According to the abstract, the researchers fabricated the composites by hand layup using an LY-556 epoxy matrix cured with HY-951 at room temperature. They tested particle concentrations of 4, 8, 12, 16 and 20 wt% and evaluated mechanical, tribological, water-absorption and thermal properties. Particle-size analysis found a bimodal distribution with an average hydrodynamic diameter of 1,099 nm and a polydispersity index of 0.969. Scanning electron microscopy was used to examine morphology and interfacial behaviour.

The 12 wt% composite recorded the highest tensile strength at 43.5 MPa, compared with 38.0 MPa for pure epoxy, a reported improvement of 14.5%. Maximum flexural strength was measured at 8 wt%, reaching 148.7 MPa and representing a 7.5% improvement. Water absorption increased with particle content under both test conditions, while saltwater absorption was lower than water absorption because of ion-retarded diffusion. Erosion resistance improved for every composite: the lowest erosion rate was 1.59 mg/min at 20 wt%, compared with 1.74 mg/min for pure epoxy. Conversely, the lowest wear rate was 7.560 × 10⁻⁶ mm³/(Nm) at 4 wt%, after which wear increased as particle content rose. Thermal analysis showed slower degradation and greater char residue above 450 °C as particle concentration increased.

The available evidence is limited to the article abstract rather than the complete paper, so details such as specimen numbers, statistical uncertainty and replication are not provided here. The findings are also bounded to the tested epoxy system, fabrication method, curing temperature, particle concentrations and measurement conditions. Although the authors frame agricultural seed-particle reinforcement as supporting circular-economy and sustainable-materials goals, the reported experiments do not by themselves establish cost, scalability, long-term durability or performance outside the laboratory conditions described.

Subject of Research: Mechanical, tribological, water-absorption and thermal testing of jujube-seed-reinforced epoxy composites

Article Title: Sustainable development of multifunctional epoxy composites reinforced with jujube seed particles

Article References: Tamilarasan, C., Albarakati, R., Raja, C. P., & Babu, N. B. K. (2026). Sustainable development of multifunctional epoxy composites reinforced with jujube seed particles. Discover Sustainability. https://doi.org/10.1007/s43621-026-04925-9

Image Credits: AI Generated

DOI: 10.1007/s43621-026-04925-9

Keywords: jujube seed particles, epoxy composites, mechanical properties, tribology, water absorption, thermal degradation, erosion resistance, sustainable materials, Sustainable, development, multifunctional, epoxy

The material at the center of the study, rubberized alkali-activated concrete, or RuAAC, combines two waste streams in a single matrix. The binder forms through a chemical reaction between an alkaline activator solution and aluminosilicate precursors, avoiding the high-temperature clinker process entirely. In this work, the binder comprised ground granulated blast furnace slag and Class F fly ash in a one-to-three ratio, activated by a blend of sodium silicate and 12 molar sodium hydroxide. The team tested three rubber gradations, a fine-graded fraction spanning 0 to 0.8 millimeters, a medium-graded fraction of 1 to 3 millimeters, and a wide-range blend covering 0 to 3 millimeters, each incorporated at 5, 10, and 20 percent replacement of fine aggregate by volume. Crucially, the rubber was used exactly as received from the tire recycling plant, with no chemical pre-treatment, a deliberate choice to preserve the environmental and economic case for the material, since soaking and rinsing procedures consume reagents, water, and generate effluent of their own.

The results on strength tell a story of trade-offs. The control mix, with no rubber, reached an impressive 72.3 megapascals at 28 days, reflecting the rapid reaction kinetics of the slag-rich binder. Adding rubber reduced compressive strength across the board, with losses ranging from 21 to 35 percent at 5 percent replacement, 30 to 46 percent at 10 percent, and 36 to 56 percent at 20 percent. But the gradation made an enormous difference. The fine-graded mixes retained the highest strengths at every dosage, reaching 57.1 megapascals at just 5 percent rubber, while the wide-range mixes performed worst, falling to 31.7 megapascals at 20 percent. The reason lies at the microscopic interface between the hydrophobic rubber particles and the hydrophilic alkali-activated gel. Residual zinc stearate from the tire vulcanization process repels the polar activator, entraining air voids at the interface and creating weak interfacial transition zones that act as flaws under load. Larger particles create larger, more critical defects, while sub-millimeter particles distribute the damage into smaller, less consequential discontinuities.

