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Mechanical

Distribution by Scientific Domains
Polymers and Materials Science46%
Medical Sciences17%
Chemistry13%
Life Sciences7%
Engineering7%
Physics and Astronomy3%
6 Other Domains7%
Distribution within Polymers and Materials Science
Polymer Science & Technology General52%
General & Introductory Materials Science21%
Ceramics4%
6 Other Subdomains23%

Kinds of Mechanical

  • dynamic mechanical
  • excellent mechanical
    		•
  • molecular mechanical
  • quantum mechanical
    		•
  • quantum molecular mechanical

    • Terms modified by Mechanical

  • mechanical activation
  • mechanical activity
  • mechanical adaptation
  • mechanical advantage
  • mechanical agitation
  • mechanical allodynia
  • mechanical analysis
  • mechanical analysis shows
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  • mechanical approach
  • mechanical aspect
  • mechanical barrier
  • mechanical behavior
  • mechanical behaviour
  • mechanical bowel preparation
  • mechanical calculation
  • mechanical change
  • mechanical characteristic
  • mechanical characterization
  • mechanical circulatory support
  • mechanical circulatory support device
  • mechanical competence
  • mechanical complications
  • mechanical component
  • mechanical compression
  • mechanical condition
  • mechanical constraint
  • mechanical contact
  • mechanical coupling
  • mechanical damage
  • mechanical data
    		•
  • mechanical debridement
  • mechanical deformation
  • mechanical degradation
  • mechanical demand
  • mechanical design
  • mechanical device
  • mechanical disruption
  • mechanical dissociation
  • mechanical dysfunction
  • mechanical effect
  • mechanical effects
  • mechanical energy
  • mechanical engineering
  • mechanical environment
  • mechanical factor
  • mechanical failure
  • mechanical feature
  • mechanical flexibility
  • mechanical force
  • mechanical function
  • mechanical hyperalgesia
  • mechanical hypersensitivity
  • mechanical impact
  • mechanical information
  • mechanical injury
  • mechanical inoculation
  • mechanical integrity
  • mechanical interaction
  • mechanical load
  • mechanical loading
  • mechanical mean
    		•
  • mechanical measurement
  • mechanical methods
  • mechanical milling
  • mechanical mixing
  • mechanical model
  • mechanical modeling
  • mechanical models
  • mechanical obstruction
  • mechanical pain threshold
  • mechanical parameter
  • mechanical performance
  • mechanical periodontal therapy
  • mechanical perturbation
  • mechanical polishing
  • mechanical pressure
  • mechanical problem
  • mechanical process
  • mechanical processing
  • mechanical properties.
  • mechanical property
  • mechanical prosthesis
  • mechanical protection
  • mechanical relaxation
  • mechanical removal
  • mechanical resistance
  • mechanical response
  • mechanical result
  • mechanical robustness
  • mechanical role
  • mechanical sensitivity
  • mechanical shearing
    		•
  • mechanical signal
  • mechanical stability
  • mechanical stiffness
  • mechanical stimulation
  • mechanical stimulus
  • mechanical strain
  • mechanical strength
  • mechanical stress
  • mechanical stretch
  • mechanical stretching
  • mechanical structure
  • mechanical studies
  • mechanical study
  • mechanical support
  • mechanical system
  • mechanical test
  • mechanical testing
  • mechanical thermal analysis
  • mechanical thinning
  • mechanical thrombectomy
  • mechanical treatment
  • mechanical unloading
  • mechanical valve
  • mechanical ventilation
  • mechanical ventilator
  • mechanical ventilatory support
  • mechanical work
  • mechanical wounding

    • Selected Abstracts

    FILM FORMING MECHANISM AND MECHANICAL AND THERMAL PROPERTIES OF WHEY PROTEIN ISOLATE-BASED EDIBLE FILMS AS AFFECTED BY PROTEIN CONCENTRATION, GLYCEROL RATIO AND PULLULAN CONTENT

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2010
    MAHAMADOU ELHADJI GOUNGA
    ABSTRACT Tensile strength (TS), elongation at break (EAB) and elastic modulus (EM) of edible films prepared from 5, 7 and 9% whey protein isolate (WPI) plasticized with different levels of glycerol (Gly) (WPI : Gly = 3.6:1, 3:1 and 2:1) were investigated in order to completely characterize WPI-Gly films. On increasing protein concentration an increase in TS and EAB was observed. On the other hand, increasing Gly led to a decrease in TS and EM, while EAB increased. The addition of pullulan (Pul) into the film forming solution (FFS) increased EAB while TS, EM and thermal properties were reduced. This suggested that Pul had a similar effect as plasticizers. Films with higher Pul content showed lighter protein bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Fourier transform infrared spectroscopy showed that hydrogen bonding was high in WPI : Pul films as compared with the control. This is attributed to the protein-polysaccharide interactions brought about by the dominance of Pul in the FFS. PRACTICAL APPLICATIONS This work describes some physical properties of films based on blends of whey protein isolate (WPI) and pullulan (Pul), made after a previous study on some characteristics of films based on pure WPI plasticized by glycerol. The most studied proteins in the edible films technology being gluten and WPI, the use of Pul in mixture with WPI is considered as a new investigation to explore the utilization of WPI-Pul in edible film and coating materials applied to food products. Furthermore, the use of WPI-Pul films and coatings could potentially extend the shelf life and improve the stability of the coated products as shown by the resultant properties in this investigation and previous works. [source]

