Abstract
For further analysis of the effect of nano-doping on the properties of high polymers and research into the mechanism behind modified interfacial hydrogen bonds, a study on the formation probability of nano-SiO2/meta-aramid fibre interfacial hydrogen bonds and the strengthening mechanism behind interfacial hydrogen bonds on the thermal stability of meta-aramid fibres using molecular dynamics is performed in this paper. First, the pure meta-aramid fibre and nano-SiO2/meta-aramid fibre mixed models with nanoparticle radiuses of 3, 5, 7 and 9 Å (1 Å = 10−1 nm) are built, and then the optimization process and dynamics simulation of the models are conducted. The dynamics simulation results indicate that the number of hydrogen bonds increase due to the doping by nano-SiO2 and that the number of interfacial hydrogen bonds increases with the nanoparticle radius. By analysing the hydrogen bond formation probability of all the atom pairs in the mixed model with pair correlation functions (PCFs), it can be observed that the hydrogen bond formation probability between the oxygen atom and hydrogen atom on the nanoparticle surface is the greatest. An effective way to increase the number of interfacial hydrogen bonds in nano-SiO2 and meta-aramid fibres is to increase the number of hydrogen atoms on the nano-silica surface and oxygen atoms in the meta-aramid fibre. By using the radial distribution function (RDF), the conclusion can be further drawn that the hydrogen bond formation probability is at a maximum when the atomic distance is 2.7–2.8 Å; therefore, increasing the number of atoms within this range can significantly increase the formation probability of hydrogen bonds. According to the results of chain movement, the existence of interfacial hydrogen bonds effectively limits the free movement of the molecular chains of meta-aramid fibres and enhances the thermal stability of meta-aramid fibres. The existence of interfacial hydrogen bonds is one of the important reasons for formation of the stable interface structure between nanoparticles and meta-aramid fibres. In addition, a nanoparticle with a small radius improves the interfacial hydrogen bond energy density and interfacial interaction energy density, enhancing the stability of the mixed model interface.
Highlights
Through the doping of nanoparticles for modified nano materials, the raw materials are provided with many new characteristics, and many properties of the raw materials are improved [1,2]
The formation probability of the hydrogen bonds among different atomic and SiO2 /meta-aramid fibre interfaces is reflected through the pair correlation function and radial distribution function The effect of the nano-silica particle size on the thermal stability of the meta-aramid fibres is represented by using the mean square displacement (MSD) of meta-aramid fibres in different models
In the mixed model of the nano-SiO2/meta-aramid fibre, because the –NH radical and oxygen are formed in the molecules and between the molecules of the meta-aramid fibre. –OH . . . O
Summary
Through the doping of nanoparticles for modified nano materials, the raw materials are provided with many new characteristics, and many properties of the raw materials are improved [1,2]. Because a large number of hydroxide radicals exist on the surface of nano-SiO2 , a coacervate with a dimensional network structure forms through hydrogen bond interactions among the nanoparticles. To decrease such an agglomeration phenomenon, the surface modification [3] of nanoparticles is carried out, and one of the purposes. The formation probability of the hydrogen bonds among different atomic and SiO2 /meta-aramid fibre interfaces is reflected through the pair correlation function and radial distribution function The effect of the nano-silica particle size on the thermal stability of the meta-aramid fibres is represented by using the mean square displacement (MSD) of meta-aramid fibres in different models. The effect of the interfacial hydrogen bond interactions on the overall interaction between the nanoparticle and meta-aramid fibre is described through changes in the interaction energy and hydrogen bond energy of the interface
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