Thermal Stabilization

Top PDF Thermal Stabilization:

Effects of MWNTs on Flame Retardation and Thermal Stabilization Performance of Phosphorus-containing Flame Retardants in Polypropylene

Effects of MWNTs on Flame Retardation and Thermal Stabilization Performance of Phosphorus-containing Flame Retardants in Polypropylene

It was proved that MWNTs when used at an optimum level of 4 wt% improve thermal stability and flammability of PP without any undesirable effect on its flow-ability and mechanical properties. Although, the efficiency of MWNTs in flame retardation of the polymer is significantly less than that of the both flame retardant systems, ammonium polyphosphate /pentaerythritol and red phosphorus, but MWNTs could stabilizes the polymer against thermal degradation more effective than the both flame retardant systems. However, MWNTs interfere with thermal stabilization and flame retardation efficiency of both APP/PER and RP flame retardant systems in the polymer.

7 Read more

Thermal Stabilization Based Investigations over Quenching Media for Spindle in CNC Machining Centers

Thermal Stabilization Based Investigations over Quenching Media for Spindle in CNC Machining Centers

region. Initially, the thermal stabilization of main spindle front bearing and hydraulic oil circulation around the periphery of spindle explored. Next, computation and analysis remains on the thermal stabilization of main spindle front bearing with cooling by hydraulic oil and circulating water around the periphery of oil. The observation was on the thermal effects from both theoretical and analytical aspects. Next, thermal shift of main spindle in XZ (horizontal), YZ (vertical) and axial plane has been analyzed. Next, proposed work investigated that among the three planes, thermal shift remains maximum in axial direction on the consistent patterns of references [9-10]. In the future, focus of work remains on analysis of spindle from different facets i.e. analyzing spindle cooling from different cooling media, with respect to speed and other key factors.

7 Read more

Efficient Thermal Stabilization of Polyvinyl Chloride with Tannin Ca Complex as Bio Based Thermal Stabilizer

Efficient Thermal Stabilization of Polyvinyl Chloride with Tannin Ca Complex as Bio Based Thermal Stabilizer

The potential use of tannin-Ca complex derived from tannins as bio-based thermal stabilizer and antioxidant additive for polyvinyl chloride (PVC) was investigated in this work. For this project, Reapak B-NT/7060 was applied as reference thermal stabilizer. Variable compositions: (1, 2, and 3) part per hundred ratio (phr) of tannin-Ca complex in the presence of 10 phr Dioctyl phthalate (DOP) as plasticizer in all PVC formulations were prepared by melt mixing by internal mixer at 165˚C. Tannin-Ca complex was characterized by FT-IR spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) analysis as well as by means of differential scanning calorimetry (DSC). The tannin derivative stabilization efficiency under inert atmosphere was determined by using thermogravimetric analysis (TGA). In addition, its thermal stabilization effect has been assessed in air as oxidizing atmosphere by DSC in dynamic conditions. According to TGA thermograms, the initial degradation temperature (T i ) and optimum degradation tempera-

13 Read more

Polymer stabilization of the smectic C-alpha* liquid crystal phase—Over tenfold thermal stabilization by confining networks of photo-polymerized reactive mesogens

Polymer stabilization of the smectic C-alpha* liquid crystal phase—Over tenfold thermal stabilization by confining networks of photo-polymerized reactive mesogens

and interlayer chiral interaction that can unwind the helix without polarization reversal. 25 Finally, SEM studies pro- vided more obvious clues about the structure of polymeric network and porous confinement structure when the mono- mer (particularly the reactive mesogen) concentration increased (Figure 6). The polymeric structure confining the liquid crystal host was not observed in mixture A where the reactive mesogen is absent (Figure 6(a)). However, traces of the formation of such confining network can be seen in the SEM images obtained for mixture B (Figure 6(b)). A well- defined network among and across layers was only observed for mixture C with the highest concentration of the reactive mesogen and the greatest thermal stabilization of the SmC a *

5 Read more

Three Stages of Lysozyme Thermal Stabilization by High and Medium Charge Density Anions