    EFFECT OF POLYGODIAL ON MECHANICAL, OPTICAL AND BARRIER PROPERTIES OF CHITOSAN FILMS

    JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2010
    L. MORENO-OSORIO
    ABSTRACT The mechanical, optical and barrier properties of chitosan films containing polygodial (0.0, 2.7, 13.9, 25.0 mg/g of chitosan) were studied. Water vapor permeability (WVP), tensile strength, percentage elongation at break, CIELab color parameters, hue angle and chroma of films were determined. Fourier transform infrared (FTIR) was also performed to determine functional group interaction between the matrix and polygodial added. The use of polygodial resulted in stronger films without losing their extensibility and with low WVP. Films became darker with yellow-green coloration with increasing polygodial concentration. Polygodial added to chitosan films did not have any interaction with the amino groups of chitosan as measured by FTIR. Polygodial as a natural dialdehyde can effectively be applied to enhance some physical properties of edible films prepared with chitosan. PRACTICAL APPLICATIONS There has been an increased interest in the study of edible,biodegradable packaging films during the last decade, offering an alternative and partial solution to the problem of accumulation of solid waste composed of synthetic inert polymers, and chitosan films has been studied with this purpose. Furthermore, replacing synthetic additives by natural compounds such us polygodial can be a suitable manner to improve some physical properties of those chitosan films. [source]

    MECHANICAL,ACOUSTIC AND SENSORY EVALUATIONS OF CORNSTARCH,WHEY PROTEIN ISOLATE EXTRUDATES

    JOURNAL OF TEXTURE STUDIES, Issue 4 2007
    E.M. CHENG
    ABSTRACT The mechanism relating sensory perception of brittle food foams to their mechanical and acoustic properties during crushing was investigated. Cornstarch was extruded with four levels of whey protein isolate (0, 6, 12 and 18%) and two levels of in-barrel moisture (23 and 27%). Hardness, fracturability and roughness of mass were three main sensory attributes that varied substantially between products. High correlations (r = 0.841,0.998) were observed between sensory attributes and instrumentally determined mechanical properties, including crushing force (11.2,57.9 N) and crispness work (4.6,75.8 N·mm). Based on acoustic data obtained during instrumental crushing, time-domain signal processing and a novel voice recognition technique utilizing frequency spectrograms were successfully employed for understanding the differences in the sensory properties of various products. Microstructure features, including average cell diameter (1.00,2.94 mm), average wall thickness (0.04,0.27 mm) and cell number density (7,193 cell/cm3), were characterized noninvasively using X-ray microtomography, and proved to be critical in relating sensory perception of the cellular extrudates to their mechanical,acoustic signatures. PRACTICAL APPLICATIONS The sensory perception of crispy and crunchy food products is primarily a function of their mechanical response and emission of sounds during fracture. The current study was focused on understanding these relationships in the context of brittle extruded foods. The mechanical,acoustic techniques outlined in this study have the potential of reducing the time, costs and subjectivity involved in evaluation of new foods by human panels, and can be a useful tool in the overall product development cycle. These techniques need not be limited only to food systems, as properties of any rigid, fracturable material can be characterized based on its mechanical,acoustic signature. [source]

    ,MERELY MECHANICAL': ON THE ORIGINS OF PHOTOGRAPHIC COPYRIGHT IN FRANCE AND GREAT BRITAIN

    ART HISTORY, Issue 1 2008
    ANNE MCCAULEY
    The invention of the medium of photography and its commercialization as a cheap multiple during the 1850s and 1860s led to challenges to extant copyright laws in France and Great Britain. This paper traces the ways that debates over photographic copyright confronted current understandings of originality and mechanization and repeated arguments that had already been raised by laws governing prints and casts. The British Fine Arts Copyright Act of 1862, which extended statutory protection to all photographs, is contrasted with French cases, which struggled to accommodate photographs within the fine arts as defined by the copyright law of 1793. [source]

