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Melt Processing (melt + processing)
Selected AbstractsStudy on the Influence of Melt Processing on Segmented Polyurethanes MorphologyMACROMOLECULAR SYMPOSIA, Issue 1 2010Achim Frick Abstract A study on thermoplastic polyurethanes (TPU) is described. The investigation focuses on morphology of TPU parts depending on processing conditions and its relation with mechanical and thermal properties. It was found that TPU materials present different crystalline structures depending on chemical composition and melt processing conditions during part manufacturing. Due to that fact, strong variations in mechanical and tribological properties are expected. [source] Melt processing and characterization of multicomponent polymeric nanocomposites containing organoclayPOLYMER COMPOSITES, Issue 3 2007M. Letuchi Nylon 6 (Ny)/polypropylene (PP)/maleated polypropylene (PP- g -MA)/organoclay/wollastonite composites were prepared by melt processing. The polymers' composition was kept constant ([70PP/30Ny]/4PP- g -MA). Melt compounding was conducted using a twin-screw extruder in three different methods: (1) simultaneous incorporation of the components into the compounding equipment, (2) preparation of [Ny6/clay] concentrate, and then in a second step, mixing the other components with the concentrate, and (3) mixing of PP with wollastonite and clay followed by the addition of Ny6 and PP- g -MA in the second step. Injection-molded specimens were characterized in tension, scanning electron microscopy, X-ray diffraction (XRD), and differential scanning calorimetry. The sequence of component addition greatly influences the structure and properties of the composites. Enhanced mechanical properties were achieved when the two-step mixing procedure was used for the PP/Ny6/PP- g -MA/clay system (method 2) and also for the PP/Ny6/PP- g -MA/clay/wollastonite system (method 3). The XRD pattern of the PP/Ny6/PP- g -MA/clay nanocomposites produced by the two-step mixing method does not show a characteristic basal reflection of the pristine organoclay, indicating a predominately exfoliated structure of clay. POLYM. COMPOS., 28:417,424, 2007. © 2007 Society of Plastics Engineers [source] Melt processing of PA-66/clay, HDPE/clay and HDPE/PA-66/clay nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 6 2004Mahmood Mehrabzadeh Polyamide 66/clay, high-density polyethylene (HDPE)/clay and HDPE/PA66/clay nanocomposites were prepared, using a twin-screw extruder. The nanocomposites were characterized by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), optical microscopy and tensile testing. Effects of processing conditions and clay modifier were evaluated. The results show that exfoliation in the twin-screw extruder is enhanced by the incorporation of mixing and shearing elements and high residence times. Compatibility of the clay modifier with the polymer matrix plays an important role in exfoliation. Clay does not influence the crystal form, melting temperature or crystallinity of PA-66 and HDPE. However, it acts as a nucleation agent, increases marginally the crystallization temperatures, and reduces the crystallite size. Clay in the blend nanocomposites acts as a compatibilizer and changes the morphology of the blend. TEM micrographs suggest the presence of an exfoliated structure in PA-66 and an intercalated structure in HDPE. Polym. Eng. Sci. 44:1152,1161, 2004. © 2004 Society of Plastics Engineers. [source] Influence of processing conditions and physicochemical interactions on morphology and fracture behavior of a clay/thermoplastic/thermosetting ternary blendJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010M. Hernandez Abstract This study provides information on the mechanical behavior of epoxy-poly(methyl methacrylate) (PMMA)-clay ternary composites, which have been prepared using the phase separation phenomenon of PMMA and the introduction of organophilic-modified montmorillonites (MMTs), the continuous matrix being the epoxy network. Two dispersion processing methods are used: a melt processing without any solvent and an ultrasonic technique with solvent and a high-speed stirrer. TEM analysis shows that phase separation between PMMA and the epoxy network was obtained in the shape of spherical nodules in the presence of the clay in both process methods used. Nanoclay particles were finely dispersed inside thermosetting matrix predominantly delaminated when ultrasonic blending was used; whereas micrometer-sized aggregates were formed when melt blending was used. The mechanical behavior of the ternary nanocomposites was characterized using three-point bending test, dynamic mechanical analysis (DMA), and linear elastic fracture mechanics. The corresponding fracture surfaces were examined by scanning electron microscopy to identify the relevant fracture mechanisms involved. It was evidenced that the better dispersion does not give the highest toughness because ternary nanocomposites obtained by melt blending present the highest fracture parameters (KIc). Some remaining disordered clay tactoids seem necessary to promote some specific toughening mechanisms. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effects of addition of acrylic compatibilizer on the morphology and mechanical behavior of amorphous polyamide/SAN blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010D. Becker Abstract Amorphous polyamide (aPA)/acrylonitrile-styrene copolymer (SAN) blends were prepared using methyl methacrylate-maleic anhydride copolymer MMA-MA as compatibilizer. The aPA/SAN blends can be considered as a less complex version of the aPA/ABS (acrylonitrilebutadiene-styrene) blends, due to the absence of the ABS rubber phase in the SAN material. It is known that acrylic copolymer might be miscible with SAN, whereas the maleic anhydride groups from MMA-MA can react in situ with the amine end groups of aPA during melt blending. As a result, it is possible the in situ formation of aPA-g-MMA-MA grafted copolymers at the aPA/SAN interface during the melt processing of the blends. In this study, the MA content in the MMA-MA copolymer and its molecular weight was varied independently and their effects on the blend morphology and stress,strain behavior were evaluated. The morphology of the blends aPA/SAN showed a minimum in the SAN particle size at low amounts of MA in the compatibilizer, however, as the MA content in the MMA-MA copolymer was increased larger SAN particle sizes were observed in the systems. In addition, higher MA content in the compatibilizer lead to less ductile aPA/SAN blends under tensile testing. The results shown the viscosity ratio also plays a very important role in the morphology formation and consequently on the properties of the aPA/SAN blends studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Simulation of polymer melt processingAICHE JOURNAL, Issue 7 2009Morton M. Denn Abstract Polymer melt processing requires an integration of fluid mechanics and heat transfer, with unique issues regarding boundary conditions, phase change, stability and sensitivity, and melt rheology. Simulation has been useful in industrial melt processing applications. This brief overview is a personal perspective on some of the issues that arise and how they have been addressed. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Processability and Properties of Re-Graded, Photo-Oxidized Post-Consumer Greenhouse FilmsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2005Francesco Paolo La Mantia Abstract Summary: The recycling of post-consumer plastics leads, in general, to secondary materials having properties worse than those of the reclaimed material and certainly worse than those of the same virgin polymer. This is because of the degradation undergone by the objects during their use and because of the thermo-mechanical degradation undergone during the reprocessing operations. The change of the molecular architecture is responsible for this worsening of properties. The use of stabilizing systems can slow the degradation during the melt processing but cannot give any improvement of the final properties of the material. In order to enhance the properties of the recycled plastics, some rebuilding of the molecular structure is necessary. The use of suitable additives can enlarge the molecular weight distribution or can create branching and cross-linking during the melt processing of the photo-oxidized PE. The processability in film blowing and the mechanical properties of these secondary materials are reported in this work. The rheological behavior, the filmability and most of the mechanical properties of the secondary PE with the rebuilt molecular structure are better than those of the post-consumer material and similar to those of the virgin polymer. TS in the machine and in the transverse direction for all the samples extruded at 50 rpm. [source] Melt processing and characterization of multicomponent polymeric nanocomposites containing organoclayPOLYMER COMPOSITES, Issue 3 2007M. Letuchi Nylon 6 (Ny)/polypropylene (PP)/maleated polypropylene (PP- g -MA)/organoclay/wollastonite composites were prepared by melt processing. The polymers' composition was kept constant ([70PP/30Ny]/4PP- g -MA). Melt compounding was conducted using a twin-screw extruder in three different methods: (1) simultaneous incorporation of the components