One of the most intriguing findings concerned early-age behavior. At just one day, the rubberized mixes were 40 to 72 percent weaker than the control, but this deficit narrowed substantially by 28 days. The rubber particles, it turns out, delay rather than suppress the alkali-activation reaction. The fine- and medium-graded mixes more than doubled their strength between one and seven days, recovering much of the early loss as the matrix densified around the inclusions. Statistical analysis using two-way analysis of variance confirmed this interpretation: the interaction between rubber content and gradation was significant at one day but not at later ages, meaning the gradation-specific early damage faded as the reaction progressed. By contrast, the medium-graded mix at 20 percent replacement gained almost no strength after seven days, suggesting that failure in that mix was governed by the weak interfaces around its uniform 1 to 3 millimeter particles rather than by the still-reacting matrix.

Where rubber genuinely shines is in deformation capacity. The control concrete failed in classic brittle fashion, with a sharp post-peak drop in the stress-strain curve. The rubberized mixes, by contrast, softened gradually and kept carrying load at strains approaching 0.8 percent or more. The ductility index, a measure of how much a material can deform before failure, rose by 44 percent in the fine-graded mix at 20 percent replacement compared with the control. The elastic rubber particles store strain energy and delay the coalescence of microcracks into macrocracks, transforming a sudden fracture into a controlled, gradual failure. This exchange of strength for toughness is precisely the property profile needed for applications such as crash barriers, pavement slabs, and industrial floors, where energy absorption and crack resistance matter as much as raw load capacity.

The study also broke new ground by measuring direct shear strength, load-slip response, and shear toughness of RuAAC for the first time at the material level, a gap with real safety implications. Shear failures in structural elements such as flat slabs, corbels, and deep beams occur with little warning, and design codes estimate shear capacity as a function of the square root of compressive strength using coefficients calibrated to Portland cement concrete. The team found that shear strength declined by up to 45 percent with rubber incorporation, less severely than flexural strength, which fell by as much as 67 percent, because confining stresses developed during shear testing provided mechanical interlock that partially compensated for the weak rubber-matrix bonding. Notably, at 5 percent fine-graded rubber, the shear toughness index was 25 percent higher than the control, suggesting that modest rubber dosages can genuinely improve energy dissipation along crack planes.

The durability results delivered some of the study’s most surprising wins. Water absorption in the fine-graded mix at 20 percent replacement was 9 percent lower than the control, and its capillary absorption depth at six hours was 39 percent lower, because the densely dispersed hydrophobic particles interrupt continuous capillary pathways and force water to take longer, more tortuous routes through the matrix. Bulk electrical resistivity, a proxy for resistance to chloride ingress and rebar corrosion, was 12 percent higher than the control in the same mix. Abrasion resistance told a dramatic gradation-dependent story: the fine-graded mix at 20 percent lost 29 percent less mass than the control after 500 tumbling cycles, while every medium-graded mix disintegrated completely, with the 20 percent medium-graded specimen failing by just 200 cycles. The uniform 1 to 3 millimeter particles, poorly bonded to the matrix, acted as discrete weak points that accelerated crack propagation under surface wear.

The authors distilled their findings into two practical application regimes, both built on fine-graded rubber. A mix with 5 percent fine crumb rubber retained 57.1 megapascals of compressive strength, a 25 percent higher shear toughness index, and better abrasion resistance than the control, making it suitable for pavement slabs, industrial floors, curbs, and precast panels. A mix with 20 percent fine rubber offers lower strength, 46.1 megapascals, but a 44 percent higher ductility index, reduced density, and improved workability, pointing toward crash barriers and non-structural cladding. The researchers caution that the reduced elastic modulus, between 14.2 and 19.2 gigapascals compared with 24.3 for the control, means deflection rather than strength will likely govern member sizing, and that shear-governed elements require member-scale testing before RuAAC can be deployed in them.

What makes this work resonate beyond the laboratory is its reframing of a familiar sustainability equation. Simply dumping waste into concrete is not enough; the form of the waste determines whether the resulting material is an engineering asset or a liability. By demonstrating that sub-millimeter tire rubber can simultaneously cut cement demand, divert landfill waste, improve ductility, and even enhance durability, the study offers a credible pathway for rubberized cement-free concrete to move from non-structural novelty toward genuine structural relevance. The authors call for microstructural examination of the rubber-matrix interface, extended durability testing covering chloride penetration, carbonation, freeze-thaw and creep, full-scale element testing, and a life cycle assessment quantifying embodied carbon per unit of strength. Until then, the message is clear: if you want tires to strengthen the future of concrete, grind them fine.

