Methylol-terminated phenol-formaldehyde resin curative

With EPDM/PP, the rubber is EPDM and the thermoplastic resin is polypropylene. Even though early patents show the vulcanizing agent to be sulfur with an accelerator such as 2-bis(benzothiazolyl)disulfide (MBTS) or tetramethyl thiuram disulfide (TMTD), these sulfur-based curatives are not used today for TPVs. Likely a methylol-terminated phenol-formaldehyde resin curative with a tin chloride activator is used. For a lighter color, sometimes a peroxide crosslinker is used instead. Also, paraffinic... 

Figure 6.15 The phenolic curative (methylol terminated, para-alkyl substituted, phenol-formaldehyde resin) synthesis...

Methylol-terminated para-alkyl-substituted phenol formaldehyde resin is used as the vulcanizing agent for compounds based on butyl and EPDM rubber. The alkyl group is usually octyl. It is commonly used to cure butyl rubber where superior heat resistance is needed. Therefore, this vulcanizing agent is commonly used as the curative to make butyl bladders for repetitive curing of tires. It is also sometimes used in dynamic vulcanization with a tin chloride activator to make thermoplastic vulcanizates (TPVs). 

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See also in sourсe #XX -- [ ]

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