Palygorskite (Pal) is a natural clay mineral with fibrous morphology and high surface area. Depending on the geological origin, it presents impurities, such as quartz and carbonates, which can harm some of its properties. Therefore, this work seeks to define a viable methodology for the purification of a Brazilian Pal. Two types of mixing processes (sonication and milling) and two types of dispersing agents (sodium silicate and sodium polyacrylate) were investigated. In addition, a subsequent acid activation with hydrogen peroxide and sulfuric acid was performed for complete purification. The viability of the purification of Pal was confirmed by X-ray diffraction, X-ray fluorescence, and thermogravimetric analyses. The sonication mixture process and the use of sodium polyacrylate as a dispersing agent were more effective. In addition, BET analysis showed an increase in the surface area of Pal, and scanning electron microscopy confirmed the permanence of its fibrous morphology after the purification steps.
The development of polymeric nanocomposites using clay minerals as a Nano filler is of great interest to researchers and industry. Many clay minerals are used to modify the properties of the polymers; this strategy improves the thermal and mechanical performance and changes the surface finishing and the processing characteristics. The Attapulgite (ATP), which is a clay mineral of the hydrated magnesium silicates family, has gained prominence in recent years because it combines low cost and high performance. It has a large surface area, strong absorption capacity superior to any other natural mineral, good mechanical resistance and thermal stability. These properties make ATP an ideal candidate for reinforcing polymeric materials. Different approaches and emerging technologies have been applied to improve the thermal and mechanical properties of polymer/ATP nanocomposites which can extend the different chemical treatments used in ATP. Therefore, this review article presents the latest advances related to the use of ATP in the development of polymeric nanocomposites, showing future perspectives for new trends in ATP applications. In general, ATP modifies the mechanical properties of polymers, either in the natural or modified state. And is a good alternative for the replacement of lamellar clays such as montmorillonites with the advantage of having a lower cost and a wide world market to be explored, that which drive new trends in applications for ATP, such as flame retardant of cotton fabrics, dye adsorption, hydrogel membranes for wound dressing, sustainable packaging and fuel cell applications.
Resumo obilidade e segurança são temas cada vez mais discutidos nos grandes centros urbanos, e as iniciativas nesse universo devem prever soluções práticas e econômicas, que gerem benefícios para os cidadãos. O pavimento, um dos fatores para a qualidade urbana, é a via de acesso indispensável para garantir o direito de ir e vir. Entre as soluções, o pavimento intertravado se destaca como um dos produtos mais recomendados na pavimentação das calçadas e áreas públicas. Em países da Europa e da América Latina a pavimentação com sistemas intertravados de cerâmicas é amplamente utilizada, porém essa prática ainda é pouco observada no Brasil, pela inexistência desse produto no mercado local. Desse modo, o objetivo deste projeto foi o desenvolvimento de pavimentos intertravados de cerâmica visando ao uso em passeios e áreas públicas. Também foram adicionados ao novo produto desenvolvido resíduos queimados oriundos do próprio processo de fabricação, os quais são chamados de cacos ou chamote, para diminuir a quantidade de material a ser descartado no meio ambiente. Após os resultados positivos na caracterização dos produtos, foram criados novos designs para essa tipologia de produtos, os quais foram produzidos em escala laboratorial. Ambiente Construído, Porto Alegre, v. 16, n. 4, p. 155-165, out./dez. 2016. Dias, L. L.; Menegazzo, A. P. M.; Quinteiro, E.; Serafim, M. A.
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Linear low‐density polyethylene (LLDPE) and high‐density polyethylene (HDPE) are polyolefins widely used in the packaging sector. Seeking to improve the mechanical properties with good cost‐effectiveness, attapulgite (ATP) was chosen as a reinforcing filler for the polyolefins. ATP is a hydrated magnesium and aluminum clay mineral with a microfibrous morphology, and the purity of this filler depends on the deposit. ATP is associated with the presence of accessory minerals that need to be removed so as not to interfere with its final application. Thus, an ATP purification process was carried out through physical separation and chemical treatment with hydrogen peroxide (H2O2) and sulfuric acid (H2SO4). This purification process despite having a low yield and is very effective in reducing impurities and organic matter. This ATP was named ATPa. LLDPE/ATPa and HDPE/ATPa nanocomposites with the addition of 1, 3, and 5 wt% of ATPa were prepared by extrusion and hot pressing. The mechanical properties (Shore D hardness, tensile tests, and Izod impact strength), thermal properties (differential scanning calorimetry—DSC and thermogravimetric analysis—TGA), X‐ray diffraction, rheological, and transmission scanning microscopy (TEM) were determined for these nanocomposites. The mechanical properties of the nanocomposites increased with the addition of ATPa. HDPE/ATPa nanocomposites showed more promise than LLDPE/ATPa nanocomposites. The addition of 5 wt% ATPa increased the tensile strength by 14% for the HDPE matrix and 5% for the LLDPE matrix and increased the elastic modulus by 46% for HDPE and 26% for LLDPE.
In this work, Brazilian attapulgite (ATP) with different surface modifications is used as a mineral filler in the development of linear low‐density polyethylene (LLDPE) nanocomposites. As a raw mineral, Brazilian ATP has many impurities in its structural channels (ATPr). Thus, sodium polyacrylate, hydrogen peroxide, and sulfuric acid are used to remove impurities from ATPr in a process called acid activation (ATPa). Also, inorganic materials do not have good interfacial interaction with organic polymers. Therefore, as an alternative to this challenge, two surface modifications are made to the ATPa: silanization (ATPs) and organophilization (ATPo). ATPr, ATPa, ATPs, and ATPo are characterized by FT‐IR (Fourier transform infrared spectroscopy), XRD (X‐ray diffraction), TGA (thermogravimetric analysis), and FEG‐SEM (field emission gun scanning electron microscopy). The effectiveness of surface modifications is evaluated for LLDPE/ATP nanocomposites with the addition of 3 wt% ATP (ATPr, ATPa, ATPs, and ATPo) prepared by extrusion. The nanocomposites are analyzed by XRD, thermal characterization (differential scanning calorimetry—DSC), mechanical characterization (Shore D hardness, tensile test, and Izod impact strength), and morphological characteristics (SEM micrographs). It can be noted that the addition of treated ATP increases the mechanical properties. The silanization is more effective when compared to the organophilization treatment.
Organic–inorganic nanocomposites have attracted great interest due to the remarkable improvement in mechanical properties when compared to neat polymers. The use of a low‐cost nanofiller added to good properties becomes attractive to the industry. Attapulgite (ATP) is a very interesting nanofiller alternative, especially when used with polyolefins, as in the case of high‐density polyethylene (HDPE). However, this system is not simple, as HDPE is a nonpolar polyolefin that can cause low dispersion of ATP. One way to increase the interaction between these phases is the surface modification of ATP. In this work, the surface of ATP was modified using trimethylamine hydrochloride. HDPE/ATP nanocomposites with 1 and 5 wt% of raw ATP (ATPr) or organophilic ATP (ATPo) were prepared by extrusion. The effectiveness of the organophilization process of ATP was evaluated by X‐ray diffraction, mechanical properties (Shore D hardness and tensile test), and thermal properties (thermogravimetric analysis and differential scanning calorimetry), contact angle, and scanning electron microscopy. In the HDPE/ATPo nanocomposites, it was possible to observe an improvement in mechanical and thermal properties when compared to HDPE/ATPr nanocomposites. The organophilization of ATP promoted a greater interaction between the phases, contributing to a better dispersion of ATP in the HDPE matrix.
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