Introduction: The increasing demand for environmentally responsible packaging materials has intensified the search for renewable alternatives to conventional fossil-based plastics. Among the available options, biodegradable polymers show great potential, although their mechanical performance and barrier properties still require improvement for broader industrial use. Materials and methods: In this study, films based on polyvinyl alcohol (PVA) and xanthan gum (XG), including two xanthan gum variants produced from sugarcane bagasse (XGL1 and XGL2), were prepared by the solvent-casting method and evaluated through mechanical, thermal, morphological, spectroscopic, and water vapor barrier analyses. Results: The incorporation of xanthan gum positively affected film performance, particularly for the PVA/XGL1 formulation. This film showed a 37.9% increase in tensile strength compared with pure PVA, an elongation at break of 270.97%, lower water vapor permeability (0.243 g·mm/m2·h·kPa), and a higher contact angle (80.81°), indicating reduced sensitivity to moisture. Fourier transform infrared spectroscopy (FTIR) results suggested strong intermolecular interactions between PVA and xanthan gum, while Field emission gun scanning electron microscopy (FEG-SEM) analysis revealed homogeneous and compact structures. Conclusions: Although the films remained moderately water-soluble and thermal degradation began near 200 °C, the overall performance obtained demonstrates the potential of the PVA/XGL1 blend for food packaging applications. In addition to improving material properties, the use of xanthan gum produced from sugarcane bagasse provides a productive route for valorizing agro-industrial residues, contributing to the development of sustainable packaging materials with reduced environmental impact.
Hydrogels have emerged as a crucial class of biomaterials for engineering 3D cellular microenvironments, playing a vital role in tissue engineering and regenerative medicine. Their tunable physicochemical properties, biocompatibility, and structural resemblance to the extracellular matrix (ECM) make them ideal candidates for bio-inks in 3D bioprinting applications. This manuscript comprehensively discusses the use of natural and synthetic polymers as foundational materials, along with hydrogel synthesis strategies, including crosslinking mechanisms and functionalization techniques, and their impact on bio-ink performance. The important physicochemical properties, such as swelling behavior, mechanical strength, degradation kinetics, and biological interactions (including cell viability, cytotoxicity, and immunogenicity), are critically analyzed in this work to understand their role in cellular responses and tissue formation. Factors influencing hydrogel synthesis, including polymer concentration, crosslinking density, and environmental conditions, are systematically discussed to optimize bio-ink formulations for diverse biomedical applications. Despite significant advancements, challenges such as poor mechanical stability, limited printability, and inadequate cell viability remain major hurdles in developing functional bio-inks. This review highlights recent advancements aimed at overcoming these limitations through nanocomposite hydrogels, smart (stimuli-responsive) bio-inks, and bioactive modifications. Furthermore, future perspectives on hydrogel-based bio-inks emphasize the need for multi-material printing, personalized biomaterials, emerging 4D printing technologies, and integration with biophysical and biochemical cues to create complex tissue constructs. Overall, this review provides a comprehensive insight into the design, challenges, and future potential of hydrogel-based bio-inks, fostering the development of next-generation biomaterials for advanced biomedical applications.
Introduction: Silicon dioxide (SiO2) fiber structures have attracted attention as alternative anode materials for lithium-ion batteries because of their ability to improve cycling stability compared to commercial silicon particles.Materials and methods: SiO2 composite fibers were prepared by centrifugal spinning of polyvinylpyrrolidone (PVP)/SiO2 precursor solutions followed by calcination at 500–700 °C for different holding times to produce short-fiber composites and micro-belt SiO2 fiber structures. The morphology and crystal structure of the SiO2 short fibers and micro-belts were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). Electrochemical performance was evaluated using CR2032 half-cells.Results: The calcination temperature strongly influenced morphology, oxidation behavior, and electrochemical performance. Samples treated at 500 °C retained short-fiber morphologies but exhibited unstable cycling behavior because of incomplete oxidation. The sample calcined at 600 °C for 3 h exhibited improved cycling stability associated with a more oxidized surface and belt-like morphology. Samples treated at 700 °C showed collapsed structures and reduced reversible capacity.Conclusions: The results demonstrated that the calcination conditions strongly influenced the relationship between morphology evolution, oxidation state, and electrochemical stability in centrifugally spun SiO2 composite fibers. These findings provide a foundation for the future development of SiO2 fiber structures for use as composite anodes in lithium-ion batteries.