into the compounding equipment, (2) preparation of [Ny6/clay] concentrate, and then in a second step, mixing the other components with the concentrate, and (3) mixing of PP with wollastonite and clay followed by the addition of Ny6 and PP- g -MA in the second step. Injection-molded specimens were characterized in tension, scanning electron microscopy, X-ray diffraction (XRD), and differential scanning calorimetry. The sequence of component addition greatly influences the structure and properties of the composites. Enhanced mechanical properties were achieved when the two-step mixing procedure was used for the PP/Ny6/PP- g -MA/clay system (method 2) and also for the PP/Ny6/PP- g -MA/clay/wollastonite system (method 3). The XRD pattern of the PP/Ny6/PP- g -MA/clay nanocomposites produced by the two-step mixing method does not show a characteristic basal reflection of the pristine organoclay, indicating a predominately exfoliated structure of clay. POLYM. COMPOS., 28:417,424, 2007. © 2007 Society of Plastics Engineers [source] Preparation of extruded melt-mixed polypropylene/montmorillonite nanocomposites with inline monitoringPOLYMER ENGINEERING & SCIENCE, Issue 3 2010Marcelo K. Bertolino This article advances the use of an inline optical detector to monitor the disaggregation of the montmorillonite (MMT) clay tactoids during the preparation of polypropylene (PP)/MMT nanocomposites via polymer melt compounding. During the exfoliation of the tactoids their size are reduced below the minimum particle size to produce light extinction and so, the signal of the inline detector reduces as the nanosize composite is formed. The measurement is done at the transient state with the MMT clay added as a pulse with constant weight into the PP extrusion melt flow and followed by the optical detector. The data comes out as the common residence time distribution curves having its maximum intensity related to the tactoids average particle size, keeping all other variables constants. The light extinction was measured for composites with different clays (Cloisite® 15A, 30B, Na+, and Sintered 20A) using the same PP grafted with maleic anhydride compatibilizer. The dissaglomeration/exfoliation efficiency increases as: ,,Sintered 20A'' < ,,Na+ clay'' < ,,organo-modified clay'' < ,,organo-modified clay + compatibilizer''. The best result is obtained using Cloisite® 15A and Cloisite® 20A following the expected reduction of the particle size obtained during a nanocomposite melt processing. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers [source] Effect of melt processing conditions on the morphology and properties of nylon 6 nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 11 2007F. Chavarria Nylon 6 (PA-6) organoclay nanocomposites were prepared by melt processing using three different twin screw extruders (TSEs). The effect of mixing conditions, feed port location, residence time, and number of extrusion passes on the morphology and mechanical properties of the nanocomposites were examined. Wide-angle X-ray scattering, transmission electron microscopy (TEM), and mechanical property data are reported. Particle analyses were performed on the TEM images to quantitatively characterize the extent of exfoliation. The amount of shear and the mixing conditions created by TSEs have a significant effect on the morphology and properties of PA-6 nanocomposites. Morphology and mechanical property results show that (1) melting the polymer before coming into contact with the organoclay followed by a low level of shear and (2) maintaining a medium level of shear throughout the extruder with a longer residence time lead to extremely high platelet dispersion and matrix reinforcement for PA-6 nanocomposites. Nanocomposites formed in a DSM microcompounder showed similar morphologies and modulus trends as those obtained with conventional TSEs; thus, this microcompounder is a good alternative for nanocomposite research especially when only small amounts of material are available. POLYM. ENG. SCI., 47:1847,1864, 2007. © 2007 Society of Plastics Engineers [source] Melt processed microporous films from compatibilized immiscible blends with potential as membranesPOLYMER ENGINEERING & SCIENCE, Issue 4 2002M. Xanthos Microporous flat films with potential as membranes were produced via melt processing and post-extrusion drawing from immiscible polypropylene/polystyrene blends containing a compatibilizing copolymer. The blends were first compounded in a co-rotating twin-screw extruder and subsequently extruded through a sheet die to obtain the precursor films. These were uniaxially drawn (100%,500%) with respect to the original dimensions to induce porosity and