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Compounding
Kinds of Compounding Terms modified by Compounding Selected AbstractsPoly(propylene)/Clay Nanocomposites Prepared by Reactive Compounding with an Epoxy Based MasterbatchMACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2005Ling Chen Abstract Summary: Poly(propylene) (PP)/clay nanocomposites have been prepared via a novel reactive compounding approach, in which an epoxy based masterbatch consisting of 20 wt.-% clay was introduced to poly(propylene) with the aid of a maleic anhydride grafted PP (MAPP). The masterbatch was prepared using a recently developed "slurry compounding" technique. After melt compounding, most clay particles have been exfoliated and dispersed into small stacks with several clay layers. WAXD data shows that the dispersion of clay is better at low clay content or high MAPP content. Due to the novelty of the preparation process and complication of the system, the tensile properties of nanocomposites exhibit some unique tendencies with varying the content of MAPP or masterbatch. It is believed that the yield strength and Young's modulus can be dramatically improved after minimizing the excess of unreacted epoxy and optimizing the dispersion of clay. TEM micrograph of PP/clay nanocomposites prepared with epoxy based masterbatch. [source] Influence of clay modification on the reinforcement of vinyl-terminated polydimethylsiloxane networksPOLYMER INTERNATIONAL, Issue 4 2010Eung Soo Kim Abstract A novel method was attempted to reinforce a vinyl-terminated polydimethylsiloxane (PDMS) with two commercially available clays, sodium montmorillonite and Cloisite® 25A. The two clays were functionalized with bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) to prepare Na+MMTS4 and C25AS4, respectively. Incorporation of the tetrasulfide group-containing clays, especially Na+MMTS4, was found to be effective for the enhancement of the interfacial interaction between PDMS and the clays by way of a plausible chemical reaction between the tetrasulfide groups (TSS) and the vinyl-terminated PDMS. Compounding of PDMS with the TESPT-modified clays improved the mechanical properties significantly. In particular, the elongation at break of PDMS/Na+MMTS4 composite was almost twice as high as that of neat PDMS, even if the silicate layers were not fully exfoliated in the PDMS matrix. The tear strength of PDMS was also improved greatly as a result of the incorporation of Na+MMTS4. According to toluene swelling test results, the crosslinking density of the composites was lower than that of neat PDMS, indicating that the improved mechanical properties of the composites arise from enhanced compatibility between the constituents and not from increased crosslinking density. Copyright © 2009 Society of Chemical Industry [source] A Versatile Solvent-Free "One-Pot" Route to Polymer Nanocomposites and the in situ Formation of Calcium Phosphate/Layered Silicate Hybrid NanoparticlesADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Hans Weickmann Abstract Poly(methyl methacrylate) (PMMA), polystyrene (PS), and polyurethane (PU) nanocomposites containing well-dispersed calcium phosphate/layered silicate hybrid nanoparticles were prepared in a versatile solvent-free "one-pot" process without requiring separate steps, such as organophilic modification, purification, drying, dispersing, and compounding, typical for many conventional organoclay nanocomposites. In this "one-pot" process, alkyl ammonium phosphates were added as swelling agents to a suspension of calcium/layered silicate in styrene, methyl methacrylate, or polyols prior to polymerization. Alkyl ammonium phosphates were prepared in situ by reacting phosphoric acid with an equivalent amount of alkyl amines such as stearyl amine (SA) or the corresponding ester- and methacrylate-functionalized tertiary alkyl amines, obtained via Michael Addition of SA with methyl acrylate or ethylene 2-methacryloxyethyl acrylate. Upon contact with the calcium bentonite suspension, the cation exchange of Ca2+ in the silicate interlayers for alkyl ammonium cations rendered the bentonite organophilic and enabled effective swelling in the monomer accompanied by intercalation and in situ precipitation of calcium phosphates. According to energy dispersive X-ray analysis, the calcium phosphate precipitated exclusively onto the surfaces of the bentonite nanoplatelets, thus forming easy-to-disperse calcium phosphate/layered silicate hybrid nanoparticles. Incorporation of 5,15,wt% of such hybrid nanoparticles into PMMA, PS, and PU afforded improved stiffness/toughness balances of the polymer nanocomposites. Functionalized alkyl ammonium phosphate addition enabled polymer attachment to the nanoparticle surfaces. Transmission electron microscopy (TEM) analyses of PU and PU-foam nanocomposites, prepared by dispersing hybrid nanoparticles in the polyols prior to isocyanate cure, revealed the formation of fully exfoliated hybrid nanoparticles. [source] A flammability performance comparison between synthetic and natural clays in polystyrene nanocompositesFIRE AND MATERIALS, Issue 4 2005Alexander B. Morgan Abstract Polymer-clay nanocomposites are a newer class of flame retardant materials of interest due to their balance of mechanical, thermal and