Simultaneous Thermal Analyzer (STA)

1. **Sample Preparation:** The sample is accurately weighed (using a microbalance) into a suitable crucible (aluminum, platinum, alumina, or ceramic). Crucible selection depends on temperature range and sample reactivity. 2. **Crucible Placement:** The loaded crucible is placed on the STA sensor inside the furnace chamber. A reference crucible (empty or with reference material) is placed on the opposite sensor position. 3. **Atmosphere Selection:** The chamber is sealed and purged with a chosen gas (nitrogen, argon, air, oxygen, or other) at a controlled flow rate to establish the desired environment. 4. **Temperature Program Execution:** The furnace follows a predefined temperature program: - Heating at a controlled rate (e.g., 3–30 °C/min) from initial to final temperature - Isothermal holds (if required) - Cooling at a controlled rate (if required) 5. **Simultaneous Data Collection:** The STA continuously records: - **TGA signal:** sample weight change (µg resolution) - **DSC signal:** differential heat flow (µW sensitivity) - **Temperature and time** data 6. **Data Processing and Analysis:** Software analyzes the raw data to identify: - Onset temperatures for mass loss and thermal events - Peak temperatures and peak areas for enthalpy calculations - Mass loss percentages at specific temperatures - Glass transition temperatures (Tg) - Crystallinity percentages 7. **Report Generation:** Results are documented with thermal curves, quantitative values, and interpretations.

• - **ASTM E793** – Standard Test Method for Enthalpies of Fusion and Crystallization by DSC - **ASTM E914** – Standard Practice for Evaluating Thermal Stability of Materials by TGA - **ASTM E1131** – Standard Test Method for Compositional Analysis by TGA - **ASTM E1868** – Standard Test Method for Loss-on-Drying by TGA - **ISO 11358** – Plastics – Thermogravimetry (TGA) of polymers - **ISO 7111** – Plastics – DSC measurement - **DIN 51004** – Thermal analysis
• determination of melting temperatures by DSC - **DIN 51006** – Thermal analysis (TGA) - **DIN 51007** – Thermal analysis (DSC)

- **STA instrument** (e.g., NETZSCH STA 319 Jupiter, Rigaku STA, Linseis PT1600) with integrated TGA and DSC capabilities - **High-precision microbalance:** readability 0.1 µg, measuring range up to ±200 mg - **Furnace:** temperature range from -100°C to 1600°C depending on model - **DSC sensor:** sensitivity < 1 µW to < 4 µW - **Thermocouple:** Type K (-40°C to 650°C), Type R (ambient to 1500°C) - **Gas selector system** for automated gas switching (up to 4 gases) - **Crucibles:** variety of materials (Al, Pt, Al₂O₃) and types (standard, hermetically sealed) - **Evolved Gas Analysis (EGA) interface:** for coupling to FTIR or Mass Spectrometry - **Dedicated thermal analysis software** for data acquisition and analysis

- **TGA Parameters:** - Mass loss/gain (%) - Decomposition temperature (onset, peak) - Thermal stability (temperature at specific mass loss) - Residual mass/ash content (%) - Moisture and volatile content (%) - Decomposition kinetics (activation energy, reaction order) - **DSC Parameters:** - Melting temperature (Tm) and enthalpy (ΔHm) - Glass transition temperature (Tg) - Crystallization temperature (Tc) and enthalpy (ΔHc) - Crystallinity (%) - Reaction enthalpy (ΔHr) - Specific heat capacity (Cp) - **Combined/Correlated Parameters:** - Simultaneous weight and heat flow events - Reaction stoichiometry correlated with thermal events - Decomposition mechanism identification (when coupled with EGA)

• - **Temperature:** -100°C to 1600°C (depending on instrument model and furnace) - **Mass range:** up to ±200 mg (standard)
• up to 35 g (for specialized high-capacity systems) - **Mass readability:** 0.1 µg (high-precision microbalance) - **Heating rate:** 0.1 to 100 °C/min (depending on model)

• - **Mass detection:** 0.1 µg readability
• accuracy depends on balance calibration - **DSC sensitivity:** < 1 µW to < 4 µW (depending on model) - **Enthalpy accuracy:** ± 2% (typical) - **Specific heat accuracy:** ± 3% (typical) - **Temperature accuracy:** ± 0.5°C or 0.25% (whichever is greater) - **Repeatability (TGA):** RSD < 1% for standard samples - **Repeatability (DSC):** RSD < 2% for standard samples

- **Single instrument, dual data:** Obtains both TGA and DSC data simultaneously from one sample, saving time and material - **Identical test conditions:** TGA and DSC measurements are made under perfectly identical conditions (atmosphere, heating rate, thermal contact, vapor pressure), eliminating inter-experiment variability - **Improved reproducibility:** Eliminates sample-to-sample variations that occur when running separate TGA and DSC tests - **High sensitivity:** Microgram mass resolution and microwatt DSC sensitivity detect subtle transitions - **Minimal sample requirement:** Only 5–50 mg sample needed for comprehensive analysis - **Wide temperature and heating rate range:** Adaptable to diverse materials and applications - **Versatile atmosphere control:** Can run under inert, oxidizing, reducing, or reactive gas conditions - **Real-time correlation:** Directly correlates weight changes with thermal events for mechanism elucidation - **Evolved gas capability:** Can interface with FTIR/MS for evolved gas identification - **Automated operation:** Autosampler and software automation reduce operator error

• - **Cannot distinguish mass change types:** TGA alone cannot differentiate between decomposition, evaporation, and desorption without evolved gas analysis - **Sample size constraints:** Limited to milligram-scale samples
• may not represent bulk material heterogeneity - **Heating rate effects:** Results may be influenced by heating rate
• slower rates often needed for accurate kinetics - **Reactivity with crucibles:** Some materials react with crucibles at high temperatures, affecting results - **Volatile sample loss:** Volatile materials may be lost before analysis starts or during sample loading - **Overlapping transitions:** Simultaneous weight loss and thermal events can be difficult to deconvolute without additional techniques - **Instrument cost:** Significant capital investment required - **Specialized operator skill:** Requires trained personnel for method development and data interpretation - **Not suitable for > 1500°C:** Max temperature limited to approximately 1500–1600°C

• - **Sample mass:** typically 5–50 mg
• smaller masses (5–15 mg) for reactive or high-energy materials, larger (20–50 mg) for subtle transitions - **Powders:** finely ground with particle size typically below 100 µm for homogeneous packing and thermal conductivity - **Solids:** cut to fit the crucible (dimensions not exceeding 5 mm in any direction) - **Liquids/Pastes:** 10–20 mg in hermetically sealed crucibles to prevent spillage - **Sample form:** should be representative of the bulk material and free from contamination - **Hygroscopic materials:** require careful drying before analysis - **Composites:** must maintain representative fiber-matrix distribution in the sampled portion

- **Routine analysis:** 2–5 working days (depending on sample type and temperature program complexity) - **Urgent/Express analysis:** 24–48 hours (available upon request with prior notice) - **Instrument run time:** 30 minutes to 4 hours per sample (program-dependent)

- Official test certificate/report with detailed thermal analysis results - TGA curve (mass vs. temperature) - DSC curve (heat flow vs. temperature) - Derivative TGA (DTG) curve for enhanced event identification - Tabulated numerical data (onset temperatures, peak temperatures, mass losses, enthalpy values) - Raw data file (if requested, typically in instrument-specific format or ASCII) - Graphical comparison with applicable standards or specifications (if specified)