then post-treated at elevated temperatures to stabilize the resultant structure, which consisted of uniform microcracks in the order of a few nanometers in width. The effects of blend composition and extrusion process parameters on surface and cross-sectional porosity and solvent permeability of the prepared films are presented and related to specific microstructural features of the films before and after drawing. Finite element modeling of the stretching operation in the solid state yielded a successful interpretation of the blend response to uniaxial tension that resulted in microcrack formation. Comparison of some of the novel microporous structures of this work with commercial membranes prepared by solvent-based phase inversion processes suggests comparable pore size and porosity ranges, with narrower pore size distribution. [source] Tensile fracture morphologies of nylon-6/montmorillonite nanocompositesPOLYMER INTERNATIONAL, Issue 12 2005Shaobo Xie Abstract Nylon-6/montmorillonite nanocomposites with different dispersion states of clay and different clay loadings were prepared by melt processing. The nanostructure and mechanical properties were also investigated. The influence of the montmorillonite dispersion state and clay content on the tensile fracture morphology of the injection-molded nanocomposites was studied by scanning electron microscopy. A rounded ,cabbage-like-sheet' structure was observed in the fracture surface of the well-exfoliated nanocomposites, which was absent in the intercalated and poorly dispersed nanocomposite and neat nylon-6. The formation of this ,cabbage-like-sheet' pattern has been attributed to the extensive plastic fibrillations of the nylon-6 matrix, facilitated by the stress concentration and the strengthened effect caused by the well-exfoliated clay platelets. The change in stiffness caused by the skin,core structure was also considered. The difference in the patterns observed in this present work and those reported by Uribe-Arocha et al. (Polymer, 44, 2441 (2003)) were discussed, based on the diversity in preparation of the tensile specimens. Copyright © 2005 Society of Chemical Industry [source] Effect of photo-initiators on melt degradation of polypropylene and starch-filled polymer,POLYMER INTERNATIONAL, Issue 10 2002Rouhallah Bagheri Abstract Six series of the processed polypropylene (pp) samples containing 0.25,1,wt% photo-initiators (PIs, four aromatic carbonyl, two ferric compounds) and also a series of 6,wt% corn-starch-filled pp containing 0.5,wt% of each PI, were prepared using a mixer in a closed system at 180,°C for 5,min. The melt flow index (MFI) and apparent viscosity measurments of the processed pp,PI samples showed a large increase in MFI/or decrease in apparent viscosity at 0.25,wt% of the PIs. Further increase in the amounts of PIs led these properties to reach a constant value at 0.5,wt% of the PIs. The presence of corn starch in the samples corresponded to a much lower increase in the MFI or decrease in the apparent viscosity. Ferric stearate and Irgacure 184 amoung the PIs showed the highest and lowest melt degradation effects, respectively. Carbonyl measurments of all the film samples showed good correlations between chemical changes in the pp structure and variations in the flow properties during processing. UV absorption of the films also evidenced the presence of the aromatic carbonyl PIs in the pp matrix after melt processing. © 2002 Society of Chemical Industry [source] Electrically conductive sensors for liquids based on ternary immiscible polymer blends containing polyanilinePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2004H. Cooper Abstract Electrically conductive blends, containing two immiscible polymers (ethylene vinyl acetate, EVA-19, and copolyamide 6/6.9, CoPA) and polyaniline (PANI), were produced by melt processing. These blends showed a preferred localization of PANI in the CoPA phase, thus enhancing the formation of continuous conducting networks. Electrically conductive PANI-containing filaments produced by a capillary rheometer process at various shear rate levels were studied as sensing materials for a homologous series of alcohols (methanol, ethanol and 1-propanol). All filaments showed a decreasing resistance upon exposure to these solvents. Filaments exposed to methanol, liquid or vapor, exhibited the highest resistance decrease. This behavior was related to the highest polarity of methanol, compared with ethanol and 1-propanol. The filaments' rate of production significantly affects the relative resistance change upon exposure to the various alcohols and their reproducibility. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||