flammability properties. Much more work has been done with natural clays than with synthetic clays for nanocomposite flammability applications. There are advantages and disadvantages to both natural and synthetic clay use in a nanocomposite, and some of these, both fundamental and practical, will be discussed in this paper. To compare natural and synthetic clays in regards to polymer flammability, two clays were used. The natural clay was a US mined and refined montmorillonite, while the synthetic clay was a fluorinated synthetic mica. These two clays were used as inorganic clays for control experiments in polystyrene, and then converted into an organoclay by ion exchange with an alkyl ammonium salt. The organoclays were used to synthesize polystyrene nanocomposites by melt compounding. Each of the formulations was analysed by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). Flammability performance was measured by cone calorimeter. The data from the experiments show that the synthetic clay does slightly better at reducing the heat release rate (HRR) than the natural clay. However, all the samples, including the inorganic clay polystyrene microcomposites, showed a decreased time to ignition, with the actual nanocomposites showing the most marked decrease. The reason for this is postulated to be related to the thermal instability of the organoclay (via the quaternary alkyl ammonium). An additional experiment using a more thermally stable organoclay showed a time to ignition identical to that of the base polymer. Finally, it was shown that while polymer-clay nanocomposites (either synthetic or natural clay based) greatly reduce the HRR of a material, making it more fire safe, they do not provide ignition resistance by themselves, at least, at practical loadings. Specifically, the cone calorimeter HRR curve data appear to support that these nanocomposites continue to burn once ignited, rather than self-extinguish. Copyright © 2004 John Wiley & Sons, Ltd. [source] Lichen extracts as raw materials in perfumery.FLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2009Part 2: treemoss Abstract This is a comprehensive review of extracts from the lichen Pseudevernia furfuracea (treemoss) that are used in the fragrance industry. Qualitative and quantitative analytical aspects are critically reviewed and the results are compared to those of the related oakmoss extracts. It is shown that more than 90 constituents have been identified so far in treemoss extracts, including 42 depsides, depsidones or depside-derived compounds, and 42 triterpenes or steroids. Constituents of certain host trees, mainly Pinus species, generate specific analytical and toxicological issues which need to be considered in addition to those related to the known degradation products of lichen compounds. A new classification of lichen extracts used as raw materials in fragrance compounding is proposed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Contagion and its Guises: Inequalities and Disease among Tibetan Exiles in IndiaINTERNATIONAL MIGRATION, Issue 5 2008Audrey Prost The paper outlines the trajectories of Tibetan refugees afflicted by tuberculosis (TB) within the exile community of Dharamsala (H-P). These stories reveal the political nature of TB status disclosure, highlighting the often conflicting ways in which the disease is perceived among different Tibetan exile regional and generational groups. On the basis of these case studies, I aim to show that differentiated experiences of treatment and stigma within "intermediary" host communities such as Dharamsala partially determine the ways in which Tibetans deal with the risk of TB in their "onward" journeys further afield, in Europe, Canada and the United States. With the now well-established connection between migration-related stresses and the onset or reappearance of TB symptoms, we may need to consider that, in some cases, it is the compounding of attitudes to disease in "intermediary" diasporic communities with the stigmatising label of "migrant menace" in the second stages of migration that impedes the care of migrants and even precipitates illness. With this premise the paper proposes that investigations of disease in diasporic communities should explore the totality of migration "stages" and their impact on health. [source] Influence of melt drawing on the morphology of one- and two-step processed LDPE/thermoplastic starch blendsADVANCES IN POLYMER TECHNOLOGY, Issue 4 2003F. J. Rodriguez-Gonzalez Abstract In this study the morphology of LDPE/TPS blends prepared by a one-step extrusion process is compared to that obtained by reprocessing of the original blends. The influence of composition and melt drawing is examined. A novel methodology based on the form factor of the dispersed particle was used to estimate the equivalent spherical particle size of dispersed thermoplastic starch (TPS). This approach allows for the quantitative comparison of average dispersed phase particles regardless of their shape. Blends prepared in the one-step extrusion process show increased levels of anisotropy as a consequence of a combination of coalescence and particle deformation during melt drawing. Reprocessed materials demonstrate morphologies that are highly stable to a wide range of hot stretch ratio conditions. The TPS particles of reprocessed blends show no coalescence and a low degree of deformation. This phenomenon is explained by plasticizer evaporation resulting from the second processing step. The TPS is transformed from a highly deformable phase to one resembling a partially cross-linked material. These data indicate that the one-step processing of LDPE/TPS blends can be used to generate a wide range of highly elongated morphological structures. A two-step approach, analogous to typical compounding and shaping operations and involving controlled glycerol removal in the second step can be used to prepare a wide range of highly stable, more isotropic, dispersed particle morphologies. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 297,305, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10057 [source] In-line analysis of the influence of monomeric and oligomeric hindered amine on the hydrolysis of polycarbonate in a PC/ABS blendJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Vipin V. Rajan Abstract The polycarbonate/polyacrylonitrile butadiene styrene (PC/ABS) blends lose mechanical properties when exposed to outdoor conditions. This is due to the ultraviolet (UV) induced photo-oxidation of the PC phase and the polybutadiene portion of the ABS. It is known that ABS can be stabilised against terrestrial light by the use of hindered amine in combination with a UV absorber. However, such hindered amine cannot be used when PC is present in a multi component polymer blend. The hydrolysis of PC is accelerated when a small amount of hindered amine light stabilisers (HALS) is incorporated in the resin and is exposed to elevated temperature. In this article the effect of monomeric and oligomeric hindered amine on the hydrolysis of PC during the compounding of PC/ABS blend in a twin screw extruder at 240°C is observed by means of in-line UV-vis spectroscopy. Tinuvin 765 was used as monomeric hindered amine and Tinuvin 622 as oligomeric hindered amine. The molecular weight of the compounded sample was determined by gel permeation chromatography (GPC) and the rheological properties were observed using an online viscometer. It was found that the extent of hydrolysis induced by the oligomeric hindered amine is less compared to monomeric amine. It was also observed that polymeric hindered amine imparts better dispersion of the ABS phase into the polymer blend. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effect of wood flour loading and thermal annealing on viscoelastic properties of poly(lactic acid) composite filmsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010M. Hrabalova Abstract Poly(lactic acid) (PLA) films filled with up to 50 wt % softwood flour were prepared by melt compounding and thermocompression. Thermal annealing of the melt was performed at temperatures from 90°C to 120°C, for 45 min. Responses on polymer-filler interactions, viscoelastic properties, crystallinity of PLA as well as PLA-wood flour-filled films were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The effectiveness of fillers on the storage moduli (C) was also calculated. The results reveal that wood flour (WF) in conjunction with thermal annealing affected the melting behavior of PLA matrix, and the glass transition temperature. It was further found that the effectiveness of the wood filler in biocomposites widely improved with thermal annealing as well as with higher WF concentration. Finally, it was found that the compatibility between WF and the PLA matrix can be improved when suitable annealing conditions are applied. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Impact of curing temperature on microstructures and properties of isobutylene,isoprene rubber/clay nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Yong-Lai Lu Abstract In this work, the influence of curing temperature on microstructures of isobutylene,isoprene rubber/clay nanocomposites (IIRCNs) prepared by melt compounding was characterized using wide-angle X-ray diffraction and TEM. The gas barrier and tensile properties of IIRCN cured under different temperature were examined. The results reveal that high pressure, curing reactions, and reactions of amine intercalants with curing agents together play important roles on determining the final microstructures of cured IIRCNs. Changing curing temperature would dramatically alter intercalated structure, dispersion homogeneity, filler,rubber interaction strength, and crosslinking density of obtained IIRCN, resulting in great difference in final properties. Finally, some suggestions for the preparation of successful RCNs were proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] The thermal conductivity of Nylon 6/clay nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Hu Zhou Abstract Nylon 6/clay nanocomposites (NCNs) of different clay loadings are prepared by melt compounding. The effects of clay loading and dispersion on the thermal conductivity of NCNs are investigated using XRD, TEM, DSC, and POM. The results show that the thermal conductivity of the exfoliated NCNs decreases with an increase of clay content; but the thermal conductivity of the intercalated NCNs does not decrease, indeed, it increase markedly at high clay content. Such results observed in the exfoliated NCNs are opposite to the expectation