Enhancement of Dispersion Stability on the Polymer Nanocomposites with Clay Nanoparticles through Analysis of Moisture Absorption Behavior

Abstract

To begin with, nanomaterials are widely used as reinforcing materials with specific functionalities, because they have a characteristic broad particle surface area and excellent properties in small amounts. However, the use of nanomaterial fabrication technology has many limitations, such as the arrangement and dispersion of nanomaterials for use in composite materials and for the use of general structural materials. In order to overcome these limitations, researches on the physical and chemical surface treatment of nanomaterial based reinforcing materials and the development of mechanical techniques have been actively carried out. However, from the macro perspective, fiber reinforced plastics (FRP) composites such as shipbuilding, aerospace, automobiles, still have many technical limitations to their use for commercial purposes. In addition, since the conventional nanotechnology has a high price and a complicated molding process, it has a disadvantage in that the production efficiency is inferior to the use of other materials and methods. Particularly, mass production of nanomaterials is difficult to control the structure such as particular particle size and length, and it is not easy to ensure uniformity of physical and chemical properties when working with these materials in a commercial environment. Therefore, it is necessary to study the nanomaterial pretreatment method and the process of stabilization through a uniform dispersion with the polymer matrix, and it is required to develop nanomaterials for medium and large parts structural materials that exhibit uniform characteristics which can be used for a variety of other applications in other industries. In this context, this study aims to establish the basis of a suitable manufacturing process of nanocomposite materials for general structure by applying FRP composites to applicable top-down processes, that will serve to control the grain and porosity of existing nanomaterials to below a few hundreds of nanometers, and therefore to significantly improve their properties. In this study, halloysite nanotube/epoxy (HNT/EP) matrix glass fiber reinforced plastic (GFRP) and basalt fiber reinforced plastic (BFRP) nanocomposites were prepared by separating crystalloid-HNT (C-HNT) and amorphous-HNT (A-HNT) according to the crystallinity of HNT and the state of dispersion of HNT, which was evaluated at the interface of laminates. The state of dispersion of the laminate nanocomposites fabricated in a flat plate shape was analyzed by dividing a total of eight (A―H) columns in the direction of the air outlet in the vacuum molding. The evaluation of the uniform dispersion was performed at 70。C, and the tendency and the deviation of the moisture absorption rate when immersed in distilled water for 336 h. Based on these studies, the reliability of the state of dispersion criterion of nanomaterials was suitably evaluated. As a result, the material design criteria for uniform dispersibility were obtained through a review of the identified moisture absorption characteristics. The effect of HNT on the interfacial bonding strength between EP and fiber reinforcements (GF, BF) was different depending on the notation of crystallinity that was found. In this regard, it is shown that moisture was important for controlling cohesion between HNTs. In the curing system, HNT was shown to have promoted the curing reaction, and the curing reaction caused the resin to develop properties related to shrinkage. The resin shrinkage affected the mobility of HNT and was a major factor involved in the re-aggregation. In addition, A-HNT has a strong bonding force with EP, which is relatively uniformly dispersed in EP compared with C-HNT, but also has a strong influence on the bonding strength of the interlaminar interface of laminates or weak bonds with the resulting fiber reinforcements. In other words, the crystallinity of HNT is closely related to the dispersibility of this material. In this study, the effect of HNT content and structure on the dispersion stability in GFRP and BFRP was investigated using the structural water characteristics of HNT.