equation:

H Hf f c/ ,

DHf = melting enthalpy of the crystals in sample (J/g).DHf,c = melting enthalpy of completely crystalline polymer. Values (enthalpy of the crystalline polymer) for most common polymers can

be found in the Polymer Handbook

Example of cold crystallization

• During cooling: – Crystallization of different

fractions/crystalline structures (peaks A-B)

• During heating: – Melting (peaks C-E) and

re-crystallization into more stable polymorphic structures (peak D)

S. Calligaris , G. Arrighetti, L. Barba, M.C. Nicoli, Journal of the American Oil Chemists' Society, 2008, doi 10.1007/s11746-008-1241-y

Sunflower Oil

Example of co-polymers and blends

• P(VDF-TFE) random copolymer – 80 mol% vinylidene fluoride – 20 mol% tetrafluoroethylene

• PMMA poly(methyl methacrylate)

• The endothermic peak near 220 oC is attributed to phase separation

• Simple Fox equation for miscible polymer blends:

w:s are mass fractions of the components– i.e. single Tg between the Tg:s of the

components is a proof of miscible blend

2

2

1

11

ggg T

w

T

w

T

Example of Thermoset, Curing

Comparison of first and second heating runs:First heating: Measurement of initial Tg and enthalpy of cureSecond heating: Measurement of Tg of fully cured sample. Verification that there is no residual cure exotherm

Modulated-Temperature DSC (MT-DSC)

Modulated Temperature DSC (MT-DSC)• A variant of DSC, in which the heating rate oscillates (a sinusoidal

temperature modulation of one frequency). The average heating rate is linear

• Heat flow from DSC experiments is composed of two parts, but conventional DSC can only measure their sum. MT-DSC separates the total heat flow into two parts: thermally reversing and non-reversing transitions

Ttfdt

dTC

dt

dQp ,

MT-DSC Reversing• Glass transition• Melting (some)

MT-DSC Non-reversing• Cross-linking

• Decomposition• Evaporation

• Crystallization• Curing

MT-DSC advantages

• Increased sensitivity for detecting weak transitions, eg. glass transition

• More accurate measurements of specific heat capacity

• Resolution of superimposed effects

The oscillating heating rate

The average temperature changes linearly

Quench-cooled PET: Initial crystallinity

TA Instruments

Quench-cooled PET: Initial crystallinity with MT-DSC

MT-DSC example of PET/ABS blend

Thermogravimetric Analysis (TGA)

Thermogravimetric Analysis (TGA)

• The measurement of the mass or change in mass as a function of temperature and/or time

• Changes of mass occur during:– Sublimation– Evaporation– Decomposition– Chemical reaction– Magnetic or electrical transformations

TGA Applications

• Thermal stability• Mass change• Decomposition temperatures• Decomposition kinetics• Oxidation behavior• Density change• Compositional analysis

– Filler content– Quantification of material composition– Moisture content

Polymer spectroscopy (eg. FTIR, Mass spect.)

TGA Example of PP/CaCO3

Dynamic mechanical analysis (DMA)

What is dynamic mechanical analysis?

• Dynamic mechanical analysis (DMA) can be simply described as applying an oscillating force to a sample and analysing the material’s response to that force during defined temperature program

• Properties obtained:– Major and secondary/tertiary transitions not identifiable by other methods– Bulk properties effecting material performance:

• The tendency to flow (viscosity) from the phase lag aka ability to lose energy as heat (damping)

• Stiffness (modulus) from the sample recovery aka ability to recover from deformation (elasticity)

• Data allows us to visualise what is happening within the samples– Relaxation of the polymer chains, changes in free volume (VF)

DMA principles

• Sinusoidal strain or stress applied and resultant sinusoidal stress/strain is measured– The phase difference (δ) between the two sine waves is also measured

• The phase lag will be 0° for purely elastic materials and 90° for purely viscous materials– Viscoelastic materials (e.g. polymers) will exhibit an intermediate phase

difference

• Controlled parameters are frequency, amplitude and temperature– Additionally humidity chamber can be used to determine the environmental

effects of humidity on the sample

• Most important parameters obtained are storage modulus G’() (phase difference 0°), loss modulus G’’() (phase difference 90°), and the ratio of G’’ and G’ tan

• Storage modulus can be called E’ and loss modulus E’’– Storage modulus is proportionate to elastic

modulus and describes the material ability to store mechanical energy

– Loss modulus describes viscous behavior i.e. the part of energy transformed to heat during deformation