Introduction: Polymeric nanoparticles have validated their stance in the field of drug delivery. One such polymer is PGMD, poly (glycerol-malate-dodecanedioate), a novel polymer that has been explored for its potential ability to deliver drugs for the treatment of breast cancer.Materials and methods: PGMD copolymers were synthesized at dodecanedioic acid-to-malic acid molar ratios of 7:3 and 6:4. These formulations were subjected to characterisation using dynamic light scattering (DLS), Field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). Further, encapsulation efficiency and in vitro release studies were performed. To investigate its anticancer properties, the nanoparticles were implemented for apoptosis analysis using Acridine orange/ethidium bromide (AO/EtBr) and 4′,6-diamidino-2-phenylindole (DAPI) staining, cell migration assay and western-blotting analysis.Results: The 6:4 formulation achieved a superior paclitaxel (PTX) encapsulation efficiency of 97%, compared to 64.5% for the 7:3 variant. Both formed stable, anionic nanocarriers, with the 6:4 nanoparticles exhibiting a hydrodynamic diameter of 188 nm, a polydispersity index of 0.367, and a zeta potential of −17.3 mV. In vitro assays revealed that the PTX-loaded 6:4 PGMD nanoparticles significantly inhibited breast cancer cell migration. Furthermore, the nanoparticles exhibited potent, time-dependent cytotoxicity, achieving a half-maximal inhibitory concentration (IC50) at 48 h in MCF-7 cells, demonstrating significantly enhanced therapeutic efficacy compared to free PTX. Finally, morphological alterations (observed via DAPI and AO/EtBr staining) combined with Caspase-9 overexpression confirmed that this enhanced cytotoxicity is mechanistically driven by the targeted induction of the intrinsic apoptotic pathway.Conclusions: This study validates PGMD-based polymeric nanoparticles as a superior delivery vehicle for paclitaxel in breast cancer treatment. By outperforming the free drug and minimizing toxicity to healthy cells, these nanoparticles represent a highly promising, biocompatible platform for advanced oncological therapy.
Facial soft tissue deficits arising from trauma, congenital malformation, tumor resection, or age-associated degeneration present unique reconstructive challenges. Reconstruction must withstand continuous, high-frequency deformation while maintaining millimeter-scale aesthetic fidelity. Autologous fat grafting is a biologically compatible and accessible option; however, outcomes may be limited by donor-site constraints in select patients, technique sensitivity, and variable long-term retention. Injectable fillers provide rapid correction yet fail to recreate adipose cellularity, extracellular matrix microarchitecture, or perfusable vascular networks. Over the past two decades, facial adipose has been redefined anatomically as a system of discrete superficial and deep fat compartments with distinct boundaries, vascular and cellular compositions, and remodeling trajectories. While these differences are embedded in clinical and surgical decision-making for interventions targeting facial soft tissues, adipose tissue engineering remains dominated by generic soft tissue approaches that ignore compartment-specific complexities. This mismatch of compartment-specific clinical targeting without compartment-informed regenerative material design represents an actionable opportunity for translational progress. In this narrative and conceptual review, we treat facial compartments as an engineering map: we summarize facial adipose biology and compartmental microenvironments as design inputs, and describe or propose cell-augmented engineering approaches and bioactive material strategies. We conclude with a compartment-to-construct framework to inform next-generation soft tissue engineering approaches to facial fat restoration.
Introduction: Debondable and repairable epoxy-based vitrimer adhesives offer a sustainable solution to conventional epoxy adhesives for structural applications. This study evaluated the performance of a vitrimer adhesive in structural single-lap-bonded joints and investigated its repairability and debonding characteristics in comparison with those of a conventional epoxy adhesive.Materials and methods: Metal substrates, aluminum (Al6061) and stainless steel (SS303), were used to fabricate similar and dissimilar single-lap-bonded joints with vitrimer and conventional epoxy adhesives. Lap shear strength (LSS) testing was conducted to evaluate the mechanical performance. The debonding behavior was examined using a mixed solvent system of dimethylformamide (DMF) and ethylene glycol (EG) at different temperatures. Repairability was evaluated through repeated repair cycles, and the retained properties were investigated.Results: Results revealed that the vitrimer-bonded joints exhibited a maximum lap shear strength of 8.8 MPa. A mixed cohesive–adhesive failure mode was observed in the vitrimer-bonded joints for both similar and dissimilar substrate-bonded joints. The repaired vitrimer adhesive-bonded joints retained 89%, 82%, and 67% of their original lap shear strength after the first, second, and third repair cycles, respectively. Elevated temperatures significantly accelerated the debonding process, with complete debonding achieved within 90 min at 150 °C, whereas debonding required 5–6 h at 80 °C and approximately 36 h under ambient conditions.Conclusions: The results demonstrate the successful repair of vitrimer adhesive-bonded joints up to the second cycle with 82% retained properties, and easy debonding makes them a promising candidate for applications in sustainable structural adhesives.
