scholarly journals Studies in Finishing Effects of Clay Mineral in Polymers and Synthetic Fibers

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Faheem Uddin
Keyword(s):  
Thermal Stability ◽  
Clay Mineral ◽  
Physical Stability ◽  
Polymeric Materials ◽  
Strength Properties ◽  
Research Literature ◽  
Synthetic Fibers ◽  
Peak Heat Release Rate ◽  
Recent Modification ◽  
Significant Research

The use of clay mineral in modifying the properties of polymeric material is improved in application. The current interest in modifying the polymeric materials, particularly polyethylene, polypropylene, polystyrene, and nylon using clay mineral for improved flame retardancy, thermal stability, peak heat release rate, fracture, and strength properties generated significant research literature. This paper aims to review some of the important recent modification achieved in the performance of polymeric materials using organoclay mineral. Degradation of clay mineral-polymer (nm) composite is discussed with appropriate known examples. Clay mineral (nm) loading of 5 wt.% to 7 wt.% that was significantly smaller than the percent loading of conventional fillers in polymeric materials introduced significant improvement in terms of thermal and physical stability. An attempt is made to emphasize flammability and thermal stability and to indicate the areas that are relatively little explored in modification of fiber-forming polymers to enhance further research interest.

Flammability and Thermal Degradation of Polystyrene/Cadmium Sulfate Nanocomposites

2013 ◽  
Vol 820 ◽  
pp. 84-87
Author(s):  
Zheng Zhou Wang ◽  
Charles A. Wilkie
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Cone Calorimeter ◽  
Cds Nanoparticles ◽  
Solvothermal Process ◽  
Cadmium Sulfate ◽  
Peak Heat Release Rate ◽  
Microscale Combustion Calorimeter ◽  
Combustion Calorimeter ◽  
Thermal Stability Of

Cadmin sulfate nanoparticles, hollow sphere (CdS-HS) and rode (CdS-NR) were synthesized by ultrasonic and solvothermal process, respectively. The effect of the two kinds of nanoparticles on flammability of polystyrene was investigated using cone calorimeter (Cone) and microscale combustion calorimeter (MCC). Cone data indicate that the incorporation of 1% CdS nanoparticles leads to a about 20% reduction in the peak heat release rate (PHRR) compared to the pure PS; CdS-NR is more efficient in reducing the PHRR proved by both Cone and MCC results. The TG results show that the addition of the nanoparticles mainly increases thermal stability of PS at high temepratures.

scholarly journals POLYMERS AND PLASTIC USE FOR THE HEAT-EXCHANGE EQUIPMENT (REVIEW)

2020 ◽  
pp. 59-71
Author(s):  
I.O. Mikulionok
Keyword(s):  
Heat Exchange ◽  
Heat Exchangers ◽  
Polymeric Materials ◽  
Strength Properties ◽  
Polymers And Plastics ◽  
Heat Exchange Equipment ◽  
Coefficient Of Heat Conductivity ◽  
Exchange Apparatus ◽  
Polymer Type

The possibility of use of the heat-exchangers in whole or in part manufactured with use of polymers and plastics is considered. Despite obvious, at first sight, inexpediency of use of polymeric materials in the heat-exchange equipment (low coefficient of heat conductivity, and also low, in comparison with metals, the strength properties of the majority of the most widespread polymers), «polymeric» heat-exchangers find application in various areas of the industry more and more surely. Classification of heat-exchange apparatuses which constructive elements are executed with use of polymeric materials is proposed. The following signs are the basis for classification: polymer type, a type of polymer meric material, type of the heat-exchange apparatus (a form of heat-exchange elements), reliance on polymeric materials in apparatuses, motion freedom of polymeric heat-exchange elements, level of assembly of a design, and also diameter of tubular elements. Critical analysis the most characteristic designs developed by domestic and foreign designers and inventors is carried out. Ref. 21, Fig. 13.

scholarly journals MODIFIED WITH VARIOUS ADDITIVES ARYLALYCLIC COPOLYIMIDES AND COMPOSITE FILMS BASED ON THEIR BASIS

2021 ◽  
Vol 3 ◽  
pp. 19-35
Author(s):  
М.B. Umerzakova ◽  
◽  
R.B. Sarieva ◽  
V.D. Kravtsova ◽  
◽  
...  
Keyword(s):  
Thermal Stability ◽  
Surface Resistance ◽  
Composite Films ◽  
Strength Properties ◽  
Polymer Matrix Composite ◽  
Polymer Mixtures ◽  
Porous Films ◽  
Polymer Systems ◽  
Ratio Of Components ◽  
Molecular Compounds

