scholarly journals Distribution of Heat Stabilizers in Plasticized PVC-Based Biomedical Devices: Temperature and Time Effects

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Lidia Maria Bodecchi ◽  
Caterina Durante ◽  
Marcello Malagoli ◽  
Matteo Manfredini ◽  
Andrea Marchetti ◽  
...  
Keyword(s):  
Plastic Material ◽  
Transport Reaction ◽  
Time Effects ◽  
Plasticized Pvc ◽  
Dynamic Framework ◽  
Polymeric Resins ◽  
The Fourier Transform ◽  
Increasing Temperature ◽  
Ir Bands ◽  
System Chemistry

Thermoplastic polymers can be viewed as a dynamic framework in which additives allocation is strongly dependent on the system' chemistry. Considering the complexity of the distribution phenomena that may occur in plastics obtained by blending polymeric resins with different additives, this work constitutes an attempt to the description of the behavior of PVC heat stabilizers (calcium and zinc carboxylates), as regard temperature and time. Thanks to the Fourier Transform Infrared Spectroscopy, it is possible to observe a first decreasing trend of the additives related IR-bands as a function of the increasing temperature and the higher the temperature the faster the decrease of the heat stabilizers intensities bands is, with respect to time. Additives distribution in not sterilized, sterilized, aged not sterilized and aged sterilized materials have been investigated to determine their behavior with respect to temperature, from 30 to 120°C, and time. A simulated supplementary aging process equivalent to 9 months aging was carried out on aged not sterilized and aged sterilized materials to gain more data on the transport/reaction phenomena these additives in the plastic material. Experimental evidences allow hypothesizing that reaction and redistribution phenomena probably concur to determine the additives allocation in PVC as a function of temperature and time.

scholarly journals ANOVA APPLICATION TO ASSESS THE EFFECT OF TEMPERATURE ON VALUE AND YIELD ON LIQUID FUEL FROM HDPE

Konversi ◽  
2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Nurull Fanani ◽  
Eky Novianarenti ◽  
Erlinda Ningsih ◽  
Kartika Udyani ◽  
Ari Prayitno ◽  
...  
Keyword(s):  
Liquid Fuel ◽  
Plastic Material ◽  
Calorific Value ◽  
Plastic Waste ◽  
Effect Of Temperature ◽  
Heating Value ◽  
Alkyl Chains ◽  
Thermochemical Process ◽  
Effect On Yield ◽  
Increasing Temperature

Proper processing to overcome the abundance of plastic waste is needed. Currently, pyrolysis technology is one method that can overcome plastic waste. Pyrolysis is a thermochemical process, which breaks down long alkyl chains into hydrocarbons at high temperatures. This study aims to determine the effect of temperature on yield and heating value using the analysis of variance (ANOVA) method. The pyrolysis of plastic waste is carried out with HDPE plastic material. The pyrolysis process is carried out in a reactor with 50 grams of feed at various temperatures of 500, 550, 600 and 650⁰C. The conclusion that can be drawn from this research is that there is a decrease in yield and calorific value with increasing temperature. The results of the analysis concluded that temperature had an effect on the yield produced and the calorific value of the product. The best yield was obtained at 35.86% and a heating value of 10530.461cal / g at a temperature of 100oC. Based on the results of data analysis using the ANOVA method, it was found that the experimental hypothesis was that temperature had an effect on yield and calorific value.

The on-line use of histogram data for high-speed correction and alignment of electron microscope images

1984 ◽  
Vol 42 ◽  
pp. 556-557
Author(s):  
William Krakow
Keyword(s):  
Power Spectrum ◽  
High Speed ◽  
Direct Memory Access ◽  
Digital Television ◽  
Contrast Transfer Function ◽  
The Past ◽  
High Resolution Tem ◽  
On Line ◽  
Correction Of Astigmatism ◽  
The Fourier Transform

In the past few years on-line digital television frame store devices coupled to computers have been employed to attempt to measure the microscope parameters of defocus and astigmatism. The ultimate goal of such tasks is to fully adjust the operating parameters of the microscope and obtain an optimum image for viewing in terms of its information content. The initial approach to this problem, for high resolution TEM imaging, was to obtain the power spectrum from the Fourier transform of an image, find the contrast transfer function oscillation maxima, and subsequently correct the image. This technique requires a fast computer, a direct memory access device and even an array processor to accomplish these tasks on limited size arrays in a few seconds per image. It is not clear that the power spectrum could be used for more than defocus correction since the correction of astigmatism is a formidable problem of pattern recognition.

Small Angle Electron Scattering From Vacuum Condensed Metallic Films

1968 ◽  
Vol 26 ◽  
pp. 380-381
Author(s):  
J. Silcox ◽  
R. H. Wade
Keyword(s):  
Electron Scattering ◽  
Small Angle ◽  
Ring Structure ◽  
Two Dimensional ◽  
Metallic Films ◽  
Micro Structure ◽  
Angle Scattering ◽  
The Fourier Transform ◽  
Source Of Information ◽  
Kinematical Theory

Recent work has drawn attention to the possibilities that small angle electron scattering offers as a source of information about the micro-structure of vacuum condensed films. In particular, this serves as a good detector of discontinuities within the films. A review of a kinematical theory describing the small angle scattering from a thin film composed of discrete particles packed close together will be presented. Such a model could be represented by a set of cylinders packed side by side in a two dimensional fluid-like array, the axis of the cylinders being normal to the film and the length of the cylinders becoming the thickness of the film. The Fourier transform of such an array can be regarded as a ring structure around the central beam in the plane of the film with the usual thickness transform in a direction normal to the film. The intensity profile across the ring structure is related to the radial distribution function of the spacing between cylinders.