Three Stages of Lysozyme Thermal Stabilization by High and Medium Charge Density Anions

terms of charge screening at low salt concentrations and surface tension e ff ects at high salt concentrations. 15 Preferential interaction is a theory that explains the Hofmeister e ff ect in terms of attraction or repulsion of the ions to the protein surface. 17 A development to the preferential interaction theory suggested that the e ff ect was determined by a combination of preferential interaction and the excluded volume of the ions. 18,19 It is applied to explain both protein stability and solubility. These models are in agreement with the observation that low charge density anions (chaotropes) interact with apolar surfaces on the protein and are described as having preferred interaction with the protein surface. 20 High charge density anions (kosmotropes) are described as being excluded from the protein surface at higher ion concentrations, though the mechanism for anion exclusion is not apparent. The mechanism for stabilization of proteins by high density charge ions is also not apparent unless through an indirect mechanism such as surface tension. One theory is that the presence of the stabilizing molecules results in preferential hydration of the protein surface and it is this that stabilizes the structure. 21 At present, the mechanisms for protein stabilization and destabilization by salts are subject to active debate.

5 Read more

Thermal Stabilization and Mechanical Properties of Nanocrystalline Fe-Ni-Zr Alloys.

Thermal Stabilization and Mechanical Properties of Nanocrystalline Fe-Ni-Zr Alloys.

stabilization and accuracy of ± 0.5-3 o C. The whole experiment was recorded with a video imaging in bright field (BF) mode to directly observe grain growth in the initially nanocrystalline sample. The increment of the temperature was 50 o C during in situ annealing. High temperature XRD analysis was carried out using an Anton Paar HTK 2000. Samples consisted of a thin layer of powder place onto a Pt strip. A given sample was then brought into alignment on the optical axis of the diffractometer. The heating chamber was pumped down, under a vacuum of approximately 10 -3 Torr and backfilled with a He 3 % hydrogen forming gas to prevent oxidation of the powders during examination. The sample was then resistively heated to temperature at a rate of 60 o C/min, at which point it endured a 10 min isothermal anneal, before performing a 17 min long diffraction scan at the respective temperature. The sample temperature was increased to the next desired set point and the isothermal/scanning process repeated as done previously. This process was repeated to cover the following temperature range of 30 o C, 500 o C, 600 o C, 700 o C, 750 o C, 800 o C, 900 o C and again at 31 o C to complete the test. The grain size at temperature was calculated using the Scherrer Method.

173 Read more

A Study on Synthesis and Characterization of Biobased Carbon Nanoparticles from Lignin

A Study on Synthesis and Characterization of Biobased Carbon Nanoparticles from Lignin

The freeze-drying process caused the formation of po- rous lignin samples. However, these may fuse together and form lumps during the carbonization process, which results in bulk carbon material rather than well-defined carbon nanoparticles. In order to retain this porous struc- ture, lignin samples underwent a thermal stabilization process employing a low heating rate of 1˚C/min at 250˚C for 2 hours. The effect of thermal stabilization on their structural coordination, thermal behavior, and mi- crostructure were investigated by FTIR, DSC, and SEM analysis respectively. Figure 2 shows the FTIR spectra of the as-obtained and thermo stabilized lignin with dif- ferent KOH formulations. From Figure 2, the FTIR spectra indicates a characteristic peak of the lignin at 1590 cm −1 and 1500 cm −1 , which represents the aromatic

6 Read more

Partially Invariant System for Spacecraft Center of  Mass Motion Stabilization

Partially Invariant System for Spacecraft Center of Mass Motion Stabilization

Except improvement of the navigational accuracy, reduction of spacecraft stabilization cross errors in the active phase, it also results in lower total characteristic velocity of corrective impulses, and, consequently, in reduction of fuel required for the correction. When the correction speed impulse reaches 30 reduction of gross error during the correction manoeuvre results in proportional reduction of the required characteristic velocity during the next correction. The data referred to in publications [2,3] show that improved accuracy of roll stabilization in the active phase by one order results in reduction of total characteristic correction velocity for Mars interplanetary probe from about 20 m/sec to 2 m/sec. This is corresponds to fuel savings up to 30 kg, or to increase of the payload mass. Due to the relatively small weight of modern scientific instruments (about 3-8 kg), even such small increase of payload weight can significantly extend the program of research and experiments implemented by the spacecraft [1].

