Functionalized graphene oxide/ EPDM composites with enhanced barrier properties
Topic(s) : Material science
Co-authors :
Zhehong LU (UNITED KINGDOM), Yuan ZHANG , Ziqiang ZHU , Yubing HU , Wei JIANGAbstract :
Rubber composites have been widely used in various fields such as aerospace, chemical protective equipment, and sealing rings due to their high elasticity, great barrier performance and excellent compressibility recovery. In particular, Ethylene Propylene Diene Terpolymer Rubber (EPDM), with its remarkable chemical resistance, weather resistance, and low density, has become an ideal sealing material for spacecraft. However, since the use temperature of EPDM composites is above its glass transition temperature, resulting a significant amount of free volume within the composites. This makes small molecule penetrants can easily pass through, consequently reducing the barrier properties of EPDM composites.
To effectively improve the barrier properties of EPDM composites, a common solution is to add nanofillers to the EPDM matrix. Graphene oxide (GO) is an ideal filler to enhance the barrier properties of EPDM composites. As a derivative with a similar structure to graphene, GO can get a better overall performance of composites while only using a tiny filling amount compared with traditional nanofillers. In recent years, GO has been widely used to enhance the barrier properties of polymers due to its excellent polymer compatibility, wide specific surface area and easy modification. GO nanosheets have a larger specific surface area, which enables them to form better barrier effects when dispersed in polymers. Meanwhile, GO has excellent strength and hardness, which enables it to increase strength in composites and provide excellent mechanical stability. Moreover, GO has good compatibility with many polymers and can be well dispersed in the polymer matrix to prepare composites with excellent comprehensive properties. However, due to the presence of oxygen-containing groups of GO, there is a problem of poor interfacial compatibility between GO and EPDM. Therefore, surface modification of GO is required to improve the interfacial interaction between GO and rubber molecular chains to further improve the barrier properties.
In this work, sulfur-graphene oxide (S-GO) hybrids were prepared by in-situ growth of sulfur on the surface of GO sheets through the reaction between thiosulfate and hydrochloric acid. The incorporation of S-GO hybrids into EPDM, facilitated by the emulsion compounding method, serves to further fortify its barrier performance against plasticizer migration. As the contact area between GO and sulfur particles increases, the degree of reaction between GO and sulfur increases, thereby constructing a chemical covalent cross-linked interface of GO-S-EPDM. These strong interfaces and complex filler networks contribute to a notable reduction of 24.9% and 14.1% in plasticizer migration for S-GO/EPDM in comparison to pure EPDM and GO/EPDM, respectively. This research not only advances the understanding of high-barrier EPDM composites but also provides valuable insights for their industrial applications.
To effectively improve the barrier properties of EPDM composites, a common solution is to add nanofillers to the EPDM matrix. Graphene oxide (GO) is an ideal filler to enhance the barrier properties of EPDM composites. As a derivative with a similar structure to graphene, GO can get a better overall performance of composites while only using a tiny filling amount compared with traditional nanofillers. In recent years, GO has been widely used to enhance the barrier properties of polymers due to its excellent polymer compatibility, wide specific surface area and easy modification. GO nanosheets have a larger specific surface area, which enables them to form better barrier effects when dispersed in polymers. Meanwhile, GO has excellent strength and hardness, which enables it to increase strength in composites and provide excellent mechanical stability. Moreover, GO has good compatibility with many polymers and can be well dispersed in the polymer matrix to prepare composites with excellent comprehensive properties. However, due to the presence of oxygen-containing groups of GO, there is a problem of poor interfacial compatibility between GO and EPDM. Therefore, surface modification of GO is required to improve the interfacial interaction between GO and rubber molecular chains to further improve the barrier properties.
In this work, sulfur-graphene oxide (S-GO) hybrids were prepared by in-situ growth of sulfur on the surface of GO sheets through the reaction between thiosulfate and hydrochloric acid. The incorporation of S-GO hybrids into EPDM, facilitated by the emulsion compounding method, serves to further fortify its barrier performance against plasticizer migration. As the contact area between GO and sulfur particles increases, the degree of reaction between GO and sulfur increases, thereby constructing a chemical covalent cross-linked interface of GO-S-EPDM. These strong interfaces and complex filler networks contribute to a notable reduction of 24.9% and 14.1% in plasticizer migration for S-GO/EPDM in comparison to pure EPDM and GO/EPDM, respectively. This research not only advances the understanding of high-barrier EPDM composites but also provides valuable insights for their industrial applications.