Influence of ultraviolet aging on the structure, mechanical and gas permeability properties of hydrogenated nitrile butadiene rubber

Abstract

The effect of ultraviolet (UV) radiation on the structure and performance of hydrogenated nitrile butadiene rubber (HNBR) was studied in this paper. The HNBR was exposed to UV radiation for various durations (0, 7, 14, 21 and 28 days). The Fourier transform infrared spectroscopy (FTIR) results demonstrated that the surface molecular structures were oxidized to generate oxygenated species under UV radiation. The oxidative degree enhanced with the increase of aging time, resulting in thicker and denser cracks on the surface. The plausible aging mechanism of HNBR was suggested. The free volume of HNBR before and after UV aging was characterized by positron annihilation lifetime spectroscopy (PALS) and their cross‐linking density, compression set, mechanical and gas permeability properties were also analyzed. In the first 14 days of UV irradiation, the dominant chain‐scission reaction led to a decrease in cross‐linking density of HNBR, resulting in the enhancement of free volume and thereby the increase of gas permeability. When the aging time was longer than 14 days, cross‐linking reaction played a leading role and the free volume decreased, thus causing the reduction of gas permeability. As the aging time increased, the glass transition temperature (Tg), tensile strength and storage modulus of HNBR initially reduced and then increased, which was in agreement with the changing trend of cross‐linking density.

pH-Sensitive Polydopamine–La (III) Complex Decorated on Carbon Nanofiber toward On-Demand Release Functioning of Epoxy Anti-Corrosion Coating

“…A broad peak at 3436 cm –1 in the CNF spectrum (Figure a) is attributed to the OH stretching resulting from the physical water adsorption. CH 2 asymmetric and symmetric stretching vibrations are represented by two low-intensity peaks at 2921 and 2854 cm –1 . Moreover, the peak at 1631 cm –1 is associated with the CC stretching, whereas the peak at 1384 cm –1 is related to the CN stretching …”

“…CH 2 asymmetric and symmetric stretching vibrations are represented by two low-intensity peaks at 2921 and 2854 cm −1 . 34 Moreover, the peak at 1631 cm −1 is associated with the C�C stretching, 35 whereas the peak at 1384 cm −1 is related to the C�N stretching. 34 Figure 1b presents the characteristic peaks of DA, which comprise the primary amine (∼3338 cm −1 ), C�C stretching (∼1617 cm −1 ), and C�C bending (∼1501 cm −1 ).…”

“…34 Moreover, the peak at 1631 cm −1 is associated with the C�C stretching, 35 whereas the peak at 1384 cm −1 is related to the C�N stretching. 34 Figure 1b presents the characteristic peaks of DA, which comprise the primary amine (∼3338 cm −1 ), C�C stretching (∼1617 cm −1 ), and C�C bending (∼1501 cm −1 ). In the case of the CNF−PDA spectrum (Figure 1c), the peak at 3438 cm −1 is assigned to the OH stretching, which may be linked to the physically adsorbed water, catechol OH, or amino groups in the PDA structure.…”

Aging characterization of different nitrile butadiene rubbers for sealing in a pneumatic system: Linking the change of the physicochemical state to the mechanical properties

“…In general, if chain scission is the dominant reaction, a decrease in polymer chains interaction, and consequently, an increase in the mobility of molecular chains is observed, thus leading to a decrease in . 36 However, for long aging times, crosslinking reaction usually dominates chain scission. This shows that the increase in observed hinders the macromolecular dynamics and that a crosslinking reaction has occurred on the different NBR specimens 10,37 .…”

Investigation of the properties and aging mechanisms of vulcanized hydrogenated nitrile rubber in different mediums

“…Cyclization reaction or reduction reaction may occur, affecting the service life of the rubber. [18][19][20][21][22] In the current published literatures, few studies have been reported on the aging mechanism for acrylonitrile content on HNBR, and few conclusions on the relevant aging mechanism were proposed.…”