Improved Performance in Multilayer Paper Composites Through the Incorporation of Inorganic Nanomaterials into Sodium Silicate Adhesive Douglas Lamounier Faria, Julio Soriano, Leticia Catta Preta da Silva, Anand Ramesh Sanadi, Gustavo Henrique Denzin Tonoli Materials, 2026 Multilayer paper composites have been widely applied in industrial sectors and as sustainable concrete formwork in civil construction. These materials are produced by pressing paper layers bonded with a sodium silicate adhesive; however, their structural performance is often limited by the adhesive’s low mechanical strength. Therefore, in this study, the effects of incorporating 0.5 wt.% nanoclay (NA), nanosilica (NS), and kaolin into sodium silicate on the physical, mechanical, and microstructural properties of the composites were evaluated. The composites were fabricated with 20 layers of recycled kraft paper and a final mass of 65 g/m2 of reinforced sodium silicate applied by a glue line. The adhesive was applied using a paper coating machine, followed by pressing at 4.30 MPa. The results showed that the presence of nanomaterials had no measurable effect on the apparent density of the composites; nevertheless, the inclusion of 0.5% NA promoted a 25% increase in toughness. Thus, the use of nanomaterials is efficient at obtaining better-quality composites for numerous technological applications.
Technological Properties of Biocomposites Produced With Agro-Industrial Castor Waste Applicable in the Thermal Insulation of Buildings Thamirys Andrade Lopes, Douglas Lamounier Faria, Felipe Gomes Batista, Adriele de Lima Felix, Antônio Claret Matos, et al. Polymer Composites, 2026 The production of composite particleboards with agricultural waste has been the focus of many studies that aim to address environmental problems due to waste disposal. This study aimed to evaluate the potential of using castor waste as a raw material for particleboard production with a view to its application as thermal insulation for buildings. Particleboards were composed of pinewood and castor waste particles at ratios of wt. equal to 100/0, 75/25, 50/50, 25/75, and 0/100, and were evaluated for water absorption and thickness swelling, internal bonding, static bending, scanning electron microscopy (SEM), and thermal conductivity. The addition of 100% castor waste reduced water absorption from 106.97% to 78.27% after 24 h of immersion. The replacement of pinewood particles with castor waste provided better dimensional stability to the panels because of the higher content of extractives in the castor waste. The values of the modulus of rupture (MOR) were four to eight times greater than the values recommended by standards for medium‐density particleboards (MDP). The thermal conductivity of the composites with 100% castor waste was reduced from 0.078 to 0.065 W/m K. It was concluded that castor waste, as a raw material used in the manufacture of particleboard, is an alternative and sustainable diversification.
Recycled Lignocellulosic Resources for Circular Bioeconomy Applications: Heat-Treated Eucalyptus Fibers in Polyester Composites Douglas Lamounier Faria, Tamires Galvão Tavares Pereira, Danillo Wisky Silva, Mário Vanoli Scatolino, Julio Soriano, et al. Recycling, 2026 The pursuit of alternatives to nonrenewable materials has stimulated the development of sustainable materials with improved performance, particularly polymer composites reinforced with plant-based fibers. In this study, eucalyptus fibers were thermally treated and evaluated as eco-friendly reinforcements for polyester composites, aiming to enhance their physical and mechanical properties. The fibers were subjected to heat treatments between 140 and 230 °C in a Macro-ATG oven, followed by analyses of anatomical characteristics and chemical composition. Composites containing 25% fiber reinforcement were produced using an orthophthalic unsaturated polyester matrix catalyzed with methyl ethyl ketone peroxide, with untreated fibers used as references. Thermal treatment induced significant modifications in fiber morphology and composition, including increases in cell wall fraction at 170 and 200 °C and higher cellulose contents at 140 and 170 °C. Mechanical performance was assessed through tensile, flexural (modulus of rupture—MOR), modulus of elasticity (EB), and impact tests. Composites reinforced with heat-treated fibers exhibited lower apparent density and, notably, those treated at 230 °C showed markedly reduced water absorption and enhanced tensile strength compared with the control. Overall, treatment at 230 °C proved most effective, highlighting the potential of thermally modified eucalyptus fibers as viable reinforcements for high-performance, bio-based polymer composites.
