Study of Relaxation Processes in Biopolymers Using the Example of Rosin

2021 ◽  
Vol 899 ◽  
pp. 681-687
Author(s):  
Viktor A. Lomovskoy ◽  
Anna S. Shorshina ◽  
Olga D. Platonova
Keyword(s):  
Composite Materials ◽  
Physicochemical Characteristics ◽  
Dynamic Mode ◽  
Relaxation Processes ◽  
Bounding Surface ◽  
Temperature Ranges ◽  
Main Components ◽  
Road Marking

Rosin, or colophony, and composite materials, which consist of components based on rosin and rosin products, are extensively used in various industries, in particular, as one of the main components of the composite materials for road marking. At the same time, little research has been done to study of the physicomechanical and associated physicochemical characteristics of these materials, the influence on these characteristics of the internal bounding surface of the components in wide temperature ranges and in the dynamic mode of external deforming effects.

scholarly journals Tetragonal–Cubic Phase Transition and Low-Field Dielectric Properties of CH3NH3PbI3 Crystals

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4215
Author(s):  
Roxana E. Patru ◽  
Hamidreza Khassaf ◽  
Iuliana Pasuk ◽  
Mihaela Botea ◽  
Lucian Trupina ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Current Knowledge ◽  
Cubic Phase ◽  
Relaxation Processes ◽  
Temperature Dependent ◽  
Thermally Activated ◽  
Low Field ◽  
Conduction Mechanisms ◽  
Temperature Ranges ◽  
Nyquist Plots

The frequency and temperature dependence of dielectric properties of CH3NH3PbI3 (MAPI) crystals have been studied and analyzed in connection with temperature-dependent structural studies. The obtained results bring arguments for the existence of ferroelectricity and aim to complete the current knowledge on the thermally activated conduction mechanisms, in dark equilibrium and in the presence of a small external a.c. electric field. The study correlates the frequency-dispersive dielectric spectra with the conduction mechanisms and their relaxation processes, as well as with the different transport regimes indicated by the Nyquist plots. The different energy barriers revealed by the impedance spectroscopy highlight the dominant transport mechanisms in different frequency and temperature ranges, being associated with the bulk of the grains, their boundaries, and/or the electrodes’ interfaces.

Fractionated Pyrolysis of Biomass and its Components

2014 ◽  
Vol 535 ◽  
pp. 734-737 ◽  
Author(s):  
Qian Liu ◽  
De Kui Shen
Keyword(s):  
Weight Loss ◽  
Rice Straw ◽  
Total Weight Loss ◽  
Wood Biomass ◽  
Thermogravimetric Analyzer ◽  
Dominant Component ◽  
Temperature Ranges ◽  
Biomass Components ◽  
Main Components ◽  
Pyrolysis Of Biomass

Fractionated pyrolysis of biomass and its three main components (viz. hemicellulose, cellulose and lignin) was carried out on a thermogravimetric analyzer, which effectively separated the pyrolysis progress of different compositions. Three temperature ranges of 40-300 °C, 300-400 °C and 400-700 °C were presented with hemicellulose, cellulose and lignin as the dominant component, respectively. Fir contains much more cellulose and lignin than rice straw, and thus the weight loss in 300-400 °C is much higher, as 66.4% of the total weight loss. Rice straw contains more extractives and hemicellulose, resulting in higher mass loss in the early pyrolysis stage of 40-300 °C. The pyrolysis of biomass was predicted by hemicellulose, cellulose and lignin according to the additivity law, and the fractionated pyrolysis showed good performance in the prediction of volatile and residue yields of wood biomass. The interactions of biomass components were revealed to be unneglectable.

scholarly journals The study of powdered phenol-formaldehyde resins for the manufacture of plywood

2020 ◽  
Author(s):  
Г.С. Варанкина ◽  
Д.С. Русаков ◽  
Е.Г. Соколова ◽  
А.Н. Чубинский
Keyword(s):  
Composite Materials ◽  
Phenol Formaldehyde ◽  
Phenol Formaldehyde Resin ◽  
Bonding Time ◽  
Formaldehyde Resin ◽  
Free Phenol ◽  
Adhesive Composition ◽  
Main Components ◽  
Bonding Method ◽  
Branched Chains