Determining DMA parameters

DMA parameters• Storage modulus (E’)

– Elastic component– Correlates to stiffness or flexural modulus

• Loss modulus (E”)– Viscous component– Expresses a material’s ability to dissipate

mechanical energy through molecular motion– Peak indicates region of glass transition

• Loss tangent (tan δ)– The tangent of phase difference– Expresses the relative strength of a material’s

ability to store or dissipate energy– An indication of the state of material

• High tan delta indicates viscous behaviour• Low tan delta indicates elastic behaviour

– Indicates phase transitions (Tg)

– Describes internal friction and damping properties

𝐄=𝛔′

𝛆=𝐄∗𝐜𝐨𝐬𝛅

𝐄= {{ } ^ {𝛔 ¿ ¿𝛆

=𝐄∗𝐬𝐢𝐧𝛅

𝐭𝐚𝐧𝛅=𝐄} over { ′𝐄 ¿

DMA test methods

• Static stress-strain– Creep-recovery– Stress relaxation

• Dynamic stress-strain• Dynamic temperature/time scan• Dynamic frequency scan• Thermomechanical analysis

(TMA)

Mechanical properties

Long-term behaviour, MW, crosslinks, entanglements

Thermal transitions: Tm,Tg,Tα,Tβ,Tγ etc.

Thermal expansitivity

Applications of DMA

• Glass transition• Secondary transitions• Crystallinity• Molecular weight/crosslinking• Phase separation (polymer blends, co-polymers)• Ageing (physical and chemical)• Curing of networks• Orientation• Effect of additives

DMA: operating principles

1. A non-contact, direct drive motor provides the oscillatory or static force

required

3. A high-resolution linear optical encoder is used to

measure displacement

2. Drive motor transmits force directly

to air bearing slide

Choosing the correct geometry

• How a stress is applied will effect material deformation and behaviour!

• The shape and size of specimen

• Heating rate < 3 oC/min

• Frequency usually 0.01 - 200 Hz– If necessary the time temperature superposition (TTS) principle can be

applied to expand the field– Low temperature corresponds to a high frequency response and vice-

versa

Idealised DMA temperature scan

Glass transition

• Upon heating, a polymer goes from being hard (glassy) to soft (rubbery)• Glass transition temperature (Tg):

– Temperature at which there is sufficient energy for segmental motion of polymer chains

Measuring Tg

• DMA is significantly more sensitive than DSC (~10-100 times at the glass transition)

• Tg values from DMA and DSC are not same;– DMA measured from multiple points (E’ onset, E’’ peak and tan (δ) peak)– Sample size (thermal lag)– Heating rate– Frequency – Thermal calibrations (1-point, 2-point)– Used geometry (geometry factors, mass)– Sample isotropy

Secondary and tertiary transitions

• α-transition corresponds to Tg

• β- and γ-transitions arise from side group motion with some cooperative vibrations from the main chain, as well as internal rotation within a side group

Vinyl-ester

Polyethylene - relaxations

• α-relaxations– Peak representative of the crystalline phase

• β-relaxations– Due to motion of branches in the amorphous matrix

• γ-relaxations– Joint movements of chains containing at least 3 CH2 units

• DMA is much more sensitive to detect -relaxations than DSC

• Quantitative measurement of - and -relaxations is possible with DMA

Crystallinity, molar mass and crosslinking

Tg and polymer operating temperatures

POLYMER OPERATING TEMPERATURE• Amorphous polymers (high Tg) Top < Tg

– Polycarbonate

• Semicrystalline polymer (Tg < 0 °C) Tg < Top < Tm (e.g. PE, PP)– Polyethylene, polypropylene

• Thermosets and rigid polymers Top < Tg

– Polyurethane, polyimide

• Elastomers (rubbers) Top > Tg

– Polyisoprene, silicone rubberPROCESSING TEMPERATURE

Tpr > Tg

Tpr > Tm

Literature and References

• TheoryTuri, E.A. (edit.), Thermal Characterization of Polymeric Materials

Vol. 1-2, 2nd edition, Academic Press, USA 1997, 2420 pp.Menard, DMA: Introduction to the Technique, Its Applications and

Theory, CRC Press, 1999.

