Water Expandable Polystyrene-Organoclay Nanocomposites: Role of Clay and Its Dispersion State

2009 ◽  
Vol 48 (5) ◽  
pp. 955-966 ◽  
Author(s):  
Rafieh-Sadat Norouzian Amiri ◽  
Nader Taheri Qazvini ◽  
Naser Sharifi Sanjani
Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2530
Author(s):  
Maxime Pras ◽  
Jean-François Gérard ◽  
Luana Golanski ◽  
Guilhem Quintard ◽  
Jannick Duchet-Rumeau

Carbon nanotube (CNT)-reinforced nanocomposites represent a unique opportunity in terms of designing advanced materials with mechanical reinforcement and improvements in the electrical and thermal conductivities. However, the toxic effects of these composites on human health have been studied, and very soon, some regulations on CNTs and on composites based on CNTs will be enacted. That is why the release of CNTs during the nanocomposite lifecycle must be controlled. As the releasing depends on the interfacial strength that is stronger between CNTs and polymers compared to CNTs in a CNT agglomerate, two dispersion states—one poorly dispersed versus another well dispersed—are generated and finely described. So, the main aim of this study is to check if the CNT dispersion state has an influence on the CNT releasing potential in the nanocomposite. To well tailor and characterize the CNT dispersion state in the polymer matrix, electronic microscopies (SEM and TEM) and also rheological analysis are carried out to identify whether CNTs are isolated, in bundles, or in agglomerates. When the dispersion state is known and controlled, its influence on the polymerization kinetic and on mechanical properties is discussed. It appears clearly that in the case of a good dispersion state, strong interfaces are generated, linking the isolated nanotubes with the polymer, whereas the CNT cohesion in an agglomerate seems much more weak, and it does not provide any improvement to the polymer matrix. Raman spectroscopy is relevant to analyze the interfacial properties and allows the relationship with the releasing ability of nanocomposites; i.e., CNTs poorly dispersed in the matrix are more readily released when compared to well-dispersed nanocomposites. The tribological tests confirm from released particles granulometry and observations that a CNT dispersion state sufficiently achieved in the nanocomposite avoids single CNT releasing under those solicitations.


2020 ◽  
Vol 55 (2) ◽  
pp. 265-275
Author(s):  
S Hajibabazadeh ◽  
MK Razavi Aghjeh ◽  
M Mehrabi Mazidi

The effect of microstructural evolution with hydrophilic-nanosilica (SiO2) concentration, ranging from 0 to 5 wt%, on mechanical properties and deformation micromechanisms of PP/EPDM/SiO2 (80/20/x) ternary blend-nanocomposites was investigated. Morphological observations revealed that, SiO2 nanoparticles tend to localize either around the dispersed EPDM particles or at the PP/EPDM interface, promoting the formation of three dimentional network-like EPDM/SiO2 composite structures dispersed in the PP matrix, especially at higher SiO2 loadings. This type of dispersion state was further confirmed by the rheological analysis. Synergistic toughening effect of soft EPDM particles and rigid SiO2 particles under Izod impact test was observed in these ternary systems, so that the materials with a better balance of stiffness/toughness were achieved. The results demonstrated that the extent of impact toughness increase is higher, where a large amount of the SiO2 nanoparticles surrounded the EPDM dispersed particles distributed in the PP matrix. This significant increase was attributed to the change in the size of stress concentration region and evolution of stress distribution throughout the material. The failure mechanisms were studied, and the underlying toughening micromechanisms were proposed.


2010 ◽  
Vol 18 (9) ◽  
pp. 839-844 ◽  
Author(s):  
Toshiaki Taniike ◽  
Toru Wada ◽  
Iku Kouzai ◽  
Shougo Takahashi ◽  
Minoru Terano

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.


2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.


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