Volatile content determination is a core quality-control test for advanced polymers, coatings, adhesives, composite prepregs, and battery materials, quantifying the mass fraction of water, residual solvents, and other low-boiling species released under controlled heating. This article explains the sample types, measured parameters, and internationally recognized methods—oven gravimetry, thermogravimetric analysis, headspace gas chromatography, and Karl Fischer titration—used by accredited third-party laboratories to verify volatile matter levels against ISO, ASTM, IEC, EN, and GB requirements.
Technical Overview
Volatile content refers to the fraction of a material's mass that is lost when the material is heated under strictly defined conditions of temperature, time, and atmosphere. This mass loss typically includes free and bound water, residual solvents and monomers, low-molecular-weight oligomers, and, in some formulations, low-boiling plasticizers. The result is conventionally expressed as a weight percentage and serves as a fundamental indicator of material purity, process readiness, and long-term stability.
For new and advanced materials, volatile content control is directly linked to product performance. Excessive volatiles in composite prepregs cause porosity and void defects during curing; residual moisture in lithium-battery electrodes and separators triggers unwanted side reactions and capacity fade; high volatile organic compound (VOC) levels in coatings and adhesives raise regulatory compliance and occupational health concerns. Volatile content determination therefore forms part of incoming inspection, process qualification, batch release, and failure analysis programs across the advanced manufacturing sector.
Testing Samples
Polymer and Rubber Materials
Thermoplastic and thermosetting resins in pellet, powder, or granule form, raw and compounded rubber, elastomer compounds, and recycled polymer feedstocks are tested for total volatile matter as a measure of residual monomers, moisture, and processing aids.
Coatings, Adhesives, and Sealants
Liquid coatings, paints, inks, waterborne and solvent-borne adhesives, and reactive sealants are analyzed to determine non-volatile (solids) content and VOC content, supporting both formulation development and regulatory declarations.
Composite Prepregs and Reinforcements
Carbon-fiber and glass-fiber prepregs, resin films, and unidirectional tapes are tested for volatile content because solvent and moisture levels directly influence tack, flow, and cured-part porosity in aerospace and automotive structures.
Battery and Electronic Materials
Electrode slurries and coated foils, separators, binders such as PVDF, encapsulants, epoxy molding compounds, underfills, and conformal coatings are tested for moisture and residual solvent, often at ppm-level sensitivity, because trace volatiles degrade yield and reliability.
Films, Membranes, and Powders
Functional polymer films, packaging laminates, barrier membranes, powder coatings, toners, ceramic precursor powders, and nanomaterial powders such as graphene are tested to document drying completeness and outgassing behavior.
Testing Items
Depending on the material and specification, volatile-related testing at accredited third-party laboratories typically covers the following parameters:
- Total volatile matter content (weight percent, loss on drying)
- VOC content of coatings and adhesives (g/L or weight percent)
- Moisture and water content, from percentage down to ppm levels
- Residual solvent content for specific analytes such as toluene, ethyl acetate, acetone, N-methyl-2-pyrrolidone, and dimethylformamide
- Loss of mass at elevated temperature for cable insulation and sheathing compounds
- Volatile content of prepreg and resin film
- Volatile loss by activated carbon absorption (plasticizer loss assessment)
- Outgassing profiling of unknown volatile species for research and failure analysis
Testing Methods
Oven Gravimetric Method (Loss on Drying)
The oven gravimetric method is the most widely used approach for total volatile content. A conditioned specimen, typically 1 to 10 g for solids or a defined film mass for liquids, is weighed into a tared dish on an analytical balance readable to 0.1 mg, heated in a forced-convection or vacuum oven at a standard-specified temperature, cooled in a desiccator, and reweighed. Volatile content is calculated from the mass difference. Common parameter sets include 110 °C for 60 minutes for coatings per ASTM D2369, 105 °C conditions for non-volatile content per ISO 3251, oven or hot-mill procedures for raw rubber per ISO 248 and ASTM D5668, and elevated-temperature exposure for prepreg volatiles per ASTM D3530. Vacuum ovens are preferred for heat-sensitive materials to lower the evaporation temperature and limit oxidation.
Thermogravimetric Analysis (TGA)
TGA measures mass loss continuously as temperature ramps, typically at 10 °C/min under nitrogen purge, using specimens of 5 to 20 mg. Distinct mass-loss steps allow moisture release below approximately 120 °C to be separated from residual solvent evolution between roughly 120 °C and 250 °C and from thermal decomposition at higher temperatures. ISO 11358 governs thermogravimetry of polymers, while ASTM E1131 provides full compositional analysis covering moisture, volatiles, combustibles, and ash, and ASTM E1868 addresses loss-on-drying determinations by TGA. TGA is particularly valuable for research on new materials because a single experiment maps the entire thermal release profile.
