Dispersion And Interface Of Rubber/Nanocarbons Composites

Nanocarbons,such as graphene and carbon nanotubes,exhibit excellent physical and mechanical characteristics,such as high mechanical strength/modulus,high electrical/thermal conductivity and large specific surface area,etc.As nanofillers for rubber composites,graphene and carbon nanotubes can not only reinforce the rubber efficiently,but also endow the composites with functions.However,to date,the preparation of high performance rubber/nanocarbon composites is still impeded by the dispersion control of fillers and the interfacial structure design between fillers and the rubber matrix.Accordingly,in the present dissertation,we mainly focused on the two key technical issues i.e.the dispersion and interface of nanocabons in the rubber composites.The main contents of this dissertation are as follows.(1)A straightforward yet effective slurry compounding method was developed to prepare chlorosulfonated polyethylene(CSM)/graphene composites.In this methodology,ethanol slurry contained high concentration of tea polyphenol reduced graphene(TPG)was prepared by employing TP as both reducer and modifier for graphene oxide(GO).The increased interlayer spacing of graphene due to the intercalation of TP and ethanol molecules as well as the strong hydrogen bond interaction between TPG sheets and CSM matrix facilitated the intercalation of rubber chains into the TPG sheets during melt compounding.The tensile strength and Akron abrasion resistance of the as-prepared CSM/TPG composites were accordingly improved.(2)Conductive natural rubber(NR)composites with interconnected graphene network were fabricated by the combination of Pickering emulsion templating and thermal reduction strategy.The results indicated that the Pickering emulsion templating is effective in constructing 3D interconnected GO networks and the thermal treatment during hot pressing step is able to realize the effective reduction of GO.This strategy did not rely on the toxic and corrosive reducing agents and the adopted solvents in Pickering emulsions could be recycled and reused,which made the process environmentally friendly.The interconnected graphene network can not only form electrically conductive paths within the NR matrix,but can also serve as sacrificial units that effectively dissipate energy upon external force.Compared with the H-NR composites with uniform dispersion morphology fabricated by conventional latex compounding method,the as-prepared S-NR composites exhibited much better mechanical properties,electrical conductivities and lower percolation threshold.In addition,this GO stabilized Pickering emulsion template strategy can also be used to realize the selective distribution of carbon nanotubes and assemble them into interconnected network structure,facilitating the conductivity improvement of the resulted composites.(3)Styrene-butadiene rubber(SBR)/RGO composites were prepared by in situ interfacial modification during processing,in which rhodanine was adopted as novel reducer and interfacial modifier for GO.The redox chemistry between GO and rhodanine was firstly investigated and the results indicated that GO was effectively reduced into reduced graphene oxide(RGO)during the reaction,while rhodanine monomers underwent oxidative polymerization and were converted into polyrhodanine.The polyrhodanine molecules accordingly adhered to the surface of RGO sheets through hydrogen bonds and ?-? interactions.Compared with SBR/GO composites,the tensile strength and modulus of the resulting SBR/RGO composites were significantly improved.This was because RGO can disperse in SBR matrix more uniformly and form interfacial crosslinking with rubber chains through polyrhodanine.(4)Based on the disclosed reactivity between polyrhodanine and rubber,modified carbon nanotubes(GCNTs)were synthesized from pristine multi-walled carbon nanotubes(MWCNTs)by a novel two-step strategy: first,MWCNTs were wrapped by polyrhodanine through oxidative polymerization of rhodanine and the intermediates were referred to as PCNTs,and then rubber chains were mechanochemically grafted onto the polyrhodanine coating of PCNTs.The grafted rubber chains provides sufficient steric repulsion to prevent GCNTs from agglomeration,which endowed the GCNTs with versatile solubility in various organic solvents.Through vacuum filtration of GCNT dispersions,flexible buckypapers with high conductivity could be obtained and the mechanical and electrical properties of buckypapers can be tuned by varying their polymer contents.SBR/PCNT composites were prepared by melt mixing SBR and PCNTs.The mechanical properties of SBR/PCNT composites were improved significantly,which should be ascribed to the improved dispersion of PCNTs and strengthening interfacial adhension between PCNTs and SBR matrix.