Subject of Research: Effect of recycled crumb rubber particle size and replacement level on the mechanical and durability properties of cement-free alkali-activated concrete

Article Title: Effect of recycled rubber particle size and replacement level on the properties of rubberized alkali-activated concrete

Article References: Elbaz, Y., Mwafy, A., El-Maaddawy, T., & El-Hassan, H. (2026). Effect of recycled rubber particle size and replacement level on the properties of rubberized alkali-activated concrete. Results in Engineering, 32, Article 113326. https://doi.org/10.1016/j.rineng.2026.113326

Image Credits: AI Generated

DOI: 10.1016/j.rineng.2026.113326

Keywords: alkali-activated concrete, crumb rubber, waste tires, geopolymer, compressive strength, shear strength, ductility, durability, water absorption, abrasion resistance, sustainable construction, fly ash slag binder

The core problem with recycled aggregates is well understood. When old concrete is crushed, fragments of the original natural stone remain encrusted with hydrated cement paste, the soft, capillary-rich residue of the demolished structure. This adhered mortar is far weaker and more porous than the parent rock, so it acts as a built-in weak zone. Water penetrates readily, the interfacial transition zone between aggregate and new cement paste is compromised, and the resulting concrete loses compressive strength, tensile strength, and long-term durability. Previous strategies have attacked the problem in various ways: mechanical grinding, thermal treatment, carbonation, polymer impregnation, and, most directly, acid soaking. But the acids used so far have mostly been strong inorganic acids such as hydrochloric acid and sulfuric acid, and the literature shows these can do as much harm as good, dissolving cementitious phases deep inside the aggregate and undermining its structural integrity.

The Indian team, led by Anchal Aggarwal together with Sanjeew Kumar Singh and Gaurav Goel, took a different chemical route. They chose oxalic acid, an organic acid with the formula C2H2O4, best known as the compound that gives rhubarb its sharp taste and, less glamorously, as a chief constituent of kidney stones. The choice is chemically shrewd. When oxalic acid meets the calcium-rich phases of cement mortar, it does not simply dissolve them; it reacts with calcium ions to precipitate calcium oxalate, an insoluble crystalline salt that deposits directly on the aggregate surface. Rather than etching the aggregate away, the treatment converts the troublesome outer mortar into a dense, mineralized skin. The researchers describe this as surface activation rather than surface removal, a conceptual shift that turns out to be the key to the method’s success.

To understand exactly what the acid was doing at the microscale, the team subjected the treated aggregates to a battery of advanced characterization techniques, including X-ray diffraction, field-emission scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy with elemental mapping. Together, these tools painted a consistent picture. The treated surfaces were coated with calcium oxalate crystals, calcium had been redistributed across the interfacial region, and pozzolanic crystalline deposits had formed, all of which contribute to a denser, better-bonded interface between the recycled aggregate and the surrounding cement paste in fresh concrete. In effect, the treatment builds a chemically compatible bridge between old mortar and new cement rather than leaving a porous, weak seam.

The mechanical evidence was equally striking. In impact tests, oxalic acid-treated aggregates outperformed aggregates treated with sulfuric acid by 4.6 percent and hydrochloric acid-treated aggregates by 5.9 percent, confirming that the organic treatment preserves and even enhances aggregate integrity where inorganic acids degrade it. Water absorption, the single most telling indicator of aggregate porosity, told a similar story. Untreated recycled aggregates absorbed 3.68 percent water by weight, a figure that dropped to 2.80 percent after sulfuric acid treatment and 2.75 percent after hydrochloric acid treatment. Oxalic acid pushed the figure down to 2.45 percent, evidence of genuine surface pore refinement and reduced accessible porosity rather than mere surface cleaning.

The most consequential results came when the treated aggregates were cast into concrete and tested at 28 days. Compared with concrete made from untreated recycled aggregates, the oxalic acid-treated material showed a 29.5 percent increase in compressive strength and a 35.2 percent increase in splitting tensile strength. Those are not incremental gains; they represent the difference between recycled aggregate concrete that must be derated and blended with virgin stone and concrete that can genuinely compete with conventional mixes in structural applications. The authors attribute the superior performance to the combined effects of adhered mortar modification and the formation of a calcium oxalate-rich surface, emphasizing that the benefit comes not from simply washing the old mortar away but from chemically transforming it into something useful.