    Multi-Agent Distributed Coordination of Project Schedule Changes

    COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2003
    Keesoo Kim
    This article presents the design and implementation of a multi-agent system called Distributed Subcontractor Agent System (DSAS), which consists of multiple subcontractor agents, multiple Graphic User Interfaces (GUIs), and an Agent Message Router. In the DSAS, subcontractors interact with their software agents to evaluate the impact of changes, simulate decisions, and get the negotiation results that they need to reschedule the project. This also presents the design and results of DSAS charrette tests, which demonstrated that DSAS produces the lower-cost results faster than manual centralized processes. DSAS can be useful for other domains, such as Mechanical, Electrical, and Plumbing (MEP) coordination and workspace management, if the appropriate agents are designed. [source]

    Reversal of End-Stage Heart Failure: Mechanical and Pharmacologic Interplay

    CONGESTIVE HEART FAILURE, Issue 1 2007
    Imran S. Virk MD
    No abstract is available for this article. [source]

    Myocardial Recovery After Chronic Mechanical Assist Device Support: Fact or Fiction?

    CONGESTIVE HEART FAILURE, Issue 2 2004
    Mark Slaughter MD Guest Editor
    No abstract is available for this article. [source]

    Single-step purification of the recombinant green fluorescent protein from intact Escherichia coli cells using preparative PAGE

    ELECTROPHORESIS, Issue 17 2009
    Few Ne Chew
    Abstract Mechanical and non-mechanical breakages of bacterial cells are usually the preliminary steps in intracellular protein purification. In this study, the recombinant green fluorescent protein (GFP) was purified from intact Escherichia coli cells using preparative PAGE. In this purification process, cells disruption step is not needed. The cellular content of E. coli was drifted out electrically from cells and the negatively charged GFP was further electroeluted from polyacrylamide gel column. SEM investigation of the electrophoresed cells revealed substantial structural damage at the cellular level. This integrated purification technique has successfully recovered the intracellular GFP with a yield of 82% and purity of 95%. [source]

    Ultrasonic treatment of waste activated sludge

    ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2006
    Raf Dewil
    Abstract Activated sludge processes are key technologies to treat wastewater. These biological processes produce huge amounts of waste activated sludge (WAS), now commonly called biosolids. Mechanical, thermal, and/or chemical WAS conditioning techniques have been proposed to reduce the sludge burden. The ultrasonic treatment of WAS is quite novel. The present paper reports on extensive investigations using an ultrasonic treatment of WAS, to study its potential to meet one or all of four objectives: (1) reduce WAS quantities; (2) achieve a better dewaterability; (3) provoke a release of soluble chemical oxygen demand (COD) from the biosolids, preferably transformed into biodegradable organics; and (4) possibly destroy the filamentous microorganisms responsible for sludge bulking. Although meeting these objectives would help to solve the problems cited, the energy consumption could be a considerable drawback: the paper will thus assess whether all or some objectives are met, and at what operational cost. A literature survey defines the occurring phenomena (cavitation) and the important operation parameters [such as frequency, duration, specific energy input (SE)]. The experiments are carried out in a batch reactor of volume up to 2.3 L. The ultrasonic equipment consisted of a generator, a converter, and a sonotrode, supplied by Alpha Ultrasonics under the brand name of Telsonic. Three different kinds of sludge were tested, with different concentrations of dry solids (DS) between approximately 3.5 and 14 g DS/L WAS. Ultrasonic energy was introduced in a continuous manner (against possible pulsed operation). The major operational parameters studied include duration of the ultrasonic treatment and specific energy input. The applied frequency was set at 20 kHz. The release of COD from the WAS phase into the filtrate phase is a function of the specific energy input with yields of nearly 30% achievable at SE values of 30,000 kJ/kg DS. A major fraction of the COD is transformed into biodegradable organics (BOD). The reduction in DS fraction of the sludge is proportional to the COD release rates. Although the DS content is reduced, the dewaterability of the sludge is not improved. This reflects itself in increased filtration times during vacuum filtration and in increased values of the capillary suction time (CST). This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area: more surface water is bound (CST increases) and the filterability decreases as a result of clogging of the cake. To reach the same dryness as for the untreated cake, the required dosage of polyelectrolyte is nearly doubled when the SE of the ultrasound treatment is increased from 7500 to 20,000 kJ/kg DS. The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. Microscopic analysis of the WAS identified the dominant presence of Actynomyces. The release of soluble COD and BOD certainly merit further research. © 2006 American Institute of Chemical Engineers Environ Prog, 2006 [source]

    Chemical, Mechanical, and Antibacterial Properties of Silver Nanocluster,Silica Composite Coatings Obtained by Sputtering,