В настоящее время перед отечественным производителем древесных композиционных материалов стоят задачи по увеличению объемов производства, повышению качества и конкурентоспособности, снижению токсичности выпускаемой продукции. Решение этих задач основано на разработке новых и совершенствовании имеющихся технологий современного производства клеёв и композиционных материалов на их основе. Цель исследования – повышение эффективности производства фанеры путём применения клеев на основе порошкообразных термореактивных полимеров поликонденсационного типа. Для достижения поставленной цели в работе необходимо исследовать влияние наполнителя на свойства клеевой композиции и готовой продукции. Исходными компонентами для проведения экспериментов являлись порошковая фенолоформальдегидная смола и аэросил технический. Установлено, что введение аэросила технического в клеящие составы на основе поликонденсационной порошковой фенолоформальдегидной смолы СФЖ-3013 увеличивает прочность фанеры, также с увеличением количества наполнителя уменьшается содержание свободных продуктов в смоле: содержание свободных фенола и формальдегида уменьшается до 0,05 – 0,06% и 0,02 – 0,03% соответственно. Предполагается, что при горячем способе склеивания происходит гелеобразование, частицы аэросила образуют разветвленные цепочки ~Si-O-Si~, которые целиком пронизывают объем клея, этот процесс сопровождается связыванием формальдегида в процессе структурирования. Полученные результаты исследований могут быть использованы в работе специалистов деревообрабатывающих производств при управлении технологическими процессами склеивания. Разработанные составы клеевой композиции на основе фенолоформальдегидных смол, модифицированных (наполненных) техническим аэросилом позволяют сократить расход клеевых материалов; повысить прочность и качество склеиваемой продукции; ускорить процесс отверждения связующего; сократить продолжительность склеивания; снизить энергозатраты путем уменьшения времени склеивания; уменьшить себестоимость клея, за счёт замещения основных компонентов наполнителем. At present, the domestic manufacturer of wood composite materials is faced with tasks to increase production volumes, improve quality and competitiveness, and reduce the toxicity of manufactured products. The solution to these problems is based on the development of new and improvement of existing technologies for the modern production of adhesives and composite materials based on them. The purpose of the study is to increase the efficiency of plywood production by using adhesives based on powdered thermoset polymers of the polycondensation type. To achieve this goal in the work, it is necessary to study the effect of the filler on the properties of the adhesive composition and finished products. The initial components for the experiments were powder phenol-formaldehyde resin and technical aerosil. It was found that the introduction of technical aerosil in adhesives based on polycondensation powder phenol-formaldehyde resin SFZh-3013 increases the strength of plywood, as the amount of filler increases, the content of free products in the resin decreases: the content of free phenol and formaldehyde decreases to 0.05 – 0.06% and 0.02 – 0.03%, respectively. It is assumed that during the hot bonding method, gel formation occurs, so that aerosil particles form branched chains ~ Si-O-Si ~ that completely penetrate the glue volume, this process is accompanied by formaldehyde bonding during structuring. The obtained research results can be used in the work of specialists in woodworking industries in the management of gluing processes. The developed compositions of the adhesive composition based on phenol-formaldehyde resins modified (filled) with technical aerosil allow you to: reduce the consumption of adhesive materials; to increase the strength and quality of glued products; speed up the curing process of the binder; shorten bonding time; reduce energy costs by reducing the bonding time; reduce the cost of glue, due to the replacement of the main components with filler.

Composite materials for the upper coverings railways

10.12737/2389 ◽  
2014 ◽  
Vol 6 (3) ◽  
pp. 37-41
Author(s):  
Батурин ◽  
K. Baturin ◽  
Стородубцева ◽  
Tamara Storodubtseva
Keyword(s):  
Composite Materials ◽  
Experimental Research ◽  
Mechanical Characteristics ◽  
Wood Chips ◽  
Waste Wood ◽  
Main Components

The results of theoretical and experimental research of composite materials, the main components of which are furfuralcohol resin STONE and wood chips, semi-anticipated by so from waste wood complex, their composition and physical-mechanical characteristics. They used vans for technological capacities of the wood chemical industries and railway sleepers.

scholarly journals Dielectric and piezoelectric properties of modified lead-free NaNbO3–KNbO3/PVDF composite ceramics

2021 ◽  
pp. 2160015
Author(s):  
Y. I. Yurasov ◽  
M. I. Tolstunov ◽  
A. V. Nazarenko ◽  
A. A. Pavelko ◽  
A. V. Yudin ◽  
...  
Keyword(s):  
Piezoelectric Properties ◽  
Relaxation Processes ◽  
Composite Ceramics ◽  
Dielectric Parameters ◽  
Dielectric Spectra ◽  
X Ray ◽  
Temperature Ranges ◽  
Frequency Properties ◽  
Dielectric And Piezoelectric Properties ◽  
Complex Electrical Conductivity

