scholarly journals Improvement in Physical Properties of MMA Grafted Coir Fibres

CORD ◽  
2015 ◽  
Vol 31 (2) ◽  
pp. 6
Author(s):  
Lakshmi N. S. ◽  
Sarika Babu ◽  
Sumy Sebastian ◽  
P.K. Ravi
Keyword(s):  
Physical Properties ◽  
Structural Changes ◽  
Graft Copolymerization ◽  
Flexural Rigidity ◽  
Statistical Significance ◽  
Light Fastness ◽  
Coir Fibre ◽  
Ferrous Ammonium ◽  
Thermal Stability Of ◽  
Water Absorbance

This work deals with the surface modification of Coir fibre through graft copolymerization process. Graft copolymerization of methyl methacrylate (MMA) onto coir fibre was carried out with Potassium per sulphate (PPS) as an initiator under the catalytic influence of Ferrous ammonium sulphate (FAS) in aqueous medium. Control and grafted coir fibres were subjected to evaluation of properties like tensile strength, flexural rigidity, density, water absorbance and light fastness studies. It was observed that MMA grafted coir fibre shows more resistance towards water and light fastness when compared with that of control coir fibre. Further morphological, structural changes and thermal stability of control and grafted coir fibre have also been studied by SEM and TGA techniques. For statistical significance the Analysis of variance (ANOVA) were studied and the P values obtained were less than 0.05 which revealed that the value was highly significant for the improvement of physical properties on coir fibre by graft Co- polymerization.

scholarly journals Low Temperature Grafting of MMA on to Coir Fibre

CORD ◽  
2015 ◽  
Vol 31 (1) ◽  
pp. 8
Author(s):  
Lakshmi N. S. ◽  
Sarika Babu ◽  
Sumy Sebastian ◽  
P.K. Ravi
Keyword(s):  
Low Temperature ◽  
Tensile Properties ◽  
Catalyst Concentration ◽  
Statistical Significance ◽  
Ferrous Ammonium Sulphate ◽  
P Values ◽  
Coir Fibre ◽  
Concentration Time ◽  
Ferrous Ammonium ◽  
Scanning Electron

Low temperature grafting of methyl methacrylate (MMA) on to coir fibre was carried out in aqueous medium using Potassium per sulphate (PPS) as an initiator under the catalytic influence of Ferrous ammonium sulphate (FAS). Optimization of various parameters of grafting viz. monomer, initiator and catalyst concentration, time and temperature was carried out to obtain the maximum tensile properties. Evidence of grafting was characterized from Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermal analysis (TGA). The maximum breaking stress (BS) of control and grafted coir fibre were 213.08 and 365.00 N/mm2 respectively. Hence the percentage of improvement of grafted coir fibre was found to be 71.30%. Increase in tensile properties with maximum BS observed under monomer (25%), initiator (0.75%) and catalyst (0.75%) concentration, time (150min) and temperature (500C) respectively.  The t-test and Analysis of variance (ANOVA) were studied for statistical significance and the P values obtained were less than 0.05 which revealed that the value was highly significant for the improvement of mechanical strength on coir fibre by graft Co- polymerization.

scholarly journals Extraordinary thermal behavior of graphene oxide in air for electrode applications

2021 ◽  
Author(s):  
Joong Tark Han ◽  
Joon Young Cho ◽  
Jeong Hoon Kim
Keyword(s):  
Thermal Stability ◽  
Graphene Oxide ◽  
Physical Properties ◽  
Thermal Behavior ◽  
Stability Of Solution ◽  
Exfoliated Graphene ◽  
Potential Applications ◽  
Thermal Stability Of

The thermal stability of solution-exfoliated graphene oxide (GO) in air is one of the most important physical properties influencing its potential applications. To date, majority of the GO prepared by...

scholarly journals A study into the structure and physical properties of the Cr18Ni9-grade steel following long-term irradiation as part of the BN-600 reactor internals