Computer Assisted Image Reconstruction of Oligomer Structure

1976 ◽  
Vol 34 ◽  
pp. 472-473
Author(s):  
A.M. Jones ◽  
A. Max Fiskin
Keyword(s):  
Three Dimensional ◽  
Depth Of Field ◽  
Computer Assisted ◽  
Projection Data ◽  
Two Dimensional ◽  
Single Particles ◽  
Dimensional Reconstruction ◽  
Computer Assisted Image ◽  
The Fourier Transform ◽  
Space Approach

If the tilt of a specimen can be varied either by the strategy of observing identical particles orientated randomly or by use of a eucentric goniometer stage, three dimensional reconstruction procedures are available (l). If the specimens, such as small protein aggregates, lack periodicity, direct space methods compete favorably in ease of implementation with reconstruction by the Fourier (transform) space approach (2). Regardless of method, reconstruction is possible because useful specimen thicknesses are always much less than the depth of field in an electron microscope. Thus electron images record the amount of stain in columns of the object normal to the recording plates. For single particles, practical considerations dictate that the specimen be tilted precisely about a single axis. In so doing a reconstructed image is achieved serially from two-dimensional sections which in turn are generated by a series of back-to-front lines of projection data.

Give Me Just a Little More Time: Effects of Alcohol on the Failure and Recovery of Cognitive Control

2014 ◽  
Author(s):  
Kira Bailey ◽  
Bruce D. Bartholow ◽  
J. Scott Saults ◽  
Sarah A. Lust
Keyword(s):  
Cognitive Control ◽  
Time Effects

Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

2020 ◽  
Vol 92 (1) ◽  
pp. 10901
Author(s):  
Saloua El Asri ◽  
Hamid Ahamdane ◽  
Lahoucine Hajji ◽  
Mohamed El Hadri ◽  
Moulay Ahmed El Idrissi Raghni ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Single Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Transmission Spectra ◽  
Electrical Measurements ◽  
Cation Type ◽  
Edx Analyses ◽  
The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740  °C and at 630–700  °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

Transit-time effects in saturated absorption resonances

1986 ◽  
Vol 47 (12) ◽  
pp. 2025-2039 ◽  
Author(s):  
A. Titov ◽  
Yu. Malyshev ◽  
Yu. Rastorguev
Keyword(s):  
Transit Time ◽  
Time Effects ◽  
Saturated Absorption

Theoretical study of the prestressing strand's stress by computer modeling methods

2020 ◽  
Vol 76 (11) ◽  
pp. 1139-1148
Author(s):  
A. G. Korchunov ◽  
E. M. Medvedeva ◽  
E. M. Golubchik
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Steel Microstructure ◽  
Compressive Stresses ◽  
Wide Range ◽  
Prestressing Strands ◽  
Increasing Temperature ◽  
Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

Masonry: the brittle or plastic material?

2019 ◽  
pp. 22-28
Keyword(s):  
Plastic Material ◽  
Experimental Studies ◽  
Point Of View ◽  
Plastic Properties ◽  
Plastic Deformations ◽  
Base Materials ◽  
Stress States ◽  
Creep Deformations ◽  
Structural Point

The results of experimental studies of masonry on the action of dynamic and static (short-term and long-term) loads are presented. The possibility of plastic deformations in the masonry is analyzed for different types of force effects. The falsity of the proposed approach to the estimation of the coefficient of plasticity of masonry, taking into account the ratio of elastic and total deformations of the masonry is noted. The study of the works of Soviet scientists revealed that the masonry under the action of seismic loads refers to brittle materials in the complete absence of plastic properties in it in the process of instantaneous application of forces. For the cases of uniaxial and plane stress states of the masonry, data on the coefficient of plasticity obtained from the experiment are presented. On the basis of experimental studies the influence of the strength of the so-called base materials (brick, mortar) on the bearing capacity of the masonry, regardless of the nature of the application of forces and the type of its stress state, is noted. The analysis of works of prof. S. V. Polyakov makes it possible to draw a conclusion that at the long application of the load, characteristic for the masonry are not plastic deformations, but creep deformations. It is shown that the proposals of some authors on the need to reduce the level of adhesion of the mortar to the brick for the masonry erected in earthquake-prone regions in order to improve its plastic properties are erroneous both from the structural point of view and from the point of view of ensuring the seismic resistance of structures. It is noted that the proposal to assess the plasticity of the masonry of ceramic brick walls and large-format ceramic stone with a voidness of more than 20% is incorrect, and does not meet the work of the masonry of hollow material. On the basis of the analysis of a large number of research works it is concluded about the fragile work of masonry.

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