Crosslinker free thermally induced crosslinking of hydrogenated nitrile butadiene rubber

Abstract

Hydrogenated nitrile butadiene rubbers (HNBRs) are hydrogenated copolymers of acrylonitrile and butadiene, which are often used in composites or polymer blends. These copolymers are usually cured with peroxides or vulcanized with sulfur to reinforce their mechanical resistance and improve their chemical stability. However, using such crosslinking reagents can be problematic for high value systems where residual H2O2 or S can be detrimental for the application. To address this limitation, we studied the thermally induced crosslinking of HNBR at high temperature (240 °C) with oxygen. To understand the impact of conditions (temperature, time, and atmosphere) on the chemical structure and the mechanical properties of HNBR, different thermal treatments were investigated. We show that HNBR forms a ladder structure during treatment in the presence of O2 which result in a reinforcement of the elastomer. Tensile tests and DSC show both alkene and nitrile moieties are involved in the reaction, leading to a mechanical resistance comparable with a HNBR crosslinked with peroxides or sulfur. These findings will help achieving a better control on the crosslinking to provide HNBRs with desired properties. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1825–1833

Quantification of the ion transport mechanism in protective polymer coatings on lithium metal anodes

“…Self-cyclization of PAN is an attractive approach to form chemical cross-linking between the PAN segments. 13,14 Conventionally, selfcyclization of PAN is initiated at temperatures above 200 C, [15][16][17] and the resulting cross-link density only varies in a narrow range (e.g. 1.5-2.5 Â 10 À4 mol cm À3 ) regardless of the heating time.…”

“…1.5-2.5 Â 10 À4 mol cm À3 ) regardless of the heating time. 14 The difficulty in varying the cross-link density of PAN can be attributed to the high activation energy (149 kJ mol À1 ) for cyclization, and the spontaneous propagation of cyclization aer the activation. 18 Lithium trisulde (Li 2 S 3 ¼ Li 2 S + 2S) in dimethyl formamide (DMF) solution was known to catalyze PAN cyclization at low temperatures.…”

High Energy Li‐Ion Electrodes Prepared via a Solventless Melt Process

“…HNBR was already reported as an efficient potential binder . The thermal treatment applied to remove the sacrificial polymer was found by IR to induce under air a partial crosslinking of the permanent binder . The thermal treatment on the graphitic anode was carried out under inert atmosphere to avoid the oxidation of copper.…”

“…[21] The thermal treatment applied to remove the sacrificial polymer was found by IR to induce under air a partial crosslinking of the permanent binder. [22] The thermal treatment on the graphitic anode was carried out under inert atmosphere to avoid the oxidation of copper. No changes were observed on the coated aluminum collectors.…”

The effect of hot air exposure on the mechanical properties and carbon dioxide permeability of hydrogenated nitrile butadiene rubber (HNBR) with varying carbon black content

“…These elastomers may be tailored for specific applications by changing the composition such as the acrylonitrile content or additive packages, or the type and loading of fillers to achieve the desired balance of performance for the intended application. However, it is well known that the properties of elastomers such as HNBRs change once they start to be used in a service environment, during application over extended time periods [1,2], mechanical loading [3], exposure to different chemical environments [4][5][6][7][8][9][10][11], extremes of temperatures [7,[12][13][14][15][16][17], irradiation (for example electron beam [18][19][20], ion beam [21] or gamma irradiation [22,23]) or combinations of these. Depending on the exposure conditions, these changes in properties may be attributed to increased crosslinking, molecular degradation (i.e.…”