of the classic Maxwell thermal conduction model. The further investigations indicate that such decrease observed in the exfoliated NCNs is due mainly to the exfoliation of clay layers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Isothermal crystallization of high density polyethylene and nanoscale calcium carbonate compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Jiann-Wen HuangArticle first published online: 26 NOV 200 Abstract High density polyethylene (HDPE) and calcium carbonate (CaCO3) nanocomposites with maleic anhydride grafted HDPE (manPE) as a compatibilizer were prepared via compounding in a twin-screw extruder. The CaCO3 are well dispersed in the HDPE matrix from the observation of transmission electron microscope. The isothermal crystallization kinetics was studied by differential scanning calorimetry and simulated by Avrami and Tobin models. The nucleation constants and fold surface free energy were estimated from Lauritzen,Hoffman relation. The results indicate that both manPE and well-dispersed CaCO3 particles would act as nuclei to induce heterogeneous nucleation and enhance crystallization rate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Recycled carbon fiber filled polyethylene compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Tony McNally Abstract Composites of recycled carbon fiber (CF) with up to 30 wt % loading with polyethylene (PE) were prepared via melt compounding. The morphology of the composites and the degree of dispersion of the CF in the PE matrix was examined using scanning electron microscopy, and revealed the CF to be highly dispersed at all loadings and strong interfacial adhesion to exist between the CF and PE. Raman and FTIR spectroscopy were used to characterize the surface chemistry and potential bonding sites of recycled CF. Both the Young's modulus and ultimate tensile stress increased with increasing CF loading, but the percentage stress at break was unchanged up to 5 wt % loading, then decreased with further successive addition of CF. The effect of CF on the elastic modulus of PE was examined using the Halpin-Tsai and modified Cox models, the former giving a better fit with the values determined experimentally. The electrical conductivity of the PE matrix was enhanced by about 11 orders of magnitude on addition of recycled CF with a percolation threshold of 7 and 15 wt % for 500-,m and 3-mm thick samples. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Fiber breakage and dispersion in carbon-fiber-reinforced nylon 6/clay nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Hu Zhou Abstract In this paper, short carbon-fiber-reinforced nylon 6/clay nanocomposites are prepared via melt compounding, and fiber breakage and dispersion during processing are studied. The influences of clay and processing conditions on fiber breakage and dispersion are taken into consideration. It is found that the presence of organoclay can improve fiber dispersion, which is due to dispersion at the nanoscale of exfoliated clay sheets with large aspect ratio. The bimodal distribution of fiber length is observed in fiber-reinforced nanocomposites, which is similar to that in conventional fiber-reinforced composites. The improvement of fiber breakage at moderate organoclay loadings is also observed, which is ascribed to the rheological and lubricating effects induced by organoclay. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Recycled PET nanocomposites improved by silanization of organoclaysJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2007Milan Krá, alík Abstract Recycled PET/organo-modified montmorillonite nanocomposites were prepared via melt compounding as a promising possibility of the used beverage bottles recovery. According to our previous work, the three suitable commercial organoclays Cloisite 25A, 10A, and 30B were additionally modified with [3-(glycidyloxy)propyl]trimethoxysilane, hexadecyltrimethoxysilane and (3-aminopropyl)trimethoxysilane. The selected organoclays were compounded in the concentration 5 wt % and their degree of intercalation/delamination was determined by wide-angle X-ray scattering and transmission electron microscopy. Modification of Cloisite 25A with [3-(glycidyloxy)propyl]trimethoxysilane increased homogeneity of silicate layers in recycled PET. Additional modification of Cloisite 10A and Cloisite 30B led to lower level of delamination concomitant with melt viscosity reduction. However, flow characteristics of all studied organoclay nanocomposites showed solid-like behavior at low frequencies. Silanization of commercial organoclays had remarkable impact on crystallinity and melt temperature decrease accompanied by faster formation of crystalline nuclei during injection molding. Thermogravimetric analysis showed enhancement of thermal stability of modified organoclays. The tensile tests confirmed significant increase of PET-R stiffness with organoclays loading and the system containing Cloisite 25A treated with [3-(glycidyloxy)propyl]trimethoxysilane revealed combination of high stiffness and extensibility, which could be utilized for production of high-performance materials by spinning, extrusion, and blow molding technologies. