Rheological behavior of an aluminum nitride nanoparticle suspension in Poly(amic acid)-nmp system

1997 ◽  
Vol 501 ◽  
Author(s):  
Xiaohe Chen ◽  
Kenneth Gonsalves ◽  
R. S. Rounds
Keyword(s):  
Aluminum Nitride ◽  
Viscoelastic Behavior ◽  
Amic Acid ◽  
Polymer Particle ◽  
Particle Interactions ◽  
Nanoparticle Suspension ◽  
Dispersion Process ◽  
Physicochemical Interactions ◽  
Nanoparticle Suspensions ◽  
Fluid Media

ABSTRACTPreliminary rheological characterizations of aluminum nitride (AIN) nanoparticle suspensions in nonaqueous Newtonian fluid media, NMP and NMP/poly(amic acid) solutions, reveal marked differences in viscoelastic behavior, at relatively low dispersed phase volume fractions. Dynamic mechanical and steady shear measurements provide experimental evidence of the effective interparticle and polymer/particle interactions in a dispersion process of nonoxide nanoparticles for ceramic/polymer nanocomposites. The rheological nature of the nanoparticle suspensions corresponds to interparticle physicochemical interactions that have been previously concluded and discussed.

Synthesis and properties of an aluminum nitride/polyimide nanocomposite prepared by a nonaqueous suspension process

1997 ◽  
Vol 12 (5) ◽  
pp. 1274-1286 ◽  
Author(s):  
Xiaohe Chen ◽  
Kenneth E. Gonsalves
Keyword(s):  
Aluminum Nitride ◽  
Polar Solvent ◽  
Amic Acid ◽  
Thermal And Mechanical Properties ◽  
Characteristic Model ◽  
Physicochemical Interactions ◽  
Suspension Process ◽  
Polyimide Nanocomposite ◽  
Model Reactions ◽  
Nanoscale Level

A nanocomposite of a chemically synthesized nanostructured aluminum nitride (AlN) and a polyimide has been studied. Using a nonaqueous polar solvent,N-methylpyrrolidinone (NMP), as the suspension media, the degree of particle agglomeration of AlN was reduced dramatically from micron to nanoscale size. Upon the addition of poly(amic acid) to the AlN/NMP suspension, a further deagglomeration of the particles was observed. The surface physicochemical interactions have been investigated by characteristic model reactions using FTIR spectroscopy. A mechanistic interpretation for the deagglomeration and stabilization behavior is discussed. The formation of the AlN/PI nanocomposite was achieved by the rapid solidification of the precursor suspension followed by compression molding. Such an approach for nanocomposites exhibits better homogeneity with ultrafine fillers and allows a tailorable composition and property at the nanoscale level. Finally, AlN/PI nanocomposites with an increased ceramic loading, up to 65% by volume, were attained and their thermal and mechanical properties, along with the compositional effects, have been investigated.

Nanoparticles for Biomedicine: Coagulation During Synthesis and Applications

2019 ◽  
Vol 10 (1) ◽  
pp. 155-174 ◽  
Author(s):  
Fabian H.L. Starsich ◽  
Inge K. Herrmann ◽  
Sotiris E. Pratsinis
Keyword(s):  
Colloidal Stability ◽  
Body Fluids ◽  
Particle Interactions ◽  
Coupling Effects ◽  
Synthesis Of Nanoparticles ◽  
Nanoparticle Suspensions ◽  
Scalable Synthesis ◽  
Scalable Methods ◽  
Protein Rich

