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.

Fused Filament Fabrication (FFF) is the most used additive manufacturing (AM) technique. Understanding the behavior of the in situ temperature profile during the cooling stage is crucial to enhancing the mechanical properties of the parts manufactured by FFF since adhesion between printed layers is strongly related to the polymer cooling rate. However, only some studies analyze each layer in detail. For such analysis, infrared thermographic cameras can be used as a tool for non-contact temperature measurement. Numerous variables in constructing the part offer potential for such investigation. This study may lead to the enhancement of the part manufactured and improvements in the 3D printer itself. In addition, the polymer matrix and the manufacturing software can also be optimized. This work aims to systematically evaluate the temperature profile along the deposited layers during the fabrication of three-dimensional parts using poly(lactic acid) (PLA) filament. An infrared camera was used for real-time temperature measurements, and the data were processed with MATLAB^® as a function of time and part length. A difference of up to 30 °C was observed between the edges, and non-uniform temperature profiles were also observed at the beginning, middle, and end of the part manufacturing. The highest temperatures were observed at the side where the print nozzle positions itself for the base to descend to the next layer. Several strategies are proposed to enhance the temperature distribution during the cooling process.

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.

The rise of Industry 4.0 has introduced challenges and new production models like additive manufacturing (AM), enabling the creation of complex objects previously unattainable. However, many polymers remain underutilized due to the need for improved mechanical properties and reduced process-induced anisotropy. ME-based part construction involves successive filament deposition, akin to welding. Upon exiting the nozzle, the polymer solidifies within seconds, limiting the time and temperature available for diffusion and efficient bonding with the adjacent filament. Therefore, optimizing this welding process is essential. The primary objective of this review was to report on the equipment utilized to enhance the bonding between filaments deposited during manufacturing. While higher temperatures improve welding, most equipment cannot endure prolonged high-heat operations, limiting the use of engineering-grade polymers. Modifying polymer matrices by incorporating low-molar-mass molecules can boost welding and mechanical strength. Significant gains in mechanical properties have come from matrix modifications and new in situ welding devices. Reported devices use light (laser, UV IR), electric current, radio frequency and heat collection from the nozzle. The simplest device is a heat collector, while a double laser beam system has achieved the highest mechanical properties without matrix modification. There was an improvement in properties ranging from 20% to 200%.

Thermoplastic starch (TPS) is a biodegradable polymer from renewable sources, but its limited mechanical and thermal properties restrict wider industrial use compared to petroleum-based plastics. In this study, TPS-based biocomposites were developed and optimized by incorporating agricultural and mineral Residues: coffee husks (CH), potassium feldspar (PF), and Bahia Beige marble (BB) as reinforcements. Mechanical, thermal, and morphological characterizations were carried out, and a simplex–lattice mixture design was applied to optimize the formulations. The 70/20/5/5 (TPS/CH/PF/BB, wt.%) composition achieved the highest tensile strength (2.0 MPa) and elastic modulus (70.2 MPa), while the 90/0/5/5 formulation showed superior impact resistance. FTIR and SEM analyses confirmed effective filler dispersion and strong matrix–filler interactions. Scheffé polynomial models (R² > 87%) accurately predicted performance, highlighting the reliability of the statistical approach. From a sustainability perspective, this work demonstrates that upcycling coffee husks and mineral residues into TPS-based biocomposites contributes to waste reduction, landfill diversion, and the development of cost-effective biodegradable materials. The proposed systems offer potential for eco-friendly packaging and agricultural applications, reducing dependence on fossil-based plastics and mitigating the environmental footprint of polymer industries. Statistical optimization further enhances efficiency by minimizing experimental waste. Moreover, this research supports circular economy strategies and provides scalable, sustainable solutions for waste valorization.