scholarly journals Effect of Potassium Permanganate Modification on Plasticized Spinning Polyacrylonitrile Fibers with Different Diameters

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1330
Author(s):  
Xiang Li ◽  
Xiaonan Dang
Keyword(s):  
Potassium Permanganate ◽  
Large Diameter ◽  
Small Diameter ◽  
Amorphous Region ◽  
Treatment Temperature ◽  
Crystalline Region ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Different Diameters ◽  
First Time

Plasticized spinning polyacrylonitrile (PAN) fibers with different diameters were chemically modified by potassium permanganate (KMnO4). The modification effects of different diameter fibers were studied for the first time. Differential scanning calorimetry (DSC) results show that, compared with the large diameter ones, small diameter modified fibers show lower cyclization starting temperature (Ti) and activation energy (E). Both kinds of fibers exhibit better modification effects compared with solution-spun fibers. For the small diameter fibers, chemical modification can occur at low treatment temperature, even at 70 °C. X-ray diffraction analysis (XRD) results show that modification not only occurs in the amorphous region of the fibers but also in the crystalline region.

scholarly journals Thermo-Mechanical Behaviour of Human Nasal Cartilage

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 177 ◽  
Author(s):  
Aureliano Fertuzinhos ◽  
Marta A. Teixeira ◽  
Miguel Goncalves Ferreira ◽  
Rui Fernandes ◽  
Rossana Correia ◽  
...  
Keyword(s):  
Mechanical Behaviour ◽  
Subcutaneous Tissue ◽  
Amorphous Region ◽  
Cartilage Matrix ◽  
Water Evaporation ◽  
Glass Transition Point ◽  
Crystalline Region ◽  
Scanning Calorimetry ◽  
Nasal Cartilage ◽  
Human Nose

The aim of this study was to undergo a comprehensive analysis of the thermo-mechanical properties of nasal cartilages for the future design of a composite polymeric material to be used in human nose reconstruction surgery. A thermal and dynamic mechanical analysis (DMA) in tension and compression modes within the ranges 1 to 20 Hz and 30 °C to 250 °C was performed on human nasal cartilage. Differential scanning calorimetry (DSC), as well as characterization of the nasal septum (NS), upper lateral cartilages (ULC), and lower lateral cartilages (LLC) reveals the different nature of the binding water inside the studied specimens. Three peaks at 60–80 °C, 100–130 °C, and 200 °C were attributed to melting of the crystalline region of collagen matrix, water evaporation, and the strongly bound non-interstitial water in the cartilage and composite specimens, respectively. Thermogravimetric analysis (TGA) showed that the degradation of cartilage, composite, and subcutaneous tissue of the NS, ULC, and LLC take place in three thermal events (~37 °C, ~189 °C, and ~290 °C) showing that cartilage releases more water and more rapidly than the subcutaneous tissue. The water content of nasal cartilage was estimated to be 42 wt %. The results of the DMA analyses demonstrated that tensile mode is ruled by flow-independent behaviour produced by the time-dependent deformability of the solid cartilage matrix that is strongly frequency-dependent, showing an unstable crystalline region between 80–180 °C, an amorphous region at around 120 °C, and a clear glass transition point at 200 °C (780 kJ/mol). Instead, the unconfined compressive mode is clearly ruled by a flow-dependent process caused by the frictional force of the interstitial fluid that flows within the cartilage matrix resulting in higher stiffness (from 12 MPa at 1 Hz to 16 MPa at 20 Hz in storage modulus). The outcomes of this study will support the development of an artificial material to mimic the thermo-mechanical behaviour of the natural cartilage of the human nose.

Formation and Phase Transformation of R. F. Sputter Deposited NON-BCC 6-A15 Chromium Thin Films

1996 ◽  
Vol 441 ◽  
Author(s):  
J. P. Chu ◽  
J. W. Chang ◽  
P. Y. Lee ◽  
J. K. Wu
Keyword(s):  
Thin Films ◽  
Phase Transformation ◽  
Processing Parameters ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Working Pressure ◽  
Annealing Study ◽  
First Order Transition ◽  
Sputter Deposited ◽  
First Time

AbstractFormation and phase transformation of non-BCC δ-A15 Cr thin films prepared by R. F. magnetron sputtering have been characterized. Processing parameters such as working pressure, deposition time and temperature were found to affect the formation of δ-A15 Cr films. Using differential scanning calorimetry, we have demonstrated for the first time that the phase transformation of the δ-A15 Cr phase to the equilibrium c-BCC Cr phase is an irreversible, exothermic, first-order transition. At a heating rate of 10°C/min, the onset and peak temperatures of transformation were determined to be 428°C and 437°C, respectively. Our post-deposition annealing study by X-ray diffraction further verified the occurrence of transformation.

