TLC/IR (UATR) off-line coupling for the characterization of additives in EPDM rubber compositions

Abstract

SbstractThe knowledge of the components that constitutes a rubber composition is important to justify the properties of the final device, particularly when it comes to elastomeric compositions used in the aerospace industry. The development of methodologies that can detect components, specially the smallest proportion of the rubbers composition is a constant challenge and an important gap in the studies of this nature. Therefore, methodologies by using standard techniques and/or of last generation are important in rubber industry and research laboratories, aiming application in related research. In this context, this study shows the coupling/association techniques (off-line) of thin layer chromatography and infrared spectroscopy (TLC/IR), being the IR spectra obtained by universal attenuated total reflection (UATR), applied to the analysis of additives in rubber compositions of ethylene-propylene-diene rubber (EPDM). Two EPDM compositions, a kind of eluent system and Gibbs' reagent, as developer, were used. Basically, all organic components were detected by this methodology, being possible to suggest that it can be applied for detecting additives of similar chemical structures, even though it's presents in small amounts in the composition.

Methodologies for Characterization of Aerospace Polymers/Energetic Materials - a Short Review

“…Two formulations were used in this elastomer -a type of eluent system and the Gibbs reagent, the developer. Basically, all organic components were detected by this methodology that showed to be promising for detecting additives of similar chemical structures, though small quantities of some components presented in the formulation (Damazio et al 2016).…”

Characterization of additives in NR formulations by TLC-IR (UATR)

“…FT-IR spectra were obtained, by reflection technique, using the UATR accessory. It was used 20 scans for UATR analysis, based on other papers that they have successfully published for paint [11] , rubber [12] and oil analysis [15] . This scan number is a suitable to smooth noises in the FT-IR reflection techniques, such as UATR, diffuse reflectance (DRIFT) and attenuated total reflection (ATR).…”

“…• a small number of bands (cm ) around 1240 (C=S, C-S), 1140 (C-N), 560 (S-S) characterizes the presence of TMTD [12,17] in the NR (TMTD) extract spectrum. Despite of a greater similarity between NR extract (TMTD) and TMTD spectra that was observed in the fingerprint region, there were overlaps relative to CH 3 groups bands between 3000-2900, 1400-1350, present in other additives;…”

“…After solvent evaporation, this top is removed, scraped and pressed as a KBr disc for IR analysis. This technique was started in our laboratories, in the Brazilian Institute, Instituto de Aeronáutica e Espaço (IAE), in 1996 [10] and it was used for additives analysis, in rubbers [12] as in paints, with positive results [11] . Chauveau et al [13] separated and identified several vulcanization agents (CBS, MBT, TMTM, DPG, MBT and TMTM) and antioxidants (IPPD and 6PPD) present in hospital rubbers (synthetic polyisoprene-isoprene -IR and copolymer of butadiene and styrene -SBR), by means of the TLC technique.…”

“…Damazio et al [12] applied the same technique, TLC/IR technique (off-line), for the analysis of MBT, TMQ, TMTM and TMTD additives, in ethylene propylene diene monomer terpolymer based rubber (EPDM). Two types of EPDM were evaluated with two different kinds of eluent system: an eluent system with hexane, diethyl ether and acetic acid -70: 30: 5, and Gibbs developer.…”