Yanhu Zhan

Enhancing electrical conductivity of rubber composites by constructing interconnected network of self-assembled graphene with latex mixing

Vulcanized graphene/natural rubber composites with a conductive segregated network exhibiting good electrical conductivity, water vapor permeability and high mechanical strength are prepared by self-assembly in latex and static hot pressing. The composite exhibits a percolation threshold of ∼0.62 vol% and a conductivity of 0.03 S m−1 at a content of 1.78 vol%, which is ∼5 orders of magnitude higher than that of the composites made by conventional methods at the same loading fraction.

Carbon nanotubes/carbon black synergistic reinforced natural rubber composites

Abstract Carbon black (CB) and carbon nanotubes (CNTs) filled natural rubber (NR) composites were prepared. In order to overcome the dispersion of CNTs in rubber matrix, the surface modification of CNTs with bis-(γ-triethoxysilylpropyl)-tetrasulphide (Si-69) was undertaken, and a two-step mixing process, i.e. the use of twin roll mill followed by mixing in a Haake Banbury mixer (TR-THM) was used. The structure and mechanical properties were investigated. The results show that the Si-69 treated CNTs (S-CNTs) were dispersed in the rubber matrix uniformly. Compared with CB/NR composites without CNTs, the S-CNTs/CB/NR composites have better mechanical properties. When the ratio of S-CNTs/CB/NR was 5 : 20 : 100, the tear strength was improved by ∼60%, and the mechanical properties reached a maximum. Dynamical mechanical analysis (DMA) reveals that with increasing content of CNT, the elastic modulus of composites at room temperature increases, and the maximum loss tangent and the corresponding glass transition temperature of composites decrease.

Natural rubber/carbon black/carbon nanotubes composites prepared through ultrasonic assisted latex mixing process

Abstract Carbon black (CB) and carbon nanotubes (CNTs) filled natural rubber (NR) composites were prepared through an ultrasonic assisted latex mixing process. Carbon nanotubes were dispersed into NR latex by ultrasonic irradiation and then the mixed latex were co‐coagulated to obtain the CNTs/NR masterbatch. The structure and properties of the composites were characterised. The results show that the ultrasonic assisted latex mixing process disperses CNTs more uniformly in the matrix than the conventional mixing methods. The well dispersed CNTs and CB exhibited a synergistic reinforcing effect. When the weight ratio of CB/CNTs was 20∶5 (parts per hundred of rubber), the mechanical properties reached the maximum. Dynamical mechanical analysis revealed that with increasing CNT contents, the elastic modulus of composites at room temperature increased, while the maximum loss tangent decreased. Dynamic rheological measurement showed the storage modulus and complex viscosity of rubber composites increased and the shear thinning index decreased with increasing CNT contents.

Co-compatibilising effect of carbon nanotubes and liquid isoprene rubber on carbon black filled natural rubber/polybutadiene rubber blend

Abstract Bis-(triethoxysilylpropyl)-tetrasulfane functionalised carbon nanotubes (t-CNTs) were used as compatibiliser along with liquid isoprene rubber (LIR) in the natural rubber (NR)/polybutadiene rubber (BR) blend. Their reinforcing and compatibilising effects were evaluated by mechanical, fatigue crack growth resistance properties and blend homogeneity. Scanning electron microscope and transmission electron microscope showed enhanced interfacial adhesion between the binary rubber phases and improved dispersion of the minor phase in the rubber blend respectively with the co-existence of LIR and carbon nanotubes. The tensile strength of the carbon black (CB) filled NR/BR blend reached its optimum when 3 phr CB was replaced with an equal amount of t-CNTs in the presence of 7 phr LIR, while the fatigue crack growth resistance property achieved its maximum in the presence of 3 phr LIR. This interesting co-compatibilisation behaviour of t-CNTs and LIR suggests that t-CNTs have a better effect than CB with the assistance of LIR, which is an effective plasticiser in the NR/BR blend.