The use of mineral reinforcements in polymer matrix composites has emerged as an alternative for sustainable production, reducing waste and enhancing the physical and mechanical properties of these materials. This study investigated the impact of the melt flow index (MFI) of HDPE and the particle size of two mineral reinforcements, Bahia Beige (BB) and Rio Grande do Norte Limestone (CRN), on the composites. All composites were processed via extrusion, followed by injection, with the addition of 30 wt.% reinforcement. Chemical analyses revealed similar compositions with high CaO content for both minerals, while X-ray diffraction (XRD) identified predominantly calcite, dolomite, and quartz phases. Variations in the MFI, reinforcement type, and particle size showed a minimal influence on composite properties, supported by robust statistical analyses that found no significant differences between groups. Morphological analysis indicated that composites with lower MFI exhibited less porous structures, whereas larger particles of BB and CRN formed clusters, affecting impact resistance, which was attributed to poor interfacial adhesion.

Master Valentim’s fountain has become an important historical patrimony for Brazil, being portrayed by famous artists, among them Jean-Baptiste Debret. In 1938, it was registered as cultural heritage by the Brazilian National Historical and Artistic Heritage Institute (IPHAN), and in 1990 it was subjected to excavation and restoration works. The fountain was built in Gneiss and Lioz limestone, with metallic plates and mortar connecting the Gneiss blocks. Currently, deteriorations in the fountain stones can be observed, such as light stains and some aesthetic modifications caused by inadequate restorations. Petrography, X-ray fluorescence (XRF), XRD, physical properties, colorimetry, electrical conductivity, inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), and TGA were performed in order to characterize the Gneiss blocks, the metallic plates, and the stones used in previous restorations, as well as light stains observed on the Gneiss blocks. The petrography and XRD analyses inferred that the light stains may have been caused by the formation of an insoluble salt as a result of the association of the lead from the plates with other elements. The XRD analysis on the light staining area indicated the presence of cerussite (PbCO₃) and anglesite (PbSO₄), which are the probable cause of the light stains. The SEM-EDX results suggested that sulfur is the main element associated to lead.

This article presents the development and characterization of environmentally friendly composites comprising polypropylene (PP) reinforced with Bahia Beige (BB) marble waste. The composites were prepared using different PP/BB weight ratios and analyzed for their chemical, physical, mechanical, microstructural, and thermal properties. X-ray fluorescence (XRF) analysis revealed the composition of BB, which exhibited a significant concentration of CaO, indicating the presence of calcite and other oxides. X-ray diffraction (XRD) analysis confirmed the presence of PP and identified calcite, dolomite, and quartz phases in the composites. Due to enhanced ceramic reinforcement, the composites displayed increased crystallinity with higher BB content. Fourier-transform infrared (FTIR) analysis demonstrated the interaction between PP and BB, with the bands corresponding to PP being replaced by bands related to BB as filler content increased. The density tests indicated a slight increase in composite density without deviating significantly from pure PP, which is advantageous for low-density applications. The hardness of the composites increased with filler content, while the impact resistance decreased notably. Scanning electron microscopy (SEM) images showed the good distribution of BB within the composites and the presence of ductile characteristics on the composite surface. The heat deflection temperature (HDT) results revealed that adding BB up to 40% by weight increased HDT, whereas a significant reduction occurred at a 50% BB content. These composites demonstrated favorable properties for engineering applications, offering a sustainable solution through utilizing natural waste resources and contributing to Brazilian sustainability efforts.

This article details the development of hybrid composites with a PLA matrix filled with coffee husks, potassium feldspar, and Bahia Beige marble. Comprehensive analysis included FTIR, hardness, contact angle, density tests, SEM for microstructural insights, and XRF for optimizing raw material compositions. Also, variance analysis was applied in all results. The study revealed that these biodegradable composites hold promise for sustainable applications. Density variations were noted due to particle compaction, and hardness slightly decreased with coffee husks, attributed to uneven component distribution. Increased hydrophilicity was observed with filler addition. SEM confirmed strong interfacial adhesion, and color consistency was maintained. Notably, coffee husks significantly enhanced the degradation rate of PLA, achieving a 100% higher rate compared to pure PLA. The presence of calcium and potassium minerals offers additional benefits for soil health. The study suggests that thermoformed, multi-layered composite capsules can be fully biodegradable, promoting environmental sustainability in coffee capsule production.