7 Read more

Impact of Extremely Low-Frequency Magnetic Fields on Human Postural Control

Impact of Extremely Low-Frequency Magnetic Fields on Human Postural Control

higher frequency, which brings the dB/dt in the same order of magnitude (680 mT/s in the Legros’ study). Participants were exposed for 1 hour after which they completed a series of tasks, including a postural oscillation recording. Force plate recordings showed a stabilization effect in terms of decreased velocity and amplitude of postural control oscillations for the MF condition compared to the sham condition. These effects were only observed during the eyes closed conditions. This suggests that the time-varying MF acts on proprioceptive or vestibular functions, a finding consistent with results from Glover et al. (2007). Comparing COP of Glover at al. (2007) and Legros et al. (2012), there appears to be some discrepancies in that no stabilization or destabilization effects were found for the former and a significant stabilization effect was found for the latter. This could be due to significant differences in the exposure apparatus between the two studies, thereby changing the MF distribution patterns. For example, Glover at al. (2007) used a 2.5 Hz stimulus, compared to a 60 Hz stimulus used by Legros et al. (2012). Therefore, it is possible that a frequency threshold somewhere between 2.5 and 60 Hz determines the observed stabilization response. A single study testing different frequency levels at a single MF value could provide more information on potential threshold effects. Indeed, considering the previous studies, there is likely a threshold effect to be determined in terms of exposure time, frequency, and intensity. The study we are conducting will address this possibility, as explained in the following chapters. Another consideration possibly accounting for observed differences in postural control results is the stance of each participant on the force plate. Van Nierop et al. (L. van Nierop, 2015; L. E. van Nierop et al., 2013) had participants stand with their feet together in a parallel position (0 cm apart) on a foam layer, whereas Legros et al. (2012) had participants stand with 1 cm between the feet in a parallel position with no foam layer. Glover et al. (2007) also used a foam layer, but provided no information on the spacing of participants’ feet. It is therefore possible that the destabilization effects noted in the van Nierop et al. (2013) study was found due to the participants being in a less stable position than the positioning reported by Legros et al (2012).

94 Read more

Laboratory Study of Black Cotton Soil Blended With Copper Slag and Fly-Ash

Laboratory Study of Black Cotton Soil Blended With Copper Slag and Fly-Ash

Large quantities of coal are being burnt in thermal power stations to meet the ever increasing demand for thermal power. Combustion of coal results in a residue consisting of inorganic mineral constituents and organic matter which is not fully burned. The inorganic mineral constituents from ash: about 80% of these ash sis fly ash. Environmentally safe disposal of large quantities of ash is not only tedious but also expensive. To reduce the problems of disposal, great efforts are being made to utilize fly ash.

8 Read more

Automotive Bot Prijoy Peter, Sreejith Anilkumar, Nikhil S, Sagar Shaju

Automotive Bot Prijoy Peter, Sreejith Anilkumar, Nikhil S, Sagar Shaju

A bicycle can be turned into an automotive bot, which can stabilize itself and navigate itself to the intended destination. There are two theoretical methods by which a two wheeled vehicle oriented in tandem can be stabilized: dynamic stabilization and control moment gyroscope (CMG) stabilization. Dynamic stabilization utilizes tactical steering techniques to trigger a lean in the vehicle in the intended direction for balancing, while CMG stabilization employs the reactive precession torque of a high-speed flywheel about an axis that will act to balance the vehicle. Of these two, CMG stabilization offers greater advantages for static vehicles. The conceptual stage paper proposes that the technology which was used in the auto driven cars can be successfully implemented to a highly unstable form through auto stabilization by one of the above two methods. The bike can easily navigate with the help of radar and map technology. The radar sonar system detects possible collisions and avoids them through intelligent form of cruise control that slows down and speeds up automatically to keep pace with the vehicle in front of you.

