Structural Characteristics and Thermal Properties of PE-g-MA/MgAl-LDH Exfoliation Nanocomposites Synthesized by Solution Intercalation

2003 ◽  
Vol 15 (16) ◽  
pp. 3208-3213 ◽  
Author(s):  
Wei Chen ◽  
Baojun Qu
Keyword(s):  
Thermal Properties ◽  
Structural Characteristics ◽  
Solution Intercalation

scholarly journals Opto-thermal properties of fibers — 2. Structural characteristics of cold drawn annealed Egyptian polyester (PET) fibers

1997 ◽  
Vol 16 (4) ◽  
pp. 303-325 ◽  
Author(s):  
A.A. Hamza ◽  
I.M. Fouda ◽  
M.A. Kabeel ◽  
E.A. Seisa ◽  
F.M. El-sharkawy
Keyword(s):  
Thermal Properties ◽  
Structural Characteristics ◽  
Pet Fibers

Calorific and Thermal Properties of Natural Rubber in the Oriented and Non-Oriented States

1956 ◽  
Vol 29 (3) ◽  
pp. 789-793
Author(s):  
B. I. Gengrinovich
Keyword(s):  
Thermal Properties ◽  
Natural Rubber ◽  
Physical State ◽  
Structural Characteristics ◽  
Amorphous State ◽  
Qualitative Change ◽  
Original Length ◽  
Degree Of Orientation ◽  
High Polymers

Abstract The structural characteristics of high polymers and the sharp dependence of their properties on the physical state create a need for a detailed study of these materials in the region where their physical state undergoes a qualitative change. Besides, a study of the phase transitions of high polymers which crystallize is of independent interest. The study of the transition of natural rubber from the oriented crystalline state to the non-oriented amorphous state was the problem of this work. The determination of calorific and thermal properties in the transition region was adopted as the method of investigation. It should be noted that, for rubbers, these properties have been studied to a much lesser extent than have the other thermodynamic properties, particularly the mechanical properties. In order to obtain crystalline rubber, strips of smoked sheet were subjected to repeated rapid stretching at 50°, followed by cooling of the stretched samples to 12–14° C. The stress applied to the rubber during stretching overcomes the deorienting effect of the thermal motion, which impedes the crystallization of non-deformed rubber. At the same time, the heating employed promotes a more complete straightening of the chains since, during heating, intermolecular action diminishes and the chaotically-grouped oriented portions of the macromolecules present in the samples are disrupted. Rapid cooling of the oriented rubber, obtained under such conditions, to temperatures below the melting point of the crystals which formed led to the preservation of the physical state, which was distinguished by an increase of the crystalline phase content, and by a higher degree of orientation, compared with the state of rubber crystallized during the same time by lowering the temperature without stretching. On an average, the extent of stretching amounted to 1400 per cent of the original length.

scholarly journals The Influence of Lignin Diversity on the Structural and Thermal Properties of Polymeric Microspheres Derived from Lignin, Styrene, and/or Divinylbenzene

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2847 ◽  
Author(s):  
Marta Goliszek ◽  
Beata Podkościelna ◽  
Olena Sevastyanova ◽  
Barbara Gawdzik ◽  
Artur Chabros
Keyword(s):  
Thermal Properties ◽  
Structural Characteristics ◽  
Polymer Network ◽  
Eucalyptus Grandis ◽  
Nitrogen Adsorption ◽  
Optical Microscope ◽  
Scanning Calorimetry ◽  
Promising Alternative ◽  
Synthetic Materials ◽  
The Impact

This work investigates the impact of lignin origin and structural characteristics, such as molecular weight and functionality, on the properties of corresponding porous biopolymeric microspheres obtained through suspension-emulsion polymerization of lignin with styrene (St) and/or divinylbenzene (DVB). Two types of kraft lignin, which are softwood (Picea abies L.) and hardwood (Eucalyptus grandis), fractionated by common industrial solvents, and related methacrylates, were used in the synthesis. The presence of the appropriate functional groups in the lignins and in the corresponding microspheres were investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FT-IR), while the thermal properties were studied by differential scanning calorimetry (DSC). The texture of the microspheres was characterized using low-temperature nitrogen adsorption. The swelling studies were performed in typical organic solvents and distilled water. The shapes of the microspheres were confirmed with an optical microscope. The introduction of lignin into a St and/or DVB polymeric system made it possible to obtain highly porous functionalized microspheres that increase their sorption potential. Lignin methacrylates created a polymer network with St and DVB, whereas the unmodified lignin acted mainly as an eco-friendly filler in the pores of St-DVB or DVB microspheres. The incorporation of biopolymer into the microspheres could be a promising alternative to a modification of synthetic materials and a better utilization of lignin.