2020 ◽  
Vol 6 (1) ◽  
pp. 1-6
Author(s):  
Irina A. Portnykh ◽  
Aleksandr V. Kozlov ◽  
Valery L. Panchenko ◽  
Vyacheslav S. Shikhalev
Keyword(s):  
Physical Properties ◽  
Young’S Modulus ◽  
Structural Changes ◽  
Young's Modulus ◽  
Void Size ◽  
Initial State ◽  
Porosity Distribution ◽  
Grade Steel ◽  
Reactor Internals

The microstructures and physical properties of the austenitic Cr18Ni9-grade steel after 22 and 33 years of operation as part of the reactor internals were tested for assessing the conditions of the BN-600 reactor non-replaceable components (internals) and the potential of their subsequent use in predicting the reactor ultimate life. The paper presents histograms of the porosity distribution depending on the void size, in samples taken from portions that were subjected to neutron irradiation with displacement rates ranging from 1.0×10–9 to 4.3×10–8 dpa/s at temperatures from 370 to 440 °C. The elasticity characteristics were measured by resonance-type ultrasonic technique for the samples taken from the same portions of material. It was demonstrated that swelling calculated using the histograms of the porosity distribution depending on the void size has the maximum value at ~415 °C and after 33 years of irradiation reaches values of ~3%. Long-term variations of Young’s modulus demonstrate non-monotonous dependence on the damage dose. The maximum relative variation of Young’s modulus after 22 and 33 years of operation does not exceed 2% and 6%, respectively, of the values corresponding to the initial state. It was shown that along with the irradiation-induced swelling the changes in the physical properties are also affected in the process of irradiation by other structural changes and, in particular, by the formation of secondary phases. As shown by the results of the studies, operation of the BN-600 reactor internals made of Cr18Ni9-grade steel can be extended beyond 33 years of service. The comparison of the results obtained for the material after 22 and 33 years of operation contains information required for describing subsequent changes of the structure and properties of the Cr18Ni9 internals. The obtained results can be used for forecasting the reactor ultimate life within the framework of existing and developed models.

scholarly journals Physical Properties and Non-Isothermal Crystallisation Kinetics of Primary Mechanically Recycled Poly(l-lactic acid) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3396
Author(s):  
Luboš Běhálek ◽  
Jan Novák ◽  
Pavel Brdlík ◽  
Martin Borůvka ◽  
Jiří Habr ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Physical Properties ◽  
Structural Changes ◽  
The Other ◽  
Half Time ◽  
Crystallisation Kinetics ◽  
Isothermal Crystallisation ◽  
Melt Crystallisation ◽  
Kinetics Of ◽  
Crystallisation Rate

The physical properties and non-isothermal melt- and cold-crystallisation kinetics of poly (l-lactic acid) (PLLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biobased polymers reprocessed by mechanical milling of moulded specimens and followed injection moulding with up to seven recycling cycles are investigated. Non-isothermal crystallisation kinetics are evaluated by the half-time of crystallisation and a procedure based on the mathematical treatment of DSC cumulative crystallisation curves at their inflection point (Kratochvil-Kelnar method). Thermomechanical recycling of PLLA raised structural changes that resulted in an increase in melt flow properties by up to six times, a decrease in the thermal stability by up to 80 °C, a reduction in the melt half-time crystallisation by up to about 40%, an increase in the melt crystallisation start temperature, and an increase in the maximum melt crystallisation rate (up to 2.7 times). Furthermore, reprocessing after the first recycling cycle caused the elimination of cold crystallisation when cooling at a slow rate. These structural changes also lowered the cold crystallisation temperature without impacting the maximum cold crystallisation rate. The structural changes of reprocessed PHBV had no significant effect on the non-isothermal crystallisation kinetics of this material. Additionally, the thermomechanical behaviour of reprocessed PHBV indicates that the technological waste of this biopolymer is suitable for recycling as a reusable additive to the virgin polymer matrix. In the case of reprocessed PLLA, on the other hand, a significant decrease in tensile and flexural strength (by 22% and 46%, respectively) was detected, which reflected changes within the biobased polymer structure. Apart from the elastic modulus, all the other thermomechanical properties of PLLA dropped down with an increasing level of recycling.

