Primary process to fabricate functional groups on acrylonitrile-butadiene rubber surface during peroxide curing

• We provide a innovative method to obtain functional surfaces on NBR through primary process.
• OH, CO, COOH were fabricated on cured NBR surface during peroxide curing.
• NBR surface functional groups change with moulds surface changing.
• Reactions of NBR surface and interior are different.
• NBR surface chemical structures can be designed and controlled by moulds.

To satisfy the demand of low cost, shortening process and environmentally friendly products in industry, it becomes increasingly important to get functional surfaces of oxide without secondary processing of surface modification such as corona and plasma charge, especially for the soft matters of elastomeric rubber surfaces. In terms of this current rubber industry, this paper developed a surface modification method to automatically fabricate oxide functional groups on acrylonitrile-butadiene rubber (NBR) surface during primary processing using different moulds. During peroxide curing, polymer materials such as PA66, metal materials such as copper, aluminum and surface modified copper by fluoride, 4 kinds of moulds were used. Surface functional groups of cured NBR using various moulds at different curing temperature are investigated by X-ray photoelectron spectroscopy (XPS). Hydroxyl (OH), carbonyl (CO), carboxyl groups (COOH) were fabricated on cured NBR surface. Cured NBR surface using Cu mould had the maximum concentrations of O element (9.0 at.%, at curing temperature of 180 °C). The possible surface reactions are discussed and the effects of moulds and curing temperature on NBR surface free energy have been investigated. This presented research demonstrated the reactions of NBR surfaces and interiors are different. Additionally, this surface modification method of NBR has great advantages of process, cost and thus should have a significant value to obtain functional surface in rubber industry and should have a promising future in expanding the applications of NBR.