lopment of arylalicyclic copolyimides based on alicyclic dianhydride, aromatic dianhydrides of benzophenone- and diphenyloxidetetracarboxylic acids with 4,4'-diaminodiphenyl oxide at various ratios of alicyclic and aromatic dianhydrides, as well as various compositions based on these copolymers with low- or other high-molecular compounds that enhance the characteristics of the polymer matrix. Composite films were formed from solutions of the obtained polymer mixtures, and their properties were studied. It was noted that at optimal ratio of components, the films have improved thermal and strength properties, etc., exceeding the analogous properties of the initial arylalicyclic copolymer, while the elasticity has acceptable values for such material. The best characteristics had the composite films formed from a ternary composition of copo-lyimide-polyethylene glycol-alkylated montmorillonite. Metal-containing composite films, along with higher thermal stability compared to unmodified copolyimide, were resistant to aggressive reagents, lower values of specific volume and surface resistance, higher viscosity values, and different colors depending on the nature of the salt. By introducing a silicon-containing compound into the copolyimide solution, the new polymer systems have been obtained, and the porous films could be formed.

Chemical-heat treatment influence on thermal stability of microstructure, mechanical properties and fracture features of V-Cr-Ta-Zr alloy

2021 ◽  
pp. 36-42
Author(s):  
I.V. Smirnov ◽  
◽  
K.V. Grinyaev ◽  
A.N. Tyumentsev ◽  
A.D. Korotaev ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Stability ◽  
Structural Phase ◽  
Strength Properties ◽  
Chemical Heat Treatment ◽  
Chemical Heat ◽  
High Level ◽  
Fracture Features ◽  
Zr Alloy

A study of the features of structural-phase state, thermal stability, mechanical properties characteristics and fracture features of V-Cr-Ta-Zr alloy after chemical-heat treatment by the method of nonequilibrium internal oxidation has been carried out. It has been established that, in contrast to chemical-heat treatment in a defect state, the effect of oxygen when introduced into a material with a stabilized structure is observed only at high concentrations. At such oxygen concentrations, which ensure the maximum binding of Zr into particles based on ZrO2, the alloy under study demonstrates a high level of thermal stability and strength properties. These effects are associated with the implementation of disperse strengthening according to the Orowan mechanism by nanosized ZrO2 particles characterized by high thermal stability. The concentration and nature of the distribution of oxygen predetermine the spatial distribution of nanosized ZrO2 particles formed during chemical-heat treatment, which manifests itself in fracture features of the material at different temperatures.

Indole-based high-performance polymeric materials with enhanced mechanical and thermal properties via cation-π interaction

2019 ◽  
Vol 32 (6) ◽  
pp. 662-668
Author(s):  
Xiao-fang Guan ◽  
Cong Liao ◽  
Li Yang ◽  
Guan-jun Chang
Keyword(s):  
Thermal Stability ◽  
Heat Resistance ◽  
Self Assembly ◽  
High Performance ◽  
Mechanical Performance ◽  
Polymeric Materials ◽  
Design Strategy ◽  
Mechanical And Thermal Properties ◽  
Innovative Design ◽  
High Performance Polymers

The preparation of high-performance polymeric materials with both excellent overall mechanical properties and heat resistance remains a considerable challenge. Inspired by the delicate self-assembly processes in nature, a facile strategy is reported for the preparation of high-performance polymeric materials with enhanced mechanical strength and improved thermal stability. In this instance, we successfully constructed a cation- π cross-linked polyimide (Na-poly(aryl indole) imide (Na-PINI)) film with enhanced mechanical performance and heat resistance (∼490°C). This work presents an innovative design strategy for realizing robust polymeric materials with integrated strength and thermal stability; the cation- π interaction is demonstrated to be a new method that may achieve many useful properties for high-performance polymers.

scholarly journals Entrapment of α-Amylase in Agar Beads for Biocatalysis of Macromolecular Substrate

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Manu Sharma ◽  
Vinay Sharma ◽  
Dipak K. Majumdar
Keyword(s):  
Thermal Stability ◽  
Half Life ◽  
Thermal Inactivation ◽  
Scale Up ◽  
Physical Stability ◽  
Entrapment Efficiency ◽  
Substrate Affinity ◽  
Michaelis Constant ◽  
Size Dependent ◽  
Temperature Optima

Attempts have been made to optimize immobilization parameters, catalytic property, and stability of immobilized α-amylase in agar. The work compares natural entrapment efficiency of agar with the ionotropically cross-linked agar hydrogel, with the advantage of easy scale-up and cost and time effectiveness. Beads prepared with 3% (w/v) agar and 75 mM calcium chloride and hardened for 20 minutes were selected for further studies on the basis of entrapment efficiency (80%) and physical stability. Following entrapment, pH and temperature optima of enzyme were shifted from 6 to 6.5 and 50 to 55°C, respectively. Michaelis constant (Km) for both free and entrapped enzymes remained the same (0.83%) suggesting no change in substrate affinity. However, Vmax⁡ of entrapped enzyme decreased ~37.5-fold. The midpoint of thermal inactivation for entrapped enzyme increased by 8 ± 1°C implying its higher thermal stability. The entrapped enzyme in calcium agar bead had an Ea value of 27.49 kcal/mol compared to 17.6 kcal/mol for free enzyme indicating increased stability on entrapment. Half-life of enzyme increased ~2.2 times after entrapment in calcium agar at 60°C indicating stabilization of enzyme. The reusability of beads was size dependent. Beads with diameter <710 μm were stable and could be reused for 6 cycles with ~22% loss in activity.

