Filler Dispersion (filler + dispersion)

Distribution by Scientific Domains


Selected Abstracts


Structure and properties of phase change materials based on HDPE, soft Fischer-Tropsch paraffin wax, and wood flour

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010
M. E. Mngomezulu
Abstract Phase-change materials based on high density polyethylene (HDPE), soft Fischer-Tropsch paraffin wax (M3), and alkali-treated wood flour (WF) were investigated. The blend and composite samples were prepared by melt mixing using a Brabender Plastograph, followed by melt pressing. They were characterized in terms of their morphology, as well as thermal, mechanical, thermo-mechanical, and water absorption properties. Although SEM micrographs showed some evidence of intimate contact between the WF particles and the HDPE matrix as a result of alkali treatment, poor filler dispersion, and interfacial adhesion were also observed. Partial immiscibility of the HDPE and the M3 wax was noticed, with the WF particles covered by wax. There was plasticization of the HDPE matrix by the wax, as well as partial cocrystallization, inhomogeneity and uneven wax dispersion in the polymer matrix. The HDPE/WF/M3 wax composites were more homogeneous than the blends. The presence of wax reduced the thermal stability of the blends and composites. Both the presence of M3 wax and WF influenced the viscoelastic behavior of HDPE. The HDPE/M3 wax blends showed an increase in the interfacial amorphous content as the wax content increases, which resulted in the appearance of a ,-relaxation peak. The presence of M3 wax in HDPE reduced the mechanical properties of the blends. For the composites these properties varied with WF content. An increase in wax content resulted to a decrease in water uptake by the composites, probably because the wax covered the WF particles and penetrated the pores in these particles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]


Polymer nanocomposites based on needle-like sepiolite clays: Effect of functionalized polymers on the dispersion of nanofiller, crystallinity, and mechanical properties

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008
E. Bilotti
Abstract Polypropylene (PP)/sepiolite (Sep) nanocomposites are prepared by melt compounding in a mini-extruder apparatus. The often used maleic anhydride-modified polypropylene (PP-g-MA) is compared with two custom-made functionalized polymers, PP-acid and the di-block copolymer PP-PEO, with respect to the filler dispersion and filler reinforcement efficiency. For that purpose, morphological and mechanical studies are carried out by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and mechanical tensile tests. In addition, the nanocomposites are characterized by wide-angle X-ray scattering (WAXS) and differential scanning calorimetric (DSC) techniques, to assess the effect of the nanofiller on the crystalline structure of the PP matrix nano-filler. The use of PP-PEO and PP-acid resulted in a better nanofiller dispersion compared with traditional PP-g-MA-modified systems. Sepiolite acts as nucleating agent for the crystallization of PP and seems to lead to an orientation of the ,-phase crystals. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source]


Application of ultrasound and neural networks in the determination of filler dispersion during polymer extrusion processes

POLYMER ENGINEERING & SCIENCE, Issue 6 2005
Zhigang Sun
Mineral filler dispersion is important information for the production of mineral-charged polymers. In order to achieve timely control of product quality, a technique capable of providing real-time information on filler dispersion is highly desirable. In this work, ultrasound, temperature, and pressure sensors as well as an amperemeter of the extruder motor drive were used to monitor the extrusion of mineral-filled polymers under various experimental conditions in terms of filler type, filler concentration, feeding rate, screw rotation speed, and barrel temperature. Then, neural network relationships were established among the filler dispersion index and three categories of variables, namely, control variables of the extruder, extruder-dependent measured variables, and extruder-independent measured variables (based on ultrasonic measurement). Of the three categories of variables, the process control variables and extruder-independent ultrasonically measured variables performed best in inferring the dispersion index through a neural network model. While the neural network model based on control variables could help determine the optimal experimental conditions to achieve a dispersion index, the extruder-independent network model based on ultrasonic measurement is suitable for in-line measurement of the quality of dispersion. This study has demonstrated the feasibility of using ultrasound and neural networks for in-line monitoring of dispersion during extrusion processes of mineral-charged polymers. POLYM. ENG. SCI., 45:764,772, 2005. © 2005 Society of Plastics Engineers [source]


Optimizing Melt-Processing Conditions for the Preparation of iPP/Fumed Silica Nanocomposites: Morphology, Mechanical and Gas Permeability Properties

MACROMOLECULAR REACTION ENGINEERING, Issue 4 2007
Alexandros Vassiliou
Abstract A series of iPP/SiO2 nanocomposites, containing 1, 2.5, 5, 7.5, and 10 wt.-% fumed silica nanoparticles, were prepared by melt mixing in a twin screw co-rotating extruder. The effect of different extrusion parameters was evaluated. The size of aggregates increased with increase in SiO2 content and repetition of the mixing process improved the filler's dispersion. A similar effect was also exhibited by either increasing the rotor speed or the mixing temperature, with the latter being more pronounced at the ranges studied. The mechanical properties of the prepared nanocomposites were evaluated and various models used to explain the observed enhancements. However, only the three-phase model could provide some correlation with the experimental results. All nanocomposites displayed lower permeability to gases. [source]