Clogging mechanisms of filter barriers against debris-flow hazard

2021 ◽  
Author(s):  
Filippo Mauro ◽  
Alessandro Leonardi ◽  
Marina Pirulli
Keyword(s):  
Debris Flows ◽  
Large Diameter ◽  
Particle Diameter ◽  
Small Diameter ◽  
Equivalent Diameter ◽  
Threshold Values ◽  
Different Diameters ◽  
Debris Flow Hazard ◽  
Key Parameter

<p>Debris flows are amongst the most hazardous landslide phenomena (Jakob & Hungr, 2005). They are mixtures of flowing water and granular materials, which range in size from microscopic soil particles to massive rock boulders. Due to their unpredictability and rapidity, they pose severe hazard on infrastructure, structures, and human lives. To dissipate the destructive kinetic energy of debris flows and induce deposition of the coarsest fraction of the flow, mitigation systems often include the use of filter barriers. Filter barriers are built both in steel and reinforced concrete, and their openings should be designed according to a reference grain diameter. This key parameter is often chosen arbitrarily due to the difficulties in considering the full grain size distribution of the deposit. Sufficiently small outlets, however, leads to premature clogging of the barriers, blocking further outflow (Ashour et al., 2017). This can result in excessive maintenance costs.</p><p>This work focuses on the clogging mechanism of three different kinds of filter barriers: nets, slit dams, and slot dams. The aim is to evaluate the influence of grainsize dispersity into the clogging/non-clogging transition. Starting from simpler monodisperse granular material, we determine via DEM simulations the particle diameter D that induces clogging in the openings, as a function of the opening size S. Thus, for monodisperse grains, a set of threshold values for S/D can be detected: on one side of the threshold the particles are too small to clog the opening, on the other side they are too large to allow free passage of the material.</p><p>However, natural debris deposits are far from uniform. To analyse the role of grainsize dispersity, bidisperse specimens are created mixing grains with two different diameters: a small diameter and a large diameter. By varying the composition of large and small particles, a transition is observed between clogging and free-flow, in analogy with what obtained in the simulation with monodisperse grains. The comparison of results obtained with bidisperse and monodisperse samples indicates that an analogy in terms of trends and thresholds exists, as long as an equivalent diameter D* is introduced for bidisperse mixtures (Marchelli, 2018). This parameter is therefore suggested as the reference diameter to be adopted in the barrier design.</p>

Chalcogenide glasses Ge–Sn–Se, Ge–Se–Te, and Ge–Sn–Se–Te for infrared optical fibers

1990 ◽  
Vol 5 (6) ◽  
pp. 1215-1223 ◽  
Author(s):  
I. Haruvi-Busnach ◽  
J. Dror ◽  
N. Croitoru
Keyword(s):  
Differential Scanning Calorimetry ◽  
Optical Fibers ◽  
Chalcogenide Glasses ◽  
Glass Composition ◽  
Amorphous Region ◽  
Maximum Power Density ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ftir Spectrometry

Chalcogenide glasses of the systems Ge–Sn–Se, Ge–Se–Te, and Ge–Sn–Se–Te have been prepared. Several compositions were found suitable for drawing fibers for CO2 laser radiation (λ = 10.6 μm) transmission. The glasses were characterized by x-ray diffraction, DSC (Differential Scanning Calorimetry), SEM with EDX analysis, FTIR spectrometry, density, and microhardness measurements. The glass transition temperature and microhardness of Ge–Se–Sn and Ge–Sn–Se–Te glasses decreased with increasing Sn content, for most of the samples. The region of high IR transparency of Ge–Se–Sn, Ge–Se–Te, and Ge–Sn–Se–Te glasses was slightly expanded (1–2 μm) toward longer wavelengths, compared to Ge–Se glasses, mainly for the glasses containing 70 at.% Se. The intensity of the impurity absorption peak of Ge–O (at λ ∼ 12.8 μm), which usually appears in Ge–Se glasses, was reduced or absent in Ge–Sn–Se–Te glasses. The best fibers were produced with the glass composition Ge–0.8Sn0.2Se3.5Te0.5. An attenuation of 20 dB/m at 10.6 μm, and a transmitted maximum power density of 2.4 ⊠ 106 W/m2 were measured. The mechanical and optical characteristics of these glasses have been related to the glasses structure. Corresponding to the reduced masses of the bonds formed in the Ge–Sn–Se–Te system (in the amorphous region), it is expected that the multiphonon edge is slightly shifted. As a consequence, as was measured, the transparency region has been expanded by less than 2 μm toward longer wavelengths.

scholarly journals Study on the Evaluation of Thermal Damage According to the Manufacturing Conditions of Korean Paper