7 Read more

Mathematical Structure for Electromagnetic Frequencies that May Reflect Pilot Waves of Bohm’s Implicate Order

Mathematical Structure for Electromagnetic Frequencies that May Reflect Pilot Waves of Bohm’s Implicate Order

Research in the framework of electromagnetic pulses in and on living cells has been systematically undertaken the past eighty years. About 25.000 biologi- cal/physical reports are available, of which a part is dealing with non-thermal biological effects on cells. Influences of electromagnetic waves causing thermal effects on biological systems are relatively well understood, yet the knowledge about non-thermal effects of electromagnetic waves is rapidly increasing. The Polaron model of Fröhlich (1968) and the Soliton model of Davydov (1973) de- scribe both the effects of coherent states of waves for inanimate as well as ani- mate systems. Polarons are quasi-particles in which an electron is dressed with one or phonons and are also called solitons. Solitons, as self-reinforcing solitary waves, have been shown to interact with biological phenomena in the framework of cellular self-organisation [6] [18] [21]. It is proposed that stabilisation of cell states occur at typical discrete frequencies, described by particular wave func- tions, in which either each type of cell or bio-molecule or even a well-defined part of the bio-molecule will exhibit their own eigen-frequencies. The particular life-sustaining effects analysed are exerted by a range of electromagnetic wave eigen-frequencies of one-tenth of a Hertz till Peta Hertz that show repeating patterns of twelve bands, and can be positioned on a “coherent scale of 12 num-

47 Read more

Improving the quality of positioning and reducing the rotation factor during pediatric portable chest radiography using infant immobilizer

Improving the quality of positioning and reducing the rotation factor during pediatric portable chest radiography using infant immobilizer

Suitable position and stabilization of the infants can be very effective in imaging findings. The stan- dard position and stabilization prevent the repeti- tion of radiography due to the rotation as well as contribute to improving diagnostic details of lung imaging. The sandbags or patient’s accompanies or both are used to stabilize the baby in most centers. Our study indicates that these methods are usually associated with some degree of rotation for children, have no good efficiency, and make exposure of the patients accompanies. As an alternative approach, a special type of body immobilizer was employed in this project and has yielded good results and the mean rotation of the infant was reduced signifi- cantly after positioning by the radiographer. The use of this immobilizer, in addition to improving the positioning of the baby, had other advantages:

6 Read more

Stabilization of Earthwork by Introducing Reinforcing Additives When Mixing Soil

Stabilization of Earthwork by Introducing Reinforcing Additives When Mixing Soil

Methods of earthwork stabilization by introducing reinforcing additives when mixing soil are given. Stabilization is provided in areas with deformations of embankment slopes on a firm footing and of recesses, embankment footings on swamps and weak soils and on thawing permafrost soils. Deep soil reinforcement by columns is provided within karst-hazardous areas, in places of settling above mines, in areas with soil protrusion in recesses and in areas of long-term embankment settling in approaches to bridges and culverts. Stabilization is done in a mechanized way. The characteristics of the units for deep wet and dry mixing are given. Cement, lime, and other materials are used as binders. Stabilized areas are explored using the geophysical methods of ground penetrating radar and DPT in a differentiate manner by types of deformations and earthwork defects. Methods of calculation of stabilization structures are given.

13 Read more

An Output Stabilization Problem of Distributed Linear Systems Approaches and Simulations

An Output Stabilization Problem of Distributed Linear Systems Approaches and Simulations

The goal of this paper is to study an output stabilization problem: the gradient stabilization for linear distributed systems. Firstly, we give definitions and properties of the gradient stability. Then we characterize controls which stabilize the gradient of the state. We also give the stabilizing control which minimizes a performance given cost. The obtained re- sults are illustrated by simulations in the case of one-dimensional distributed systems.