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Adhesion properties and thermal degradation of silicone rubberJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2007Eung-Soo Kim Abstract Silicone rubber is suitable for the thermal insulator of the rocket motors owing to its heat resisting properties as well as its excellent elasticity and restoring force. However, the adhesion properties of the silicone rubber should be improved greatly to be used as the thermal insulator because of its poor adhesiveness coming from the low surface tension. Functional groups were incorporated through copolymerization to the silicone rubber to induce chemical reaction with the functional groups in the propellant/liner components to enhance the adhesion properties. Peeling tests results disclosed that the incorporation of amine groups was the most efficient for the adhesiveness enhancement and that addition of carbon black improved the adhesiveness still more. Stability against thermal degradation of the silicone rubber was examined by measuring the activation energy through the thermogravimetric analysis. The results revealed that the compounding of the Cloisite® clays boosted up the thermal stability of the silicone rubber much more greatly than that of carbon black. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2782,2787, 2007 [source] Selection, structure and the heritability of behaviourJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2002D. G. Stirling Characters which are closely linked to fitness often have low heritabilities (VA/VP). Low heritabilities could be because of low additive genetic variation (VA), that had been depleted by directional selection. Alternatively, low heritabilities may be caused by large residual variation (VR=VP , VA) compounded at a disproportionately higher rate than VA across integrated characters. Both hypotheses assume that each component of quantitative variation has an independent effect on heritability. However, VA and VR may also covary, in which case differences in heritability cannot be fully explained by the independent effects of elimination-selection or compounded residual variation. We compared the central tendency of published behavioural heritabilities (mean=0.31, median=0.23) with morphological and life history data collected by Mousseau & Roff (1987). Average behavioural heritability was not significantly different from average life history heritability, but both were smaller than average morphological heritability. We cross-classified behavioural traits to test whether variation in heritability was related to selection (dominance, domestic/wild) or variance compounding (integration level). There was a significant three-way interaction between indices of selection and variance compounding, related to the absence of either effect at the highest integration level. At lower integration levels, high dominance variance indicated effects of selection. It was also indicated by the low CVA of domestic species. At the same time CVR increased disproportionately faster than CVA across integration levels, demonstrating variance compounding. However, neither CVR nor CVA had a predominant effect on heritability. The partial regression coefficients of CVR and CVA on heritability were similar and a path analysis indicated that their (positive) correlation was also necessary to explain variation in heritability. These results suggest that relationships between additive genetic and residual components of quantitative genetic variation can constrain their independent direct effects on behavioural heritability. [source] Greenhouse Gas Profile of a Plastic Material Derived from a Genetically Modified PlantJOURNAL OF INDUSTRIAL ECOLOGY, Issue 3 2000Devdatt Kurdikar Abstract: This article reports an assessment of the global warming potential associated with the life cycle of a biopolymer (poly(hydroxyalkanoate) or PHA) produced in genetically engineered corn developed by Monsanto. The grain corn is harvested in a conventional manner, and the polymer is extracted from the corn stover (i.e., residues such as stalks, leaves and cobs), which would be otherwise left on the field. While corn farming was assessed based on current practice, four different hypothetical PHA production scenarios were tested for the extraction process. Each scenario differed in the energy source used for polymer extraction and compounding, and the results were compared to polyethylene (PE). The first scenario involved burning of the residual biomass (primarily cellulose) remaining after the polymer was extracted from the stover. In the three other scenarios, the use of conventional energy sources of coal, oil, and natural gas were investigated. This study indicates that an integrated system, wherein biomass energy from corn stover provides energy for polymer processing, would result in a better greenhouse gas profile for PHA than for PE. However, plant-based PHA production using fossil fuel sources provides no greenhouse gas advantage over PE, in fact scoring worse than PE. These results are based on a "cradle-to-pellet" modeling as the PHA end-of-life was not quantitatively studied due to complex issues surrounding the actual fate of postconsumer PHA. [source] Rigid PVC/(layered silicate) nanocomposites produced through a novel melt-blending approach,JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 2 2009Laurent M. Matuana On the basis of the fusion behavior of poly(vinyl chloride) (PVC), the influence of compounding route on the properties of PVC/(layered silicate) nanocomposites was studied. Four different compounding addition sequences were examined during the melt compounding of PVC with montmorillonite (MMT) clay, including (a) a direct dry mixing of PVC and nanoclay, (b) an addition of nanoclay at compaction, (c) an addition of nanoclay at the onset of fusion, and (d) an addition of nanoclay at equilibrium torque. Both unmodified sodium montmorillonite (Na+ -MMT) and organically modified montmorillonite (Org.