Post on 30-Dec-2020
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