Beyond raw performance, the choice of oxalic acid carries practical and safety advantages that could matter enormously for industrial adoption. Concentrated hydrochloric and sulfuric acids are among the most hazardous reagents in routine industrial use, demanding corrosive-resistant equipment, specialized storage, and rigorous worker protection protocols. Oxalic acid, while still requiring sensible handling, is comparatively less hazardous to store and manage, which lowers both operational costs and the regulatory burden of scaling the process to the enormous throughputs that aggregate processing plants demand. For an industry that consumes billions of tons of material annually, even modest simplifications in chemical handling translate into significant economic and safety dividends.

The environmental case was reinforced by a preliminary screening-level carbon and life-cycle assessment, which indicated a potential environmental advantage for the oxalic acid route relative to conventional treatments. Life-cycle thinking is essential here, because a treatment that improves concrete strength but imposes a heavy chemical or energy footprint would simply shift the environmental burden rather than reduce it. The screening assessment suggests that the mild conditions, lower hazards, and improved durability of the resulting concrete combine to make the overall proposition favorable, though the authors are careful to frame this as a preliminary, screening-level result rather than a definitive full life-cycle audit.

The work also fits into a broader and rapidly evolving research landscape. Other groups have pursued accelerated carbonation of recycled aggregates, slag-coated carbonation, nano-silica hydrophobic treatments, cement slurry coating, and thermo-mechanical upgrading, each with its own trade-offs in cost, energy, and scalability. Calcium oxalate chemistry itself has been gaining attention in materials science, from biomimetic conservation treatments for carbonate building stones to newly developed oxalate-activated calcium silicate cements, suggesting that the Indian team’s approach taps into a wider vein of promising mineral chemistry. What distinguishes the new study is its application of that chemistry directly to the adhered mortar problem, converting the recycled aggregate’s greatest liability into a strengthening feature.

If the process can be scaled economically, the implications for urban mining and circular construction are considerable. Cities effectively sit atop vast above-ground mines of demolished concrete, and technologies that upgrade this waste into high-performance raw material could simultaneously relieve landfill pressure, reduce demand for virgin sand and gravel extraction, and cut the carbon intensity of new construction. The authors position oxalic acid treatment as a sustainable route to producing high-performance recycled aggregates for circular concrete applications, and their data lend that claim real substance. Much work remains, from optimizing acid concentration and treatment duration to validating long-term durability in field structures, but the central insight is likely to endure: sometimes the best way to deal with a weak surface is not to remove it, but to grow a better one in its place.

Subject of Research: Oxalic acid surface activation of recycled construction and demolition waste aggregates for high-performance circular concrete

Article Title: Upcycling of construction and demolition waste by oxalic acid surface activation of recycled aggregates: a novel processing approach

Article References: Aggarwal, A., Singh, S. K., & Goel, G. (2026). Upcycling of construction and demolition waste by oxalic acid surface activation of recycled aggregates: a novel processing approach. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-026-38250-5

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38250-5

Keywords: construction and demolition waste, recycled aggregates, oxalic acid, calcium oxalate, concrete, circular economy, surface activation, water absorption, compressive strength, life-cycle assessment, sustainable construction, adhered mortar

The motivation is rooted in a serious waste-management problem. In Ethiopia, PET bottles from single-use beverages and eggshells, which are roughly 94 percent calcium carbonate, are dumped in open sites, contributing to soil and water pollution, pest-borne health risks and mounting disposal costs for local governments. At the same time, the country’s road development programs have pushed demand for cement and aggregates upward, straining both budgets and natural resources. Recycling these abundant waste streams into durable infrastructure products offers a double payoff, cutting pollution while providing cheaper construction materials. The researchers note that their country’s ambition to expand paved road coverage made an alternative, cement-free paver especially attractive.

Previous studies have mostly treated PET and eggshells as partial substitutes: shredded PET replacing a fraction of aggregate, or eggshell powder replacing up to about 10 to 20 percent of cement. Typical recommendations cap PET at roughly 10 percent of a concrete mix, beyond which mechanical performance drops. The novelty of the new work lies in flipping the roles entirely. Here, PET is melted at high temperature to become the continuous matrix that encapsulates and bonds the fillers, fully replacing cement, while eggshell powder and washed river sand together fully replace conventional aggregates. No prior study, the authors say, has combined melted PET with both eggshell and river sand as fillers in a hybrid paver tile.