    ADVANCED ENGINEERING MATERIALS, Issue 7 2010
    Monica Ferraris
    Abstract Silver nanocluster,silica matrix composite coatings have been deposited by radio frequency (RF) co-sputtering on silica substrates. Field emission scanning electron microscopy and X-ray diffraction spectra of the as deposited and heated samples (150,600,°C) revealed the presence of metal silver nanoclusters, their size depending on the heating treatment. The antibacterial activity of the as deposited and heated samples has been measured in accordance to National Committee for Clinical Laboratory Standards, and it has been demonstrated on samples heated up to 450,°C in contact mode and for samples heated at 600,°C in a liquid environment. Their antibacterial activity was still present after gamma ray and ethylene oxide gas (EtO) sterilization of the samples. Silver leaching tests on the as deposited and heated samples has been measured by graphite furnace atomic absorption spectrometer, revealing an amount ranging from 0.1 to 0.9,µg mm,2, over 28 days. Tape resistance (ASTM D3359-97) and scratch resistance tests have been done on each sample revealing a good adhesion of the coatings on silica. [source]

    Investigation of Mechanical and Microstructural Characteristics of Al,Mg Compounds,

    ADVANCED ENGINEERING MATERIALS, Issue 7 2009
    Reimund Neugebauer
    The presented approach of generating composites offers new possibilities for the combination of two light metal alloys into one semifinished product of high specific strength and corrosion resistance. A test device based on the forming method of lateral extrusion was designed to manufacture metallic compounds. The created interface layer is characterized by the formation of new phases and affects the mechanical properties of the whole compound. [source]

    Mechanical and Fatigue Behavior of Ca65Mg15Zn20 Bulk-Metallic Glass,

    ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009
    Gongyao Wang
    The compression behavior of a Ca65Mg15Zn20 bulk-metallic glass (BMG) was studied. The specimens showed no macroscopic plasticity. They fractured by exploding into many very small pieces. The Vickers hardness of the Ca65Mg15Zn20 BMG was about 1.42 GPa. The fatigue limit for compression,compression fatigue was found to be about 140 MPa after 106 cycles. The fracture strength was inversely proportional to the fracture time. The proposed mechanism of the splitting and shear fracture modes clearly explained these properties. [source]

    Neuronal sensitization for itch in patients with chronic pruritus

    EXPERIMENTAL DERMATOLOGY, Issue 9 2004
    A. Ikoma
    Itch is one of the major symptoms of various skin diseases. Although specific neuronal pathways for itch were identified both peripherally and centrally, they still fail to explain itchy skin observed in patients with chronic pruritus. In this study, sensitivity to itchy and painful stimuli in patients with atopic dermatitis was investigated. Histamine-prick evoked enormous itch in their lesional skin, while less itch in their non-lesional skin than healthy subjects. Flare reaction was not significantly different between their non-lesional and lesional skin, rather smaller than healthy subjects. Mechanical (pin-pricks), electrical, heat and chemical (injection of pH3 solution) stimuli evoked intense itch in their lesional skin and partly also in their non-lesional skin, while only pain in healthy subjects. Itch was also, but not intensely, evoked in healthy subjects by injection of pH3 solution after sufficient histamine stimuli. These results confirm the presence of itchy skin with hyperkinesis (excessive itch by itchy stimuli) and allokinesis (itch by non-itchy stimuli) in patients with atopic dermatitis, which is so intense that painful stimuli cannot suppress but evoke itch, and suggest that neuronal sensitization is involved in their itch not only peripherally but also centrally. [source]

    Mechanical and microstructural investigations into the crack arrest behaviour of a modern 2¼Cr-1 Mo pressure vessel steel

    FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 2 2001
    E. Bouyne
    Tests were performed on a 2¼ Cr,1 Mo steel to measure the fracture toughness at initiation, KIc and at arrest, KIa,. The results were compared with those obtained on another pressure vessel steel (A508) of similar strength. Two techniques were used to measure KIa,: (i) isothermal compact crack arrest (CCA) tests, and (ii) specially designed thermal shock experiments using an externally notched ring. These specimens were cooled to ,196 °C and then heated by induction in the centre of the ring to produce very steep thermal gradients. This caused crack initiation from the notch. The crack propagates very rapidly (,500 m s,1,) and stopped when it reached the warmer region of the specimen. The specimens were analysed using an elastic,plastic finite element method to determine KIa values. These tests reveal a greater temperature shift (,100 °C) between KIc and KIa in 2¼ Cr,1 Mo steel than in A508 steel. Detailed metallographical examinations of the micromechanisms of crack propagation and arrest in the 2¼ Cr,1 Mo steel showed that this involves the nucleation of a three-dimensional network of cleavage microcracks which change their direction at bainitic packet boundaries. The remaining uncracked ligaments between the cleavage microcracks break by ductile rupture mechanism [source]

    Net changes in regional woody vegetation cover and carbon storage in Texas Drylands, 1937,1999

