Colloidal characteristics of gelatin-treated clay: Intercalation, stability, wettability, and rheological properties

In this paper, sodium montmorillonite was modified with gelatin of different concentrations, and various colloidal characteristics of the gelatin-treated clays were measured and analyzed in detail. First, the influence of gelatin on the interlayer space of Mt layers was investigated by X-ray diffraction analysis. Moreover, the aggregation of Mt particles was examined using a combination of electron microscopy and particle size distribution experiments, while the variation of the electrical property of Mt was measured using ζ potential test. Gelatin of different concentrations can increase the particle size of Mt in different degrees. The addition of 4% gelatin could improve the ζ potential of Mt from −30.65 to −15.55 mV. The wettability change of modified Mt induced by the adsorption of gelatin was followed by measurements of water contact angle and observations of the morphology of Mt/gelatin membrane through SEM images. 4% gelatin could improve the water contact angle of Mt to 81.3°. Finally, the rheological properties of Mt/gelatin dispersion including shear viscosity and shear stress were measured using a stress-controlled rheometer. All of the results were consistent by showing that the overall colloidal characteristics and behavior of the gelatin-treated Mt strongly varied depending on the gelatin concentration used in the modification process. These results can provide a deep and comprehensive understanding of the colloidal properties of clay/gelatin systems and give important guidance for the performance design and improvement of Mt/gelatin composite materials. Furthermore, this study can also be expanded the application of gelatin and its composites to other fields.

Chitosan and pectin core–shell beads encapsulating metformin–clay intercalation compounds for controlled delivery

Clay–metformin intercalation compounds as a reservoir in biopolymer core–shell beads as an example of targeted controlled release systems for oral drug administration.

Effect of sequence of melt mixing on the properties and morphology of blends of polypropylene, styrene–ethylene–butylene–styrene copolymer grafted with maleic anhydride, and organophilic montmorillonite clay

Styrene–ethylene–butylene–styrene (SEBS) copolymer, grafted or not, with maleic anhydride and organophilic montmorillonite clay was melt mixed with polypropylene (PP) using different mixing sequences to understand its effect on properties and morphology. The addition of clay changed the blend morphology from large elongated domains to droplets. The nanocomposites without maleic anhydride presented clay in the intercalated form. In the formulation containing maleic anhydride, clay is exfoliated on the blend, indicating that the maleic anhydride group acted to increase the interaction between the clay lamellae and the polymer chains. The best balance of mechanical properties was achieved in the formulation in which the clay was first melt mixed in SEBS without maleic anhydride and afterward melt mixed with clay and PP. It is reported in the literature that nanocomposites with exfoliated structures have better mechanical properties than nanocomposites with intercalated structure. However, in this study, an opposite trend was found, which may be related to the higher amount of crystalline phase formed in the intercalated structure nanocomposites, since the clay intercalation phenomenon in the polymer chains favored the polymer crystallization process.

SÍNTESE E CARACTERIZAÇÃO DE NANOCOMPÓSITOS POLIMÉRICOS REFORÇADOS COM VERMICULITAS

<p><em>As propriedades de proteção de um material por um revestimento polimérico são enfraquecidas por mecanismos térmicos e químicos, onde a reação de corrosão é favorecida na interface entre o material protegido e o material protetor. Para isso, faz-se necessário o estudo de sínteses menos complexas e eficientes de materiais que atuem com essa finalidade. </em><em>Este trabalho busca analisar o efeito das propriedades térmicas, mecânicas e morfológicas na resina epóxi, a partir da adição de argila vermiculita paraibana nos teores de 1 e 3% em massa numa matriz à base de resina epóxi, após o processo de organofilização das argilas, que se apresentam naturalmente hidrofílicas e sem afinidade à compostos orgânicos. Os resultados mostraram uma estabilidade na temperatura de degradação do nanocompósito e um impressionante aumento na temperatura de transição vítrea. Houve também uma melhora na resistência à tração em relação a resina não modificada, sugerindo a intercalação polímero/argila, estrutura essa, comprovada a partir da técnica de Microscopia Eletrônica de Varredura (MEV).</em></p><p><em> </em></p><p><em>ABSTRACT</em></p><p><em></em><em>The protective properties of a material by a polymer coating are weakened by thermal and chemical mechanisms, where the corrosion reaction is favored at the interface between the protected material and the protective material. For this, it is necessary to study less complex and efficient syntheses of materials that act for this purpose. This work aims at analyzing the effect of thermal, mechanical and morphological properties on the epoxy resin, from the addition of vermiculite paraibaan clay at 1 and 3% by mass in a matrix based on epoxy resin, after the organophilization process of the clays, which are naturally hydrophilic and have no affinity for organic compounds. The results showed a stability in the degradation temperature of the nanocomposite and an impressive increase in the glass transition temperature. There was also an improvement in the tensile strength in relation to the unmodified resin, suggesting the polymer / clay intercalation, a structure that was proven using the Scanning Electron Microscopy technique (SEM).</em></p>

Influence of Laurolactam Content on the Clay Intercalation of Polyamide 6,12/Clay Nanocomposites Synthesized by Open Ring Anionic Polymerization

In situanionic homo- and copolymerization of caprolactam (CL) and laurolactam (LL) with sodium montmorillonite clay (NaMMT) was carried out using two different initiators, sodium caprolactamate (CLNa) and caprolactam magnesium bromide (CLMgBr). Degree of conversion and final molecular weight were used to assess the advancement and efficiency of the polymerization reaction and X-ray diffraction and electron microscopy were used to evaluate the sodium montmorillonite clay intercalation/exfoliation. The use of CLNa as initiator produced a higher conversion degree and molecular weight than the use of CLMgBr. Through DSC, it was observed that CLNa and CLMgBr tended to produce random and block copolymer structures, respectively, and either random or block, this eventually has an effect on the clay dispersion within the polymer matrix. In all cases, increasing the LL content produced a decrease in the conversion degree and in the molecular weight of the resulting polymer.