2021 ◽  
Vol 37 (6) ◽  
pp. 648-658
Author(s):  
Ji Won Kim ◽  
Se Rin Park ◽  
Ki Ok Han ◽  
Seon Hwa Jeong
Keyword(s):  
Crystallinity Index ◽  
Amorphous Region ◽  
Xrd Analysis ◽  
Crystalline Region ◽  
X Ray Diffraction ◽  
Raman Spectroscopic ◽  
Ft Ir ◽  
Ir Analysis ◽  
Ph Level ◽  
Ft Ir Spectroscopy

In this study, we aimed to analyze the chemical changes that occur in Korean paper in an accelerated deterioration environment of 105℃. We selected the Korean paper produced with different types of cooking agents (plant lye, Na2CO3) and during different manufacturing seasons (winter, summer). The degree of deterioration of the Korean paper was confirmed by measuring the brightness, yellowness, and pH level, and the degree of change in each vibrational region of cellulose as deterioration progressed through infrared (FT-IR) spectroscopy. The FT-IR analysis showed that, as deterioration progressed, the absorbance of the amorphous region in cellulose decreased, whereas the absorbance of the crystalline region slightly increased. X-Ray diffraction (XRD) analysis and Raman spectroscopy were performed to verify the changes in the crystalline and amorphous regions in cellulose indicated by the FT-IR results. Furthermore, the crystallinity index (CI) was calculated; it showed a slight increase after deterioration; therefore, CI was confirmed to follow the same trend as that observed for absorbance in the FT-IR results. In addition, as a result of Raman spectroscopic analysis, the degree of decomposition of the amorphous region in the cellulose under the manufacturing conditions was confirmed by the fluorescence measured after the deterioration.

scholarly journals EFFECT OF INORGANIC ALTERNATIVE SCOURING AGENTS ON STRUCTURE OF CELLULOSE/POLYESTER BLEND FABRIC

2020 ◽  
Vol 45 (4) ◽  
Author(s):  
A. U. Barambu ◽  
D. E. A. Boryo ◽  
H. M Adamu ◽  
K. M Yahuza ◽  
A. Abdulkadir
Keyword(s):  
Structural Modification ◽  
Crystallinity Index ◽  
Amorphous Region ◽  
The Other ◽  
Crystalline Region ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scouring Process ◽  
20 Nm ◽  
Blend Fabric

In this research, a structural modification for a cellulose/polyester blend has been carried out using NH4OH, (NH4)2C2O4 and liquid NH3 which are environmentally friendly alternative scouring agents with NaOH as control. The scouring process was carried out on the samples with these alternative agents. Investigation into structural modification of cellulose/polyester blend fabric using NH4OH, (NH4)2C2O4 and liquid NH3 and its structural characterization with X-ray diffraction was carried. The results showed the inferences variation in the crystallinity index of scoured samples from (3.21-65.30%), the crystallite size of scoured samples (1.9-15 nm) in the crystalline region and (7-20 nm) in the amorphous region, inter-planar spacing of the scoured samples (0.340-0.350 nm) of the crystalline region and (0.350-0.340 nm) of the amorphous region and number of crystalline planes of the scoured samples is (3-11) of the cellulose/polyester blend fabric samples via X-ray diffraction studies. Among these alternative agents (NH4)2C2O4 and NH4OH showed better interaction with both amorphous and crystalline regions of the cellulose/polyester blend fabric samples without loss in crystallinity when used as scouring agents, and the possibilities of being a superior alternative with significant effect on the structures of the cellulose/polyester blend, while the other samples showed possibilities of being highly competitive with the conventional agent.

Symmetric Beauty: Multi-Point Press Based on Parallel and Synchronous Toggle Mechanism Driven by Pneumatic Muscle

2011 ◽  
Vol 201-203 ◽  
pp. 2745-2748
Author(s):  
Pei Liang Qin ◽  
Ming Di Wang ◽  
Kang Min Zhong
Keyword(s):  
Large Diameter ◽  
Small Diameter ◽  
Pneumatic Cylinder ◽  
Full Account ◽  
Pneumatic Muscle ◽  
Large Ratio ◽  
Output Force ◽  
The Press ◽  
New Type ◽  
Different Diameters

Compared with the traditional rigid pneumatic cylinder, the pneumatic muscle has many outstanding advantages such as large ratio between output force and diameter, large ratio between output force and weight. However, it can only provide the tension, can not provide the thrust force, it is a one-orientation output force component. In this paper, two different diameters pneumatic muscle, combined with the parallel and synchronous toggle force-amplified mechanism,a new type of multi-point press has been innovated. The large-diameter pneumatic muscle will be used for the working stroke of the pressure travel, while the small-diameter pneumatic muscle will be used for the return travel. The tension of the pneumatic muscle will decrease with the increases of the contraction; the force-amplified coefficient of the toggle mechanism will increase with the decrease of the pressure angle, which is taken full account of this complementary relationship between them. So the output force curve of the press is improved smoothly.