Mechanical and Basic Physical Properties of High-Strength Concrete Exposed to Elevated Temperatures

2018 ◽  
Vol 760 ◽  
pp. 108-113 ◽  
Author(s):  
Lenka Scheinherrová ◽  
Monika Čáchová ◽  
Michaela Petříková ◽  
Lukáš Fiala ◽  
Eva Vejmelková ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Water Environment ◽  
High Strength ◽  
Steel Fibers ◽  
Quartz Powder ◽  
Matrix Density ◽  
Drying Treatment

In this paper, the effect of elevated temperatures on the mechanical and basic properties of two different newly-designed high-strength concretes is studied. The studied materials were prepared from Portland cement, steel fibers, reactive finely milled quartz powder and quartz sand, silica fume, plasticizer, and with a relatively low water/cement ratio of 0.24. The samples were stored in water environment for the first 28 days of hydration to achieve better mechanical properties. Then, after pre-drying at 105 °C to constant mass, the materials were exposed to elevated temperatures of 600 °C and 1000 °C where they were kept for 2 hours. The basic physical properties, such as matrix density, bulk density and open porosity were determined as a function of temperature. Mechanical properties (compressive and flexural strength) were also studied. The measured parameters exhibited a high dependence on temperature and the obtained results pointed to the structural changes of the studied materials. Spalling was not observed because of the pre-drying treatment.

Structure of [(CH3)2NH2]2CoCl4 at elevated temperatures

1999 ◽  
Vol 55 (5) ◽  
pp. 752-757 ◽  
Author(s):  
Amir H. Mahmoudkhani ◽  
Vratislav Langer
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Phase Transitions ◽  
Physical Properties ◽  
Electric Conductivity ◽  
Title Compound ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
The Other ◽  
Cell Parameters

The crystal structure of the title compound, dimethylammonium tetrachlorocobaltate(II), has been determined at four temperatures between 297 and 366 K, in order to investigate possible phase transitions at 313 and 353 K [Kapustianik, Polovinko & Kaluza et al. (1996). Phys. Status Solidi A, 153, 117–122]. We found that there is no significant change either in the hydrogen-bonding network or in the cell parameters, apart from a linear dilatation with temperature. This study reveals that the anomalous variation in electric conductivity and some of the other physical properties of the compound cannot be explained by structural changes.

scholarly journals Role of Ionic Headgroups on the Thermal, Rheological, and Foaming Properties of Novel Betaine-Based Polyoxyethylene Zwitterionic Surfactants for Enhanced Oil Recovery

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 908 ◽  
Author(s):  
Muhammad Shahzad Kamal ◽  
Syed Muhammad Shakil Hussain ◽  
Lionel Talley Fogang
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Oil Recovery ◽  
Structural Changes ◽  
Foam Stability ◽  
Foaming Properties ◽  
Zwitterionic Surfactants ◽  
Reservoir Conditions ◽  
Thermal Stability Of

Long-term thermal stability of surfactants under harsh reservoir conditions is one of the main challenges for surfactant injection. Most of the commercially available surfactants thermally degrade or precipitate when exposed to high-temperature and high-salinity conditions. In this work, we designed and synthesized three novel betaine-based polyoxyethylene zwitterionic surfactants containing different head groups (carboxybetaine, sulfobetaine, and hydroxysulfobetaine) and bearing an unsaturated tail. The impact of the surfactant head group on the long-term thermal stability, foam stability, and surfactant–polymer interactions were examined. The thermal stability of the surfactants was assessed by monitoring the structural changes when exposed at high temperature (90 °C) for three months using 1H-NMR, 13C-NMR, and FTIR analysis. All surfactants were found thermally stable regardless of the headgroup and no structural changes were evidenced. The surfactant–polymer interactions were dominant in deionized water. However, in seawater, the surfactant addition had no effect on the rheological properties. Similarly, changing the headgroup of polyoxyethylene zwitterionic surfactants had no major effect on the foamability and foam stability. The findings of the present study reveal that the betaine-based polyoxyethylene zwitterionic surfactant can be a good choice for enhanced oil recovery application and the nature of the headgroup has no major impact on the thermal, rheological, and foaming properties of the surfactant in typical harsh reservoir conditions (high salinity, high temperature).

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