Introduction: Although composite materials have been studied and validated through several tests, research on torsional behavior in tubular structures remains limited. Tubular configurations are common in diverse engineering fields, and composites, particularly those reinforced with synthetic and natural fibers, hold promise for advancing technology by offering a combination of good strength and low density. In this context, the main objective of this work is to compare the torsional behavior of laminated composite and hybrid (aluminum/composites) tubes.Materials and methods: In this study, prepregs were manufactured by hand lay-up using fibers and epoxy with different numbers of layers and fiber angle dispositions, maintaining a 30% volume fraction. The specimens were fabricated using the roll-wrap method, in which prepregs were manually wound onto tubular molds, obtaining the following configurations: sisal4 [45°]/epoxy, glass2 [45°]/epoxy, sisal2 [0°]/epoxy/Al, and glass:aramid [0°]/epoxy/Al. Sisal fiber was pretreated with 5% (w/v) sodium hydroxide (NaOH) to enhance adhesion to the matrix. Subsequently, the specimens were subjected to thermal analysis and torsional tests.Results: The results indicate that the glass:aramid [0°]/epoxy laminate, after curing, exhibited higher thermal stability (343.24 °C) than the cured sisal2 [0°]/epoxy laminate (322.82 °C). The degree of cure was essentially the same for both systems, although the glass:aramid [0°]/epoxy sample showed a slightly higher degree of cure (98.57%) than the sisal2 [0°]/epoxy sample. In addition, the sisal2 [0°]/epoxy/Al specimen under torsional loading reached a higher torque (19.65 N·m) than the glass:aramid [0°]/epoxy/Al specimen (17.98 N·m).Conclusions: The hybrid composites exhibited superior properties compared to sisal4 [45°]/epoxy and glass2 [45°]/epoxy composite tubes. Nonetheless, sisal fiber shows potential as a substitute for synthetic fibers in select projects, contingent on specific performance criteria.
Introduction: Discarded automobile tires represent a problem for recycling worldwide. The reuse of tire waste can be an opportunity for repurposing in plaster mortars, especially in improving some properties such as sound absorption.Materials and methods: This research investigated the resistance to deformation, adhesion, water absorption, and sound absorption capacity of plaster mortars with the addition of tire waste with particle sizes of 0.15 and 2 mm, in additional percentages of 1 and 3% of the total mass in a 1:4 cement and sand mortar mix by volume.Results: The results indicated that the resistance to deformation did not show significant variations compared to the standard, although the addition of waste influenced the increase in water absorption. In turn, the adhesion resistance was better than the standard only with the addition of 0.15 mm waste. Above this dimension, there was an increase in air incorporation, hindering adhesion. Regarding sound absorption, above 1000 Hz up to a limit of 4000 Hz, the rubber proved effective in dimensions of 2.0 mm.Conclusions: This study emphasizes the possibility of using tire rubber as a raw material for mortar production. Besides being a sustainable alternative, it can contribute to improving acoustic comfort to a certain extent.