-MMT) clays were used, and the effect of the addition sequence of the clay during compounding on its dispersion in the matrix was evaluated by X-ray diffraction and transmission electron miscroscopy. The surface color change, dynamic mechanical analysis, and flexural and tensile properties of PVC/clay nanocomposites were also studied. The experimental results indicated that both the extent of property improvement and the dispersion of nanoparticles in PVC/(layered silicate) nanocomposites are strongly influenced by the degree of gelation achieved in PVC compounds during processing. The addition of nanoclay to PVC must be accomplished at the onset of fusion, when PVC particles are reduced in size, in order to produce nanocomposites with better nanodispersion and enhanced mechanical properties. Overall, rigid PVC nanocomposites with unmodified clay (Na+ -MMT) were more thermally stable and exhibited better mechanical properties than their counterparts with organically modified clay (Org.-MMT). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers [source] Effect of calcium carbonate particle size on PVC foamJOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 2 2006Bahar Azimipour Calcium carbonate is the predominant filler used in polyvinyl chloride compounding. Selection of fillers, as in the case with other compounding ingredients, involves consideration of available types and their effects on processing, product properties, and economics. In this article the effect of the particle size of CaCO3 on the properties of PVC foam is investigated. The study analyzes the correlation between fusion time, extrusion torque, and foam density as well as foam cell structure with the filler particle size. J. VINYL. ADDIT. TECHNOL. 12:55,57, 2006. © 2006 Society of Plastics Engineers. [source] In Situ Polymerisation of Polyamide-6 Nanocompounds from Caprolactam and Layered SilicatesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2009Bernd Rothe Abstract An in situ process for the production of polyamide-6 nanocompounds is investigated as an alternative to melt compounding. During the in situ production, the layered silicates are dispersed in the monomer caprolactam before the polymerisation in a twin screw extruder, leading to an intercalation of the silicates. The production of a polyamide compound containing 0, 2 and 4 wt.-% nanoscale silicates was successful. An improvement of the elastic modulus of approximately 30,60% was reached. The figure shows the TEM micrograph of a nanocompound containing 2 wt.-% nanoclay at a magnification of 30,000×. [source] Poly(propylene)/Clay Nanocomposites Prepared by Reactive Compounding with an Epoxy Based MasterbatchMACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2005Ling Chen Abstract Summary: Poly(propylene) (PP)/clay nanocomposites have been prepared via a novel reactive compounding approach, in which an epoxy based masterbatch consisting of 20 wt.-% clay was introduced to poly(propylene) with the aid of a maleic anhydride grafted PP (MAPP). The masterbatch was prepared using a recently developed "slurry compounding" technique. After melt compounding, most clay particles have been exfoliated and dispersed into small stacks with several clay layers. WAXD data shows that the dispersion of clay is better at low clay content or high MAPP content. Due to the novelty of the preparation process and complication of the system, the tensile properties of nanocomposites exhibit some unique tendencies with varying the content of MAPP or masterbatch. It is believed that the yield strength and Young's modulus can be dramatically improved after minimizing the excess of unreacted epoxy and optimizing the dispersion of clay. TEM micrograph of PP/clay nanocomposites prepared with epoxy based masterbatch. [source] The Role of Functional Group on the Exfoliation of Clay in Poly(L -lactide)MACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2005Guang-Xin Chen Abstract Summary: A new method was attempted to improve the interaction between poly(L -lactide) (PLLA) with a commercially available organoclay, Cloisite 25A (C25A), which was functionalized with (glycidoxypropyl)trimethoxysilane to introduce epoxy groups, and is referred to as twice-functionalized organoclay (TFC). Tethering PLLA molecules to the epoxy groups on the surface of the TFC was attempted by melt compounding. X-Ray diffraction and transmission electron microscopy images showed that fully exfoliated PLLA/TFC nanocomposites were prepared successfully. Transmission electron micrographs of the PLLA composites of the three clays used here. [source] Polycarbonate Crystallization by Vapor-Grown Carbon Fiber with and without Magnetic FieldMACROMOLECULAR