Automotive Application Tech Brief
Analyzing Adhesive & Sealant Materials in the Automotive Industry Using Pyrolysis
This tech brief explores how the Frontier Multi-Shot Pyrolyzer can be used to rapidly evaluate the photo, thermal, and oxidative degradation of EPDM rubber, a commonly used sealant in the automotive industry.
Ethylene Propylene Diene Rubber (EPDM) is widely used in the automotive industry as a sealant, because it reduces thermal and weather degradation. In fact, this rubber can be used in an automotive door, window, and truck as the sealant material. Polymers, such as EPDM are known to undergo photo, thermal and oxidative degradation when irradiated by ultraviolet (UV) light. The degree of degradation is often temperature dependent.
The following tech brief explores an online UV irradiation UV/Py-GCMS system which enables the determination of volatile products formed because of the UV irradiation. The residual polymer can be further characterized using Evolved Gas Analysis (EGA-MS) or Pyrolysis (Py)-GCMS. The online ultraviolet (UV)/Py-GC/MS system can be used to rapidly evaluate the photo, thermal, and oxidative degradation of EPDM rubber.
EPDM rubber (Diene based rubber containing 5.1 wt% of ethylidene norbornene) was used as a test sample. 200 µg of the sample was placed in a sample cup which was attached to the end of the optical fiber on the UV irradiator (UV-1047Xe, 280-450 nm, 700 mW/cm2) equipped with a xenon/Hg light source. The furnace temperature of the Frontier EGA/PY-3030D Pyrolyzer was set to 60 ºC and the cup was positioned in the furnace. The sample was irradiated in an air atmosphere for one hour. Volatile degradation products released during the irradiation were Cyro-trapped at the head of a metal capillary separation column (Ultra ALLOY+1) using liquid nitrogen. After one hour of irradiation, the trap was balletically heated and the volatiles analyzed using GC/MS. The irradiated sample residue was analyzed using evolved gas analysis (EGA)-MS.
A comparison of the volatile products released from the EPDM rubber sample during UV irradiation and from the control EPDM sample (no UV irradiation) is shown in Fig. 1 below.
Acetaldehyde, acetone, acetophenone, acetic acid, and propylene are derived from the propylene unit. Straight-chain aldehydes such as nonanal are derived from the ethylene sequence. The EGA thermograms of the EPDM rubber sample before and after UV irradiation were also obtained and are shown in Fig. 2.
Py. temp.: 100 – 700ºC (20 ºC/min) GC oven temp.: 300ºC EGA tube: deactivated metal tube, L=2.5 m, i.d.=0.15 mm, Column flow rate: 1 mL/min He, Split ratio: 1/50, Sample wt.: 0.2 mg
The EGA thermogram of EPDM rubber which was irradiated exhibits a decrease in the intensity of the peak near 480ºC. The peak apex temperature shifts to lower temperatures by 10ºC and the half-height width (Wh) increases from 30ºC to 50ºC.
Conclusion: These results indicate that the photo, thermal, and oxidative degradation of EPDM rubber can be evaluated using the peak intensity, peak apex temperature, and the Wh of the peak in the thermogram. It is also shown that the UV degradation of EPDM can be evaluated in a few hours using the Frontier online UV/Py-GC/MS.
A growing number of laboratories in the automotive industry are integrating the Frontier Multi-Shot Pyrolyzer into their mainstream analytical protocols due to the advantages and immediate quality improvements this technique provides. The Frontier Multi-Shot Pyrolyzer offers reproducibility and accuracy because every facet of the system is designed to ensure reliability and data quality. All surfaces in the sample path are quartz deactivated using a proprietary process; there is no transfer line and no cross contamination. The system also increases laboratory productivity as sample preparation takes less than five minutes, and the low mass ceramic furnace heats and cools in record time for efficient and continuous sample analysis.
Want more? Check out other automotive applications using pyrolysis:
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