Abstract
In this study, Fourier transform infrared spectroscopy (FT-IR) was employed to investigate the gaseous pyrolysis products of ethylene - propylene - diene rubber (EPDM). The objective was to evaluate the potential of FT-IR analysis of gaseous pyrolyzates (PY-G/FT-IR) for characterization of EPDM additives. Two EPDM formulations, containing additives typically employed in EPDM rubbers, were analyzed. Initially, gaseous pyrolysis products from paraffin oil, stearic acid, 2,2,4-trimethyl-1,2-dihydroquinoline, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), and 2-mercaptobenzothiazole (MBT) were characterized separately, and their main absorptions were identified. Subsequently, the gaseous pyrolysis products of raw, unvulcanized, and vulcanized EPDM formulations were analyzed. The similarities observed in the FT-IR spectra of unvulcanized and vulcanized EPDM show that the vulcanization process does not interfere with the pyrolysis products. The identification of the functional groups of the studied additives was possible in both unvulcanized and vulcanized EPDM samples, without solvent extraction. Results also demonstrate that the PY-G/FT-IR technique can identify additives containing sulfur in concentrations as low as 1.4 phr (1.26%) in both unvulcanized and vulcanized EPDM. However, the method showed some limitation due to overlapping and to similarities of TMTM and TMTD PY-G/FT-IR spectra, which could not be distinguished from each other. The PY-G/FT-IR technique is a faster and cheaper alternative to the sophisticated techniques usually applied to detection of additives in rubbers.
Highlights
The detection of polymeric additives is a matter of Additive analysis can be challenging because ofF great relevance because it enables the reconstruction the complex and tedious process of isolating additives of formulations in unknown rubbers, the solving from compounded rubber[4]
The present study focused on the detection of additives in EPDM rubber by PY-G/Fourier transform infrared spectroscopy (FT-IR), without prior extraction
Only the gaseous phase was analyzed by FT-IR, which is a powerful tool for identification and characterization of gaseous pyrolysis products[24]
Summary
F great relevance because it enables the reconstruction the complex and tedious process of isolating additives of formulations in unknown rubbers, the solving from compounded rubber[4]. Some of the methods used to identify accelerators and antioxidants containing sulfur compounds are GC/MS, thermal desorption (TD)-GC/MS, high-performance liquid chromatography, and thin-layer chromatography These methods require solvent extraction of the additives and are time-consuming[17]. Nunes et al [18] compared the results of a tracking resistance test and PY-G/FT-IR analysis to study the degradation mechanisms of EPDM rubber They identified ethene, methane, CO, and CO as the products of EPDM pyrolysis. Even though the PY-G/FT-IR technique was used, none of the cited studies applied infrared spectroscopy to detect additives in gaseous products after rubber pyrolysis. Raw rubber was analyzed as a reference sample, and its FT-IR spectrum was compared to the spectra of unvulcanized and vulcanized EPDM to distinguish polymer-only absorptions. Unvulcanized rubber was analyzed to obtain the spectra prior to the vulcanization process, when additives are supposed to be chemically preserved. Spectra were collected with 4 cm−1 resolution and an average of 20 scans over the wavenumber range 4000–500 cm−1 in transmission mode
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