• Practice (and theory)Ehrenstein, G.W., Riedel, G., Trawiel, P., Thermal Analysis of

Plastics, Hanser, Germany 2004, 368 pp.Internet: Manufacturers of equipment

• TA Instruments• Perking Elmer• Netzch• Mettler Toledo

Spectrocopy methods

FTIRRamanNMR

Chemical structure

• Chemical composition– Co-monomer ratio– Sequences (block length)

• Stereoregularity

• Branching

• Based on absorption or emission of electromagnetic radiation• Studies of transitions between different energy levels:

• Electronic, vibrational, and magnetic states are all relevant in the spectroscopic analysis of polymers

What is spectroscopy

Requires that:

DE = hn

is fulfilled

n frequency of the photon, contains molecular information

photon photon

Examples of various spectroscopic methods

• Electron spectroscopy (X-ray photoelectron spectroscopy (XPS), electron spectroscopy for chemical analysis (ESCA)

• Electronic spectroscopy (UV/VIS)• Vibrational spectroscopy (IR, Raman)• Rotational spectroscopy (microwave region)• NMR spectroscopy (magnetic states)

Vibrational spectroscopy

• Photon energies associated with this part of the spectrum are not large enough to excite electrons, but may induce vibrational excitation of covalently-bonded atoms and groups

• Detection of transitions between energy levels in molecules, which result from vibrations of the interatomic bonds

• IR and Raman spectroscopy

Examples of molecular vibrations

http://chemwiki.ucdavis.edu

Fourier transform infrared spectroscopy (FT-IR)

FTIR

• Widely used method to characterize polymers– Qualitatively easy to use, quantitatively more challenging

• Polymer samples can be in the form of film, solution or pellet containing a mixture of the polymer powder and an IR-transparent powder such as potassium bromide (KBr)

• Bulk samples can be analyzed with reflection or attenuated total reflectance (ATR)

• Polymer spectra is unique and a large number of spectra libraries are available for identification

FTIR spectra

• Molecular vibrations result in a change in the bond dipole moment

• Groups like –CH, -C=O, and -CH3 are readily identified by a single absorption band

• Exact location of a band can be affected by local chemical environment i.e. intra- and intermolecular hydrogen bonding

• Carbonyl group can easily bond with hydrogen and absorption may occur from 1700-1900cm-1

Structural characterization of polymers using FT-IR

• Measurement of stereoregularity– Assignment of an IR frequency to a particular isomer for

example with NMR• Copolymer analysis (composition)• Measurement of branching• Characterization of polymer blends• Monitoring structural changes produced by oxidation, reduction and

hydrolysis• Average molecular weight by end group analysis

Structural characterization of polymers using FT-IR

• Extent of crosslinking

• Degree of crystallinity – The location of an absorbance peak can be sensitive to whether

the chemical groups lie in crystalline lamellae or in amorphous regions

• Studying surface species and reactions occurring at interfaces

Regions of the spectrogram

http://faculty.sdmiramar.edu/fgarces/LabMatters/Instruments/FTIR/FTIR.htm

Example of a FTIR spectrum

http://www.wcaslab.com/tech/tbftir.htm

IR spectrum of PS

3081,2 cm-1 - 3001,11 cm-1 C-H aromatic tension 2923,91 cm-1 and 2850,40 cm-1 CH2 asymmetric and symmetric tension 1943,19 -1728,23 cm-1 aromatic ring mono-substitution1452,28 cm-1 deformation CH2 + C=C of the aromatic ring1069,65 cm-1 flexion C-H in the plane

http://www.scielo.org.co/scielo.php?pid=S0122-53832008000100011&script=sci_arttext

Attenuated total reflectance (ATR)

• In the ATR technique, the IR radiation emitted by the source is internally reflected in a high refractive index crystal

• Some of the IR radiation (evanescent waves) interact with the sample in direct contact with the crystal

• Therefore a surface IR spectrum of the sample is obtained

Case study: FT-IR for measuring the degree of crosslinking in poly(ester-anhydride)Risto Hakala, PhD

OO

OO

PCL

PCL

PCL

PCLO

O

O

O

O

O

O

O

O

O

O

O O

O

O

O

Checking crosslinking using ATR (attenuated total reflectance)

Incoming IR beam

Mattson FT-IR and Pike ATR ATR extension

ATR diamond

SampleOutgoing IR beam

OO

OO

PCL

PCL

PCL

PCLO

O

O

O

O

O

O

O

O

O

O

O O

O

O

O

3000 2000 1000Wavenumber (cm-1)