Preparing the materials demanded careful cleaning and sizing. Discarded bottles were sorted, shredded to roughly 2 millimeters, washed and sun-dried for two days. Eggshells from cafeteria waste were soaked for 24 hours, boiled for 5 to 10 minutes to remove organic residue, dried and ground, then sieved through a No. 16 mesh so that particles were smaller than 1.18 millimeters. River sand was washed to strip away clay and organic impurities, which would otherwise weaken bonding between the plastic and the reinforcement, and dried for two to three days. These steps were critical because contaminant films at the matrix-filler interface directly undermine the strength of the finished composite.

The team then blended four weight-based formulations of PET, eggshell powder and sand: 50:25:25, 60:15:25, 70:20:10 and 85:10:5, producing three specimens for each mix and each test, for 36 samples in total. Shredded PET was melted in an oil furnace between 150 and 260 degrees Celsius, with full melting at about 200 degrees. The fillers were stirred in at around 150 to 160 degrees as the polymer softened, and the homogeneous molten blend was poured into steel molds, compacted to expel trapped air and cooled. Unlike cement-based pavers, which need weeks of water curing to hydrate, the plastic-based tiles required no curing at all, stabilizing at room temperature for 24 hours before testing.

The results revealed a clear optimum. Flexural strengths averaged 3.34, 2.89, 4.10 and 2.54 megapascals for the four mixes respectively, while compressive strengths reached 13.01, 12.10, 18.63 and 6.20 megapascals. The 70:20:10 blend dominated both metrics, with individual cube specimens peaking at 19.71 megapascals and a coefficient of variation of only about 4.8 percent, indicating highly reproducible manufacturing. Water absorption fell steadily as PET content rose, from 1.30 percent at 50 percent PET to just 0.41 percent at 85 percent PET, thanks to the hydrophobic polymer sealing capillary pores around the filler particles. The best mix’s absorption of 0.53 percent sits far below the 6 to 7 percent ceiling allowed by standards such as ASTM C902 and EN 1338.

The explanation for the optimum lies in the microstructure. Scanning electron microscopy of the 70:20:10 tiles showed uniformly dispersed eggshell and sand particles, strong interfacial adhesion and minimal voids, creating efficient stress transfer between the polymer and its rigid reinforcements. Energy-dispersive X-ray spectroscopy confirmed calcium from the eggshell and silicon from the sand distributed through the carbon- and oxygen-rich PET matrix. By contrast, the 50 percent PET mix left filler poorly encapsulated, producing microvoids and weak bonding, while the 85 percent PET mix, despite its dense matrix, starved the composite of reinforcement and became brittle, cracking easily and losing most of its strength.

Statistical analysis reinforced the experimental picture. One-way analysis of variance found that composition significantly influenced flexural strength (F = 9.95, p = 0.004), compressive strength (F = 82.43, p < 0.001) and water absorption (F = 5.27, p = 0.027). Compressive strength proved most sensitive to formulation, and regression between measured and predicted values yielded coefficients of determination as high as 1.000, confirming the reliability of the data. The 70:20:10 mix also showed the tightest variability, an important quality for any material intended for mass production.

Against international benchmarks, the tiles qualify as Quality C pavers, appropriate for pedestrian facilities, courtyards, garden paths and light-traffic driveways under IS 15658:2006, ASTM C902 and EN 1338. The flexural strength also exceeds the roughly 3-megapascal minimum in British and Ethiopian standards for outdoor pavers and compares favorably with prior plastic-composite tiles, which typically absorbed between 1.16 and 6.98 percent water. The authors caution that the study is limited to laboratory-scale testing of four compositions, leaving long-term durability, abrasion resistance, cost analysis and life-cycle assessment to future work, along with field trials and further mix optimization.

Even so, the demonstration carries broad significance. It shows that three of the world’s most ubiquitous waste streams can be reengineered, with a simple melt-and-mold process requiring no cement kilns and no quarrying, into infrastructure components that pass international strength and durability thresholds. For rapidly urbanizing economies facing both plastic pollution and costly construction materials, the message is blunt and practical: the raw ingredients for tomorrow’s sidewalks may already be lying in the trash.