Introduction: Fatigue damage remains a major challenge in the design of composite structures, as cracks may initiate under low stress levels and evolve through multiple interacting failure mechanisms. To reduce reliance on extensive physical testing, finite element methods based on progressive damage analysis are increasingly used to predict fatigue-driven crack growth within structural substantiation workflows. However, most existing approaches require prior knowledge of the crack path, limiting their ability to represent complex, solution-dependent fracture trajectories. The eXtended Finite Element Method (XFEM) offers a promising alternative, as cracks can be modeled independently of the mesh, yet commercial implementations remain limited for fatigue loading.Materials and methods: This work introduces a fatigue-capable XFEM framework that combines the cohesive segments approach with a stress–life-based degradation law using only Abaqus built-in user subroutines and native elements. Crack initiation is governed by a fatigue endurance limit criterion, and damage evolution is driven by a user-defined internal variable that controls cohesive stiffness degradation along the crack interface. A dedicated bookkeeping strategy enables access and transfer of interfacial crack-opening quantities, ensuring consistent evaluation of the fatigue damage variable across the enriched interface.Results: The framework is verified against a classical Cohesive Zone Model (CZM) and applied to a two-dimensional single element model as well as Double Cantilever Beam (DCB) specimen under Mode I static and fatigue using the IM7/8552 carbon/epoxy material system. The results demonstrate excellent convergence between the proposed method and CZM approach for the single element model. Furthermore, the DCB results demonstrate accurate prediction of delamination growth and highlight the proposed formulation as a practical and more flexible alternative to the existing Virtual Crack Closure Technique (VCCT)-based XFEM fatigue capability in Abaqus, without requiring a pre-existing crack or inheriting the restrictions of linear elastic fracture mechanics.Conclusions: The proposed methodology effectively bridges cohesive zone modeling and XFEM, providing a tool for simulating progressive damage in composite structures without the limitations imposed by linear fracture mechanics. Future developments will extend the framework to mixed-mode loading and three-dimensional configurations, broadening its applicability to aerospace-grade laminates and structural components.
Introduction: In recent years, hydrogels have gained significant importance in the pharmaceutical industry as an alternative system for controlled drug delivery. Conventional administration methods often fail to maintain optimal therapeutic concentrations, limiting drug action at the target site. Owing to their versatility and biocompatibility, hydrogels offer significant advantages by enabling the incorporation of active molecules and supporting a wide range of biomedical applications.Materials and methods: In this study, kraft lignin and polyethylene glycol were chemically modified via nucleophilic substitution reactions to introduce vinyl groups and were characterized using different spectroscopical techniques to ensure the success of the synthesis. These substances were subsequently used as crosslinking agents and comonomers for the synthesis of hydrogels, using acrylic acid as the monomer. The hydrogels were tested as potential materials for the release of trimethoprim based on preliminary studies.Results: The resulting hydrogels were characterized by evaluating their swelling behavior in water and buffer solutions at pH 4, 7, and 10, revealing a pronounced pH-sensitive response. Additionally, the adsorption and release behavior of the drug trimethoprim from polymeric hydrogel matrices was studied using Ultraviolet – Visible (UV–Vis) spectroscopy. The swelling analyses confirmed that the hydrogels provide tunable diffusion properties suitable for controlled drug delivery applications.Conclusions: The results demonstrate that modified kraft lignin and polyethylene glycol hydrogels possess favorable physicochemical and drug release properties, highlighting their potential as effective controlled-release systems for pH-sensitive drugs in pharmaceutical applications.
Introduction: Carbon nanotubes (CNTs) are flexible and can be utilized to braid the fabric that possess strong and flexible properties. However, regarding CNT fabric, almost any strategies for making textile have not been elucidated.Materials and methods: Finite element modelling of the carbon nanotube fabric was conducted via ANSYS software (ANSYS R2023 R2), employing a triangular structure of CNT yarns combined with a reverse pattern featuring a 90-degree phase difference. The analysis incorporated contact element analysis with a weak spring assumption. We investigated the stress variation among the components and analyzed the relationship between the maximum and minimum stresses.Results: A fabric structural pattern, specifically designed for energy production applications, such as wind turbine blades and automotive engines, has been proposed. Stability analysis, which considers yarn–yarn interactions, including sliding and wrinkling, has been performed to investigate the structural stability of composites. We also discuss the relationship between the braiding patterns and composite properties in the context of actual engineering applications.Conclusions: A CNT braiding pattern has been proposed and validated for its higher strength and higher failure strain, which are associated with an increase in strain when detachment occurs. Local strain concentration mitigation will lead to a balance in local stress and total stiffness, yielding high reliability in turbine blades and/or construction usage of CNT fabrics as reinforcements.
