Water Absorption Rate Research Articles

Physicochemical, mechanical and thermal analysis of unfired clay bricks: Kaolinite-PEG 6000 composite

This study aims to evaluate the potential of polyethylene glycol (PEG 6000), a recycled material, as an additive to improve unfired clay bricks. By proposing a sustainable alternative to traditional methods potentially linked to medical waste. This research explores the physicochemical, mechanical and thermal properties of unfired clay bricks modified by different contents of PEG 6000 (0%, 1%, 3%, 7%, 15% and 20% by weight) according to the standard NM 13.1 0.0442005. The testing methods comply with recognized building sector standards (Belgian NBN EN 771-3+A1 and American ASTM C675-17). The clay used was extracted from Berrechid city and it is identified as kaolinite and some trace of illite, which has non-swelling properties. The incorporation of PEG 6000 into the unfired clay bricks has notably reduced the porosity rate from 3.91 % to 1.21 %, an improvement of 69 % compared to the reference sample, leading to a decrease in the rate of capillary water absorption. The bulk density of the bricks has slightly decreased to 1670.07 kg/m3, which still allowed them to be classified as light bricks. The incorporation of 7% of PEG 6000 increased compressive strength and flexural strength up to 15.98 MPa and 0.959 KN respectively, an improvement of 63.23 % compared to the reference sample, making them suitable for the construction of interior and exterior walls according to the standard NBN EN 771-3+A1. However, thermal conductivity and specific heat capacity have been improved by 42.22 % compared to the reference sample, reaching 0.26 W/m.K and 0.89 kJ/kg.K respectively. Optimization showed that 7% of PEG 6000 is the optimal percentage for manufacturing high-performance bricks, taking into account all properties studied previously. Moreover, the simulations carried out by the TRANSYS software suggest significant energy gains in terms of insulation, achieving up to 58.33% energy savings. In essence, this research demonstrates the potential of PEG 6000 as a sustainable additive for unfired clay bricks, offering improved properties and promising energy efficiency benefits.

Experimental Study on the Physical Properties of Autoclaved Bricks Made from Desert Sand and Their Resistance to Sulfate Attacks

In order to optimize the application of desert sand autoclaved bricks in rural construction in Xinjiang, this study focuses on the research and development of MU15-grade desert sand autoclaved bricks. Experimental investigations were conducted to examine the relationship between the water absorption rate of desert sand autoclaved bricks and the duration of water absorption while analyzing the impact of the water absorption rate on the compressive strength of these bricks. Additionally, experimental research was carried out to evaluate the appearance, compressive strength, and pore structure of autoclaved bricks after sulfate erosion. The results indicate the following. (1) With an increasing immersion time, the water absorption rate of desert sand-based autoclaved bricks initially rises and then declines, reaching approximately 14.74% when immersed for 4 h, which is close to the saturation water absorption rate. (2) The compressive strength of desert sand-based autoclaved bricks gradually decreases with an increasing water absorption rate, reaching its lowest point when saturation is attained, with a strength loss rate of approximately 33.18%. (3) Finally, after sulfate erosion, cracks and detachment appear on the surface of desert sand-based autoclaved bricks, and these cracks extend and propagate with the continuous accumulation of eroded products. Simultaneously, this process leads to an increase in the proportion of harmful pores by 0.96%, thereby causing a deterioration in strength. Through data analysis, a decay curve of the compressive strength erosion coefficient of desert sand-based autoclaved bricks with the number of sulfate erosion cycles was established, with good accuracy. This study provides theoretical references and technical support for the performance characteristics of desert sand-based autoclaved bricks and their application in rural construction in Xinjiang.

Carbon nitride/polyaniline/metal oxide composite system endows epoxy resin with reinforcements in the fire safety, thermal stability, and water resistance

AbstractReducing the fire risk of epoxy coatings has been a significant focus in the research of thermosetting resin materials. Various carbon nitride/polyaniline/metal oxide hybrids (CNPMOs) were synthesized using in‐situ oxidative polymerization and modified adsorption methods. Combustion analysis results indicated that CNPMOs effectively reduced the heat release of epoxy coatings during combustion. The epoxy coatings containing various CNPMOs (EFe, EY, and ETi) exhibited excellent smoke suppression and toxicity reduction properties. Furthermore, in comparison to the pure sample (E0) and reference sample (E1), the epoxy coatings EFe, EY, and ETi demonstrated improved thermal stability. In water resistance tests, the water absorption rates of EFe, EY, and ETi were significantly lower than that of E0. The CNPMOs enhanced the hydrophobicity of the epoxy coating to better protect the substrate in humid environments.

