Chemical Materials Mass Loss Rate Testing: Methods, Standards, and Applications

Mass loss rate testing is a fundamental quality control and characterization technique used to evaluate the thermal stability, volatility, and compositional integrity of chemical materials such as polymers, rubbers, coatings, adhesives, and lubricants. By precisely measuring the percentage of mass a specimen loses under controlled temperature, time, and atmospheric conditions, manufacturers can verify compliance with international standards such as ISO, ASTM, IEC, and GB. This article provides a comprehensive technical overview of chemical materials mass loss rate testing, covering sample types, testing items, standard methods, and typical industrial applications.

Technical Overview

Mass loss rate refers to the percentage of mass that a chemical material loses when exposed to specified environmental conditions, typically elevated temperature, controlled atmosphere, vacuum, or prolonged thermal aging. The result is calculated as the ratio of the mass difference before and after conditioning to the initial mass, expressed as a percentage. For most chemical materials, the mass loss originates from the evaporation of moisture, residual solvents, plasticizers, volatile additives, or thermal decomposition products.

Mass loss rate is a sensitive indicator of several critical material properties. Excessive mass loss in polymeric materials may signal insufficient thermal stability, plasticizer migration, inadequate curing, or the presence of unreacted monomers. In coatings and adhesives, mass loss data correlate with solids content and volatile organic compound (VOC) emissions. In lubricants, evaporation loss directly affects oil consumption, emissions, and equipment protection. Consequently, mass loss rate testing is widely integrated into raw material acceptance inspection, product certification, process optimization, and durability studies conducted by accredited third-party laboratories and in-house quality departments.

Testing Samples

Polymer Compounds and Plastic Materials

Typical specimens include flexible and rigid PVC compounds, polyethylene and polypropylene resins, engineering plastics, masterbatches, and recycled polymer feedstocks. These materials are frequently evaluated for volatile loss and plasticizer retention, particularly when used in wire and cable insulation, flexible films, and molded components.

Rubber and Elastomeric Materials

Vulcanized rubber compounds, thermoplastic elastomers, seals, gaskets, and hoses are tested for mass change after accelerated heat aging. Mass loss in rubber reflects the volatilization of processing oils, accelerators, and antidegradants, which strongly influences long-term mechanical performance.

Coatings, Paints, and Adhesives

Liquid and powder coatings, solvent-based and waterborne paints, sealants, and structural adhesives are analyzed to determine non-volatile matter content and volatile fraction. These results are essential for formulation control, coverage calculations, and VOC regulatory compliance.

Lubricants, Oils, and Greases

Engine oils, hydraulic fluids, industrial gear oils, and lubricating greases are tested for evaporation loss at elevated temperatures. Volatility data support viscosity grade selection, base oil characterization, and service life prediction.

Chemical Raw Materials and Additives

Plasticizers, pigments, fillers, flame retardants, catalysts, ceramic powders, and fine chemical intermediates are routinely tested for moisture content, volatile impurities, and loss on ignition to confirm purity and batch consistency.

Testing Items

Common testing items offered under chemical materials mass loss rate evaluation include:

• Thermal mass loss (mass loss on heating at a specified temperature and duration)
• Mass loss after accelerated heat aging
• Volatile matter content and non-volatile matter content
• Moisture and water content (drying method, vacuum method, or Karl Fischer titration)
• Plasticizer volatile loss using activated carbon methods
• Noack evaporation loss of lubricating oils
• Evaporation loss of lubricating greases
• Loss on drying and loss on ignition (ash-related mass loss)
• Total mass loss (TML) and collected volatile condensable materials (CVCM) for outgassing evaluation
• Compositional mass loss profiles by thermogravimetric analysis (moisture, volatiles, combustion, ash fractions)

Testing Methods

Standardized methods are selected according to the material type, expected volatility range, and end-use requirements. All measurements are performed using calibrated analytical balances, precision ovens, and controlled-atmosphere equipment:

• Thermogravimetric analysis (TGA): Measures continuous mass change as a function of temperature or time under nitrogen or air, enabling quantification of moisture, volatiles, and decomposition stages. Reference standards include ISO 11358, ASTM E1131, ASTM E2550, and JIS K 7120.
• Oven drying and constant-weight method: Specimens are conditioned at a defined temperature (for example 105 °C) until constant mass, suitable for moisture and general volatile content. Reference standards include ISO 3251 and ASTM D2369.
• Activated carbon method: Evaluates plasticizer volatile loss from flexible plastics by contacting specimens with activated carbon at elevated temperature. Reference standards include ISO 176 and ASTM D1203.
• Heating loss of plasticizers and polymers: Static oven exposure at specified temperatures to determine weight loss. Reference standards include ASTM D2288 and GB/T 8815 for PVC cable compounds.
• Mass loss of PVC compounds on heating: A dedicated cable material test measuring mass loss after prolonged oven aging at 80 °C, specified in IEC 60811-509 and the corresponding GB standard series.
• Heat aging mass change of rubber: Specimens are aged in air ovens per ISO 188 or JIS K 6257, followed by gravimetric determination.
• Noack evaporation loss: Simulates evaporation from engine oil at 250 °C using the Noack principle per ASTM D5800.
• Grease and oil evaporation loss: Gravimetric determination after heated air exposure per ASTM D972 and the wide-temperature variant ASTM D2595.
• Moisture determination by Karl Fischer titration: Precise coulometric or volumetric water quantification per ISO 15512, ASTM E203, and related GB methods.
• Loss on ignition: Determines mass loss after high-temperature ignition, applied to inorganic fillers, powders, and combustion residues per ASTM D7348 and EN 196-2.
• Vacuum outgassing screening: Measures total mass loss and condensable volatiles for aerospace and electronics materials per ASTM E595.

Mass loss rate is generally reported as: Mass Loss Rate (%) = (m₁ − m₂) / m₁ × 100, where m₁ is the initial conditioned mass and m₂ is the mass after the specified exposure. Results are interpreted against product specifications, applicable standard limits, or comparative baseline data.

Applications

Mass loss rate testing supports quality assurance and product development across numerous industries:

• Wire and cable manufacturing: Verifying thermal stability and plasticizer retention of PVC insulation and sheathing compounds to satisfy IEC, GB, and UL-based cable specifications.
• Polymer and plastics processing: Incoming resin inspection, masterbatch quality control, and evaluation of recycled materials for volatile contamination.
• Automotive and machinery: Characterizing lubricant volatility, grease evaporation loss, and elastomer aging behavior for engine, transmission, and chassis components.
• Coatings and construction: Determining solids content, VOC emissions, and curing completeness for industrial paints, powder coatings, sealants, and adhesives.
• Aerospace and electronics: Screening polymeric materials for outgassing tendencies that could contaminate optical surfaces, sensors, or critical assemblies.
• Research and failure analysis: Comparing formulation stability, assessing antioxidant effectiveness, and diagnosing premature material degradation in service failures.
• Regulatory compliance and certification: Generating test data required for product certification, tender documents, and supplier qualification under internationally recognized standards.

FAQ

What is mass loss rate in chemical materials testing?

Mass loss rate is the percentage of a specimen's initial mass that is lost after exposure to defined temperature, time, and atmosphere conditions. It quantifies the release of moisture, solvents, plasticizers, and other volatile components, providing a direct measure of material stability and compositional integrity.

Which standards govern mass loss rate testing?

The most commonly applied standards include ISO 11358 and ASTM E1131 for thermogravimetric analysis, ISO 176 and ASTM D1203 for plasticizer volatile loss, IEC 60811-509 for PVC cable compound mass loss, ISO 3251 and ASTM D2369 for non-volatile content, ASTM D5800 and ASTM D972 for lubricant evaporation loss, ISO 188 for rubber heat aging, and ASTM E595 for vacuum outgassing. The appropriate method is selected based on the material type and product specification.

What sample size and preparation are required?

Typical gravimetric tests require between 1 g and 100 g of representative material, depending on the standard. Solid samples are cut or ground to the specified geometry to ensure uniform heat exposure, while liquids are weighed into preconditioned dishes. Specimens are usually conditioned to constant weight before the initial mass is recorded.

What does an excessively high mass loss result indicate?

Elevated mass loss may indicate excessive volatiles, high moisture content, plasticizer instability, incomplete curing or polymerization, contamination with low-boiling impurities, or early-stage thermal decomposition. Such results typically trigger formulation review, process investigation, or rejection of the material batch.

How long does mass loss rate testing take?

Simple oven drying or heating loss tests can often be completed within one day, while accelerated heat aging tests, such as the PVC mass loss test at 80 °C for 168 hours, require longer conditioning periods. Thermogravimetric analysis is typically completed within a few hours per specimen. Accredited third-party laboratories can advise on specific turnaround times based on the selected standard.