Introduction: After the ban on toxic lead (Pb) in solder alloys, Pb-free solder alloys are extensively used in the applications of electronic packaging, with tin (Sn) comprising over 90% of the composition. The formation of an intermetallic layer at the solder/substrate interface due to chemical bonding is a common phenomenon. However, during continuous service conditions, the growth of the IMC layer may affect the electrical and thermal properties. In real conditions, the IMC thickness associated with ageing is very important. This is because the reliability of the joint is allied to the growth of the IMC layer. Therefore, investigating the formation of intermetallic layers during joining and ageing is challenging. In the current research, Sn/Cu plates were welded using controlled underwater shock waves without the formation of intermetallic phases. Further, studies on the evolution of interfacial morphology in isothermally heat-treated tin/copper joints over extended periods were also assessed.Materials and methods: Pure Sn and Cu plates were bonded by adopting the underwater shockwaves method at a water distance from 30 mm to 60 mm. Fused Sn/Cu plates were isothermally aged at 150 °C from 1 day to 4 days. After sectioning, the formation of intermetallic phases between explosively welded Sn/Cu plates have been characterised using a metallurgical and scanning electron microscope (SEM). The growth rate constant for each intermetallic layer was calculated assuming a thermally activated diffusion-controlled (parabolic) growth model.Results: The wavelength as well as amplitude of wavy interface found to be decreased with increase in water distance. A changeover from a wavy morphology to (straight) interface was noticed at d = 60 mm by confirming that an increase in the wave parameters was related to shorter distances. Discussion: A thin continuous intermetallic layer was exhibited at the interface of Sn/Cu joints heat-treated for 1 day, further increase in heat treatment time resulted in an increase in the growth of IMCs towards Sn matrix. The growth of intermetallic compounds (IMCs) at the interface for all the samples obeyed a thermally activated diffusion-controlled mechanism.Conclusions: The wavy interface significantly affects the morphology of the IMC interface. IMC growth of all the samples obeyed thermally activated diffusion-controlled mechanism. Plates welded at a water distance of d = 40 mm exhibited a faster IMC growth rate, and d = 30 mm had the slowest rate. The growth of the intermetallic layer will be impeded if the interface exhibits a larger wavy interface.
Conventional single-wire additive manufacturing (AM) has several limitations, including low production efficiency and poor material utilization. These limitations hinder the development of metal 3D printing. Using combined cable wire (CCW) effectively solves these problems. Thus, this study introduces CCW based on plasma arc additive manufacturing (PAAM) to fabricate 2209 duplex stainless steel thin-walled parts (2209 DSS-TWPs). Through orthogonal experiments with range analysis and ANOVA, process optimization reveals the following optimal parameter set: a dry extension (DE) of 10 mm, a current (C) of 100 A, a scanning speed (SS) of 0.015 m/s, and a wire feeding speed (WFS) of 0.8 m/min. The 2209 DSS-TWP fabricated using these optimized parameters exhibits excellent forming quality (excellent surface finish and absence of defects). The microstructure shows an ideal 1:1 ferrite (α)/austenite (γ) ratio in the middle region. The top region has the highest α content, while the bottom region has predominant γ content. The 2209 DSS-TWP demonstrates excellent mechanical properties. Its overall average hardness (303 HV), strength, and elongation (EL) all meet GB/T 4237-2015 and ASTM-A890 guidelines. The middle region exhibits superior mechanical performance due to its balanced phase ratio. Compared to GB/T 4237-2015, ultimate tensile strength (UTS), yield strength (YS) and EL have increased by approximately 14%, 48%, and 56%. These results demonstrate the potential of CCW-PAAM technology for manufacturing high-performance DSS parts in industry.
The use of sustainable and ecological materials in the development of new products has led to an increase in research projects focused on the total or partial replacement of synthetic reinforcements with vegetable fibers in composites. This study proposes applying layers of vegetable sponge (Luffa cylindrica) together with a random glass fiber mat (FG) to produce hybrid composites with a polyester matrix, aiming to determine their physical and mechanical properties, including their density, moisture content, water absorption, thickness swelling, tensile strength, flexural strength, and Rockwell hardness. The composites were manufactured by cold pressing in a closed mold. The vegetable sponge (Luffa cylindrica) and a random glass fiber mat were arranged by varying the quantities and positions of the central and outer layers in the composites. The results showed that reinforcing the vegetable sponge (Luffa cylindrica) decreased the density of all hybrid composites, with the lowest value of 1.12 g × cm−3 observed for the configuration with sponges on the outside (90°/FG/90°). In the flexural strength test, the hybrid composite reinforced with vegetable sponge (Luffa cylindrica) in the center (FG/90°/FG) showed the highest stress and stiffness values, at 91.8 MPa and 3704.9 MPa, respectively. In the Rockwell hardness tests, the hybrid treatment reinforced with fibers in the (FG/90°/FG) configuration showed the highest value among the hybrid and natural treatments, with a value of 104.7 HHR (Rockwell R Hardness). The results showed that the reinforcement and layer position of the vegetable sponge (Luffa cylindrica) and the random glass fiber mat significantly influenced the physical and mechanical properties of the manufactured composites. These characteristics demonstrate that hybridization between layers of synthetic and natural fibers can produce materials with distinct properties from the same constituents. The hybrid composites also exhibited light weight, reduced economic costs of obtaining and processing, reduced synthetic constituents, and good physical and mechanical properties, in addition to being natural, biodegradable, and renewable.
