Preparation And Properties Of Graphene/white Carbon Black/natural Rubber Composite Materials

Environment-friendly tires are prepared by using nature rubber?NR?as matrix,silica?SiO₂?as filler and various additives commonly used in rubber processing.This kind of tires have excellent wet skid resistance,mechanical performance,wear resistance,low rolling resistance,which can reduce fuel consumption.However,both SiO₂ and NR have so low thermal conductivity and electrical conductivity that a large amount of heat can't be transferred in time,which will accelerate the aging of tires and shorten the service life.Moreover,static electricity generated by the friction between the surface of the tire and the ground easily cause sparks and discharges,which is harmful and dangerous.Graphene has been widely used in composites due to its excellent mechanical property,electrical conductivity,thermal conductivity,optical property and barrier property.Therefore,we adopted an environmentally friendly and efficient method to prepare graphene nanosheets?GNs?in this paper,and GNs and modified SiO₂ were together used to fill NR.We studied the influence of GNs usage of GNs/SiO₂/NR composites on thermal conductivity,antistatic property,mechanical property and so on.Main research contents and results are as follows:?1?SiO₂ was modified wetly with different kinds of coupling agents?KH550,KH570,KH580,NXT?.SiO₂/NR composites were prepared by mixing the modified?unmodified?SiO₂and NR.And the effects of different coupling agents on the properties of NR filled with SiO₂ were investigated.Unmodified and modified SiO₂were characterized,and vulcanization characteristic parameters,processing properties,mechanical properties,solvent resistance and other properties of SiO₂/NR composites were studied.The main conclusions are as follows.Dehydration condensation reaction occurred between the coupling agent and hydroxyl on the surface of SiO₂,which can reduce the surface energy of SiO₂,making SiO₂ change from hydrophilic to hydrophobic and improving the compatibility between filler and matrix.Compared with unmodified SiO₂/NR composites,modified SiO₂/NR composites possessed better mechanical strength,solvent resistance and cutting resistance,and SiO₂ was more evenly dispersed in the NR.Due to the long carbon chain structure of NXT,NXT-SiO₂had better compatibility with NR,and sulfhydryl group was involved in the formation of three-dimensional crosslinking network during the curing process.Therefore,compared with other modified SiO₂,NXT-SiO₂/NR composites had better properties.?2?Graphite worm?GW?with high aspect ratio was obtained by expanding expandable graphite?EG?at high temperature for 1min,which greatly reduced the energy demand of stripping process.GW was oxidized by O₃,graphite oxide worms?GWO?with different oxygen content were obtained by controlling the oxidation time.GWO with moderate oxygen content was dispersed in ethanol solution and grounded in a colloidal mill for 3h to obtain graphene nanometer sheet?GNs?slurry.The solvent was evaporated by a rotary evaporator to obtain GNs powder.GNs was evenly dispersed in NR latex,and concentrated GNs/NR masterbatch was prepared by flocculating and drying.Finally,GNs/NR composites with GNs content of 0,0.2wt%,0.5wt%,1.0wt%and 2.0wt%were prepared by mechanical blending.GNs were characterized by XPS,XRD,TEM and SEM,and the results showed that EG was successfully transformed into GNs.The thermal conductivity,electrical conductivity,mechanical properties and dynamic mechanical properties of the composites were tested.The results showed that above properties changed regularly with the increase of GNs in the composites.Compared with pure NR,the thermal conductivity of 2.0wt%GNs/NR composites increased by 50%,and the conductivity increased by 5 orders of magnitude.?3?SiO₂ was modified by NXT,and GNs was prepared by edge oxidation and mechanical stripping with EG as raw material.20wt%GNs/NR concentrated masterbatch was prepared by latex blending.Finally,GNs/SiO₂/NR composites were prepared by simple mechanical blending method,and the effect of the combination of GNs and SiO₂ on the properties of NR was discussed.The vulcanization properties,processing properties,mechanical properties,thermal conductivity,antistatic properties,dynamic mechanical property and thermal stability of ternary composites were studied.The results showed that the combination of GNs and SiO₂ was helpful to improve the dispersion in the NR matrix.And with the increase of GNs content,the mechanical properties and processability of composites were improved.Compared with SiO₂/NR composites,the in-plane thermal conductivity of 2wt%GNs/SiO₂/NR composites increased by 38.1%,the through-plane thermal conductivity increased by 36.21%,and the electrical conductivity reached 4.2×10^-8S/m,making NR become an antistatic material.