    GLOBAL CHANGE BIOLOGY, Issue 3 2003
    GREGORY P. ASNER
    Abstract Although local increases in woody plant cover have been documented in arid and semiarid ecosystems worldwide, there have been few long-term, large-scale analyses of changes in woody plant cover and aboveground carbon (C) stocks. We used historical aerial photography, contemporary Landsat satellite data, field observations, and image analysis techniques to assess spatially specific changes in woody vegetation cover and aboveground C stocks between 1937 and 1999 in a 400-km2 region of northern Texas, USA. Changes in land cover were then related to topo-edaphic setting and historical land-use practices. Mechanical or chemical brush management occurred over much of the region in the 1940,1950s. Rangelands not targeted for brush management experienced woody cover increases of up to 500% in 63 years. Areas managed with herbicides, mechanical treatments or fire exhibited a wide range of woody cover changes relative to 1937 (,75% to + 280%), depending on soil type and time since last management action. At the integrated regional scale, there was a net 30% increase in woody plant cover over the 63-year period. Regional increases were greatest in riparian corridors (33%) and shallow clay uplands (26%) and least on upland clay loams (15%). Allometric relationships between canopy cover and aboveground biomass were used to estimate net aboveground C storage changes in upland (nonriparian) portions of regional landscapes. Carbon stocks increased from 380 g C m,2 in 1937 to 500 g C m,2 in 1999, a 32% net increase across the 400 km2 region over the 63-year period. These plant C storage change estimates are highly conservative in that they did not include the substantial increases in woody plant cover observed within riparian landscape elements. Results are discussed in terms of implications for ,carbon accounting' and the global C cycle. [source]

    Nanoparticle Coating for Advanced Optical, Mechanical and Rheological Properties,

    ADVANCED FUNCTIONAL MATERIALS, Issue 16 2007
    F. Hakim
    Abstract Primary titania nanoparticles were coated with ultrathin alumina films using Atomic Layer Deposition (ALD). The deposited films were highly uniform and conformal with an average growth rate of 0.2,nm per coating cycle. The alumina films eliminated the surface photocatalytic activity of titania nanoparticles, while maintained their original extinction efficiency of ultraviolet light. Deposited films provided a physical barrier that effectively prevented the titania surface from oxidizing organic material whereas conserving its bulk optical properties. Parts fabricated from coated powders by pressureless sintering had a 13,% increase in surface hardness over parts similarly fabricated from uncoated particles. Owing to its homogeneous distribution, the secondary alumina phase suppressed excessive grain growth. Alumina films completely reacted during sintering to form aluminum titanate composites, as verified by XRD. Coated particles showed a pseudoplastic behavior at low shear rates due to modified colloidal forces. This behavior became similar to the Newtonian flow of uncoated nanoparticle slurries as the shear rate increased. Suspensions of coated particles also showed a decreased viscosity relative to the viscosity of uncoated particle suspensions. [source]

    Preliminary Results from the Use of New Vascular Access (Hemaport) for Hemodialysis

    HEMODIALYSIS INTERNATIONAL, Issue 1 2003
    J Ahlmén
    One of the most important factors for an optimal chronic hemodialysis is a well- functioning vascular access. Still the A-V-fistula is the best alternative. When repeated failures arise new access alternatives are needed. The Hemaport combines a PTFE-graft with a percutaneous housing of titan. Starting and stopping the dialysis session is simple and needle-free. The first clinical experiences are presented. Thirteen patients (m-age 60 years) in 6 centres had used the Hemaport system. Out of 11 functioning devices 7 were placed on the upper arm and 4 were located on the thigh. The total days in observation were 2.156 days with 769 dialysis sessions performed. Six patients had used the Hemaport system for more than 6 months. Mean blood flow was 364, range 100,450 ml/min with a mean venous and arterial pressure of 100 mm Hg, range 30,250, and 16 mm Hg respectively, range , 140 to + 259. Thrombosis interventions have been required in 14 percent to obtain a functioning vascular access. Two patients contributed with more than half of these events. Mechanical or pharmacological thrombolysis can be performed through the Hemaport dialysis lid without open surgery. Six implants have been removed and in 5 of these cases a new Hemaport was implanted. The reasons for removing the device were related to insufficient vascular flow, thrombosis, and/or infection. In patients with repeated access problems, a new vascular access (Hemaport) has been clinically used for about 1 year. By its design, Hemaport offers a novel approach. [source]

    The Effect of NaF In Vitro on the Mechanical and Material Properties of Trabecular and Cortical Bone

    ADVANCED MATERIALS, Issue 4 2009
    Philipp J. Thurner
    High doses of sodium fluoride in bones lead to severe softening, by weakening interfacial properties between the inorganic minerals and the organic components, while leaving mineralization unchanged. This leads to reduction of microdamage and associated stress-whitening pointing to a change in failure mode. Accordingly, elastic modulus, failure stress, and indentation-distance increase are decreased, whereas failure strain is increased. [source]

    Mechanical and fracture properties for predicting cracking in semi-sweet biscuits