Subject of Research: Paver tiles made entirely from waste PET plastic, eggshell powder and river sand

Article Title: Fully waste-derived PET-eggshell-sand composite paver tiles: processing, microstructure, and mechanical performance

Article References: Damise, M. A., & Yigezu, B. S. (2026). Fully waste-derived PET-eggshell-sand composite paver tiles: processing, microstructure, and mechanical performance. Journal of Materials Science: Polymers, 1(1), Article 15. https://doi.org/10.1007/s44493-026-00015-4

Image Credits: AI Generated

DOI: 10.1007/s44493-026-00015-4

Keywords: waste recycling, PET plastic, eggshell powder, paver tiles, composite materials, compressive strength, flexural strength, water absorption, sustainable construction, microstructure, polymer matrix, circular economy

Mycelium-based composites are grown rather than manufactured in the conventional sense. Living fungal hyphae are inoculated onto lignocellulosic substrates, where they colonize the particles and weave them into a coherent, self-binding matrix. After the growth phase, the material is dried and heat-treated, killing the fungus and stabilizing the structure. The result is a foam-like solid that is predominantly organic, compostable, and produced at ambient temperatures, in contrast to the energy-intensive polymerization and molding processes behind expanded polystyrene. Despite a decade of enthusiasm, the field has lacked careful, statistically controlled comparisons of how substrate formulation controls performance—precisely the gap the new study set out to close.

The team, led by Diana S. Ocegueda-Vega, Nelly Flores-Ramirez, and Salomon R. Vasquez-Garcia of the Universidad Michoacana de San Nicolás de Hidalgo, together with colleagues at the Tecnológico Nacional de México in Aguascalientes, produced five P. ostreatus composites labeled S1 through S5. Formulations S1 through S4 varied the proportions and particle sizes of oak wood chips, sawdust, and corn cob, while S5 served as a 100 wt% corn-cob reference. Particle architecture proved to be a decisive variable: scanning electron microscopy showed that the geometry of the underlying particles shaped how the fungal hyphae organized, branched, and consolidated the matrix. Coarse wood chips yielded an open, loosely knit structure, whereas finer particles enabled denser hyphal packing and better mechanical integration.

That microstructural difference translated directly into bulk properties. The sawdust-based formulation, S3, achieved the highest apparent density at 178.0 kilograms per cubic meter and the highest compressive strength at 0.63 megapascals. In contrast, the coarse wood-chip formulation S1, with its more open skeleton, delivered the weakest mechanical performance. For context, these densities sit in the same low range as commercial foam packaging materials, but the strength values remain modest—confirming that current mycelium composites are best suited to low-load protective applications such as cushioning inserts, rather than structural load-bearing roles.

Moisture behavior, a long-standing Achilles heel of fungal materials, received detailed treatment. Static water contact angle measurements on the dried surfaces ranged from 107.7 to 110.7 degrees across all five formulations—values comfortably above 90 degrees that indicate hydrophobic character, likely aided by fungal hydrophobin proteins that coat aerial hyphae. Notably, these contact angles did not differ significantly between formulations, suggesting that surface wettability is largely dictated by the mycelium itself rather than the substrate. However, bulk water absorption after 24 hours told a different story: values spread from 30.6 to 46.6 percent, with statistically significant differences. Dunnett-adjusted comparisons against the corn-cob reference showed that S1 absorbed significantly less water while S3 absorbed significantly more, a finding the authors attribute to differences in pore connectivity and particle porosity.

Surface hardness, measured with a Shore D durometer, spanned 27.6 to 37.7 across the formulations. S1 and S2 fell significantly below the corn-cob reference, whereas S3 and S4 were statistically indistinguishable from it. This gradient again tracks the density trend: harder, more consolidated surfaces come from tighter particle packing and more thorough hyphal colonization. The result gives manufacturers a practical dial—adjusting particle size distribution can shift surface robustness without changing the organism or the growth protocol.

Flexural testing exposed one of the field’s persistent limitations. Three-point bending strengths ranged only from 0.07 to 0.10 megapascals, and Tukey’s all-pairwise comparison detected no statistically significant differences among the formulations. In other words, no substrate recipe in this study meaningfully improved bending resistance, which remains the weakest mechanical attribute of mycelium composites. Interestingly, S4 and S5 did post the highest mean compressive and flexural moduli, indicating that stiffness and strength respond differently to formulation—stiffness can be tuned through substrate choice even when ultimate bending strength cannot, at least not within the ranges explored here.

The statistical framework of the study deserves attention because it strengthens the practical value of the findings. Beyond one-way analysis of variance and Tukey’s honestly significant difference test for all pairwise comparisons, the authors applied Dunnett-adjusted comparisons to test each experimental formulation S1 through S4 specifically against the corn-cob reference S5. This design mirrors what an industrial formulator would actually ask: not which recipe wins overall, but whether a given blend of local residues performs as well as, or better than, a baseline single-substrate material. The answers were property-dependent—no single formulation dominated every metric, underscoring that composite design must be matched to the end-use requirements of the packaging component.