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

Abso

rb

ance

2150 2100 2050 2000 1950 1900 1850 1800 1750 1700 1650 1600 1550 1500 1450 1400 1350Wavenumber (cm-1)

-0.05

-0.04

-0.03

-0.02

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

0.14

0.15

0.16

0.17

0.18

0.19

0.20

0.21

0.22

0.23

Ab

so

rb

an

ce

-C=C- (1634 cm-1)-C=C- (1634 cm-1)-CH2 peak-CH2 peak

-O=C-O-C=O (1808 cm-1)-O=C-O-C=O (1808 cm-1)-C=O (1726 cm-1)-C=O (1726 cm-1)

Polyesteranhydride macromer IR

10 6

1,8

2,0

2,2

2,4

2,6

2,8

3,0

3,2

3,4

3,6

3,8

4,0

4,2

4,4

4,6

4,8

5,0

Ab

sorb

ance

1600 1620 1640 1660

Wavenumbers (cm-1)

0 200 400 600 800 1000

0.0

0.2

0.4

0.6

0.8

1.0

Co

nve

rsio

n (

%)

Exposure Time (s)

2150 2100 2050 2000 1950 1900 1850 1800 1750 1700 1650 1600 1550 1500 1450 1400 1350Wavenumber (cm-1)

-0.05

-0.04

-0.03

-0.02

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

0.14

0.15

0.16

0.17

0.18

0.19

0.20

0.21

0.22

0.23

Ab

so

rb

an

ce

-C=C diminishes as crosslinking proceeds (1634 cm)

t = 0s

t = 600s

OO

OO

PCL

PCL

PCL

PCLO

O

O

O

O

O

O

O

O

O

O

O O

O

O

O

Extent of crosslinking with time

Raman spectroscopy

Scattering

Transmitted beam

Raman scattering, anti-Stokes

Rayleigh scattering

Raman scattering, Stokes

Laserbeam

Sample

Raman spectroscopy

The major features of Raman spectroscopy are:– Essential prerequisite for Raman scattering is a change in the

polarizability of the bond when vibrations occur– The information regarding molecular structure is complementary

to that obtained from infrared spectroscopy– Functional groups that give weak absorptions in the infrared,

such as S-S, C=C, and N=N, give strong Raman signals– It is a non-contact, non-destructive technique– No sample preparation is required– Dangerous or delicate samples may be examined in sealed

containers

IR vs. Raman

• IR depends on the change in the permanent dipole moment of the chemical bond or molecule to produce absorption

• Raman depends on a change in the induced dipole moment or polarization to produce Raman scattering

• The more symmetric the molecule is, the greater the differences in the IR and Raman spectra

• Strong Raman scattering arises from non-polar molecular groupings and strong IR absorption occurs when the molecule contains polar groups

• In chain-like polymer molecules, the substituents on the carbon chain are most easily studied by IR, while vibrations of the backbone carbon chain can be studied by Raman

Assignments in FTIR and Raman

International Journal of Pharmaceutical Sciences Review and Research Volume 2, Issue 2, May – June 2010; Article 019

Nuclear magnetic resonance spectroscopy (NMR)

NMR

• Nuclear magnetic resonance spectroscopy is a powerful tool for molecule characterization

• The study of energy levels of certain atomic nuclei of molecules in a magnetic field– Nuclei most commonly used in polymer NMR are 13C and 1H;

additionally 17O, 19F and 29Si

MHz

resonancefrequency

1H400.000

13C100.577

15N40.531

31P161.923

19F

376.308

0100200300400

NMR

• When an atomic nucleus with a magnetic moment is placed in a magnetic field, it tends to align with the applied field

• The energy required to reverse this alignment depends on the strength of the magnetic field and (to a minor extent) the environment of the nucleus, i.e., the nature of the chemical bonds between the atom of interest and its immediate vicinity in the molecule

• The minor spectral shifts due to chemical environment are the essential features for interpreting structure and are normally expressed in terms of part-per-million (ppm) shifts from the reference frequency of a standard such as tetramethylsilane

• The most common nuclei examined by NMR are 1H and 13C

NMR

• Any atomic nuclei having a non-zero spin quantum number, I, possess a magnetic moment

• When placed in magnetic field these nuclei occupy 2I+1 quantized magnetic energy levels (Zeeman levels)

• Transitions (resonance) for a particular nucleus will occur at slightly different frequencies depending on its chemical environment

