Home About us Contact
|
Home About us Contact | ||
|
|
||
Twin-screw Extrusion (twin-screw + extrusion)
Selected AbstractsTwin-screw extrusion of polypropylene-clay nanocomposites: Influence of masterbatch processing, screw rotation mode, and sequencePOLYMER ENGINEERING & SCIENCE, Issue 6 2007Mark A. Treece This work seeks to optimize the twin-screw compounding of polymer-clay nanocomposites (PCNs). Proportional amounts (3:1) of maleic anhydride functionalized polypropylene compatibilizer (PP- g -MA) and organically modified montmorillonite clay at clay loadings of 1, 3, and 5 wt% were melt-blended with a polypropylene (PP) homopolymer using a Leistritz Micro 27 twin-screw extruder. Three melt-blending approaches were pursued: (1) a masterbatch of PP- g -MA and organoclay were blended in one pass followed by dilution with the PP resin in a second pass; (2) all three components were processed in a single pass; and (3) uncompatibilized PP and organoclay were processed twice. Both corotation and counterrotation operation were utilized to investigate the effect of screw rotation mode and sequence on organoclay exfoliation and dispersion. X-ray diffraction was employed to characterize basal spacing; however, since rheology is known to be highly sensitive to mesoscale organoclay structure, it is an ideal tool to examine the relationship between the various processing methods and exfoliation and dispersion. A holistic analysis of rheological data demonstrates the efficacy of the masterbatch approach, particularly when compatibilizer and organoclay are blended in counterrotating mode followed by dilution with matrix polymer in corotating mode. POLYM. ENG. SCI., 47:898,911, 2007. © 2007 Society of Plastics Engineers [source] Comparison of polyamide 66,organoclay binary and ternary nanocompositesADVANCES IN POLYMER TECHNOLOGY, Issue 3 2009Miray Mert Abstract Polyamide 66,Lotader® 2210 blends (95/5 w/w), polyamide 66,Cloisite® 15A binary nanocomposites (98/2 w/w), and polyamide 66,Lotader® 2210,Cloisite® 15A ternary nanocomposites (93/5/2 w/w) were prepared by twin-screw extrusion, and the changes in mechanical properties, morphology, and flow properties of the materials prepared by different mixing sequences were investigated in this study. Lotader® 2210, which is a random terpolymer of ethylene, butyl acrylate, and maleic anhydride, was used as the impact modifier for polyamide 66 blends as well as polyamide 66 based nanocomposites. The best dispersion level, highest mechanical properties, highest viscosity values, and smallest elastomeric domain sizes were obtained for the mixing sequence in which all the components forming the ternary nanocomposites were compounded simultaneously. Incorporation sequence of either the organoclay or the impact modifier into the polymeric matrix was varied in the other mixing sequences, and this resulted in poorer distribution of the organoclay platelets and elastomeric domains in the matrix owing to insufficient shear intensity applied on the components in a single extrusion step. Toughness values of the ternary nanocomposites were improved compared with the binary nanocomposites upon addition of the impact modifier into polymer,organoclay combination. It was concluded that the compounding sequence of the components plays a significant role in the dispersion of organoclay and the properties of the nanocomposites, because it directly affects the interaction between the different phases. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:155,164, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20158 [source] Evaluating Energy Consumption and Efficiency of a Twin-Screw ExtruderJOURNAL OF FOOD SCIENCE, Issue 5 2002M. Liang ABSTRACT: Using the results from twin-screw extrusion of corn meal, both energy consumption and extruder efficiency were found to be significantly correlated with screw speed and specific feeding load (SFL). An increase in the SFL decreased the total specific mechanical energy, but increased the extruder efficiency. SFL influenced the extruder efficiency more than the screw speed. Increasing the screw speed from 300 to 450 rpm at a constant SFL level increased the extruder efficiency by 6 to 11%, whereas an increase of SFL from 0.0026 to 0.0038 kg rev 1 raised the extruder efficiency by 30%. Of the mechanical energy consumed per unit mass of extrudate, over 98% were used for shearing or viscous dissipation and less than 1.5% were for pumping during twin-screw extrusion of corn meal. [source] Compatibilizing effect of ethylene,propylene,diene grafted maleic anhydride terpolymer on the blend of polyamide 