The structural changes of rubber during thermal oxidative aging can be divided into two categories: one is thermal oxidative aging reaction (cracking) with molecular chain degradation as the main reaction; the other is thermal oxidative aging (structuring) with cross-linking between molecular chains as the main reaction.
Natural rubber contains isoprene rubber, butyl rubber, EPDM rubber, homopolymerized epichlorohydrin rubber and copolymerized epichlorohydrin rubber. The appearance of this type of rubber after thermal oxidative aging is soft and sticky.
Butadiene rubber contains butadiene, and the main reaction during thermal oxidative aging is cross-linking reaction. Similar rubber varieties include NBR/SBR/CR/ERDM/FPM/CSM. The appearance of this type of rubber after thermal oxidative aging is hardening and brittleness.
What are the protective methods for rubber aging?
Since rubber aging is a complex comprehensive chemical reaction process, and it is impossible to absolutely prevent rubber aging, appropriate measures can be taken to slow down the aging rate of rubber, thereby achieving the purpose of extending the service life of rubber. Anti-aging measures mainly include physical protection and chemical protection.
The physical protection method is to avoid the interaction between rubber and various aging factors as much as possible, such as using surface coating or treatment, adding light shielding agent, adding paraffin, etc.
The chemical protection method is to add certain substances to prevent or delay the aging of rubber, such as adding amine or phenol chemical antioxidants.