Headspace Gas Chromatography and GC-MS
Static headspace gas chromatography quantifies individual residual solvents at ppm levels. The specimen is sealed in a vial, equilibrated at 80 °C to 120 °C so that volatiles partition into the headspace, and the vapor phase is injected into a GC equipped with flame ionization detection or a mass spectrometer. GC-MS additionally identifies unknown volatile species in outgassing studies. Standards such as ISO 11890-2 and ASTM D6886 apply gas chromatographic determination of VOC content to coatings, and equivalent headspace procedures are routinely adapted for battery materials, films, and pharmaceutical packaging. This method offers far greater sensitivity and specificity than gravimetric techniques.
Karl Fischer Titration
Karl Fischer titration selectively determines water content rather than total volatiles, which is essential when moisture must be isolated from organic solvent loss. Volumetric titration suits water levels from about 0.1 percent upward, coulometric titration reaches microgram-level detection limits, and oven-KF configurations heat solid specimens so that evolved water is transferred into the titration cell without dissolving the matrix. ISO 15512 covers water content determination for plastics, and ASTM D4017 applies the technique to paints and paint materials. For battery-grade materials, Karl Fischer results are often specified at tens of ppm maximum.
Supplementary Techniques
Halogen rapid moisture analyzers support fast incoming inspection with results in minutes, activated carbon absorption methods per ISO 176 and ASTM D1203 estimate volatile loss related to plasticizer migration, and vacuum desiccation is used for ultra-heat-sensitive specimens. Specimen conditioning at 23 °C and 50 percent relative humidity per ISO 291 or ASTM D618, calibrated ovens with mapped temperature uniformity, traceable balances, and replicate determinations are required for defensible results, and testing is best entrusted to ISO/IEC 17025 accredited third-party laboratories with validated methods.
Applications
Volatile content determination supports quality assurance, certification, and research across all major advanced-materials sectors:
- Aerospace and automotive composites: prepreg volatile control to minimize void content and secure mechanical property acceptance
- Lithium-ion battery manufacturing: moisture verification of electrodes, separators, binders, and cell components to prevent capacity fade and gas generation
- Paints, coatings, and inks: solids content determination and VOC compliance testing against limits such as ISO 11890 procedures and GB 30981, GB 33372, and related GB regulatory standards
- Wire and cable: loss of mass testing of PVC insulation and sheathing in accordance with IEC 60811 series and GB/T 2951 series test methods
- Electronics and semiconductors: outgassing and residual solvent screening of molding compounds, encapsulants, and adhesives to prevent delamination and voiding
- Pharmaceutical and food packaging: residual solvent and moisture verification for films, laminates, and sealing layers
- New material research and development: thermal release profiling of nanocomposites, aerogels, functional films, and specialty powders for datasheets and patent documentation
FAQ
What is the difference between volatile matter and moisture content?
Volatile matter is the total mass lost under specified heating conditions and can include water, solvents, monomers, and other low-boiling species. Moisture content refers only to water and is best measured selectively by Karl Fischer titration. Reporting both values together fully characterizes a material's volatile profile.
Which standard applies to volatile content testing of coatings?
ASTM D2369 determines total volatile content by the oven method, ISO 3251 determines non-volatile matter content, and ISO 11890 and ASTM D6886 provide gas chromatographic VOC determination. The correct choice depends on whether the specification targets total volatiles or regulated VOC content.
How much sample is required?
Gravimetric oven methods generally require 1 to 10 g per determination, headspace GC typically needs 0.1 to 1 g, Karl Fischer requires 0.1 to 2 g depending on expected water level, and TGA uses only 5 to 20 mg. Submitting sufficient material for at least two or three replicate determinations is recommended.
What heating conditions are typically used?
General-purpose drying is commonly performed at 105 °C until constant mass, coatings are tested at 110 °C for 60 minutes under ASTM D2369, prepregs are evaluated at 150 °C to 170 °C per ASTM D3530, and battery materials are often assessed with oven-KF at 120 °C to 200 °C. Product specifications always take precedence over generic conditions.
Can water and organic solvents be distinguished in one report?
Yes. A combined test plan pairing Karl Fischer titration for water with headspace GC for organic solvents, or a TGA profile with stepwise interpretation, separates the individual volatile contributions and is routinely provided by accredited third-party laboratories.
How should a testing laboratory be selected?
Choose an ISO/IEC 17025 accredited third-party laboratory with validated gravimetric, TGA, GC, and Karl Fischer capabilities, documented detection limits, sector-specific experience, and the ability to recommend the most appropriate standard for each material specification.