Study On Processing,Microstructure And Properties For Hydrogenated Nitrile/Fluoroelastomer Binary Alloy Composites

Hydrogenated nitrile butadiene rubber（HNBR）and fluoroelastomer（FKM）have excellent aging resistance and heat resistance,which are the preferred materials for the preparation of packer rubber barrel in oil drilling operations.However,packer rubber barrel material used in oil and gas extraction engineering must be able to withstand high pressure,high temperature,and corrosive media,However,available rubber sealing materials are not capable of working under above mentioned harsh conditions for long service time.Therefore,profoundly understanding the aging mechanisms of rubber sealing materials in different aging environments is crucial for solving the long-term durability issues of rubber sealing materials.This thesis focuses on the aging mechanism of rubber sealing materials and prepares a series of HNBR/FKM binary alloy composites by adding novel fillers,and mainly carries out the following research work:Four different Hydrogenated Nitrile Butadiene Rubbers（HNBR）with varying Acrylonitrile content（17%,21%,34%,and 43%）and HNBR/FKM binary alloy composite materials with different blending ratios were prepared to investigate the effect of-CN content on the mechanical properties,aging resistance,and dynamic mechanical properties of HNBR,as well as the effect of two rubber blending ratios on the properties of HNBR/FKM binary alloy composite materials.The results showed that the higher the-CN content,the higher the physical and mechanical strength of HNBR.At high temperatures,the higher the-CN content,the faster the tensile strength decay rate of HNBR.Thermal oxygen aging data revealed that excessive cross-linking reactions occurring during the thermal oxygen aging process were the main internal cause of the deterioration in HNBR properties.In liquid media at 180℃,the-CN groups of the HNBR molecule’s main chain undergo hydrolysis reactions to form-CONH₂,-COOH,and-COO^-groups.The-COOH groups further undergo condensation reactions with-CONH₂ in deionized water media to form cross-links.The-COO^-groups react with Ca²⁺and Mg²⁺in mineral water and oil-water media,respectively,to form a cross-linked network that affects the mechanical properties of the HNBR.FKM can be uniformly dispersed in the HNBR matrix,and HNBR and FKM exhibit good compatibility.When the blending ratio of HNBR and FKM is 90:10,the HNBR/FKM binary alloy composite material exhibits the best mechanical properties.A composite modifier was prepared by blending carbon black（CB）,hydroxide zinc monomethacrylate（HZMMA）,and multi-walled carbon nanotubes（MWCNTs）into a hydrogenated nitrile rubber/fluoroelastomer（HNBR/FKM）binary rubber alloy matrix,to produce an HNBR/FKM binary alloy composite material.The effect of the composite reinforcing agent on the vulcanization characteristics,mechanical properties,aging resistance,and dynamic mechanical properties of the HNBR/FKM binary alloy composite material was studied.The results showed that the addition of HZMMA and MWCNTs to the rubber alloy matrix increased the rubber’s vulcanization rate and cross-linking degree.The tensile strength of the rubber composite material synergistically reinforced with HZMMA and MWCNTs increased by 1.2 times.Compared with the composite material reinforced with pure carbon black,the composite material reinforced with 3 phr MWCNTs and HZMMA had a lower decrease in elongation at break from170%to 109%after thermal oxygen aging,with an elongation at break retention rate of 55%,and the hardness change rate was the lowest,indicating good aging resistance.With increasing MWCNTs content,the glass transition temperature（T_g）of the composite material shifted towards lower temperatures,and the tanδvalue gradually decreased.In-situ synthesis of zinc dimethacrylate（ZDMA）within the one-dimensional nanotube cavities of halloysite nanotubes（HNTs）was carried out to prepare one-dimensional halloysite nanotubes loaded with ZDMA（RHNTs）.Modification of hydrogenated nitrile butadiene rubber/fluoroelastomer（HNBR/FKM）binary rubber compound with RHNTs and processing of new anti-aging HNBR/FKM/RHNTs composite.The effect of RHNTs on the mechanical properties and aging resistance of HNBR/FKM composites was investigated.The results showed that the HNBR/FKM/RHNTs composites exhibited improved tensile strength compared to blank samples.Especially,Si-69 modified RHNTs showed better dispersion in the polymer matrix,resulting in the highest tensile strength and maximum elongation at break of the processed HNBR/FKM/RHNTs composite materials,indicating a significant improvement in modification.In a thermal oxidative medium at 150℃,the tensile strength of the blank rubber composite,HNTs composite,and HNTs-1 composite all showed a peak phenomenon of aging enhancement within the initial 72 hours,while the tensile strength of RHNTs composite remained stable,and the elongation at break showed a slow decline.RHNTs as an active additive significantly improved the aging resistance of HNBR/FKM binary rubber composites and proposed a new mechanism for anti-thermal oxidative aging.