Plasma-based surface modification has been used as a method to impart specific surface properties onto medical devices. In this work, plasma-polymerized hexamethyldisiloxane (HMDSO) coatings were deposited on flat, stent-like substrates using pulsed-DC plasma-enhanced chemical vapor deposition (PECVD) and evaluated as anti-biofouling coatings to inhibit or promote the accumulation of specific cells on the surface. Coatings with differing chemical properties were deposited on 316 L stainless steel foil by varying the settings used for the plasma polymerization process (applied voltage and current). Organosilicon polymer-like (OrgSi) coatings, prepared with an applied voltage of 1000 V, presented an average water contact angle of 97° and Raman peaks associated with C–H stretching. Silicon oxycarbide (SiOC) coatings, prepared with an applied voltage of 1500 V, showed a water contact angle of 75° and Raman peaks in the C-C stretching region. The cellular response of human umbilical vein endothelial cells (HUVECs) and human coronary artery smooth muscle cells (HCASMCs) to the two different coated stent-like materials revealed a reduction in HCASMC cell adhesion and proliferation across the OrgSi coating in comparison to uncoated 316 L SS foil. These results suggest that modulation of plasma polymerization conditions in pulsed-DC PECVD results in distinct drug-free coating chemistries that selectively suppress smooth muscle cell adhesion and proliferation through a passive coating.
The impact of prior heat treatment on the welding performance and corrosion resistance of sand-cast Al-Zn-Mg alloys was investigated by treating samples before the welding process. The study utilized a 3 × 2 experimental designs consisting of six groups: three prior heat treatment states (as-cast, normalized, and quenched) and two welding conditions (welded and unwelded). All these samples were subjected to tensile and hardness tests as well as corrosion resistance assessments. Ultimate tensile strength (UTS) ranged from a minimum of 220 MPa for the as-cast welded samples to a maximum of 350 MPa for the quenched unwelded samples. A significant reduction in hardness was observed in the as-cast welded fusion zone (56.1 Hv) compared to the quenched unwelded condition, which maintained a maximum value of 92.8 Hv. The heat-treated Al-Zn-Mg alloy demonstrated superior corrosion resistance in near-neutral media but suffered a significant decline in stability when exposed to acidic environments. The research validates that the properties of sand-cast Al-Zn-Mg alloys can be successfully tailored and improved through targeted prior heat treatment processes.
Introduction: Namibia faces challenges of bush encroachment, affecting over 45 million hectares of rangeland and reducing biodiversity, grazing capacity, and agricultural productivity. The utilization of encroacher bush biomass is an opportunity for sustainable material innovation.Materials and methods: The research investigated the compressive strength of mycelium-based composites (MBCs) created from two encroacher bush species, Terminalia sericea and Senegalia mellifera, using Ganoderma lucidum mycelium as a natural binder. The bush biomass was harvested through random selection from the Okondjatu district and processed into wood chips ranging from 1 to 5 mm. The substrates were supplemented with wheat bran and chalk powder, then pasteurized and inoculated with G. lucidum spawn. Mycelium-based composites were cultivated in controlled cylindrical molds for a period of 47 days and subsequently oven-dried at 99 °C. Compressive strength testing was conducted using a GCTS flat load machine, followed by data analysis through one-way ANOVA to assess the effects of substrate species and processing method.Results: Results indicated significant variability in the compressive strength of MBCs based on substrate type and pressing condition. Composites derived from S. mellifera typically exhibited higher strength in pressed conditions, with an average of 0.76 ± 0.16 MPa, compared to non-pressed samples, which averaged 0.57 ± 0.46 MPa. This development suggested enhanced densification and mycelial bonding from pressing. Conversely, T. sericea composites displayed greater variability, with some non-pressed samples achieving compressive strength levels of up to 4.23 MPa, likely due to differences in fiber structure and porosity.Conclusions: This study emphasizes that substrate type significantly affects the density, uniformity, and strength of mycelium-based composites. Pressing enhances composite compactness, but its impact differs based on substrate morphology. The findings suggest that Namibian encroacher bush biomass is a promising raw material for sustainable, biodegradable, non-structural construction materials. Future research should focus on optimizing substrate preparation, moisture control, and pressing conditions to improve the material consistency and mechanical performance of MBCs.