• The frequency changes are termed chemical shifts and are given in reference to tetramethylsilane (TMS) as a standard

field off field on

Zeeman interaction

Proton NMR

• 1H resonances are fairly specific for the types of carbon they are attached to, and to a lesser extent to the adjacent carbons– Resonances may be split into multiples, as hydrogen nuclei can

couple to other nearby hydrogen nuclei

• The magnitude of the splitting, and the multiplicity, can be used to better determine the chemical structure in the vicinity of a given hydrogen

• Sample requirements:– 10mg/10ml for 1H– Up to 1g/10ml for 13C

Carbon NMR

• 13C resonances can be used to directly determine the skeleton of an organic molecule

• The resonance lines are narrow and the chemical shift range (in ppm) is much larger than for 1H resonances

• Shift is dependent on the structure of the molecule for up to three bonds in all directions from the site of interest

• Each shift becomes quite specific, and the structure can be easily assigned

Solid-State NMR

• Not all polymers are soluble

• In solids, there is not sufficient motion of molecules and stronger interactions are present

• Immobility of molecules induces broad peaks in the spectrum

• Several techniques are used to produce narrow peaks:– Dipolar decoupling (DD)– Magic angle spinning (MAS)

• A cylindrical sample is rotated at high speed at an angle of 54.7o

– Cross-polarziation (CP)

2D NMR experiments

• In order to avoid severe signal overlap and obtain additional information, it is possible to carry out NMR experiments in two (or more) dimensions

• One usually distinguish between homonuclear and heteronuclear 2D experiments:– Examples of homonuclear 2D experiments: COSY, TOCSY,

NOESY, and ROESY– Examples of heteronuclear 2D experiments: HSQC, HMQC,

and HMBC

What type of information can NMR provide

• Molecular structure:– Tacticity– Branching– Co-polymer structure– Structural defects (such as head-to-tail, head-to-head, tail-to-

tail)

• Molecular dynamics

• Molecular interactions

• Chemical kinetics

• Molecular identity etc.

Chemical shifts

0TMS

ppm

210 7 515

aliphatics

alcohols, protons to ketones

olefinsaromatics,

amidesacids,aldehydes

ppm

50150 100 80210

aliphatic CH3,CH2, CH

carbons adjacent to alcohols, ketones

olefins

aromatics,conjugated alkenes

C=O of acids,aldehydes, esters

0TMS

C=O inketones

1H

13C

Useful for identification of functional groups!

1H-NMR

• Monomer conversion

13C-NMRP(CL/L-LA) copolymer with 50/50 molar ratio

Block lengths

Carbonyl peak area in13C-NMR

used for sequence analysis

ICC is two caprolactone units

ICL is caprolactone next to lactic acid

ILLLis sequence lactic acid units LLL

ILLC and ICLL is two lactic acid and one caprolactone units

ICLC is caprolactone-lactic acid-caprolactone units

• Integrals of the particular peaks can then be used to calculate the average sequence lengths

Molecular weight

13C-NMR of alternating copolymer of ethylene and styrene

A. the alternating styrene-ethylene-styrene structure with regioregular styrene insertions

B. alternating structure with one regioirregular styrene insertion

C. regioirregular tail-to-tail styrene block formation

D. the amount of isolated methylene units formed after two or more consecutive ethylene insertions was low

• Integrals of the particular peaks was used to calculate the styrene content in the copolymer 47 mol-%

)A 1.5(A A A A

A A%Mol

35.5-34.037.1-36.628.0-27.525.529.8

35.5-34.037.1-36.6

Structural characterization: NMR spectroscopy• Solid state 13C CP-MAS NMR spectroscopy

NFC

NFC modified with130 mol% ODSA

(= C18 alkenyl chain)

a

b

O

OH

OH

HO O12

3

4 5

6

n

• Both carbonyl signal (a) and aliphatic signal (b) can be observed after modification

• Only a rough estimation (non-quantitative) on the substitution can be obtained:

DS=

Youtube/edu

• University of Warwick

• Measuring proton NMR of ethanol– http://www.youtube.com/watch?v=uNM801B9Y84&feature=related 8:43min

• Measuring FTIR, liquid sample and solid sample using ATR– http://www.youtube.com/watch?v=DDTIJgIh86E&feature=relmfu 6:32 min

 • Using UV/vis

– http://www.youtube.com/watch?v=O39avevqndU&feature=relmfu 4:52min

Next week:

• Polymer rheology