RAPID COMMUNICATIONS, Issue 13 2003Tatsuhiro Takahashi Abstract Polycarbonate (PC)/vapor-grown carbon fiber (VGCFÔ) composite was prepared through melt compounding. It was unexpectedly found from differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) that the crystallization of PC was substantially accelerated in the presence of the ordered graphite surface of VGCFÔ. To make an aligned structure of PC crystallization together with the orientation of VGCFÔ, a magnetic field of 2.4 T was applied to the composite under several temperature profiles. The WAXD pattern revealed that not only dispersed VGCFÔ but also matrix PC crystallization was magnetically aligned through the optimization of processes. The evidence for PC crystallization by VGCFÔ with and without magnetic force is described. Optical micrograph (a) and WAXD pattern (b) of PC/VGCFÔ (95:5 wt. ratio) composite which was treated under a magnetic field (vertical direction) of 2.4 T under an optimized heating profile. [source] Crops and genotypes differ in efficiency of potassium uptake and usePHYSIOLOGIA PLANTARUM, Issue 4 2008Zed Rengel Cultivars with increased efficiency of uptake and utilization of soil nutrients are likely to have positive environmental effects through reduced usage of chemicals in agriculture. This review assesses the available literature on differential uptake and utilization efficiency of K in farming systems. Large areas of agricultural land in the world are deficient in K (e.g. 3/4 of paddy soils in China, 2/3 of the wheatbelt in Southern Australia), with export in agricultural produce (especially hay) and leaching (especially in sandy soils) contributing to lowering of K content in the soil. The capacity of a genotype to grow and yield well in soils low in available K is K efficiency. Genotypic differences in efficiency of K uptake and utilization have been reported for all major economically important plants. The K-efficient phenotype is a complex one comprising a mixture of uptake and utilization efficiency mechanisms. Differential exudation of organic compounds to facilitate release of non-exchangeable K is one of the mechanisms of differential K uptake efficiency. Genotypes efficient in K uptake may have a larger surface area of contact between roots and soil and increased uptake at the root,soil interface to maintain a larger diffusive gradient towards roots. Better translocation of K into different organs, greater capacity to maintain cytosolic K+ concentration within optimal ranges and increased capacity to substitute Na+ for K+ are the main mechanisms underlying K utilization efficiency. Further breeding for increased K efficiency will be dependent on identification of suitable markers and compounding of efficiency mechanisms into locally adapted germplasm. [source] Nonisothermal melt crystallization kinetics of poly(ethylene terephthalate)/Barite nanocompositesPOLYMER COMPOSITES, Issue 9 2010Chunhua Ge Poly(ethylene terephthalate) (PET)/Barite nanocomposites were prepared by direct melt compounding. The nonisothermal melt crystallization kinetics of pure PET and PET/Barite nanocomposites, containing unmodified Barite and surface-modified Barite (SABarite), was investigated by differential scanning calorimetry (DSC) under different cooling rates. With the addition of barite nanoparticles, the crystallization peak became wider and shifted to higher temperature and the crystallization rate increased. Several analysis methods were used to describe the nonisothermal crystallization behavior of pure PET and its nanocomposites. The Jeziorny modification of the Avrami analysis was only valid for describing the early stage of crystallization but was not able to describe the later stage of PET crystallization. Also, the Ozawa method failed to describe the nonisothermal crystallization behavior of PET. A combined Avrami and Ozawa equation, developed by Liu, was used to more accurately model the nonisothermal crystallization kinetics of PET. The crystallization activation energies calculated by Kissinger, Takhor, and Augis-Bennett models were comparable. The results reveal that the different interfacial interactions between matrix and nanoparticles are responsible for the disparate effect on the crystallization ability of PET. POLYM. COMPOS., 31:1504,1514, 2010. © 2009 Society of Plastics Engineers [source] Effect of clay modification on the morphological, mechanical, and thermal properties of polyamide 6/polypropylene/montmorillonite nanocompositesPOLYMER COMPOSITES, Issue 7 2010Kusmono Polyamide 6/polypropylene (PA6/PP = 70/30 parts) blends containing 4 phr (parts per hundred resin) of organophilic montmorillonite (OMMT) were prepared by melt compounding. The sodium montmorillonite (Na-MMT) was modified using three different types of alkyl ammonium salts, namely dodecylamine, 12-aminolauric acid, and stearylamine. The effect of clay modification on the morphological and mechanical properties of PA6/PP nanocomposites was investigated using x-ray diffraction (XRD), transmission electron microscopy (TEM), tensile, flexural, and impact tests. The thermal properties of PA6/PP nanocomposites were characterized using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and heat distortion temperature (HDT). XRD and TEM results indicated the formation of