66 and thermal liquid crystalline polymerPOLYMER COMPOSITES, Issue 6 2006Qunfeng Yue Polyamide 66,thermal liquid crystalline polymer (PA66/TLCP) composites containing 10 wt% TLCP was compatibilized by ethylene,propylene,diene-grafted maleic anhydride terpolymer (MAH- g -EPDM). The blending was performed on a twin-screw extrusion, followed by an injection molding. The rheological, dynamic mechanical analysis (DMA), thermal, mechanical properties, as well as the morphology and FTIR spectra, of the blends were investigated and discussed. Rheological, DMA, and FTIR spectra results showed that MAH- g -EPDM is an effective compatibilizer for PA66/TLCP blends. The mechanical test indicated that the tensile strength, tensile elongation, and the bending strength of the blends were improved with the increase of the content of MAH- g -EPDM, which implied that the blends probably have a great frictional shear force, resulting from strong adhesion at the interface between the matrix and the dispersion phase; while the bending modulus was weakened with the increase of MAH- g -EPDM content, which is attributed to the development of the crystalline phase of PA66 hampered by adding MAH- g -EPDM. POLYM. COMPOS., 27:608,613, 2006. © 2006 Society of Plastics Engineers [source] Influence of ionomeric compatibilizers on the morphology and properties of amorphous polyester/polyamide blendsPOLYMER ENGINEERING & SCIENCE, Issue 9 2004Gregory C. Gemeinhardt The utilization of sulfonated polyester ionomers as minor-component compatibilizers in blends of an amorphous polyester and polyamide was investigated. The blends were prepared using twin-screw extrusion and compared to solution blends to investigate the effect of elevated temperatures and shear mixing on blend miscibility and/or phase behavior. The phase domain sizes of the solution blends with respect to ionomer content were studied using small angle light scattering (SALS) and phase contrast optical microscopy. The thermal and mechanical properties of the extruded blends were investigated using dynamic mechanical analysis (DMA) and tensile testing while the morphology was investigated using environmental scanning electron microscopy (ESEM). The interactions between the sulfonate group of the ionomer and the polyamide were characterized using FT-IR spectroscopy. Binary blends of the amorphous polyester and polyamide were immiscible with poor mechanical properties, while blends containing the polyester ionomer as a minor-component compatibilizer showed a significant reduction in the dispersed domain sizes and enhanced ultimate mechanical properties. The compatibilization mechanism is attributed to specific interactions between the sulfonate groups on the polyester ionomer and the amide groups of the polyamide. Polym. Eng. Sci. 44:1721,1731, 2004. © 2004 Society of Plastics Engineers. [source] Use of a new natural clay to produce poly(methyl methacrylate)-based nanocompositesPOLYMER INTERNATIONAL, Issue 1 2010Djahida Lerari Abstract Nanocomposites of poly(methyl methacrylate) (PMMA) filled with 3 wt% of modified natural Algerian clay (AC; montmorillonite type) were prepared by either in situ polymerization of methyl methacrylate initiated by 2,2,-azobisisobutyronitrile or a melt-mixing process with preformed PMMA via twin-screw extrusion. The organo-modification of the AC montmorillonite was achieved by ion exchange of Na+ with octadecyldimethylhydroxyethylammonium bromide. Up to now, this AC montmorillonite has found applications only in the petroleum industry as a rheological additive for drilling muds and in water purification processes; its use as reinforcement in polymer matrices has not been reported yet. The modified clay was characterized using X-ray diffraction (XRD), which showed an important shift of the interlayer spacing after organo-modification. The degree of dispersion of the clay in the polymer matrix and the resulting morphology of nanocomposites were evaluated using XRD and transmission electron microscopy. The resulting intercalated PMMA nanocomposites were analysed using thermogravimetric analysis and differential scanning calorimetry. The glass transition temperature of the nanocomposites was not significantly influenced by the presence of the modified clay while the thermal stability was considerably improved compared to unfilled PMMA. This Algerian natural montmorillonite can serve as reinforcing nanofiller for polymer matrices and is of real interest for the fabrication of nanocomposite materials with improved properties. Copyright © 2009 Society of Chemical Industry [source] | |||||||||||||