Nanoparticle-based systems offer fascinating possibilities for biomedicine, but their translation into clinics is slow. Missing sterile, reproducible, and scalable methods for their synthesis along with challenges in characterization and poor colloidal stability of nanoparticles in body fluids are key obstacles. Flame aerosol technology gives proven access to scalable synthesis of nanoparticles with diverse compositions and architectures. Although highly promising in terms of product reproducibility and sterility, this technology is frequently overlooked, as its products are of fractal-like aggregated and/or agglomerated morphology. However, coagulation is a widely occurring phenomenon in all kinds of particle-based systems. In particular, protein-rich body fluids encountered in biomedical settings often lead to destabilization of colloidal nanoparticle suspensions in vivo. We aim to provide insights into how particle–particle interactions can be measured and controlled. Moreover, we show how particle coupling effects driven by coagulation may even be beneficial for certain sensing, therapeutic, and bioimaging applications.

scholarly journals The Protection of Building Materials of Historical Monuments with Nanoparticle Suspensions

Heritage ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 3970-3986
Author(s):  
Efstathia I. Pavlakou ◽  
Anastasios G. Agrafiotis ◽  
Theokleiti G. Tsolaki ◽  
Christine Lemonia ◽  
Emily Zouvani ◽  
...  
Keyword(s):  
Building Materials ◽  
Protective Coatings ◽  
Inorganic Nanoparticles ◽  
Test Material ◽  
Amorphous Calcium Carbonate ◽  
Nanoparticle Suspension ◽  
Constant Ph ◽  
Rate Of Dissolution ◽  
Historical Monuments ◽  
Nanoparticle Suspensions

Marble and limestone have been extensively used as building materials in historical monuments. Environmental, physical, chemical and biological factors contribute to stone deterioration. The rehabilitation of stone damage and the delay of further deterioration is of utmost importance. Inorganic nanoparticles having chemical and crystallographic affinity with building materials is very important for the formation of protective coatings or overlayers. In the present work, we have tested the possibility of treating calcitic materials with suspensions of amorphous calcium carbonate (am-CaCO3, ACC) and amorphous silica (AmSiO2). Pentelic marble (PM) was selected as the test material to validate the efficiency of the nanoparticle suspension treatment towards dissolution in undersaturated solutions and slightly acidic pH (6.50). Suspensions of ACC and AnSiO2 nanoparticles were prepared by spontaneous precipitation from supersaturated solutions and by tetraethyl orthosilicate (TEOS) hydrolysis, respectively. The suspensions were quite stable (nine days for ACC and months for AmSiO2). ACC and Am SiO2 particles were deposited on the surface of powdered PM. The rates of dissolution of PM were measured in solutions undersaturated with respect to calcite at a constant pH of 6.50. For specimens treated with ACC and AmSiO2 suspensions, the measured dissolution rates were significantly lower. The extent of the rate of dissolution reduction was higher for AmSiO2 particles on PM. Moreover, application of the nanoparticles on the substrate during their precipitation was most efficient method.

Nanofluid Properties and Their Effects on Convective Heat Transfer in an Electronics Cooling Application

2009 ◽  
Vol 1 (3) ◽  
Author(s):  
Jessica Townsend ◽  
Rebecca J. Christianson
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Cooling System ◽  
Electronics Cooling ◽  
Nanoparticle Suspension ◽  
System Combination ◽  
Conductivity Increase ◽  
Viscosity Increase ◽  
Nanoparticle Suspensions ◽  
Complicated Geometries

In the search for new, more effective coolant fluids, nanoparticle suspensions have shown promise due to their enhanced thermal conductivity. However, there is a concomitant increase in the viscosity, requiring an increase in pumping power to achieve the same flow rate. Studies of flow cooling in simple geometries indicate that there is a benefit to using nanofluids, but it is difficult to justify extending these results to the far more complicated geometries. Moreover, with the variability of property measurements found in literature, it is possible to show conflicting results from the same set of flow-cooling data. In this work we present a self-contained study of the properties and effectiveness of an alumina in water nanofluid. Flow-cooling is studied in an off-the-shelf fluid cooling package for electronics to examine the effects of the particulates in a practical scenario. We measure the thermal conductivity and viscosity of the same suspensions to assure consistent interpretation of our results. We find that, while there is no anomalous enhancement of the thermal properties or transport, there is a benefit to using a low volume fraction alumina nanoparticle suspension over using the base fluid alone. In fact, there is an optimal volume fraction (1%) for this nanofluid and electronics cooling system combination that maximizes the heat dissipated. However, we find that this benefit decreases as the volume fraction, and hence the viscosity, increases. Understanding where the trade-off between viscosity increase and thermal conductivity increase occurs is critical to designing an electronics cooling system using a nanofluid as a coolant.

