Investigation Into Compounding Technologies Of Conjugated Structural Additives And Their Effectiveness On HNBR

The modification and ageing resistance of hydrogenated nitrile butadiene rubber(HNBR)in high temperature media has been attracting the attention of scientists.The unique sp~2 superconjugated structure of carbon nanomaterials exhibits the ability to scavenge free radicals,making them important functional additives in the preparation of rubber composites.In order to investigate the relevance of carbon nanomaterials to the ageing resistance of HNBR,this thesis focuses on the effect of their specific structure on the ageing resistance,and a series of HNBR composites were prepared using four carbon materials as the additives,with the following main investigations.HNBR composites with graphite as an additive were prepared by an open refining process.The effects of graphite with sizes of 13?m and 700 nm on the vulcanisation parameters,mechanical properties,thermal oxidative ageing,thermal conductivity and dynamic mechanical properties of the HNBR composites were investigated.The results show that the scorch time(T₁₀)and positive vulcanisation time(T₉₀)of the HNBR/graphite composites increase with increasing graphite content and the torque difference(M_H-M_L)gradually increases under the effect of physical and chemical cross-linking of graphite.At a nano-graphite content of 15 phr,the HNBR composites showed47%higher tensile strength;24%higher thermal conductivity;3.27 times higher ageing coefficient;and 37%higher energy storage modulus of the HNBR/graphite composites compared to the blank samples,while the corresponding glass transition temperature(Tg)shifted to higher temperatures.The flake structure of graphite particles in the rubber matrix facilitates the improvement of the mechanical properties and ageing resistance of the HNBR composites due to the reinforced and sp~2 hybridised structure of the graphite particles.A series of HNBR/CNTs/GE nanocomposites were prepared by a wet process of solution blending desolventization using a combination of carbon-based nanomaterials(graphene and carbon nanotubes)as additives.The effects of the carbon-based nanomaterials on the mechanical properties as well as the heat and oxygen aging resistance of hydrogenated nitrile rubber were investigated.The results showed that the carbon-based nanomaterials had no significant toxic effect on the vulcanisation stage and the addition of the carbon-based nanomaterials increased the torque difference of M_H-M_L.The carbon-based nanomaterials had a good reinforcing effect on the rubber matrix,and the tensile strength as well as the tear strength of rubber/carbon nanotubes were better than that of graphene.The mechanical properties and ageing resistance were improved to varying degrees when modified with GE:CNTs synergistically compared with blank samples.The optimum ratio of 1:2 for the co-modification resulted in the construction of an approximate long-range conjugate system within the rubber matrix,which increased the tensile strength of the rubber/carbon material by 23.9%and the tear resistance by 3.21 times,and improved the ageing coefficient by 5.2 times and the thermal conductivity by 43.6%compared to the blank sample after 24 hours of ageing at 180°C.The addition of the carbon-based nanomaterials also increased the energy storage modulus of the rubber composite by 32%,shifting the glass transition temperature towards the high temperature region and showing a shift towards the high temperature region corresponding to the fastest thermal decomposition rate in terms of thermal stability.HNBR/C₆₀composites were prepared by a wet process using HNBR as the matrix and zero-dimensional carbon material fullerene as the antioxidant by solution blending desolventizing.The effects of C₆₀ content on the vulcanisation parameters,mechanical properties,hot air ageing and dynamic mechanical properties of the HNBR composites were investigated.It was found that:during the vulcanisation stage,fullerenes absorbed some of the radicals generated by the vulcanising agent,and the scorch time and positive vulcanisation time were prolonged;the crosslink density of HNBR/C₆₀composites before and after ageing was determined by the equilibrium swelling method,and it was found that the crosslink density of fullerenes with the addition of the antioxidant was smaller than that of the blank sample;the ageing coefficient of 180°C hot air accelerated ageing was used as a comparison,and the ageing coefficient at a fullerene content of 3phr The glass transition temperature of the blank sample before and after ageing was6.83°C,which was much higher than that of the HNBR/C₆₀ composite at 2.86°C.In addition,the onset decomposition temperature of the HNBR/C₆₀ composite was increased by 4?7°C,and the maximum thermal decomposition temperature could be increased by 2?5°C.Fullerene showed excellent radical trapping effect in the HNBR matrix.