9 Read more

Performance Analysis for Stabilization of Black Cotton Soil Using Alkali Fly ash

Performance Analysis for Stabilization of Black Cotton Soil Using Alkali Fly ash

highways, railways, water reservoirs, reclamation and many others. Require earthfabric in huge quantity. In urban areas, borrow earth is not easy on hand, which needs to behauled from an extended distance. Relatively often, huge areas are protected with incredibly plastic and expansivesoil, which isn't suitable for such rationale. This analysis offers the stabilization of a regionalexpansive soil utilizing alkali-activated fly ash. First the elemental houses of black cotton soil are found out, the fly ash ofdifferent percentages such as 10, 20, 30, 40 and 50% are blended with black cotton soil and premiere amount used to befound out, The activated fly ashes at distinct alkali concentrations zero, 0.5, 1, 1.5 and 2 molarities are used to performtests. Unique Geotechnical residences like Atterberg’s limits, compaction, CBR and UCS of stabilized expansive soilhave been demonstrated. It was once determined that there is a huge growth in Geotechnical residences of expansive soil withthe addition of alkali-activated fly ash and the outcome of alkali- activated fly ash is found extra suitable than naturalfly ash mix.

5 Read more

Reduction of chromium toxicity by applying various soil amendments in artificially contaminated soil

Reduction of chromium toxicity by applying various soil amendments in artificially contaminated soil

Stabilization of heavy metals is a cost effective soil remediation method, which is used to reduce the mobile contaminant fraction in soil by low-cost and widely available amendments. In the present study, 6 types of soil amendments were investigated for their abilities to reduce Cr mobility in soil; CFA, MSWC, rice husk biochar prepared at 300°C (B300) and 600°C (B600), zerovalent iron (Fe 0 ) and zerovalent manganese

12 Read more

Magnetically Levitated Linear Drive with Repulsive Magnetic Guidance

Magnetically Levitated Linear Drive with Repulsive Magnetic Guidance

Abstract: Linear direct drives are often used when high performance is required, because of their high dynamic and their good position accuracy. Usually direct drives are used with linear rolling guidance. In clean room and vacuum applications linear rolling guidance cannot be used as particles can be cause problems. In this paper a magnetically levitated linear direct drive with a combination of repulsive permanent magnet stabilization and Lorentz force based stabilization is presented. With the joint use of magnet fields high dynamic can be achieved in combination with a cost efficient hardware. Due to the use of repulsive permanent magnet forces, it is possible to levitate an armature with nearly no power dissipation. An ad-hoc control reduces the power dissipation to a value less than 10 mW.

9 Read more

Sport and physical activity after ankle arthrodesis with Ilizarov fixation and internal fixation

Sport and physical activity after ankle arthrodesis with Ilizarov fixation and internal fixation

The exclusion criteria consisted of: ankle arthrodesis without Ilizarov external fixator stabilization or internal stabilization with cannulated screws; a lack of baseline val- ues of ankle pathology etiology and/or demographic data in medical records; a lack of preoperative and postoperative sport and physical activity level scores; a follow-up period shorter than 24 months; Charcot neuroarthropathy; mul- tiple joint or bilateral ankle injuries; and undergoing associ- ated procedures during surgical intervention.

6 Read more

A Review- Thermal Degradation and Stabilization of Poly (Vinyl Chloride)

A Review- Thermal Degradation and Stabilization of Poly (Vinyl Chloride)

Polyvinyl chloride is used as a third-most widely produced plastic formed by the polymerization of vinyl chloride and has tremendous applications all around. It is thermally degraded by dehydro- chlorination, in the absence of oxygen and evolves HCl. Thermogravimetry (TG/DTG) coupled with evolved gas analysis (MS de- tection) of volatiles was used to characterize the thermal behavior of commercial PVC cable insulation material during heating in the range 20-800°C in air and nitrogen, re- spectively. In addition, simultaneous TG/FTIR was used to elucidate chemical processes that caused the thermal degrada- tion of the sample. There are two general approaches to the stabilization of polymers by modification of molecular structure and the use of additives. This degradation must be controlled by the addition of stabilizers. The mainly used stabilizers are Schiff bases, Alkyltin Stabilizers, Mixed Metal Stabilizers, Alkyl Phosphites Stabilizers, -Diketones

19 Read more

Show all 10000 documents...