Polybutadiene rubber/exfoliated graphite nanocomposites: Impact of filler on the thermal, mechanical and permeability characteristics

2019 ◽  
Vol 35 (3) ◽  
pp. 138-148
Author(s):  
Soney C George ◽  
Jiji Abraham ◽  
Thomasukutty Jose ◽  
Riya Thomas ◽  
Teresa Jacob ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Thermal Properties ◽  
Structural Characteristics ◽  
Nitrogen Atmosphere ◽  
Exfoliated Graphite ◽  
Melt Mixing ◽  
Permeability Characteristics ◽  
Polybutadiene Rubber ◽  
Permeation Studies

In this report, we demonstrate that both mechanical behaviour and thermal stability of polybutadiene rubber (PBR) nanocomposites could be improved by incorporating exfoliated graphite (EG) using melt mixing method. Incorporation of the filler EG in the polybutadiene (PBD) matrix is confirmed by infrared spectra and X-ray diffraction analysis. The structural characteristics, mechanical properties and thermal properties of these newly modified PBR nanocomposites were systematically analysed and studied. Thermal properties of the nanocomposites were studied using thermogravimetric analysis under nitrogen atmosphere. Thermogravimetric studies showed that PBR8 is having higher thermal stability than that of the PBR gum sample. Mechanical properties like tensile strength, Young’s modulus, tear strength, hardness and compression set of the nanocomposites were studied. Mechanical properties are also high for the modified PBR nanocomposites with maximum filler content. The permeability of organic vapours such as dichloromethane (CH2Cl2), chloroform (CHCl3) and carbon tetrachloride (CCl4) through PBR/EG nanocomposites was also studied. In vapour permeation studies, PBR4 exhibits the least permeability in CH2Cl2, CHCl3 and CCl4 solvents. Polybutadiene rubber–natural graphite (PBR/NG) nanocomposites were also prepared for comparison.

Effect of Nest Characteristics on Thermal Properties, Clutch Size, and Reproductive Performance for an Open-Cup Nesting Songbird

2017 ◽  
Vol 10 (2) ◽  
pp. 107-118 ◽  
Author(s):  
Michael E. Akresh ◽  
Daniel R. Ardia ◽  
David I. King
Keyword(s):  
Thermal Properties ◽  
Heat Loss ◽  
Clutch Size ◽  
Structural Characteristics ◽  
Nest Structure ◽  
Cavity Nesting ◽  
Nestling Condition ◽  
Hot Days ◽  
Fitness Benefits ◽  
Prairie Warbler

Maintaining avian eggs and young at optimum temperatures for development can increase hatching success and nestling condition, but this maintenance requires parental energetic demands. Bird nests, which often provide a structure to safely hold the eggs and nestlings and protect them from predators, can additionally be designed to help maintain eggs’ optimum temperatures by minimising heat loss, especially in climates where eggs cool rapidly when unattended. We collected and measured Prairie Warbler ( Setophaga discolor) nests in western Massachusetts, U.S. in 2009 and conducted a climate-controlled, nest-cooling experiment to determine how nest characteristics affect thermal properties for small, open-cup nesting birds. We then assessed if nests with better insulation properties resulted in any fitness benefits, and also tested if nest structural characteristics affected birds’ fitness. We found that nest characteristics influenced their thermal properties, with thicker, heavier, and larger nests having slower cooling rates and higher predicted equilibrium egg temperatures. Both nest cup depth and clutch size significantly declined over the breeding season, and we observed a trend, although non-significant, that nests with shallower cups had smaller clutches. Contrary to studies on cavity-nesting birds, we found no significant effects of nest thermal properties or nest structure on hatching and fledging success, nestling condition, brood parasitism, or nest survival. Prairie Warblers in our study site may already be adapted to build nests within a range that maximises their fitness. Furthermore, studies have shown that open-cup nests of other species are relatively thicker and more insulated in colder environments at higher latitudes than our study. Instead of building nests to solely minimise heat loss, open-cup nesting birds in temperate climates may also be driven by opposing selection pressures when building their nests, such as to prevent nestlings from overheating during hot days.

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