This work presents the results of study of the electrophysical properties of composite polymer ceramics (1[Formula: see text][KNN-LTSN]–[Formula: see text]PVDF at [Formula: see text] = 25 vol.% and [Formula: see text]= 50 vol.% in the temperature range of [Formula: see text] = 20–160[Formula: see text]C and frequency range of [Formula: see text] = 2 × 101–2 × 106 Hz. The concentration dependence of piezomodules of the studied materials has been analyzed as a function of temperature. X-ray measurements have also been carried out. A model of description of revealed dielectric parameters dispersion in the material is presented. The nonclassical modified Havriliak–Negami model written for complex electrical conductivity has been used to describe the temperature–frequency properties. It is shown that the dielectric spectra of the studied composites include three relaxation processes in the temperature ranges of 40–80[Formula: see text]C, 80–120[Formula: see text]C and 120–150 [Formula: see text]C, which were confirmed by the dynamics of changes in the dependences of [Formula: see text], tg[Formula: see text], [Formula: see text], [Formula: see text]([Formula: see text]) and [Formula: see text]([Formula: see text]. All three processes are almost exactly described by this model and well correlated with the studies by other researchers of the composites based on PVDF. The results of this work show that the use of such experimental model is suitable for describing the complex dielectric spectra of any nonlinear dielectrics including composite materials.

scholarly journals Nutritional Contribution of an Undervalued Ancestral Cucurbita, Study of Sicana sp. Endocarp, Epicarp and Seeds Composition

2021 ◽  
Vol 8 (1) ◽  
pp. 1
Author(s):  
Silvia Caballero ◽  
Eva Coronal ◽  
Anggie Burgos ◽  
Loida Galeano ◽  
Patricia Adelaida Piris Jara ◽  
...  
Keyword(s):  
Dietary Fiber ◽  
Beta Carotene ◽  
Physicochemical Characteristics ◽  
Dietary Guidelines ◽  
High Moisture Content ◽  
Fresh Weight ◽  
High Moisture ◽  
Peel Color ◽  
Potential Applications ◽  
Main Components

Native to South America, the Sicana sp. fruits, known in Paraguay as “kurugua”, belongs to the Cucurbit family and is almost extinct in the region. The aim of this study was to determine the physicochemical characteristics, composition and antioxidant activity of “kurugua” with reddish peel color. The determinations were made by official and regional standardized methodologies on fresh weight (FW). The pulp has an alkaline pH (7.41 ± 0.11), and its main components are carbohydrates (9.44 ± 0.45 g·100 g−1), followed by dietary fiber (1.74 ± 0, 04 g·100 g−1), as minor proteins (0.53 ± 0.05 g·100 g−1) and lipids (0.08 ± 0.01 g·100 g−1). On the evaluated antioxidants compounds, they were higher in peel than in pulp as; total phenols (279.2 ± 12.1, 55.7 ± 10.3 mg of GAE·100 g−1), Vitamin C (9.67 ± 0.09, 7.84 ± 1.71 mg·100 g−1) and beta-carotene (0.37 ± 0.03, 0.19 ± 0.01 mg·100 g−1), respectively. Fresh seeds have a high moisture content (38.8%), dietary fiber (40.2%) and lipids (11.74%), they mineral composition showed a high content of Mg and Ca and a high content of micronutrients such as Cu, Mn, Fe and Zn, which can represent a great contribution to the daily requirements of the diet. The red kurugua fruits are a natural source of nutritious and bioactive compounds beneficial to health, with multiple potential applications in foodstuff, which should be promoted in healthy dietary guidelines for the benefit of the populations.

scholarly journals Investigation of the films based on the uronate polysaccharides by the method of differential scanning calorimetry

2018 ◽  
Vol 12 (3) ◽  
Author(s):  
N. Коndratjuk ◽  
Ye. Pyvovarov ◽  
Т. Stepanova ◽  
Yu. Matsuk
Keyword(s):  
Heat Treatment ◽  
Differential Scanning Calorimetry ◽  
Calcium Ions ◽  
Total Concentration ◽  
Moisture Loss ◽  
Dynamic Mode ◽  
Scanning Calorimetry ◽  
Ionotropic Gelation ◽  
Complete Disintegration ◽  
Temperature Ranges