The broader significance lies in waste valorization. Quercus castanea wood residues and corn cobs are abundant, inexpensive, and locally available in many agricultural regions, including central Mexico where the research was conducted. Growing packaging from these streams couples two sustainability gains at once: it diverts lignocellulosic waste from open burning or landfilling, and it displaces petroleum-derived foams that persist for centuries and fragment into microplastics. Because mycelium composites are produced at ambient temperature and pressure and are fully biodegradable, their lifecycle emissions profile contrasts sharply with conventional expanded polystyrene, even before accounting for end-of-life benefits.

Realistic caveats remain, and the authors state them plainly. The composites are appropriate for low-load protective packaging only when shielded from direct or prolonged moisture exposure, since bulk water uptake above 30 percent would degrade cushioning performance over time in wet conditions. Mitigation strategies reported elsewhere in the literature—such as beeswax or natural oil coatings—could extend service envelopes, but were outside the scope of this study. Scaling from laboratory samples to mass production will also demand consistent control of colonization time, humidity, and sterilization. Nonetheless, by quantifying exactly how substrate composition and particle architecture govern density, moisture response, hardness, and mechanical performance, the Mexican team has converted a promising but diffuse concept into an engineerable material platform, bringing grown packaging one measurable step closer to the shipping box.

Subject of Research: Physicomechanical properties of Pleurotus ostreatus mycelium biocomposites made from agroforestry residues for sustainable packaging

Article Title: Physicomechanical properties of Pleurotus ostreatus mycelium biocomposites from agroforestry residues for sustainable packaging

Article References: Ocegueda-Vega, D. S., Flores-Ramirez, N., Vasquez-Garcia, S. R., Martínez-Flores, H. E., Velazquez-Becerra, C., & Meza-de Luna, A. (2026). Physicomechanical properties of Pleurotus ostreatus mycelium biocomposites from agroforestry residues for sustainable packaging. Polymer Bulletin, 83(11), Article 630. https://doi.org/10.1007/s00289-026-06683-0

Image Credits: AI Generated

DOI: 10.1007/s00289-026-06683-0

Keywords: mycelium composites, Pleurotus ostreatus, sustainable packaging, agroforestry residues, biodegradable materials, lignocellulosic waste, water absorption, mechanical properties, biocomposites, waste valorization, circular economy, Polymer Bulletin

The motivation is stark. Composite materials such as carbon fibre reinforced plastics and glass fibre reinforced plastics dominate industries from aviation to wind turbine manufacturing because of their exceptional strength-to-weight ratios, yet their end-of-life story is grim. Recycling these composites is expensive and energy-intensive, and enormous volumes of decommissioned wind turbine blades already pile up in landfills worldwide. Even composites made with natural fibres typically fall short of true sustainability because their binding matrices are synthetic polymers that resist degradation. The Mauritian team set out to close that gap by making both components—the fibre and the matrix—fully biodegradable, drawing on a locally abundant plant species that also offers carbon-offsetting benefits while it grows.

The path from leaf to composite began with mechanical extraction. Fibres were harvested from Pandanus utilis leaves, stripped of their cuticle and epidermal layers using a conventional fibre decorticator, and oven dried at 60 degrees Celsius for 24 hours. The researchers then applied mercerization, an alkali treatment with sodium hydroxide at concentrations of 2.5 and 3.0 percent, to prepare the fibre surfaces for bonding with the PLA matrix. Fourier transform infrared spectroscopy confirmed that the treatment worked at the molecular level: characteristic peaks associated with lignin and hemicellulose—those at roughly 1239 and 1730 wavenumbers—flattened noticeably after treatment, while peaks tied to adsorbed water at 1640 and 3400 wavenumbers also diminished. In practical terms, the alkali bath dissolved much of the lignin and hemicellulose that interferes with adhesion, enriched the fibre in cellulose, and reduced its tendency to draw in moisture.

Composite specimens were fabricated by hand lay-up in aluminium-faced moulds, with chopped fibres of 4, 5 and 6 centimetres randomly arranged between two layers of PLA filament, then melted in an oven at 250 degrees Celsius for one hour, compressed, and cooled gradually to prevent cracking. Fibre loadings of 5, 10 and 15 percent by weight were tested against the pure polymer. Differential scanning calorimetry showed textbook PLA behaviour: a glass transition between roughly 50 and 70 degrees Celsius, crystallization peaks near 120 degrees, melting at 171.2 degrees, and thermal decomposition onset around 275 degrees—evidence that the reinforced material remains thermally stable across ordinary service conditions.

