Based on your previous research on the detection and determination of volatile contamination in hot runner thread sealant, the volatile content of hot runner sealant changes significantly at different temperatures, generally increasing significantly with rising temperature.
I. Core Laws of Temperature Influence
Room Temperature Range (23℃-50℃): Low-molecular-weight substances in the sealant evaporate slowly, resulting in extremely low overall volatile content. The volatile release concentration of most qualified products remains within safe thresholds.
Medium Temperature Range (50℃-120℃): Increased molecular thermal motion significantly accelerates the evaporation rate of solvents and residual small molecules, increasing the volatile content by 2-3 times compared to room temperature. The performance of some room temperature curing sealants begins to change.
High Temperature Range (Above 120℃): When the temperature approaches or reaches the thermal decomposition temperature of the sealant, the high molecular weight substances within the sealant layer rapidly transform into volatile low molecular weight substances, resulting in a dramatic increase in evaporation several times over. Some inferior sealants may even exhibit smoking and the release of large amounts of oily volatiles, completely losing their sealing performance.
II. Differences in Temperature Tolerance Among Different Products: Low-volatility hot runner sealants (such as Loctite SI598) maintain extremely low evaporation rates and stable performance even at typical hot runner operating temperatures around 200℃.
Ordinary, inexpensive sealants show a significant surge in evaporation rates above 100℃, making them unsuitable for the high-temperature conditions of hot runners.
III. Relevant Testing Standards: The industry typically conducts release tests at multiple temperature gradients, such as 23℃, 40℃, 65℃, and 85℃. Using a dedicated climate chamber and gas chromatography-mass spectrometry (GC-MS), the evaporation rate changes at different temperatures are systematically measured to assess the risk of volatile contamination under actual operating conditions.
