Heat-Flux Differential Scanning Calorimeter (DSC)
Measures differential heat flow between sample and reference pans across -50 to 300 °C with ±0.04 mW sensitivity.
Chemical & Process Engineering / DSC Polymer Glass Transition
FREE TO EXPLORELABORATORY 34 · CHEMICAL & PROCESS ENGINEERING
Differential Scanning Calorimetry (DSC) Determination of Polymer Glass Transition & Kinetic Activation
Operate a heat-flux differential scanning calorimeter (DSC) across heating rates from 5.0 to 30.0 °C/min to measure the glass transition temperature (T_g) and specific heat capacity step (ΔC_p) of poly(methyl methacrylate) (PMMA), evaluate thermal relaxation kinetics, and determine the Moynihan glass transition activation slope. Explore interactive transport phenomena, unit operations simulation, and chemical engineering telemetry.
TRANSPORT PHENOMENA · UNIT OPERATIONS · PROCESS CONTROL · REACTION ENGINEERING
Your virtual chemical and process engineering laboratory.
MEASURED GLASS TRANSITION TEMPERATURE T_G—
PROCESS & PILOT PLANT TELEMETRY
Ready to sample with Scan Rate β = 15.0 °C/min.
Adjust Scan Rate β, then execute chemical process trial.
Chemical and process engineering telemetry is evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity transport phenomena and unit operations modeling.
Process engineering assumptions and boundary condition limits
The transport and thermodynamic models apply within the specified calibrated operating window (5.0 to 30.0 °C/min). Evaluated using a TA Instruments Q2000 heat-flux DSC with refrigerated cooling system (RCS90) and purge gas flow of 50 mL/min dry N_2. Temperature and heat flow calibrated with high-purity Indium (T_m = 156.60 °C, ΔH_m = 28.57 J/g) and Sapphire specific heat standards.
Process apparatus & industrial sensors.
Microbalance with 0.001 mg Resolution
Determines PMMA specimen mass (10.000 ± 0.005 mg) for quantitative normalized specific heat capacity measurement.
Hermetic Aluminum Pan Encapsulation Press
Crimps sample and reference pans with uniform hermetic seal to prevent volatile mass loss and ensure thermal contact.
Ultra-High Purity Nitrogen Gas Purge System
Supplies dry N_2 at 50.0 mL/min to prevent oxidative degradation and moisture condensation inside the cell.
Refrigerated Cooling System (RCS)
Maintains linear heating and cooling profiles down to -40 °C with rapid thermal response.
High-Purity Indium and Sapphire Calibration Standards
Calibrates DSC temperature scale (Indium T_m = 156.60 °C) and heat capacity baseline (synthetic sapphire).
FOLLOW THE METHOD
A reason behind every step.
Operate a heat-flux differential scanning calorimeter (DSC) across heating rates from 5.0 to 30.0 °C/min to measure the glass transition temperature (T_g) and specific heat capacity step (ΔC_p) of poly(methyl methacrylate) (PMMA), evaluate thermal relaxation kinetics, and determine the Moynihan glass transition activation slope. Standardized parameter settings: 5.0, 10.0, 15.0, 20.0, 25.0, 30.0 °C/min.
01
Instrument Baseline & Temperature Calibration
Run an empty pan baseline and calibrate temperature and cell constant using standard high-purity indium (156.60 °C, 28.57 J/g).
02
Sample Preparation & Hermetic Sealing
Weigh exactly 10.00 ± 0.01 mg of PMMA into an aluminum pan, crimp hermetically with lid, and place on sample sensor next to an identical empty reference pan.
03
Thermal History Erasure Scan
Heat sample to 160.0 °C at 20 °C/min, hold isothermally for 5 minutes to erase prior processing stress and enthalpy relaxation, and cool at 10 °C/min to 40 °C.
04
First Heating Rate Scan (β = 5.0 °C/min)
Initiate DSC heating scan from 40.0 °C to 150.0 °C at β = 5.0 °C/min under 50 mL/min N_2 purge; record heat flow signal.
05
Midpoint Glass Transition Evaluation
Construct pre-transition and post-transition heat capacity baselines; determine midpoint T_g where heat capacity reaches half of the step ΔC_p.
06
Scan Rate Progression & Moynihan Regression
Repeat heating scans at β = 10.0, 15.0, 20.0, 25.0, and 30.0 °C/min; plot T_g versus ln(β) to evaluate kinetic activation slope S.
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into chemical process engineering insight.
Points are your recorded observations. The solid regression line validates DSC Polymer Glass Transition mathematical scaling.
LINEAR REGRESSION FIT · y = mx + b
T_g = S · ln(β) + T_g0 = 2.1500 · ln(β) + 100.0000
| # | DSC Heating Scan Rate β (°C/min) | Measured Glass Transition Temperature T_g (°C) | Natural logarithm of scan rate ln(β) | Glass transition temperature T_g (°C) | Remove |
|---|
No readings yet. Execute a process trial and record it.
Calculate it yourself.
CHECK YOUR UNDERSTANDING
Explain what the process engineering metrics mean.
During a DSC heating scan of an amorphous polymer, the glass transition appears as:
As the DSC heating scan rate β is increased from 5 to 30 °C/min, the measured glass transition temperature T_g:
The step change in specific heat capacity at the glass transition ΔC_p is defined as:
Which equation relates polymer glass transition temperature to number-average molecular weight?
THEORY AND UNIT OPERATIONS CONTEXT
Process engineering background & physical principles.
Differential Scanning Calorimetry (DSC) is the primary thermal analysis technique employed in chemical, materials, and process engineering to characterize thermodynamic phase transitions, crystallization kinetics, chemical crosslinking, and polymeric glass transitions. When an amorphous polymer is heated, it undergoes a reversible second-order-like kinetic transition from a rigid, glassy state to a compliant, rubbery state known as the glass transition (T_g). At the microscopic level, this transition corresponds to the onset of cooperative segmental mobility of 20 to 50 repeating polymer backbone units. Unlike first-order phase transitions (such as melting or vaporization) which exhibit latent heat and discrete discontinuities in enthalpy and volume, the glass transition exhibits an endothermic step-change in heat capacity: ΔC_p = C_p(rubbery) - C_p(glassy). Because the glass transition is an inherently kinetic phenomenon governed by structural relaxation times, the observed transition temperature T_g shifts systematically toward higher temperatures as the instrumental heating rate β (dT/dt) increases. According to Moynihan, Richardson, and Flynn–Wall–Ozawa kinetic relaxation theories, the scan-rate dependence of the glass transition temperature obeys the logarithmic relation: T_g = T_g0 + S · ln(β), where the thermal shift slope S = R · T_g^2 / ΔH* is inversely proportional to the apparent activation energy for segmental relaxation ΔH*. In this laboratory exercise, high-purity amorphous poly(methyl methacrylate) (PMMA) specimens (10.0 mg) sealed in hermetic aluminum pans are subjected to controlled heating scans from 5.0 to 30.0 °C/min under an inert nitrogen purge to determine the step change in heat capacity ΔC_p, extract the baseline glass transition temperature T_g0 = 100.00 °C, and evaluate the kinetic shift slope S = 2.1500 °C.
T_g = S · ln(β) + T_g0 = 2.1500 · ln(β) + 100.0000
Evaluated using a TA Instruments Q2000 heat-flux DSC with refrigerated cooling system (RCS90) and purge gas flow of 50 mL/min dry N_2. Temperature and heat flow calibrated with high-purity Indium (T_m = 156.60 °C, ΔH_m = 28.57 J/g) and Sapphire specific heat standards.