The physical tests revealed a familiar trade-off in biocomposites. Water absorption, measured over a 24-hour immersion following the ASTM D570-98 standard, was negligible for pure PLA but climbed to between 2 and 2.75 percent in the composites, rising consistently with fibre content—a statistically significant effect driven by the hydrophilic nature of natural fibres and by microscopic voids at imperfect fibre-matrix interfaces. Fibre length, by contrast, made no statistical difference. The soil burial test, in which specimens spent 30 days in open soil teeming with aerobic bacteria, told a similar story: specimens with 15 percent fibre lost up to 1.6 percent of their mass, compared with only 0.25 percent for plain PLA, confirming that the material genuinely degrades in a biological environment rather than merely fragmenting.

Mechanically, the sweet spot was unambiguous. Both tensile and flexural performance peaked at a fibre loading of 10 percent by weight, where stress distributes more evenly through the structure. The best flexural result—around 270 newtons of load capacity—came from a specimen with 4-centimetre fibres at 10 percent loading, more than double the 110 newtons that plain PLA could bear. Beyond that optimum, at 15 percent fibre content, performance dropped sharply as fibre-to-fibre crowding reduced matrix dispersion and left insufficient adhesive contact, generating stress concentrations and defects. Analysis of variance confirmed that fibre content, though not fibre length, significantly influenced the strength of the unexposed specimens.

The study’s most sobering finding concerns marine conditions, a critical consideration for a material intended for maritime applications. When a full set of reinforced specimens was submerged in seawater for 30 days before tensile testing, the pattern of results inverted: strength now fell with increasing fibre content, dropping from a high of 1400 newtons at 5 percent fibre to a low of 200 newtons at 15 percent. The researchers attribute this to capillary water penetration that progressively undermined the fibre-matrix interface, compounded by the slow hydrolytic degradation of the PLA matrix itself—a reminder that biodegradability, the material’s central virtue, is also its principal vulnerability in wet service environments.

To see failure coming before it happened, the team turned to digital image correlation, a contactless optical technique that tracks a speckled pattern on the specimen surface through a calibrated camera system during tensile loading. The resulting von Mises strain maps revealed localized hot spots of concentrated strain that reliably predicted where each specimen would ultimately fracture in a brittle mode. These hot spots traced back to manufacturing imperfections—randomized void formation, incomplete fibre-matrix adhesion and minor misalignments of the fibres—demonstrating how internal defects, invisible to the naked eye, orchestrate the failure of a composite long before its average material properties would suggest.

Finally, the researchers built a finite element model of the dog-bone tensile specimen in LS-DYNA, meshing it into nearly 75,000 elements with longitudinally aligned fibre bundles and boundary conditions mirroring the physical test. The simulation showed maximum tensile forces of 1400 newtons for the pristine composite and 600 newtons for the seawater-exposed model—at a displacement of 1.5 millimetres, figures that closely matched the experimental data for equivalent specimens. Crucially, the model confirmed that sea exposure cuts the material’s tensile load-bearing capacity roughly in half. With manufacturing defects addressed and fibre loading optimized near 10 percent, the authors conclude, Pandanus-based composites could offer a genuinely sustainable, high strength-to-weight alternative for everyday structural applications—crafted from a tree that grows, quite literally, along the shoreline where these materials may one day serve.

Subject of Research: Development and characterization of biodegradable Pandanus utilis fibre-reinforced PLA composites

Article Title: Biodegradable Pandanus Utilis fibre-reinforced PLA composites: characterization, mechanical behaviour, and fracture analysis

Article References: Dabee, C., Casarejos, E., & Ramful, R. (2026). Biodegradable Pandanus Utilis fibre-reinforced PLA composites: characterization, mechanical behaviour, and fracture analysis. Journal of Materials Science: Polymers, 1(1), Article 17. https://doi.org/10.1007/s44493-026-00019-0

Image Credits: AI Generated

DOI: 10.1007/s44493-026-00019-0

Keywords: Pandanus utilis, PLA, biodegradable composites, natural fibre composites, mercerization, tensile strength, flexural strength, water absorption, soil degradation, digital image correlation, finite element analysis, seawater exposure