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2005
    Qasim Saleem
    Summary Mechanical and fracture properties required for predicting crack development in semi-sweet (,rich tea') biscuits have been experimentally determined. Pilot-scale biscuits of different fat concentrations were prepared and studied with commercial biscuits at different moisture contents. Bending modulus, fracture stress and strain were measured using three-point bending tests. All biscuit types showed considerable dependence on moisture content over a range of 4,12%. Young's modulus and failure stress showed a uniform decrease and failure strain showed an increase with increasing moisture content. For pilot-scale biscuits of different fat concentrations, an increase in fat level caused a decrease in modulus and failure stress values; however, the failure strains were very similar for all the fat types. The testing of the samples with top surface up and top surface down revealed that the sample orientation does not affect the measured parameters. The measured parameters also did not show any directional dependence within the plane, thus assuring that the assumption of an isotropic material would be valid for modelling. The mechanical and fracture properties measured in this study will serve as a very useful set of data to predict the stress state and cracking of the checked biscuits. [source]

    Polyamide 66 binary and ternary nanocomposites: Mechanical and morphological properties

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010
    Miray Mert
    Abstract Polyamide 66 (PA 66)/impact modifier blends and polyamide/organoclay binary and PA 66/organoclay/impact modifier ternary nanocomposites were prepared by the melt-compounding method, and the effects of the mixing sequences on the morphology and mechanical and flow properties were investigated. Lotader AX8840 and Lotader AX8900 were used as impact modifiers. The concentrations of the impact modifiers and the organoclay (Cloisite 25A) were maintained at 2 and 5 wt %, respectively. Both the binary and ternary nanocomposites displayed high tensile strength and Young's modulus values compared to the PA 66/impact modifier blends. Decreases occurred in the strength and stiffness of the binary nanocomposites upon incorporation of the elastomeric materials into the polymeric matrix. In general, the mixing sequence in which all three ingredients were added simultaneously and extruded twice (the All-S mixing sequence) exhibited the most enhanced mechanical properties in comparison with the mixing sequences in which two of the components were extruded in the first extrusion step and the third ingredient was added in the second extrusion step. The mechanical test results were in accordance with the organoclay dispersion. The impact strength was highly affected by the elastomeric domain sizes, interdomain distances, interfacial interactions, and organoclay delamination. The smallest elastomeric domain size was obtained for the All-S mixing sequence, whereas the elastomeric domain sizes of the other mixing sequences were quite close to each other. Drastic variations were not observed between the melt viscosities of the ternary nanocomposites prepared with different mixing sequences. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Mechanical and morphological properties for sandwich composites of wood/PVC and glass fiber/PVC layers

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
    Narudol Mongkollapkit
    Abstract This work manufactured sandwich composites from glass fiber/poly(vinyl chloride) (GF/PVC) and wood/PVC layers, and their mechanical and morphological properties of the composites in three GF orientation angles were assessed. The effects of K value (or viscosity index) of PVC and Dioctyl phthalate (DOP) loading were of our interests. The GF/PVC was used as core layer whereas wood/PVC was the cover layers. The experimental results indicated that PVC with low K value was recommended for the GF/PVC core layer for fabrication of GF/WPVC sandwich composites. The improvement of PVC diffusion at the interface between the GF and the PVC core layer was obtained when using PVC with K value of 58. This was because it could prevent de-lamination between composite layers which would lead to higher mechanical properties of the sandwich composites, except for the tensile modulus. The sandwich composites with 0° GF orientation possessed relatively much higher mechanical properties as compared with those with 45° and 90° GF orientations, especially for the impact strength. Low mechanical properties of the sandwich composites with 45° and 90° GF orientation angles could be overcome by incorporation of DOP plasticizer into the GF/PVC core layer with the recommended DOP loadings of 5,10 parts per hundred by weight of PVC components. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Mechanical and functional properties of composites based on graphite and carboxylated acrylonitrile butadiene rubber

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010
    Jian Yang
    Abstract In this study, carboxylated acrylonitrile butadiene rubber (xNBR)/expanded graphite (EG) nanocomposites were prepared with a latex compounding technique by ultrasonic stirring. The dispersion of EG in the xNBR matrix was investigated with transmission electron microscopy, scanning electron microscopy, and X-ray diffraction analysis. EG could be exfoliated into lots of nanosheets dispersing in the xNBR matrix. More EG loading resulted in the presence of a few incompletely exfoliated agglomerates. The mechanical properties (hardness, tensile modulus, and tensile strength) of the xNBR/EG composites were determined. Dynamic mechanical thermal analysis was also performed, and it showed that the nanosheets of EG somewhat immobilized the motion of rubber macromolecular chains and led to the shifting and broadening of the tan , peak toward higher temperatures. Many other functional properties of EG-filled xNBR composites were studied, and it was established that the composites had excellent electrical conductivity as well as gas-barrier and wear properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Mechanical and thermal properties of poly(butylene succinate)/plant fiber biodegradable composite

