MI2 2019MÉTODOS INSTRUMENTAIS

Licenciatura em Química ... 2019-2020

Luís M. N. B. F. SantosGabinete 3.56 (3º Andar)

Tel. +351 220402536 Int. 30536email: lbsantos@fc.up.ptemail: lbelchiorsantos@gmail.comURL: http://www.fc.up.pt/pessoas/lbsantos

DAQ Block Diagram2

DAQ Block Diagram3

DAQ Block Diagram4

Instrumental Methodologies5

Real World

Properties

Voltage ImpedanceFrequency

Voltage ImpedanceFrequency

I/O

Sensors

Actuators

pH; conductivity, radiation, Temperature, pressure, level, mass, force …

Gate, Relay, flow, power, ON/OFF, voltage,….

ADC

Processing

DAC

DAQAD/DA

Communication

RS232:USB:

IEEE488:WIFI:LAN

Instrumental Methodologies6

Sensors Transducers 7

Thermocouple

Voltage

Sensors Transducers 8

ThermocoupleVoltage

Sensors Transducers 9

RTD : Resistance Temperature Detectorhave an near linear change of R with temperature

Pt100sensor, standard resistance value of 100Ω at 0oC.

Pt1000sensor, standard resistance value of 1000Ω at 0oC.

Thermistor

The Thermistor, have an exponential change of R with temperature

Sensors Transducers 10

Pressure sensorResistive or piezoelectric

Sensors Transducers 11

Counter Light Sensor used to produce an Digital Signal

Sensors Transducers 12

Position SensorsVoltage output

Sensors Transducers 13

Position SensorsVoltage excitation (AC)Voltage output (AC)

Sensors Transducers 14

Light Sensorsphotoelectric devices that convert light energy (photons) whether visible or infra-red light into an electrical (electrons) signal

Light Dependent Resistor (LDR)

Sensors Transducers 15

Light Sensorsphotoelectric devices that convert light energy (photons) whether visible or infra-red light into an electrical (electrons) signal

Light Dependent Resistor (LDR)

Sensors Transducers 16

Light SensorsPhotodiode light sensor is similar to that of a conventional PN-junction diode

Photo-diode

Sensors Transducers 17

Light SensorsSolar Cell

Photovoltaic Cell

made from single crystal silicon PN junctions,

the same as photodiodes with a very large light sensitive region

Sensors Transducers 18

Photovoltaic energyPhotovoltaic panels: electrical energy for domestic and industrial use

Sensors Transducers19

20

Energy balances.

Chemical reactions

Physical processes

Materials Characterization

Biophysics/Biochemistry

Engineering

to measure and follow heat changes in processesCalorimetry:

21

But Heat , q... Is not possible to measure directly

e.g. Heat flux ...versus... Time

to measure and follow heat changes in processesCalorimetry:

22

e.g. Heat flux ...versus... Time

T heatT

time

time

23

to measure and follow heat changes in processesCalorimetry:

DEPENDS:

Size of the Sample / Process

How strong is the heat change

What heat change we want to measure

Which process we want to follow

RESOLUTION/ACCURACY measurement

• isoperibolic (static and dynamic)

• heat exchanging (isothermal and temperature scanning)

• adiabatic (static and dynamic)

24

Case ..1To measure lots of HEAT.... (e.g Chemical Reaction..combustion)

Temperature homogeneity

Lots of heat involved

MOTOR

Local

T control

Heating

cooling

Precise

T control

T measurement>Isoperibol Calorimeter

25

Local

T control

Region

T change

High heat capacityReasonable time constant

Fixe

d T

emp

erat

ure

Heat/energy content of :

Materials

Food

Fuels

Chemicals

>Isoperibol Calorimeter

26

Case ..2Smal samples and low HEAT change involved

Differential Calorimetry / Microcalorimetry

temperature flutuation of the furnace

Strategy to cancel :

heat capacity of the cell/container

27

Calvet-typeHeat flux

Differential calorimeters

Differential power

Reaction

28

MicroCal VP-DSC

Setaram mDSC IIIDSC

Heat fluxDifferential power

Differential calorimeters

29

Heat Flow Sensors

Peltier elementHeat Flow measurement & Heat Transfer Device

30

Temperature scan & HEAT change involved

Differential Scanning Calorimetry / Microcalorimetry

temperature flutuation of the furnace

Strategy to cancel :

heat capacity of the cell/container

Sample temperature correction

Scanning > Temperature scan rate

31

Differential Scanning Calorimetry / Microcalorimetry

Scanning > Temperature scan rate

e.g. Ionic liquids

32

Thermal & Phase Behavior ….

