Ethylene Propylene Diene Rubber (EPDM) is a versatile synthetic rubber used in a variety of applications, such as automotive parts and construction. EPDM bonds quickly with metal, creating a strong barrier against the weather while it is a cost-effective material. In automotive manufacturing, EPDM can be used in hoses, gaskets, door weather pathways, car windows, and windscreens.[1]
Weather-induced degradation testing often requires several weeks or months to complete. In contrast, the online ultraviolet (UV)/Pyrolysis-GC/MS system can be used to rapidly evaluate the photo, thermal, and oxidative degradation of polymeric materials. This short technical note demonstrates the applicability of the UV/Pyrolysis-GC/MS system using a micro-furnace multi-mode pyrolyzer for analysis of EPDM rubber.
Experimental: EPDM rubber (JSR. EP25, 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 deactivated 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 Multi-Shot Micro-Furnace Pyrolyzer (EGA/PY-3030D) was set to 60ºC, 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 cryo-trapped at the head of a metal capillary separation column (Ultra ALLOY+-1) using liquid nitrogen. After one hour of irradiation, the liquid nitrogen trap was removed, and the volatiles analyzed using GC/MS. The irradiated sample residue was analyzed using evolved gas analysis (EGA)-MS (EGA is one of the modes of operations in multi-mode micro-furnace pyrolyzer).[2]
Results: 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. 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 are shown in Fig. 2. The EGA thermogram of EPDM rubber, which was irradiated, exhibits a decrease in the intensity for 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.
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 EGA thermogram. It is also shown that the UV degradation of EPDM can be evaluated in a few hours using the online UV/Pyrolysis-GC/MS. [2]
Using UV/Pyrolysis-GC/MS technique, the effects of weather upon exposure to the photo, thermal, and oxidative degradation process can be quickly evaluated. This technique can also be applied to other analytical testings, such as the elucidation of the effects of additives on a polymer’s physical and chemical behavior, photochemical reactions, and UV curing. To learn more about the UV irradiator and the multi-mode micro-furnace pyrolyzer system, visit our site or simply connect with us.
References:
- What is EPDM Rubber and Its Uses for Automotive? Retrieved from https://foamsealant.com.au/what-is-epdm-rubber-and-its-uses-for-automotive/ (2013-2020 Foam Sealant)
- This technical note was developed by Frontier Laboratories Ltd. 4-16-20 Saikon, Koriyama, Fukushima, 963-8862 JAPAN