scholarly journals Exploring the Role of Nanoparticles in Enhancing Mechanical Properties of Hydrogel Nanocomposites

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 882 ◽  
Author(s):  
Josergio Zaragoza ◽  
Scott Fukuoka ◽  
Marcus Kraus ◽  
James Thomin ◽  
Prashanth Asuri
Keyword(s):  
Mechanical Properties ◽  
Elastic Moduli ◽  
Maximum Modulus ◽  
Polymer Particle ◽  
Particle Interactions ◽  
Polyacrylamide Hydrogels ◽  
The Past ◽  
Wide Range ◽  
Hydrogel Nanocomposites

Over the past few decades, research studies have established that the mechanical properties of hydrogels can be largely impacted by the addition of nanoparticles. However, the exact mechanisms behind such enhancements are not yet fully understood. To further explore the role of nanoparticles on the enhanced mechanical properties of hydrogel nanocomposites, we used chemically crosslinked polyacrylamide hydrogels incorporating silica nanoparticles as the model system. Rheological measurements indicate that nanoparticle-mediated increases in hydrogel elastic modulus can exceed the maximum modulus that can be obtained through purely chemical crosslinking. Moreover, the data reveal that nanoparticle, monomer, and chemical crosslinker concentrations can all play an important role on the nanoparticle mediated-enhancements in mechanical properties. These results also demonstrate a strong role for pseudo crosslinking facilitated by polymer–particle interactions on the observed enhancements in elastic moduli. Taken together, our work delves into the role of nanoparticles on enhancing hydrogel properties, which is vital to the development of hydrogel nanocomposites with a wide range of specific mechanical properties.

Transient Response of Viscoplastic and Viscoelastic Shells Submerged in Fluid Media

1976 ◽  
Vol 43 (1) ◽  
pp. 137-143 ◽  
Author(s):  
T. A. Duffey
Keyword(s):  
Surrounding Medium ◽  
Viscoelastic Behavior ◽  
Rate Sensitivity ◽  
Viscoelastic Materials ◽  
Elementary Functions ◽  
Fluid Medium ◽  
Fluid Media ◽  
Viscoelastic Shells ◽  
Interaction Problem ◽  
Linearly Elastic Materials

The transient fluid-shell interaction problem is investigated for thin shells constructed of other than linearly elastic materials. Specifically, solutions are developed in terms of elementary functions for the transient responses of impulsively loaded, fluid-surrounded spherical shells constructed of either viscoplastic or viscoelastic materials. In all cases the fluid medium surrounding the shell is taken as inviscid and compressible and only spherically symmetric shell motions and radiation of sound into the surrounding medium are considered. It is found that the influence of material strain hardening and strain-rate sensitivity can be significant in reducing fluid-shell displacement responses. Further, limited investigations for viscoelastic materials indicate that for higher loss materials, displacement response of the shell is significantly altered by the inclusion of the viscoelastic behavior.

A rheological study of associating polymer-particle interactions in tricalcium silicate pastes

2003 ◽  
Vol 52 (4) ◽  
pp. 633-637 ◽  
Author(s):  
Katy Rastoul ◽  
Henri Van Damme ◽  
Fran�oise Lafuma ◽  
Fran�ois Lequeux ◽  
Pierre Colombet ◽  
...  
Keyword(s):  
Tricalcium Silicate ◽  
Polymer Particle ◽  
Particle Interactions ◽  
Rheological Study ◽  
Associating Polymer
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