scholarly journals Galliformes science and species extinctions: what we know and what we need to know

2012 ◽  
Vol 35 (2) ◽  
pp. 321-331 ◽  
Author(s):  
P. J. K. McGowan, ◽  
◽  
L. L. Owens ◽  
M. J. Grainger ◽  
◽  
...  
Keyword(s):  
Significant Role ◽  
Biological Diversity ◽  
Bird Species ◽  
Threat Assessment ◽  
Research Literature ◽  
Convention On Biological Diversity ◽  
Strategic Direction ◽  
Use Of Resources ◽  
Significant Research ◽  
Species Extinctions

In early 2010, the 193 Parties that had signed up to the Convention on Biological Diversity all acknowledged that they had failed to meet the target that they had set themselves in 1992 of significantly reducing species extinctions by 2010. At the end of the year they set a new and more ambitious target of preventing species extinctions by 2020. Achieving that target will require much greater efficiency in the use of resources and research has a very significant role to play in making this happen. There are 290 species of Galliformes of which 26 % are considered at risk of extinction, compared with 12 % of all 10,000 bird species. At the same time there is significant research literature on the group that stretches back decades for some species. It is timely, therefore, to consider whether it is possible to increase the efficiency and global impact of gamebird research so that, with careful planning that involves more strategic direction and sharing of lessons learnt, game biologists can play a significant role in achieving the 2020 target for species adopted by the Convention on Biological Diversity. Specific areas in need of this lesson sharing approach are population estimation and threat assessment, analysis of exploitation and determining the ecological basis of successful interventions.

scholarly journals Solid Wastes Toward Flame Retardants for Polymeric Materials: A Review

2021 ◽  
Vol 8 ◽  
Author(s):  
Chuanhua Gao ◽  
Siqi Huo ◽  
Zhenhu Cao
Keyword(s):  
Thermal Stability ◽  
Flame Retardant ◽  
Flame Retardancy ◽  
Mass Production ◽  
Flame Retardants ◽  
Polymeric Materials ◽  
Solid Wastes ◽  
Smoke Suppression ◽  
Future Perspectives ◽  
Recycle And Reuse

It has been significant yet challenging to recycle and reuse different kinds of wastes because of their mass production within society. Many efforts have been conducted to reuse wastes in different fields. Interestingly, some wastes have been employed to replace traditional petroleum-based flame retardants for polymeric materials. This review focuses on the recent development of waste flame retardants and their impacts on thermal stability, flame retardancy, and smoke suppression of polymers, followed by representative flame-retardant mechanisms. Finally, the key challenges associated with waste flame retardants are presented, and some future perspectives are proposed.

Polymeric Tribotechnical Composites on the Basis of Polytetrafluoroethylene and Complex Fillers

2020 ◽  
Vol 992 ◽  
pp. 733-738
Author(s):  
T.A. Isakova ◽  
P.N. Petrova
Keyword(s):  
Wear Resistance ◽  
Low Temperatures ◽  
High Performance ◽  
Polymeric Materials ◽  
Strength Properties ◽  
Planetary Mill ◽  
Magnesium Aluminate ◽  
Magnesium Aluminate Spinel ◽  
Initial Polymer ◽  
Properties Of Composites

Perspective polymeric materials for use in frictional units as bearings and sliding supports, the mobile sealants of piston rings, cuffs are composites on the basis of polytetrafluoroethylene (PTFE). They significantly improve the performance of equipment at low temperatures, reduce repair expenses and losses from idle times. When modifying polymers, physical methods of exposure are increasingly used, ensuring the activation of materials and high performance characteristics. Objective: the effect of complex fillers, obtained by their joint activation in a planetary mill, on the deformation and strength and tribological characteristics of composites based on PTFE. This work shows the promise of using the joint mechanical activation of components of different nature to obtain complex fillers. The use of the modified ultradispersed polytetrafluoroethylene (UPTFE) of zeolite as a filler of PTFE leads to complex improvement of properties of composites: the tensile strength and elongation at rupture increase by 20% in comparison with initial polymer. The wear resistance increases by 3-6 times in comparison with the composites containing only the activated zeolite and by 900 times in comparison with initial polymer. The addition of the modified UPTFE of a magnesium aluminate spinel (MAS) leads to increase in deformation and strength properties by 10-30% and an increase in wear resistance by 140 times in comparison with initial polymer.

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