Glass transition temperature of PMMA/modified alumina nanocomposite: molecular dynamic study

Abstract

In this study, the effect of alumina and modified alumina nanoparticles in a PMMA/alumina nanocomposite was investigated. To attain this goal, the glass transition behavior of poly methyl methacrylate (PMMA), PMMA/alumina and PMMA/hydroxylated alumina nanocomposites were investigated by molecular dynamic simulations (MD). All the MD simulations were performed using the Materials Studio 6.0 software package of Accelrys. To obtain the glass transition temperature, the variation of density vs. temperature was obtained. The temperature at which the slope of the density-temperature curve observably changes is defined as the glass transition temperature (Tg). The effect of alumina nanoparticles on the Tg was related to the free volume and the mobility of chain segments and the interaction between the alumina nanoparticles and the polymer. The mobility of the chain segments was investigated based on the mean square displacement and radius gyration. The results show that the increasement the Tg of the PMMA/hydroxylated alumina nanocomposite is more than that of the PMMA/alumina nanocomposite due to the modification of the alumina nanoparticles. Highlights: The glass transition of PMMA/modified alumina and PMMA/alumina nanocomposite was calculated  The mobility, Energy and gyration radius and energy of system was investigated.

Dielectric Properties of Fluorinated Aromatic Polyimide Films with Rigid Polymer Backbones

“…Radius of Gyration ( R g ) and Kuhn segment length ( l b ) were utilized to reflect the flexibility of molecular chains of studied PIs. R g is defined as the distance from the point of concentration assumed by the differential mass of the object to the axis of rotation [ 30 ], and l b is defined as the segment length of the polymer chain regarded as a free-connected chain with segments as statistical units. In general, the lower the R g and l b , the better the chain’s flexibility.…”

Preparation of Nano-PbWO4 Particles by Polymaleic Acid Modification: A Highly Filled Nonwoven Membrane Used To Improve the Wearing Comfort and Radiation Safety of γ-ray Protection Products

“…This finding confirms that adding PMA improves both the compatibility of PWO particles with PVA and the stability of the nonwoven membrane. 59,60 In order to verify the difference between the theoretical and actual filling amounts of nonwoven membranes before and after PMA participation, TG tests were conducted on 50 wt % PWO@PMA/PVA and PWO/PVA nonwoven membranes (Figure 6d). It should be noted that the 50 wt % PWO@ PMA/PVA nonwoven membrane exhibits a residue of 54.08% at 600 °C, whereas the 50 wt % PWO/PVA nonwoven membrane only shows a residue of 51.61%.…”

Molecular Cage-Mediated Radial Gradient Porous Sponge Nanofiber for Selective Adsorption of a Mustard Gas Simulant

“…In this approach, the stiffness matrix components ( C ij ) could be calculated based on Hooke’s law for elastic materials (Tables S3–S6), and the relevant Lamé constants consisting of λ and μ could be determined (Figure c). Additionally, the amorphous cell was equilibrated and carried out by NVT ensemble dynamics with 200 ps. − The mean square displacement curves were obtained, suggesting the ability of the hypercross-linked networks to move (Figure d). In contrast to the Lamé constants, the square displacement curves displayed a conflicting tendency.…”