Study On Scattered Orientation Mechanism Of 2D Nanoparticles In Polymer Matrix Via Micro-Layer Co-Extrusion Technology

Polymer/layered silicate nanocomposites(PLSN) have evoked intense research interests lately due to their excellent and valuable properties compared to the conventional polymer composite. Processing conditions play a key role on the nanoparticle dispersion in matrix, which directly related to the properties of nanocomposites. However, dispersion and orientation distribution randomness of filled two-dimensional nanoparticles in matrix makes nanocomposites performance is far from to achieve the desired requirements by current processing ways. In this study, nano micro-layer drag flow field was introduced into the preparation of PLSN via autonomously developed micro-layer co-extrusion technology, and research on the mechanism between the morphology and properties under nano micro-layer drag flow field, and eventually the controllable dispersion and orientation method of two-dimensional nanoparticles in matrix was obtained. The contents and achievements of the study mainly include:1?Analysis of flow field based on torsional laminating unit. Shear-force produced during the melt flowing not only has a positive effect on orientation of molecule chain, but plays an important role in intercalating the MMT spacing as well, which makes the analysis of shear-rate field of torsional laminating unit is necessary. Shear-rate distribution in torsional laminating unit and effects on the shear-rate distribution of flow mass, viscosity and matrix materials were researched. The results show that shear-rate exists along the machine direction and perpendicular to the machine direction in the torsional laminating unit, and shear-rate distribution in torsional laminating unit had not been effected under the change of flow mass, viscosity and matrix materials. The difference viscosity of matrix materials is the mainly reason to influence the shear-rate value, and the main factors which influence the shear-rate is flow mass and the effect of viscosity is not obviously. The flow mass is the main factors that affect the shear tress for the same kind of matrix material and the melt viscosity is the key factors which influence the shear stress for different kinds of matrix materials.2?Effects on the properties of single materials via mico-layer co-extrusion technology. Samples of LLDPE and PP materials were prepared via micro-layer co-extrusion technology based on the nano micro-layer drag flow field of torsional laminating unit, and the degree of molecule orientation, crystallinity, tensile strength and et.al were tested. The results show that the polymer chain orderly arrangement along the direction of the shear stress under the nano micro-layer drag flow field which produced along the machine direction and perpendicular to the machine direction because the special structure of torsional laminating unit. The orientation degree of polymer chain and crystallinity of polymer material were significantly improved and the size of grain was refined. A significant phenomena of double yielding during the drawing process was appeared and excellent strength and toughness were performed along the machine direction and perpendicular to the machine direction, which is similar to the effect of biaxial stretching.3?Controllable dispersion and orientation research of two-dimensional nanoparticles in polymer matrix. The effects on the dispersion and orientation of MMT in matrix of micro-layer thickness(adjust the number of micro-layers), drag flow velocity gradient (adjust the screw rotation speed), and the different physico-chemical properties of matrix(change the matrix materials) based on the nano micro-layer drag flow field were researched. Samples with different layers, screw rotation and matrix were prepared via micro-layer co-extrusion technology and microstructure and properties were tested.The results indicate that the dispersion and orientation degree of MMT in matrix were effectively improved by the way of adjusting the number of layers to changing the micro-layer thickness, and the thinner micro-layer thickness was, the more obviously dispersion and orientation degree of MMT would be. The effect on enlarging the MMT layer spacing was not effectively and effect on improving the orientation degree of MMT was effectively by the of adjusting the screw rotation to changing drag flow velocity gradient. Effects of different physico-chemical properties matrix on the dispersion and orientation of MMT are different. The higher viscosity of matrix and simpler molecular chain structure were, the exfoliated structure was easier to obtained. According to the research results, the controllable dispersion and orientation degree of MMT was achieved through adjusting the layer numbers to control the micro-layer thickness, adjusting the screw rotation to control the drag flow velocity gradient and changing the matrix material.