CnC1im [PF6]

Differential Scanning Calorimetry

Thermal Behavior

CAL ...n=6

33

Differential Scanning Calorimetry

Thermal Behavior

Sample Ref.

DSC

34

Differential Calorimetry / Microcalorimetry

Scanning > Temperature scan rate

Flash Differential Scanning Calorimetry (Flash DSC)

35

Differential Calorimetry / Microcalorimetry

Scanning > Temperature scan rate

Flash Differential Scanning Calorimetry (Flash DSC)

36

Differential Calorimetry / Microcalorimetry

Scanning > Temperature scan rate

Flash Differential Scanning Calorimetry (Flash DSC)

Low-tech ???

Quite high-tech!!

Calvet Microcalorimetry

38

Calvet Microcalorimetry

38

Time/ s

0 500 1000 1500 2000 2500 3000

Hea

t fl

ow

/ m

W

-12

-10

-8

-6

-4

-2

0

2

Flu

xo

tér

mic

o /

mW

Tempo / s

Sample ReferenceInitial Temperature

Calorimeter Temperature

Vacuum

~ 100 seconds

39

Microcalorimetry

Calvet Microcalorimetry drop methodDirect determination of vaporization enthalpies

Capilary tubes: 20 – 30 mgSample: 3 – 5 mg ∆g

cr/lHo

m (T=298.15 K) = ∆g, Tcr/l, 298.15 KHo

m —∆T298.15 KHo

m(g)

“Drop methodology”

Tf K

TiK

<T> = 298.15 K

40

Calvet Microcalorimetry

Calvet Microcalorimetry drop methodDirect determination of vaporization enthalpies

“Drop methodology”

TiK

<T> = 298.15 K

Tf K

41

Heat Capacity …by DSC

DSC & mDSC

Step or Continuos Scan Mode

42

Heat Capacity …by DSC

DSC & mDSC

Step or Continuos Scan Mode

43

Drop Differential Microcalorimetry

“Drop methodology”

293.15 K

303.15 K

<T> = 298.15 K

Calorimeter (Tf)293.15 K

Furnace (Ti)303.15 K

Very accurate Heat capacity measurements

44

Drop Differential Microcalorimetry

High-Precision Heat Capacity Drop Calorimeter

N

2 4 6 8 10 12 14 16 18 20

Co

p /V

/

J·K

-1·c

m-3

1.86

1.88

1.90

1.92

1.94

1.96

1.98

2.00

2.02

Heat Capacities of Ionic Liquids – Cp /V= f(N), T=298.15 K

CAL ...n=6

Alkyl Side Chain Length effect

CAL ...N=2x6 =12

Density measurement. Methodologies45

https://www.nist.gov/video/determination-liquid-density

ρ =m / v

mass (m) and divide by the volume (v):

GasesLiquidsSolids

Phase separationGravimetric methods

Density measurement. Methodologies46

https://www.nist.gov/video/determination-liquid-density

ρ =m / v mass (m) and divide by the volume (v):

Oscillating U-tube method

Density measurement. Methodologies47

https://www.nist.gov/video/determination-liquid-density

ρ =m / v mass (m) and divide by the volume (v):

Oscillating U-tube method Density and Speed of Sound

Density measurement. Methodologies48

ρ =m / v mass (m) and divide by the volume (v):Density and Speed of Sound

https://www.anton-paar.com/br-pt/produtos/detalhes/medidor-de-densidade-dmatm-5000-m/

Density measurement. Methodologies49

https://www.nist.gov/video/determination-liquid-density

ρ =m / v

mass (m) and divide by the volume (v):

Thermal expansion coefficient

Linear expansion coefficient

Liquids

Solids

L

V (K-1)

(K-1)V =Mw /ρ

Molar Mass (Mw) and divide by the density (ρ):

