Degradation of electron beam irradiated hydrogenated butadiene-acrylonitrile rubber. Influence of bounded acrylonitrile content

Abstract

Sieciowanie i degradacja uwodornionego kauczuku butadienowo-akrylonitrylowego pod wp³ywem promieniowania elektronowego. Wp³yw zawartooeci zwi¹zanego akrylonitrylu DEGRADATION OF ELECTRON BEAM IRRADIATED HYDROGENATED BUTADIENE-ACRYLONITRILE RUBBER. INFLUENCE OF BOUNDED ACRYLONITRILE CONTENT Summary-Influence of polarity of hydrogenated butadiene-acrylonitrile rubber (HNBR) on its crosslinking and radiation degradation was investigated. HNBR samples differing in bounded acrylonitrile (AN) content (34, 39 or 43 wt. %) (denoted with the symbols H34, H39 and H43, respectively) (Table 1) were irradiated with 10 MeV electron beam. Doses varied from 20 to 300 kGy. The following properties have been determined: Mooney-Rivlin elasticity constant (2C 1 N-Fig. 2), sol content (S-Fig. 3 and 4), radiation crosslinking efficiency (E) and gel dose (D g) (Table 2). It was found HNBR undergoes radiation crosslinking and its network density is directly proportional to the dose (D). Bounded acrylonitrile content does not influence the processes of HNBR crosslinking and degradation. Ratio of scission acts (p) and crosslinking acts (q) has been determined using Charlesby-Pinner equation [equation (3)]. It has been found that the process of HNBR radiation crosslinking was accompanied with moderate degradation of the chains (p/q = 0.05-0.10, Table 2) going probably according to β-scission mechanism. Relative intensity of absorption band at 810 cm-1 related to >C=CH 2 end groups (Table 3) was determined by internal reflection spectroscopy (IRS).

Interelastomer Reactions Occurring during the Cross-Linking of Hydrogenated Acrylonitrile-Butadiene (HNBR) and Chloroprene (CR) Rubbers Blends in the Presence of Silver(I) Oxide (Ag2O) and Mechanical Properties of Cured Products

“…Fully hydrogenated HNBR (<1% of the initial number of double bonds), due to its saturated nature, can only be cross-linked with organic peroxides (usually in the presence of coagents) or by ionizing radiation. On the other hand, the cross-linking of partially hydrogenated HNBR (2–5% of the initial number of double bonds) can be classically carried out with sulfur in the presence of ultra- or semi-ultra-accelerators or with tetraalkylthiuram disulfides as sulfur donors [ 4 , 5 , 6 ]. Compared to peroxide-cured HNBR, sulfur-cured HNBR products have higher tear and tensile strengths, but, unfortunately, they exhibit worse resistance to thermal and ozone aging and higher permanent deformation [ 4 , 5 ].…”

“…On the other hand, the cross-linking of partially hydrogenated HNBR (2–5% of the initial number of double bonds) can be classically carried out with sulfur in the presence of ultra- or semi-ultra-accelerators or with tetraalkylthiuram disulfides as sulfur donors [ 4 , 5 , 6 ]. Compared to peroxide-cured HNBR, sulfur-cured HNBR products have higher tear and tensile strengths, but, unfortunately, they exhibit worse resistance to thermal and ozone aging and higher permanent deformation [ 4 , 5 ]. Currently, the use of high-energy ionizing radiation as a method of HNBR cross-linking is of increasing importance in the industry.…”

Crosslinking of new elastomers functionalized with carboxyl groups

“…The crosslinking degree and structure of functionalized rubber were characterized by IR method and by the swelling degree in selected solvents, determined with standard procedures used in our earlier studies [8,9].…”