Temperature‐/Frequency‐dependent complex viscosity and tensile modulus of polymer nanocomposites from the glassy state to the melting point

• Published in: Polymer engineering and science Vol. 61; no. 10; pp. 2600 - 2615
• Main Authors: Sharifzadeh, Esmail, Mohammadi, Reza
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.10.2021; Society of Plastics Engineers, Inc; Blackwell Publishing Ltd
• Subjects: Analysis; Comparative studies; Conduction heating; Conductive heat transfer; glass transition; Mechanical analysis; Mechanical properties; Melting points; Model accuracy; Modulus of elasticity; Molecular structure; Nanocomposites; Nanoparticles; Nanotechnology; Percolation theory; Polymers; Silicon dioxide; Structure; Surface stability; Temperature dependence; Thermal conductivity; Thermal properties; Viscosity; Iran
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.25786

In this study, the temperature‐/frequency‐dependent viscosity and tensile modulus of polymer nanocomposites were evaluated using the combination of developed Arrhenius's equation and percolation theory. To involve the drastic effects of the polymer/particles interphase region and the aggregation/agglomeration of nanoparticles in the model, the Nielsen–Lewis model was developed and used to interpret the related parameters from heat conduction test results. The value of different state‐to‐state conversion degrees was calculated using the developed percolation theory whose validity was evaluated via comparative studies with theoretical results obtained from developed Arrhenius's equations. The simultaneous effects of the nanoparticles content and temperature/frequency on the viscosity and tensile modulus were also studied, which defined the role of some important phenomena such as the breakdown of the nanoparticle clusters, the increased cluster stability by polar surface modifiers, the increased thermal conductivity of the nanocomposite due to the presence of nanoparticles, etc. Different PA nanocomposites samples, containing 1–4 vol% of spherical silica nanoparticles, were prepared and subject to dynamical mechanical analysis, by temperature ramps and frequency sweep, and the results were used to evaluate the accuracy of the model. The surface of the nanoparticles was chemically modified with (3‐aminopropyl)triethoxysilane to ensure their perfect compatibility with PA phase. The variation pattern of (A) tensile modulus and (B) complex viscosity as a function of frequency and nanoparticles content (for all samples μ=0.24 and τ=12.01).