Study on Carbon Nanotube Dispersion Behavior in Epoxy Resin under Synergistic Effect of Continuous Stretching Flow and Ultrasound Oscillation

In this paper, carbon nanotubes (CNTs) dispersion behavior in epoxy resin under synergistic effect of continuous stretching flow and ultrasound oscillation was studied. A small continuous stretching machine which could provide continuous stretching flow for polymer was designed and manufactured for studying the synergistic effect of continuous stretching flow and ultrasound oscillation on dispersive property. Firstly, the influence of different initial phase angle of dual rotor and mixing time on dispersive property were studied by preparing specimens of CNTs/epoxy resin composite under continuous stretching machine. Then, the synergistic effect of continuous stretching flow and ultrasound oscillation on dispersive property was studied with various ultrasonic power and synergistic time. In this study, the morphology of blends was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that initial phase angle of dual rotor and mixing time had great effect on the dispersion of CNTs in epoxy resin. The degree of CNTs dispersion was best when the initial phase angle of dual rotor was 0°, and increasing mixing time could improve the degree of CNTs dispersion. Increasing ultrasonic power and synergistic time were helpful to disperse CNTs in epoxy resin. It demonstrated that the synergistic effect of continuous stretching flow and ultrasound oscillation had obviously effect on the dispersion of CNTs.

Influence of Acid/Ether-Ratio on Composition and Dispersive Property of Polycarboxylic Type Water Reducers

Polycarboxylic type water reducers were synthesized at different molar ratios of acrylic acid to methyl-allyl polyethylene glycol2400 (acid/ether-ratio). Influence of the acid/ether ratio on its composition and dispersive property were studied by means of Gel Permeation in Chromatography (GPC) and fluidity test of cement paste. The GPC analysis results showed that the average molecular weight and polydispersity were increased with the increase of acid/ether-ratio, but the polymerization degree should be no longer increased as which reached to a certain value, the excessive small-monomers would be self-polymerized when macro-monomers had been consumed. As the final product of polymer at an acid/ether ratio of 5:1, was composed of un-reacting macro monomer (about 6%) and the copolymer of water reducers (about 92%) and the copolymer of small monomers (about 2%). The result of fluidity of cement paste showed that the acid/ether-ratio also influenced the dispersive property to different cement, its ability would be bad if at the ratio of 2:1, then the property of dispersive and fluidity retaining should be all well if at 3.5:1, and the beginning dispersive ability might be high but the ability of fluidity retaining be low as the ratio was beyond 4.5:1.