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
    Zhichao Liang
    Abstract Biodegradable polymeric composites were fabricated from poly(butylene succinate) (PBS) and kenaf fiber (KF) by melt mixing technique. The mechanical and dynamic mechanical properties, morphology and crystallization behavior were investigated for PBS/KF composites with different KF contents (0, 10, 20, and 30 wt %). The tensile modulus, storage modulus and the crystallization rate of PBS in the composites were all efficiently enhanced. With the incorporation of 30% KF, the tensile modulus and storage modulus (at 40°C) of the PBS/KF composite were increased by 53 and 154%, respectively, the crystallization temperature in cooling process at 10°C/min from the melt was increased from 76.3 to 87.7°C, and the half-time of PBS/KF composite in isothermal crystallization at 96 and 100°C were reduced to 10.8% and 14.3% of that of the neat PBS, respectively. SEM analysis indicates that the adhesion between PBS and KF needs further improvement. These results signify that KF is efficient in improving the tensile modulus, storage modulus and the crystallization rate of PBS. Hence, this study provides a good option for preparing economical biodegradable composite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Compatibilization and development of layered silicate nanocomposites based of unsatured polyester resin and customized intercalation agent

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
    Luigi Torre
    Abstract In this study a procedure for the preparation of compatibilized nanoclays was used to produce effective nanocomposites based on unsatured polyester (UP) resin. A compatibilization procedure of the filler with a selected surfactant has been developed and optimized, the effect of organic modifiers on the synthesized nanocomposites properties was studied. Moreover, polyester/clay nanocomposites were prepared. In particular, samples were prepared using two different mixing methods. The properties and formation processes of the nanocomposites obtained using the two methods were compared. X-ray diffraction studies revealed the formation of intercalated/exfoliated nanocomposites structures. The effect of processing parameters, used for both the compatibilization procedure and the preparation of nanocomposites, was studied. Dynamic mechanical, thermal analysis, and rheological tests were performed to investigate the formation mechanism of UP/montmorillonite nanocomposite. In particular, mechanical properties of nanocomposites were studied using dynamic mechanical analysis and tensile tests. Mechanical, rheological, and thermal characterization have confirmed the validity of the used approach to compatibilize the nanoclay and to produce nanocomposites. Tensile strength and Young's modulus were modified by the loading of the organoclays. Furthermore, the rheology of the nanocomposite formulation provided processing information, while mechanical and dynamic mechanical characterization was performed on the nanocomposites produced with the newly compatibilized formulation. The results have shown that nanocomposites with better mechanical properties can be obtained through the selection of an appropriate compatibilization process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Nanoclay and long-fiber-reinforced composites based on epoxy and phenolic resins

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008
    Gang Zhou
    Abstract In this study, high-performance thermoset polymer composites are synthesized by using both long fibers and nanoclays. Epoxy and phenolic resins, the two most important thermoset polymers, are used as the polymer matrix. The hydrophobic epoxy resin is mixed with surface modified nanoclay, while the hydrophilic phenolic resin is mixed with unmodified raw nanoclay to form nanocomposites. Long carbon fibers are also added into the nanocomposites to produce hybrid composites. Mechanical and thermal properties of synthesized composites are compared with both long-fiber-reinforced composites and polymer- layered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites. It is found that mechanical and thermal properties of epoxy and phenolic nanocomposites can be substantially improved. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Mechanical and morphological properties of organic,inorganic, hybrid, clay-filled, and cyanate ester/siloxane toughened epoxy nanocomposites

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2007
    S. Nagendiran
    Abstract Organic,inorganic hybrids involving cyanate ester and hydroxyl-terminated polydimethylsiloxane (HTPDMS) modified diglycidyl ether of bisphenol A (DGEBA; epoxy resin) filled with organomodified clay [montmorillonite (MMT)] nanocomposites were prepared via in situ polymerization and compared with unfilled-clay macrocomposites. The epoxy-organomodified MMT clay nanocomposites were prepared by the homogeneous dispersion of various percentages (1,5%), and the resulting homogeneous epoxy/clay hybrids were modified with 10% HTPDMS and ,-aminopropyltriethoxysilane as a coupling agent in the presence of a tin catalyst. The siliconized epoxy/clay prepolymer was further modified separately with 10% of three different types of cyanate esters, namely, 4,4,-dicyanato-2,2,-diphenylpropane, 1,1,-bis(3-methyl-4-cyanatophenyl) cyclohexane, and 1,3-dicyanato benzene, and cured with diaminodiphenylmethane as a curing agent. The reactions during the curing process between the epoxy, siloxane, and cyanate were confirmed by Fourier transform infrared analysis. The results of dynamic mechanical analysis showed that the glass-transition temperatures of the clay-filled hybrid epoxy systems were lower than that of neat epoxy. The data obtained from mechanical studies implied that there was a significant improvement in the strength and modulus by the nanoscale reinforcement of organomodified MMT clay with the matrix resin. The morphologies of the siloxane-containing, hybrid epoxy/clay systems showed heterogeneous character due to the partial incompatibility of HTPDMS. The exfoliation of the organoclay was ascertained from X-ray diffraction patterns. The increase in the percentage of organomodified MMT clay up to 5 wt % led to a significant improvement in the mechanical properties and an insignificant decrease in the glass-transition temperature versus the unfilled-clay systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