Density measurement. Methodologies50

https://www.nist.gov/video/determination-liquid-density

ρ =m / v mass (m) and divide by the volume (v):

Thermal expansion coefficient

Linear expansion coefficient

Liquids

Solids

Density measurement. Methodologies51

https://www.nist.gov/video/determination-liquid-density

ρ =m / v mass (m) and divide by the volume (v):

Linear expansion coefficient

Solids

Surface tension52

Surface tension53

Surface tension54

Temperature dependence

Surface tension55

Capillary-rise method

Surface tension56

Wilhelmy plate method

Surface tension57

Du Noüy ring method

Surface tension58

Pendant drop method

Surface tension59

Pendant drop method

γ = gde2

Surface tension60

Pendant drop method

Viscosity61

Viscosity62

Viscosity63

Capillary Viscometer

η = K ρ t

Viscosity64

Falling sphere Viscometer

η = K (σ ‒ ρ) t

Viscosity65

T = C η f

Rotational Viscometer

Viscosity66

Stabinger Viscometer

η = K / (n2/n1 ‒ 1)

Spectroscopy67

Espectrofotómetro UV-Vis de Feixe Duplo

A = log (Io / I )

A = ε.l.c

Spectroscopy68

Diode Array UV-vis spectrometer

Refractive index69

Condutores

Refractive index

c - velocidade da radiação no vácuo

’ - velocidade da radiação no meio

Refractive index70

Refractive index71

α1 = angle of incidence of light

α2 = angle of the refracted light beam

n1 = refractive index medium 1 (prism)

n2 = refractive index medium 2 (sample)

Is α1 = αcrit then α2 = 90°

=n2

Sin crit

n1

Snell’s law results in:

n1 Sin 1 = n2 Sin 2

Snell’s law

Molar Refraction

Rm = x Vm

(n2 - 1)

(n2 + 2)

α = 3Rm/4πNA

Polarizability

Refractive index72

Radiation Transmission and Reflection

Polarimetry73

Polarimetry is the key to understanding chiral molecules in terms of optical activity. Chiral molecules are characterized by their property to rotate the plane of polarized light. Called optically active. The effect caused by this property is referred to as optical rotation.

Polarimetry74

Measurements

Polarimetry75

Specific rotation Concentration

Based on Measurements of optical rotation

Polarimetry76

Measurements

https://www.anton-paar.com/corp-en/products/details/mcp-150-modular-compact-polarimeter/

Electrical conductivity77

ResistivityResistivity of materials is the resistance to the flow of

an electric current with some materials resisting the

current flow more than others

Electrical conductivity78

ResistivityResistivity of materials is the resistance to the flow of

an electric current with some materials resisting the

current flow more than others

Electrical conductivity79

CONDUCTIVITY

Electrical conductivity80

Electrical CONDUCTIVITY of solutions

Electrical conductivity81

Electrical CONDUCTIVITY sensors

Electrical conductivity82

Temperature dependence of conductivity

•Nature of the ions: charge, size and mobility

•Nature of the solvent: dielectric constant and viscosity

•Concentration of ions: .

•Temperature

CONDUCTIVITY

83

ITC, Microcalorimetry

So

lva

tio

n

AlcoholsIonic Liquids

DifferentialHeat Flux Signal

R S

Solvation of alcohols in Ionic Liquids

MOLECULAR PROBES

84

ITC, Microcalorimetry

Solvation of alcohols in Ionic Liquids (ITC)

[CN-1C1im][NTf2]

Alkyl side chain length (N = 3 – 13)

AlcoholsTrend Shift .. C6C1imNTf2

MOLECULAR PROBES

85

ITC, Microcalorimetry

K, H, S

86

Microcalorimetry

87

DSC …phase diagrams

DSC & mDSC

Phase diagrams

C2C1 C3 C4

88

DSC …phase diagrams

Mixtures of Hexadecane - Methyl Stearate ..mole fraction ....0.1

DSC …phase diagrams89

C2C1 C3 C4

DSC: Supercooled Liquid90

Cold CrystallizationGlass to Liquid .. Tg

MeltingNo Glass transition found .. Tg

G l

l cr cr lNo Glass transition

91

DSC: Supercooled Liquid

G l

l cr

cr l

92

Thermo Gravimetrical analysis

93

Optical imaging

Birefringence material

is the optical property of a material having a refractive index

that depends on the polarization and propagation direction of lightMany plastics are birefringent because their molecules are "frozen" in a stretched conformation when the plastic is molded or extruded.