The search for sustainable solutions in civil construction has driven the use of natural fibers to replace synthetic fibers, leading to a reduction in environmental impact and the reuse of agricultural waste. Therefore, this work investigates the performance of cementitious composites reinforced with the addition of 1% corn straw and polypropylene fibers, and the effect of hybridization of these fibers in cementitious composites. To this end, corn straw was cut and subjected to alkaline treatment with calcium hydroxide (Ca(OH)2) to remove impurities, reduce water absorption, and improve adhesion to the cementitious matrix. Consistency index, density in fresh and hardened states, capillary water absorption, flexural tensile strength, and axial compression strength tests were performed at 7, 28, and 42 days, in addition to scanning electron microscopy (SEM-FEG) and Energy Dispersive Spectroscopy (EDS) at 28 days for the mixes containing corn fiber and synthetic fiber. The results demonstrated that the addition of treated fibers showed good performance in terms of workability, reduced water absorption, and increased toughness of the cementitious composites at 7 days, highlighting the efficiency of the alkaline treatment with Ca(OH)2. At 28 and 42 days, a reduction in performance was observed compared to the mixes with lower corn straw fiber content, pointing to a possible degradation of the fiber due to the alkaline medium. It is concluded that the use of treated natural fibers presents technical viability and environmental benefits, representing a promising alternative for the production of sustainable cementitious composites.
The utilization of seawater and sea sand in a reactive powder concrete offers a sustainable alternative for marine infrastructure. However, chloride-induced corrosion and autogenous shrinkage remain critical challenges. This study systematically addresses these issues through a dual strategy: optimizing a ternary cementitious system (fly ash, metakaolin, and slag) and incorporating functional fibre. The effects of different factors on the properties of seawater sand reactive powder concrete (RPC)were investigated by designing an orthogonal test to test the pH value, Cl− concentration, mechanical properties, fluidity, and chemical shrinkage. Orthogonal experiments reveal that fly ash plays a dominant role in chloride immobilization, reducing Cl− concentration by 5.9% at 11% dosage via Friedel’s salt formation. Slag enhances flexural strength by 21.1% at 11% content, while metakaolin significantly improves early-age microstructural densification, albeit at the cost of reduced workability. Fibre hybridization further elevates mechanical performance: 0.2% polypropylene fibre increases the 3-day flexural strength to 22–23 MPa through effective crack bridging, and 0.2% basalt fibre maximizes compressive strength by enhancing interfacial compatibility in saline conditions. A 0.3% carbon fibre exhibits minimal impact on fluidity due to its hydrophobic nature. Chemically, the synergistic pozzolanic reactions convert free chlorides into stable phases, reducing pore solution pH by 1.9% and decreasing chloride permeability by over 20%. These results demonstrate a scientifically robust approach to designing durable, high-performance sea-sand seawater reactive powder concrete (SSRPC), with significant implications for resource-efficient and corrosion-resistant marine construction.
The development of biodegradable materials has intensified as an alternative to petroleum-based polymers, yet achieving suitable properties at a competitive cost remains challenging. This study evaluated mono- and bilayer films of polyvinyl alcohol (PVA) and xanthan gum (XG) incorporating cellulose nanofibrils (CNFs) and subjected to corona treatment. The films were produced by casting and coating and characterized for physical, thermal, chemical, optical, and mechanical properties. In monolayers, CNF promoted structural compaction, reduced solubility, and improved thermal stability, raising degradation onset temperature by 33% and tensile strength by 37% while decreasing elongation at break. In bilayers, CNF increased tensile strength and Young’s modulus but reduced flexibility; corona treatment reversed this effect, enhancing adhesion and elongation at break by 286%. FTIR confirmed hydrogen bonding and corona-induced modifications, while optical analysis showed higher opacity with CNF. The results demonstrate that CNF and corona treatment synergistically improve film performance, supporting applications in sustainable food packaging.