Structure and performance of polybutene-1 pipes produced via mandrel rotation extrusion

2014 ◽  
Vol 34 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Wei Liu ◽  
Qi Wang ◽  
Min Nie
Keyword(s):  
Rotation Speed ◽  
Processing System ◽  
Axial Direction ◽  
Amorphous Region ◽  
Thermal Shrinkage ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Extrusion Processing ◽  
And Performance ◽  
Mechanical Performances

Abstract In this article, a new rotational extrusion processing system was adopted for manufacturing of polybutene-1 (PB-1) pipes, and the effects of mandrel rotation speed on their structures and mechanical performances were studied. The experimental results showed that besides the conventional axial extrusion flow field, a hoop shear stress field imposed to the melt, which was generated by the introduction of mandrel rotation, could lead the combined stress apart from the axial direction of the pipes to induce the molecular orientation deviated from the axial direction. Thus, the axial orientation of PB-1 was restrained, which was revealed by thermal shrinkage measurements and polarized infrared spectra. Moreover, it was also found and confirmed by scanning electron microscopy and two-dimensional wide-angle X-ray diffraction that orientation mainly existed in the amorphous region rather than the crystal region. Differential scanning calorimetry tests showed that the mandrel rotation could facilitate the formation of more perfect crystals and higher crystallinity. As a result, compared with the PB-1 pipe produced by conventional extrusion, the hoop strength of the PB-1 pipes manufactured at a mandrel rotation speed of 8 rpm increased from 20.2 to 24.9 MPa, achieving a mechanical balance in both axial and hoop directions.

Growth, morphology, structure and characterization ofL-histidinium dihydrogen arsenate orthoarsenic acid single crystal

2016 ◽  
Vol 72 (4) ◽  
pp. 593-601 ◽  
Author(s):  
Nidhi Tyagi ◽  
Nidhi Sinha ◽  
Harsh Yadav ◽  
Binay Kumar
Keyword(s):  
Single Crystal ◽  
Grown Crystal ◽  
Paraelectric Phase ◽  
Ferroelectric Properties ◽  
Electronic Devices ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Paraelectric Phase Transition ◽  
X Ray ◽  
First Time

L-Histidinium dihydrogen arsenate orthoarsenic acid (LHAS) crystals were grown by the slow evaporation method. Single-crystal X-ray diffraction confirms monoclinic structure. The growth rates of various planes of LHAS crystals were estimated by morphological study. Hirshfeld surface and fingerprint plots were analyzed to investigate the intermolecular interactions at 0.002 a.u. present in the crystal structure. The functional groups and phase behavior of the compound are studied by FTIR spectroscopy and differential scanning calorimetry (DSC). A ferroelectric to paraelectric phase transition at 307 K was observed in dielectric studies. The piezoelectric charge coefficients of the grown crystal were found to be 2 pC/N. The values of coercive field (Ec), remnant polarization (Pr) and spontaneous polarization (Ps) in the hysteresis loop are found to be 5.236 kV cm−1, 0.654 µC cm−2and 2.841 µC cm−2, respectively. Piezoelectricity and ferroelectricity are reported for the first time in LHAS crystals. The mechanical strength was confirmed from microhardness study and void volume. Due to the low value of the dielectric constant, and good piezoelectric and ferroelectric properties, LHAS crystals can be used in microelectronics, sensors and advanced electronic devices.

Tribological Effects of Nano-Copper with Different Diameters in Lubricants

2010 ◽  
Vol 123-125 ◽  
pp. 1059-1062 ◽  
Author(s):  
Cai Xiang Gu ◽  
Guan Jun Zhu ◽  
Xiao Yu Tian ◽  
Jian Feng Shi ◽  
Yan Yan Feng
Keyword(s):  
Tribological Properties ◽  
Large Diameter ◽  
Testing Machine ◽  
Small Diameter ◽  
Vital Role ◽  
Wear Testing ◽  
Weight Percentage ◽  
Copper Particles ◽  
Wear And Friction ◽  
Different Diameters

Diameter of nanoparticles plays a vital role in tribological properties of lubricanting oil. Three kinds of nano-copper with different diameters (50nm, 65nm, 80nm) were produced using the electric explosion of metallic wire (EEW), and their diameters were characterized by Scanning Electron Microscope (SEM). The tribological properties of the lubricating oils containing nano-copper additives were investigated using friction wear testing machine, and the wear scar morphology photographs were observed by means of continuously multiple microscope. The results show that lubricanting oil with the large diameter of 80nm copper particles and the weight percentage of 1.0% ~ 1.2% has good characteristic of extreme pressure ; while the lubricanting oil with the small diameter of 50nm copper particles and the weight percentage of 1.2% provides good properties of anti-wear and friction reducing. This has a guiding role in selecting nanooil additives.

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