Light polarization shown on clear polystyrene cutlery between crossed polarizers

94

Cross Polarized Light imaging

Optical imaging

95

Cross Polarized Light imaging

colorful Sucrose micro crystals Pictures

https://www.news-medical.net/life-sciences/How-Do-Polarized-Light-Microscopes-Work.aspx

Optical imaging

96

Cross Polarized Light imagingOptical imaging

Polarized Light Microscope ConfigurationTransmission microscopy

light components become out of phase, but are recombined with constructive and destructive interference when they pass through the analyzer

97

Cross Polarized Light imagingOptical imaging

Polarized Light Microscope ConfigurationReflected Polarized Light Microscopy

light components become out of phase, but are recombined with constructive and destructive interference when they pass through the analyzer

(a) surface features of a microprocessor integrated circuit

(b) birefringent crystalline areas with interference colors interspersed with grain boundaries

98

Cross Polarized Light imagingOptical imaging

Polarized Light Microscope Configuration

(a) tangential arrangement of the polymer chainsSpherulites.. polymer chains to grow out in spirals

(c) birefringent columnar-hexatic liquid crystalline phase exhibited by rod-like DNA molecules

(b) Polycarbonate … which do not display substantial secondary or tertiary structure

99

http://zeiss-campus.magnet.fsu.edu/articles/basics/contrast.html

Optical imaging

100

Optical morphology imaging

Birefringence material

is the optical property of a material having a refractive index

that depends on the polarization and propagation direction of light

While birefringence is usually obtained using an anisotropic crystal, it can result from an optically isotropic material in a few ways:

•Stress birefringence results when isotropic materials are stressed or deformed (i.e., stretched or bent) causing a loss of physical isotropy and

consequently a loss of isotropy in the material's permittivity tensor.

•Circular birefringence in liquids where there is an enantiomeric excess in a solution containing a molecule which has stereo isomers.

•Form birefringence, whereby structure elements such as rods, having one refractive index, are suspended in a medium with a different refractive

index. When the lattice spacing is much smaller than a wavelength, such a structure is described as a metamaterial.

•By the Kerr effect, whereby an applied electric field induces birefringence at optical frequencies through the effect of nonlinear optics;

•By the Faraday effect, where a magnetic field causes some materials to become circularly birefringent (having slightly different indices of refraction

for left- and right-handed circular polarizations), making the material optically active until the field is removed;

•By the self or forced alignment into thin films of amphiphilic molecules such as lipids, some surfactants or liquid crystals

101

Mechanical Properties

Stress / Strain : Specify deformation = / L = d / dx

102

Mechanical Properties

Stress / Strain : Specify deformation = / L = d / dx

https://aapt.scitation.org/doi/pdf/10.1119/1.3543590?class=pdf

103

Mechanical Properties

Stress / Strain : Specify deformation = / L = d / dx

https://aapt.scitation.org/doi/pdf/10.1119/1.3543590?class=pdf

104

Mechanical Properties

= / L = d / dx

eyy [%] - Lagrange

Strain Field Distribution of the Specimen

before the Failure

Digital Image Correlation System Set-upSurface Preparation of

Specimens for Tensile Tests

Properties of Materials(Mechanical properties)

105

Mechanical Properties

Material PropertiesCNT epoxy composite

106

Mechanical Properties

Compression Sample before and after the Test

Material PropertiesCNT epoxy composite

107

Mechanical Properties

Stress / Strain : Specify deformation = / L = d / dx

Stress-strain curve

108

Mechanical Properties

Condutores

Compressão e tracção para o Betão

Região comcomportamento elástico

Stress-strain curveHOOKE LAW; MÓDULO DE ELASTICIDADE

= E .

- Stress (Pa)

- Specific deformation

E - Elastic modulus …Young Modulus)

109

Mechanical Properties

Material PropertiesCNT epoxy composite

Typical strain–stress curve of cork obtained by compression