In this paper, the problem of studying of the films properties on the basis of uronate polysaccharides (sodium alginate and pectin low-esterified amidated), created on the principle of ionotropic gelation with the participation of calcium ions, has being considered. The purpose of the study is to determine the patterns of films formation based on the composition of the uronate polysaccharides, to determine their properties when heated and conditions of destruction or combustion. The thermophysical properties of the films in the temperature range 20–500°C were controlled by the method of differential scanning calorimetry in the dynamic mode. The temperature at which the loss of external and internal moisture is occurring have been determined. The temperatures when films are subjected to destruction have been founded. Thus, the mass loss of samples was noted in the following temperature ranges: 52–100°С and 40–100°С; the maximum moisture loss was noted at 83 and 85°C for specimens with a total concentration of uronate polysaccharides 2% and 3% respectively. Maximum external moisture losses were 6% and 9%; intra-linked moisture – 28.5 and 29% respectively. Complete disintegration of polymers occurs after 300 and 310°C for specimens with a total concentration of uronate polysaccharides 2% and 3% respectively. The investigation of the destraction temperatures of the above systems allows us to predict the principle of heat treatment of semi-finished products contained in films, created on the basis of the reaction of ionotropic gelation of polysaccharides and calcium ions.

Durability and Reliability of Semiconductor Devices

1998 ◽  
Vol 531 ◽  
Author(s):  
V. G. Sidorov ◽  
V. I. Sokolov ◽  
D. V. Sidorov
Keyword(s):  
Composite Materials ◽  
Defect Structure ◽  
Driving Force ◽  
Semiconductor Device ◽  
Semiconductor Devices ◽  
Life Time ◽  
Structure Evolution ◽  
Relaxation Processes ◽  
Device Structure ◽  
General Aspects

AbstractThe aim of the study is to discuss the most general aspects of semiconductor devices durability and reliability. The life time of a semiconductor device is related to the defect structure evolution of the crystalline and noncrystalline components involved. The driving force for the evolution of defect device structure is associated with relaxation processes of internal mechanical stresses. In this report the degradational effects in LEDs based on GaAs(Si) have been analyzed. The discussion of the necessity for research on composite materials creation is also included.

Recent Development in the Fabrication of Collagen Scaffolds for Tissue Engineering Applications: A Review

2019 ◽  
Vol 20 (12) ◽  
pp. 992-1003 ◽  
Author(s):  
Mohammad F. Mh Busra ◽  
Yogeswaran Lokanathan
Keyword(s):  
Tissue Engineering ◽  
Ex Vivo ◽  
Physicochemical Characteristics ◽  
Collagen Scaffolds ◽  
Engineering Applications ◽  
Hydrogel Beads ◽  
Structural Support ◽  
Main Components ◽  
Sheet Membrane

Tissue engineering focuses on developing biological substitutes to restore, maintain or improve tissue functions. The three main components of its application are scaffold, cell and growthstimulating signals. Scaffolds composed of biomaterials mainly function as the structural support for ex vivo cells to attach and proliferate. They also provide physical, mechanical and biochemical cues for the differentiation of cells before transferring to the in vivo site. Collagen has been long used in various clinical applications, including drug delivery. The wide usage of collagen in the clinical field can be attributed to its abundance in nature, biocompatibility, low antigenicity and biodegradability. In addition, the high tensile strength and fibril-forming ability of collagen enable its fabrication into various forms, such as sheet/membrane, sponge, hydrogel, beads, nanofibre and nanoparticle, and as a coating material. The wide option of fabrication technology together with the excellent biological and physicochemical characteristics of collagen has stimulated the use of collagen scaffolds in various tissue engineering applications. This review describes the fabrication methods used to produce various forms of scaffolds used in tissue engineering applications.

Characteristics of electrical properties of wide temperature range TGB phases in liquid crystal dimers

2009 ◽  
Vol 17 (2) ◽  
Author(s):  
R. Dhar ◽  
M. Pandey ◽  
V. Pandey ◽  
A. Pandey ◽  
I. Das ◽  
...  
Keyword(s):  
Soft Mode ◽  
Electrical Parameter ◽  
Optically Active ◽  
Dielectric Anisotropy ◽  
Relaxation Processes ◽  
Goldstone Mode ◽  
Dielectric Studies ◽  
Frequency Range ◽  
Temperature Ranges ◽  
Dimeric Compound

Abstract4-n-decyloxy-4′-(cholesteryloxycarbonyl-1-butyloxy) chalcone and its two successive homologous are optically active dimeric compound derived from cholesterol. They possess wide temperature ranges of two twist grain boundary (TGB) phases namely TGBA and TGBC*. Comprehensive dielectric studies have been carried out for these compounds in the frequency range of 1 Hz to 10 MHz for different conditions of molecular anchoring. Various electrical parameter viz. dielectric permittivity, dielectric anisotropy, dc conductivity, and activation energy have been determined for these two TGB phases. Weak relaxation processes have been detected under planar anchoring of molecules in the TGBA and TGBC* phases presumably due to amplitude (soft mode) and phase (Goldstone mode) fluctuations.

Sign in / Sign up

Export Citation Format

Share Document