Offensive odor analysis of acrylic adhesive by thermal desorption (TD)-GC/MS

Význam tématu

In modern manufacturing, pressure-sensitive acrylic adhesives play a critical role in electronics, aerospace and automotive industries. However, heat-curing-induced offensive odors can compromise product quality and worker safety. Rapid identification of odor-causing compounds is essential for quality assurance and process optimization.

Cíle a přehled studie / článku

This technical note compares a defect-free acrylic adhesive with a batch exhibiting an offensive odor during thermal curing. The primary objective is to pinpoint volatile species responsible for the malodor and to assess monomer polymerization efficacy. Evolved gas analysis (EGA-MS) and thermal desorption gas chromatography–mass spectrometry (TD-GC/MS) were combined to characterize volatiles released upon heating.

Použitá metodika a instrumentace

The adhesive layers were excised from tape samples and subjected to two complementary analyses using a Pyrolyzer®-GC/MS system:

• EGA-MS: Furnace ramp from 100 °C to 700 °C at 20 °C/min; UADTM-2.5N capillary tube; carrier He at 1 mL/min; split 1:50; GC oven at 300 °C.
• TD-GC/MS: Thermal desorption from 100 °C to 200 °C at 20 °C/min with 1 min hold; UA+-1 column (30 m×0.25 mm, df=1.0 μm); He at 1 mL/min; split 1:10; GC temperature from 40 °C (2 min) to 320 °C at 20 °C/min; cryo-trapping via MicroJet Cryo-Trap.

Hlavní výsledky a diskuse

EGA thermograms for both samples were largely similar except in the 100–200 °C window (Zone A), correlating with the odor onset temperature. TD-GC/MS chromatograms of Zone A revealed:

• Common peaks from residual solvent and monomer.
• In the defective sample: a distinct carbon disulfide peak, known for a pungent smell.
• An elevated level of unreacted 2-ethylhexyl acrylate, indicating incomplete polymerization.

These findings confirm that carbon disulfide is the primary malodor contributor and that monomer conversion was insufficient in the faulty batch.

Přínosy a praktické využití metody

The combined EGA-MS and TD-GC/MS approach allows rapid, sensitive detection of trace volatiles responsible for odors in polymeric adhesives. Implementation in production QC workflows enables early detection of problematic batches, reducing waste and ensuring product consistency.

Budoucí trendy a možnosti využití

Emerging trends include automated sampling integrated with real-time data analysis, coupling with two-dimensional GC for enhanced separation of complex mixtures, and applying chemometric models or machine learning to correlate thermal profiles with odor thresholds. These advances can further streamline odor diagnostics and broaden applications to other materials exhibiting off-gassing issues.

Závěr

This study demonstrates that combining EGA-MS and TD-GC/MS effectively identifies odor-causing compounds in acrylic adhesives. Detection of carbon disulfide and residual monomer provides clear targets for process improvement. Adoption of these analytical workflows strengthens quality assurance and supports odor control in industrial adhesive manufacturing.

Reference

Frontier Laboratories Ltd. Multi-functional Pyrolyzer® Technical Note PYA1-102E.