Study On The Dispersion Of Polymer/Additive Blends In A Rotor-stator Dynamic Mixer

The development of modern society has higher requirements for the performance of polymer materials.At present,composite materials with special properties,can be prepared by blending existing polymers with solid additives or liquid additives,such as silica and color paste.For the blending process,it is difficult to achieve rapid and uniform mixing and dispersion due to the large differences in viscosity,phase state and volume between the polymers and additives.Therefore,it is significant for polymer blending to study the mixing device that can achieve rapid and uniform dispersion.In this paper,a new type of rotor-stator dynamic mixer was proposed as the dispersing device to promote the mixng and dispersion of polymer blend systems.The flow characteristics of highly viscous fluids in this mixer were systematically studied by means of fluorescence on-line measurement of residence time distribution(RTD),and the effects of rotational speed,flow rate,rotor structure and arrangement on the mixing and dispersion of different polymer blend systems were also investigated.The mixing performance in the rotor-stator dynamic mixer was compared with that in the traditional mixer using the same polymer blend systems.The following research results were obtained:(1)The back-mixing of high-viscosity fluid in the rotor-stator dynamic mixer was caused by the entrainment effect generated from the rotation of the rotor.The larger the rotational speed,the stronger the entrainment effect and the degree of back-mixing increased.Nevertheless,the variances of the dimensionless RTDs of the fluid in the rotor-stator mixer were all less than 0.3,indicating that their flow form was close to plug flow.Increasing the number of rotor-stator groups had little effect on the RTD,but could greatly enhance the mixing in the radial direction and promote dispersion.(2)Increasing the rotational speed and the number of rotor-stator groups,and using the arc-shaped rotor-stator could enhance the shear flow field in the rotor-stator dynamic mixer.In methyl vinyl silicone rubber(MVQ)/the silica blend system,the strong shear stress destroyed the aggregated structure of the silica and reduced the size of the silica.In the MVQ/color paste system,the drag force generated by the strong shearing action was far greater than the internal force of the color paste,which caused the deformation and rupture of the droplet.(3)Under the same mixing time,the mechanical properties of the vulcanizated rubber prepared by the rotor-stator dynamic mixer with strong shearing effect were better than that by the roll mill,indicating that the rotor-stator dynamic mixer had better mixing capability for the MVQ/silica blend system.Under the same rotational speed,the multiple rotor-stator allowed the color paste droplets in the rotor-stator dynamic mixer to continuously deform and split,which was more conducive to the mixing and dispersion of polyethylene terephthalate/color oil blend systems than the traditional internal mixer.