exfoliated structure for the PA6/PP nanocomposites prepared using stearylamine modified montmorillonite. On the other hand, a mixture of intercalated and exfoliated structures was found for the PA6/PP nanocomposites prepared using 12-aminolauric acid and dodecylamine modified montmorillonite. Incorporation of OMMT increased the stiffness but decreased the ductility and toughness of PA6/PP blend. The PA6/PP nanocomposite containing stearylamine modified montmorillonite showed the highest tensile, flexural, and thermal properties among all nanocomposites. This could be attributed to better exfoliated structure in the PA6/PP nanocomposite containing stearylamine modified montmorillonite. The storage modulus and HDT of PA6/PP blend were increased significantly with the incorporation of both Na-MMT and OMMT. The highest value in both storage modulus and HDT was found in the PA6/PP nanocomposite containing stearylamine modified montmorillonite due to its better exfoliated structure. POLYM. COMPOS., 31:1156,1167, 2010. © 2009 Society of Plastics Engineers [source] Mechanical and thermal properties of polypropylene nanocomposites using organically modified Indian bentonitePOLYMER COMPOSITES, Issue 3 2010Hasmukh A. Patel We report preparation and characterization of nanoclay from Indian bentonite and imported nanoclays, and their compounding with polypropylene (PP) and maleic anhydride-grafted PP (MA-g-PP) in twin screw extruder. The compounded polymer/nanoclay nanocomposites (PNCs) are molded into a standard specimen for studying its tensile, flexural and impact strength. A wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) study demonstrates intercalation of PP in nanoclays rather than exfoliation for both, indigenous and imported nanoclays. The tensile modulus increased by 41 and 39% for PNC1 (PNC with imported nanoclay) and PNC2 (PNC with indigenous nanoclay) with respect to PP. The flexural modulus for PNC1 and PNC2 also increases by 23 and 22% due to incorporation of 5% nanoclay in PP along with 5% MA-g-PP. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Poly(methyl methacrylate)/montmorillonite nanocomposites prepared by bulk polymerization and melt compoundingPOLYMER COMPOSITES, Issue 11 2009Krajnc, Matja This article focuses on structural, thermal, and mechanical properties of nanocomposites in dependence of preparation method and poly(methyl mathacrylate) (PMMA)/organically modified montmorillonite (OMMT) ratio. PMMA/OMMT nanocomposites were prepared by bulk polymerization and by melt compounding. Properties of nanocomposites of the same composition prepared by the two methods were compared. It was observed that nanocomposites prepared via melt compounding at 200°C had a highly oriented structure with lower interlayer spacing values than nanocomposites prepared via bulk polymerization. Two reasons for the observed smaller interlayer spacing obtained by melt compounding were identified. The first is enhanced PMMA penetration and/or formation between layers in the case of bulk polymerization, which was confirmed by determination of stronger interactions between OMMT and PMMA by Soxhlet extraction, infrared spectroscopy, and differential dynamic calorimery. The second reason for smaller interlayer spacing for nanocomposites prepared by melt compounding is organic modifier degradation during melt compounding process, which was confirmed by thermogravimetric analysis. Both reasons lead to the fracture of melt compounded nanocomposites on the OMMT-polymer interface, which was observed by scanning electron microscopy. For nanocomposites with disoriented structure and larger interlayer spacing prepared via bulk polymerization the fracture occurred in the polymer matrix. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] Characterization and properties of activated nanosilica/polypropylene composites with coupling agentsPOLYMER COMPOSITES, Issue 11 2009Ong Hui Lin In this work, nanosilica/polypropylene composites containing 1 wt% of silica nanoparticles were prepared by melt mixing in a Thermo Haake internal mixer. Prior compounding, nanosilica was subjected to surface activation using sodium hydroxide (NaOH) solution. The effectiveness of the activation process was evaluated by measuring the amount of hydroxyl groups (OH) on the surface of nanosilica via titration method and supported by FTIR analysis. Two coupling agents namely 3-aminopropyl triethoxysilane (APTES) and neopentyl (diallyl)oxy, tri(dioctyl) phosphate titanate (Lica 12) were used for surface treatment after activation process. The mechanical properties of polypropylene matrix reinforced with silica nanoparticles were determined by tensile and impact test. Hydroxyl groups on the nanosilica surface played an important role in enhancing the treatment with silane coupling agents. To increase the amount of hydroxyl groups on the nanosilica surface, the optimum concentration of NaOH is 1 mol%. Tensile strength, tensile modulus, and impact strength of nanosilica/PP composites improved with activation process. As the coupling agent is concerned, APTES coupling agent is more pronounced in enhancing the mechanical properties of the composites when compared with Lica 12 coupling agent. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] | ||||||||||||||||||||||||||||||||||