Search

Aggregation of nanofiller in polymer matrix is the key barrier to enhance the mechanical and thermal properties of polymer nanocomposites. Here, we report a novel vane mixer based on elongation flow processing, which is facial to achieve the homogeneous dispersion of functional graphene oxide sheets (FGs) in isotactic polypropylene (iPP). Scanning electron microscopy reveals that FGs in iPP matrix are fully exfoliated and uniformly dispersed. The crystallization behavior, mechanical properties and thermal stability of the nanocomposites with different FGs loadings are investigated by differential scanning calorimetry, dynamic thermomechanical analysis, and thermogravimetric analysis, respectively. The results illustrate that the mechanical and thermal stability of the iPP/FGs composites has enhancement obviously at low FGs loadings., INTRODUCTION Over the past few years, graphene, due to its unique conductivity, thermal and superior mechanical properties, has been identified as a promising candidate for reinforcing polymer composites [1-4]. Polymer [...]

The preparation of ultra-high-molecular weight polyethylene (UHMWPE)/organoclay nanocomposites by continuous elongational flow technique was investigated in a novel eccentric rotor extruder (ERE). The distribution and dispersion morphologies of organo-modified montmorillonite (OMMT) layers were revealed and observed by ash determination, wide angle X-ray diffraction and transmission electron microscopy. The thermal and thermal-mechanical behaviors were characterized by differential scanning calorimeter, thermal gravimetric analysis and dynamic mechanical thermal analysis. The mechanical performances was measured by tensile and impact test. The morphologies of the nanocomposites evidenced that the OMMT layers can be well intercalated or/and exfoliated by UHMWPE matrix, then the fabrication mechanism of intercalated and exfoliated OMMT structures under continuous elongational flow was discussed. The ideal dispersion of OMMT in UHMWPE matrix obviously improved the crystallinity and the mechanical properties at a certain concentration of OMMT loading, indicating that the lower OMMT addition can lead an effective strengthening and toughening for UHMWPE., INTRODUCTION Ultra-high-molecular weight polyethylene (UHMWPE) is a widely applied thermoplastic polymer with low friction coefficient, excellent impact resistance and chemical stability as well as recognized biocompatibility [1-6]. However, the ordinary [...]

On the basis of the forces on the differential element in the solids bed, a function between bulk density and pressure, and the nonisotropic pressure distribution in the element, an expression of pressure in the circumferential direction is derived. And the total power introduced through the positive conveying and the friction dragging conveying is also deduced. Experimental data are obtained using a self-developed and simplified vane extruder with an adjustable rotor eccentricity. The solids conveying mechanism in the solids compaction zone of a vane extruder is theoretically and semiempirically confirmed. Besides, the various portions of total power consumption including the power dissipated on the surfaces of the stator and baffles, the power used to build pressure and the power converted into rotational kinetic energy are derived. The effects of the eccentricity on the solids conveying are also discussed theoretically and semiempirically., INTRODUCTION Before plastic products are shaped by various methods such as injection molding, blow molding, film blowing, and so forth, the thermoplastic raw materials, either in particle or powder form, [...]

An experimental instrument is developed with a purpose to study solids compaction behaviors in vane extruder in a direct manner. The effects of eccentricity, temperature, velocity, and polymer properties on the compressibility of polymer solids are reported in terms of compaction coefficient as a function of rotor torque. The results show that a relatively larger eccentricity or a lower external temperature can bring a smaller compaction coefficient, which results in higher pressure in the solids conveying zone of the vane extruder. However, rotor velocities almost have no influence on the compaction coefficient under the same condition. In addition, a difference is observed between the effects of the semicrystalline polymers and the noncrystalline polymers on the compaction coefficient, which should be taken into consideration in vane extrusion processing operations. POLYM. ENG. SCI., 54:1403-1411, 2014. © 2013 Society of Plastics Engineers, INTRODUCTION In the feed section of screw extruder, the classic solids conveying theory was developed by Darnell and Mol in 1956 [1], In their hypotheses, the density of the solid [...]

The pressure establishment in the solid conveying section of a vane extruder was theoretically and experimentally studied in the present article. Based on the structural and conveying characteristics of the vane extruder, a four-plate model was developed. The effects of the device geometry (eccentricity ζ and discharge port β), the polymer properties (different materials), and the operating conditions (temperature and rotating speed) on the pressure were also studied using a visual experimental device. The results showed that the experimental data were highly consistent with the theoretical data, which indicated that the theoretical model was sensible. Considering the optimization design of the device and its processing parameters, the eccentricity ζ and the discharge port β of the discharge baffle should be appropriately selected, and the setting temperature of the feeding section should be set to a low value. The rotating speed of the rotor had no significant influence on the pressure establishment. In addition, the thereto-mechanical history of the vane extruder was shorter than that of the conventional screw extruder. POLYM. ENG. SCI., 52:2147-2156, 2012. © 2012 Society of Plastics Engineers, INTRODUCTION Most polymer processing instruments are based on screws, such as screw extruder, screw injection molding machine, and so on. In general, screw-based plasticating and conveying extruder can be divided [...]

This article reports a facile approach for industrial‐scale manufacturing of multilayer coextrusion‐blown films by developing a novel rotation homogenization distribution (RHD) method. Materials in this unique process are subjected to a flow field combining both shear circulation and pressure flow. In RHD, circumferential shear causes a laminar flow, where the stable interface between layers can be obtained, and assigns melt evenly to the entire circumferential direction. This equipment has been used to prepare multilayer low‐density polyethylene (LDPE) films under various shear rates by altering the mandrel rotation speed. The effects of mandrel rotation speed on the microstructure, morphology, and properties of bilayer LDPE films were investigated. Multilayer LDPE films with superior interfacial stability and uniform layer distribution, which differ from the multiple melt channels in conventional multilayer coextrusion blown facilities, were successfully fabricated using the proposed equipment. Evident enhancements were observed in thermal shrinkage and mechanical properties of the multilayer films, especially in the transverse direction. © 2018 Society of Plastics Engineers POLYM. ENG. SCI., 59:E339–E349, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]