Small additions of nanofiber materials make it possible to change the properties of polymers. However, the uniformity of the additive distribution and the strength of its bond with the polymer matrix are determined by the surface of the nanofibers. Silanes, in particular, allow you to customize the surface for better interaction with the matrix. The aim of our work is to study an approach to silanization of nanofibers of aluminum oxide to obtain a perfect interface between the additive and the matrix. The presence of target silanes on the surface of nanofibers was shown by XPS methods. The presence of functional groups on the surface of nanofibers was also shown by the methods of simultaneous thermal analysis, and the stoichiometry of functional groups with respect to the initial hydroxyl groups was studied. The number of functional groups precipitated from silanes is close to the number of the initial hydroxyl groups, which indicates a high uniformity of the coating in the proposed method of silanization. The presented technology for silanizing alumina nanofibers is an important approach to the subsequent use of this additive in various polymer matrices.
The paper deals with the production and study of nanocomposite powder paints based on alumina nanofibers. For nanodispersed fillers, the nature of the surface states on the filler particles is important. The problem of introducing nanomaterials into a polymer matrix cannot provide an effective solution without matching the surface states of the nanomaterial filler and the polymer matrix for the resulting composite materials. The consistency of the surface states of the nanomaterial filler and the polymer matrix determines the quality of transfer of the necessary properties to the resulting polymer composite. In order to increase the affinity of alumina nanofibers with a matrix of powder paint, the nanofibers were treated with 3-glycidyloxypropyltrimethoxysilane (GLYMO) in toluene. It is shown in the work that the addition of alumina nanofibers leads to a hardening of the coating, an increase in its elasticity, and an increase in corrosion resistance. Finishing of alumina nanofibers in a solution of silane in toluene leads to its functionalization, which is sufficient for the distribution of nanofibers in the polymer matrix of the paint and improvement of its operational properties.
In this paper, the morphology of nanocomposite polyester resins has been studied. The basis was polyester resin NH6586 produced by Kinte. Aluminum oxide nanofibers were introduced into the resin, which are single crystals or chains of single crystals with the γ- Al2O3 structure with a diameter of 5 to 15 nm and up to 1 mm in length. The additive was introduced into the resin by the industry standard twin screw extrusion method. At the same time, the influence on the uniformity of distribution of the addition of mineral filler - submicron particles of titanium dioxide - was studied. It has been shown that conventional methods of mixing the additive do not allow the nanofibers to be completely distributed. In such cases, they are distributed in the form of microbundles. The addition of mineralfiller to the polyester resin improves the distribution of the alumina nanofibers so that no bundle inclusions are observed in the resin cleavage. Thus, it can be concluded that mineral additives of isometric particles are an effective homogenizer of aluminum oxide nanofibers in polymeric materials.
The paper describes the effect of the addition of alumina nanofibers on the mechanical properties of the epoxy resin. Alumina nanofibers functionalized with epoxypropyl functional groups are used in this work. The dependence of the mechanical characteristics on the amount of the additive, as well as the features of its distribution in the material, is investigated. In the work, nanocomposites were obtained, which are epoxy resin with aluminum oxide nanofibers. The mechanical properties of the samples were studied by bending tests and differential mechanical analysis (DMA). It has been shown that the addition of alumina nanofibers leads to an increase in ultimate flexural strength. The maximum of this increase is near the percolation threshold of alumina nanofibers in epoxy resin. With the addition of 0.2% alumina nanofibers, the ultimate flexural strength increases from 41 to 71 MPa. It is shown that after exceeding the percolation threshold of nanofibers, the ultimate strength decreases. In this case, the elastic modulus increases from 0.643 to 0.862 GPa. DMA is shown that the glass transition temperature decreases with increasing amount of the additive. This indicates a decrease in the molecular weight of the polymer. By implication, this suggests that the hardener connects the epoxypropyl functional groups on the nanofibers and the epoxy groups in the resin, and as a result of this process, the nanofibers become natural polymer chain length limiters. The data obtained from mechanical testing and differential mechanical analysis can be used to strengthen epoxy resins in polymer composite materials and molding compositions.
The paper studies the effect of violation of the spreading of powder paints when they are compounded with nanofibers of aluminum oxide. It is shown that with the addition of small fractions of aluminum oxide nanofibers equal to 0.05 wt%, the grains of the powder paint do not have time to wet each other, the crosslinking of the coating structure occurs up to this point, which is fixed by a characteristic granular texture. The paper also illustrates the features of the distribution of nanofibers of aluminum oxide in the coating. The increase in cohesion energy leads to a natural increase in the surface tension in the paint, which we observe in the form of the characteristic morphology of the coating. Investigation of coatings of a reference powder paint and a modified addition of aluminum oxide nanofibers) were carried out using an optical microscope. Separately, the morphology of the resin was investigated by scanning electron microscopy. Increasing the proportion of the flow agent based on acrylic compounds in the polyester resin from 0.8 to 1.8 wt% solves this problem, while the strengthening effect of nanofibers of alumina in the paint is retained.
The paper considers the production and use of alumina nanofibrous additives in nanocomposite powder paints. The main component of powder paints are polyester resins with a large number of free carboxyl groups, which are cross-linked with special hardening additives. The introduction of additives into the resin is most effective when their surface is matched in terms of physicochemical properties with the resin material. In order to increase the affinity of the alumina nanofibers with the powder paint matrix, the amphoteric surface of the nanofibers must become acidic. The paper describes a method for the functionalization of alumina nanofibers by successive silanization with aminopropyltriethoxysilane and priming with oxalic acid. The paper described about the compounding of alumina nanofibers leads to increase of the coating strength and an increase in its elasticity. Priming alumina nanofibers by aminopropyltriethoxysilane in toluene leads to its functionalization sufficient to homogenize the nanofibers in the polymer media of the powder paint and improve its product properties. The formation of an amide bond after the final stage of priming of alumina nanofibers in oxalic acid by indirectly method is shown.
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