    Mechanical, flow, and morphological properties of talc- and kaolin-filled polypropylene hybrid composites

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007
    M. B. Abu Bakar
    Abstract Polypropylene (PP) hybrid composites have been produced by compounding two types of mineral fillers, viz., talc and kaolin with PP copolymer using a twin screw extruder. The PP hybrid composite was injection-molded into dumbbell specimen for tensile, flexural, and impact properties characterizations. MFI and SEM studies were used to characterize the flow and morphological properties of the PP hybrid composites. The result shows that most of the hybrid composites showed a significant decrease in flow, tensile, flexural, and impact properties compared with the single filler-filled PP composites. However, a hybridization effect was seen for the PPT20K10 hybrid composites, through the synergistic coalescence of positive characteristics from 20 wt % of talc and 10 wt % of kaolin. This hybrid formulation have given an economically advantageous material with the mechanical properties (tensile, flexural, and impact) comparable to those of the talc-filled PP composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 434,441, 2007 [source]

    Mechanical and thermal properties of polypropylene/sugarcane Bagasse composites

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007
    B. Ramaraj
    Abstract To determine the possibility of using sugarcane bagasse (SCB) waste as reinforcing filler in the thermoplastic polymer matrix, SCB-reinforced polypropylene (PP) composites were prepared. The PP and SCB composites were prepared by the extrusion of PP resin with 5, 10, 15, and 20 wt % of SCB filler in a corotating twin screw extruder. The extruded strands were cut into pellets and injection molded to make test specimens. These specimens were tested for physicomechanical properties such as tensile, flexural, Izod, and Charpy impact strengths, density, water absorption, and thermal characteristics, namely, heat deflection temperature (HDT), melt flow index, and thermogravimetric analysis. It was found that the flexural strength increased from 23.66 to 26.84 MPa, Izod impact strength increased from 10.499 to 13.23 Kg cm/cm, Charpy impact strength increased from 10.096 to 13.98 Kg cm/cm, and HDT increased from 45.5 to 66.5°C, with increase in filler loading from 5 to 20% in the PP matrix. However, the tensile strength and elongation decreased from 32.22 to 27.21 MPa and 164.4 to 11.20% respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3827,3832, 2007 [source]

    Skeletal Myoblast Transplant in Heart Failure

    JOURNAL OF CARDIAC SURGERY, Issue 4 2003
    Eugene K.W. Sim F.R.C.S.
    Heart transplantation has emerged as a viable option but is fraught with problems of supply. Mechanical assist devices are extremely expensive and dynamic cardiomyoplasty has shown only limited success in the clinical setting. Recent insights into the pathogenesis of myocardial diseases and the progress made in the field of molecular biology have resulted in the development of new strategies at molecular as well as cellular levels for cardiac muscle repair. One such strategy is to augment ventricular function by means of cellular cardiomyoplasty through intracardiac cell grafting using adult and fetal cardiomyocytes, stem cells, and autologous skeletal myoblasts. (J Card Surg 2003; 18:319-327) [source]

    Enhancing Physical Properties and Antimicrobial Activity of Konjac Glucomannan Edible Films by Incorporating Chitosan and Nisin

    JOURNAL OF FOOD SCIENCE, Issue 3 2006
    Bin Li
    ABSTRACT: The antimicrobial effect of konjac glucomannan (KGM) edible ûlm incorporating chitosan (CHI) and nisin at various ratios or concentrations was studied. This activity was tested against pathogenic bacteria, namely, Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. Mechanical and physical properties were determined, and the results indicated that the blend film KC2 (mixing ratio KGM 80/ CHI 20) showed the maximum tensile strength (102.8 ± 3.8 MPa) and good transparency, water solubility, and water vapor transmission ratio. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were used to characterize the structural change of the blend films; and the results showed that strong intermolecular hydrogen bonds occurred between CHI and KGM. Incorporation of nisin at 463IU per disk of film for the selected KC2 was found to have antimicrobial activity against S. aureus, L. monocytogenes, and B. cereus. The mean value of inhibition zone diameter of the CHI-N series and the KC2-N series were higher than the KGM-N series at each corresponding concentration and with significant difference (P < 0.05), however, there was no significant difference in the antimicrobial effect between CHI and KC2 incorporating nisin. At all these levels, the blend ûlm KC2-nisin had a satisfactory appearance, mechanical and physical properties, and antimicrobial activity. Therefore, it could be considered as a potential "active" packaging material. [source]