Nanocomposites Based on Hyperbranched Polymers and Montmorillonite

2011 ◽  
Vol 108 ◽  
pp. 91-94 ◽  
Author(s):  
Shao Jian He ◽  
Jun Lin

Nanocomposites based on hyperbranched polymers and sodium montmorillonite were prepared over the full range of compositions. The XRD analysis showed the full exfoliation of silicate layers at lower silicate content (up to 9.1 wt%). With the further increase of silicate loading, an intercalated structure was developed with a constant d-spacing due to the unique structure of hyperbranched polymers. The heat capacity jump at the glass transition of the nanocomposites was found to deviate from the two-phase model prediction, indicating the formation of a rigid amorphous fraction. The glass transition temperature and heat capacity jump behaviors suggested that the molecular mobility of hyperbranched polymers were restricted by the introduction of silicate layers. The mechanical properties of the nanocomposites were also investigated.

2020 ◽  
Vol 53 (20) ◽  
pp. 8741-8750 ◽  
Author(s):  
Xavier Monnier ◽  
Dario Cavallo ◽  
Maria Cristina Righetti ◽  
Maria Laura Di Lorenzo ◽  
Sara Marina ◽  
...  

Polymer ◽  
2021 ◽  
pp. 123830
Author(s):  
Wei Wang ◽  
Seif Eddine Fenni ◽  
Zhe Ma ◽  
Maria Cristina Righetti ◽  
Daniele Cangialosi ◽  
...  

Soft Matter ◽  
2017 ◽  
Vol 13 (26) ◽  
pp. 4580-4590 ◽  
Author(s):  
Stefanos Koutsoumpis ◽  
Konstantinos N. Raftopoulos ◽  
Oguzhan Oguz ◽  
Christine M. Papadakis ◽  
Yusuf Z. Menceloglu ◽  
...  

Author(s):  
V.N. Moraru

The results of our work and a number of foreign studies indicate that the sharp increase in the heat transfer parameters (specific heat flux q and heat transfer coefficient _) at the boiling of nanofluids as compared to the base liquid (water) is due not only and not so much to the increase of the thermal conductivity of the nanofluids, but an intensification of the boiling process caused by a change in the state of the heating surface, its topological and chemical properties (porosity, roughness, wettability). The latter leads to a change in the internal characteristics of the boiling process and the average temperature of the superheated liquid layer. This circumstance makes it possible, on the basis of physical models of the liquids boiling and taking into account the parameters of the surface state (temperature, pressure) and properties of the coolant (the density and heat capacity of the liquid, the specific heat of vaporization and the heat capacity of the vapor), and also the internal characteristics of the boiling of liquids, to calculate the value of specific heat flux q. In this paper, the difference in the mechanisms of heat transfer during the boiling of single-phase (water) and two-phase nanofluids has been studied and a quantitative estimate of the q values for the boiling of the nanofluid is carried out based on the internal characteristics of the boiling process. The satisfactory agreement of the calculated values with the experimental data is a confirmation that the key factor in the growth of the heat transfer intensity at the boiling of nanofluids is indeed a change in the nature and microrelief of the heating surface. Bibl. 20, Fig. 9, Tab. 2.


Sign in / Sign up

Export Citation Format

Share Document