Zhaodong Xu

Enhanced mechanical properties and thermal conductivity of styrene–butadiene rubber reinforced with polyvinylpyrrolidone-modified graphene oxide

A facile non-covalent surface treatment method is reported in this paper to modify graphene oxide (GO) sheets with the assistance of polyvinylpyrrolidone (PVP). The PVP-modified GO (PGO) was further adopted to fabricate PGO/styrene–butadiene rubber (SBR) nano-composites through the latex compounding method. The properties of PGO were carefully investigated and interaction between GO and PVP molecules was confirmed. The mechanical properties, dynamic mechanical properties, thermal stability, thermal conductivity as well as swelling properties of the PGO/SBR nano-composites were thoroughly studied. It was confirmed that PVP molecules could have strong interaction with GO via hydrogen bond; thus, the PGO significantly improved the strength of SBR matrix, e.g., 517 and 387xa0% increase in tensile strength and tear strength, respectively, with the presence of only 5 phr (parts per hundred rubber) PGO in the nano-composite. The presence of PGO had also greatly reduced the glass transition temperature (Tg) and enhanced the storage modulus of SBR matrix in the nano-composites. Meanwhile, the maximum heat decomposition temperature (Tmax) was increased by 23.6xa0°C; equilibrium solvent uptake in toluene was reduced by 41xa0% and thermal conductivity was increased by 30xa0%. All the observations indicated that PVP modification of GO can achieve excellent exfoliation and dispersion of GO in the SBR matrix. These findings were further supported by X-ray diffraction and scanning electron microscopy measurements.

Polyvinyl pyrrolidone modified graphene oxide for improving the mechanical, thermal conductivity and solvent resistance properties of natural rubber

Polyvinyl pyrrolidone (PVP) was applied to modify graphene oxide (GO) to obtain PVP modified GO (PGO). The PGO/natural rubber (NR) nanocomposites were fabricated by mixing a PGO aqueous dispersion with NR latex, followed by coagulation and vulcanization. The structure of PGO was characterized using atomic force microscopy, solid state 13C NMR, Fourier transform infrared spectroscopy, Raman spectra and X-ray photoelectron spectroscopy. The interaction between GO and PVP molecules as well as the effects of PGO on the mechanical properties, thermal conductivity and solvent resistance properties of the NR matrix were thoroughly studied. The results revealed that PVP molecules might interact with GO via hydrogen bonds. With the addition of PGO, the tensile strength, tear strength and thermal conductivity as well as solvent resistance of the PGO/NR nanocomposites increased. The PGO/NR nanocomposite with 5 phr (parts per hundred rubber) PGO had an 81%, 159%, 30% increase in tensile strength, tear strength, thermal conductivity and a 46% decrease in solvent uptake, respectively, compared with pristine NR.

Enhanced mechanical, dielectric, electrical and thermal conductive properties of HXNBR/HNBR blends filled with ionic liquid-modified multiwalled carbon nanotubes

Abstract1-Butyl 3-methylimidazolium bis(trifluoromethylsulfonyl) imide (BMI)-modified multiwalled carbon nanotubes (MWCNTs) were used as nanofillers for the hydrogenated carboxylated nitrile–butadiene rubber/hydrogenated nitrile–butadiene rubber (HXNBR/HNBR) blends. The multifunctional properties of rubber nanocomposites with various filler loadings were investigated. It was found that in the presence of BMI-MWCNTs, the mechanical strength, dielectric properties, electrical and thermal conductivities of HXNBR/HNBR were significantly improved due to the better dispersibility as well as the intrinsic reinforcement effect of MWCNTs. Particularly, in comparison with unfilled rubber blend, the electrical conductivity of BMI-MWCNTs-filled HXNBR/HNBR composites exhibited three orders of magnitude enhancement with a lower electrical percolation threshold. The tensile strength and thermal conductivity of composites filled with 5xa0phr (parts per hundred rubber) BMI-MWCNTs increased by 52 and 23%, respectively. In addition, the polarizability of composites was also intensified under the applied electric field, which resulted in remarkable dielectric relaxation compared to neat rubber. Our experimental data have indicated that BMI-MWCNTs can be used as a promising candidate for fabricating multifunctional HXNBR/HNBR nanocomposites.n

Synergistic effects of hybridization of carbon black and carbon nanotubes on the mechanical properties and thermal conductivity of a rubber blend system

Abstract The effects of hybridization of multi-walled carbon nanotubes (MWCNTs) with carbon black (CB) and the structure-property relationships of nanocomposites based on hydrogenated nitrile-butadiene rubber/hydrogenated carboxylated nitrile-butadiene rubber blends were extensively studied. MWCNTs used in this work were modified through acid treatment to improve the dispersion of MWCNTs in the rubber matrix and the surface interaction between MWCNTs and matrix. Synergistic interaction between CB and MWCNTs increased the tensile modulus and tear strength of nanocomposites. The effect of MWCNTs on the transport properties invoked an increment in the thermal conductivity of the nanocomposites. A combination of 10 phr (parts per hundred rubber) MWCNTs with 40 phr CB dramatically increased the modulus at 100% elongation, tear strength, and thermal conductivity of the nanocomposite by 66%, 28%, and 36%, respectively, compared with those of nanocomposite filled with 40 phr CB.