Application of Guar Gum Treatment of Basalt Residual-Soil Shallow Slope in Early Ecological Restoration

This paper found that environmentally friendly guar gum biopolymers are helpful for stopping the erosion of basalt residual-soil shallow slopes, while also improving the problems of poor stability, difficult growth of early vegetation, and weak initial resistance to the rainfall scouring of these slopes under extreme climatic conditions. Then, to illustrate the effects of the guar gum treatment, laboratory tests have been conducted, including a soil strength test, water retention and water absorption tests, a disintegration test, and a simulated rainfall erosion test, and the pattern of its effect on vegetation growth has been explored. The results indicate that as the content of guar gum increases, both the cohesion and angle of internal friction exhibit a trend of first increasing and then decreasing; the angle of internal friction varies within a range of 21° to 26°. The evaporation rate, water absorption rate, and disintegration rate of this guar gum-treated soil were significantly reduced, while the cracking of the surface layer was significantly improved. The disintegration rate of the soil is only about 2%, as the guar gum content is greater than 1%. Moreover, there is no sign indicating that vegetation germination was affected by the guar gum, meaning that it maintains a favorable environment for vegetation to grow. Guar gum-cured slopes were significantly protected under heavy rainfall washout conditions, with a 94.85% reduction in total soil loss from the slope surface compared to untreated slopes. Since the pores of soil are filled with guar gum hydrogel, the erosion resistance of soil is greatly enhanced. The results of this study will provide a scientific basis for engineering the protection of shallow slopes of basalt residual soils.

Mechanical Characterization of Sisal Fiber Reinforced PP Composite Panels

ABSTRACT This study investigates the mechanical properties of single and double-layer woven sisal mat-reinforced PP composite panels. Sisal fibers were extracted using the manual decortication method, resulting in fibers with a density of 1.43 g/cm3 and a diameter ranging from 0.4 mm to 0.6 mm. To improve the bonding between the sisal fibers and the matrix, the fibers were hand-spun into yarn and woven into mats. The study focuses on the unique material combination and the use of sisal as a natural fiber reinforcement. The 18 mm thick panels were tested for water absorption following ASTM D570, compression strength, and tensile strength following ASTM D3039 using the UTES-100 High Precision universal strength tester machine. Composite panels with single layers of 10% and 15% woven fabric mat, loaded with 8 kg and 10 kg, exhibited compressive strengths of 11.6KN and 12.5KN, respectively. Panels reinforced with two layers of 20% and 30% sisal woven fabric mat, loaded with 8 kg and 10 kg, had compression strengths of 12.2KN and 12.5KN, respectively. Moreover, composite samples with 15% single layer and 30% double-layer sisal woven fabric mat demonstrated a equal compression strength of 12.5KN, falling within the range recommended by ISO13006:2012. The tensile strength of 16.99MPa, although slightly below the recommended ISO13006 value of 20MPa for commercial-grade panels, indicates promising results. The study’s findings suggest that higher fiber content and additional reinforcement layers lead to increased compression and tensile strength. Furthermore, the moisture absorption rate of the developed composite panels was significantly lower than the 0.5% water absorption rate authorized by the American National Standard Institute.

Influence of hydroxyl group density in propane alcohols-based deep eutectic solvents: Physicochemical properties and potential application as an extraction medium for bioactive compounds

Deep eutectic solvents (DES) composed of citric acid monohydrate (CAM) as hydrogen bond acceptor (HBA) and alcohol as hydrogen bond donor (HBD) were used for separating bioactive compounds from star anise. This study prepared three propane alcohols-based DES with different hydroxyl (OH) group densities in HBD. FTIR analysis verified the presence of hydrogen bond interactions between HBA and HBD, which strengthened with increasing the OH group densities. Increasing the OH group density in DES exhibited lower water content, but higher thermal stability, higher density, higher viscosity as well as enhanced the water absorption rate. All of the propane alcohols-based DES were miscible in high and semi-polar solvents as well as it also displayed frequency independence characteristics. Moreover, propane alcohols-based DES efficiently extracted bioactive compounds from star anise with high total phenolic and flavonoid contents more than traditional solvents. High bioactive phenolic and flavonoid contents in star anise extracts were the major contributors to potent antioxidant activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH, 84.50 %), azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS, 85.73 %), and ferric ion reducing antioxidant power (FRAP, 3.74 mM FeSO4). Therefore, DES was suggested to be a promising extraction medium for valuable bioactive compounds from natural sources that could be utilized as therapeutic agent for oxidative stress.

Preparation and performance evaluation of bio-based wood-plastic composites from ricinoleic acid ring-openning epoxidized soybean oil

With the enhancement of sustainable development concepts and environmental protection awareness, replacing fossil resources with biomass to prepare unsaturated polyester resins is an essential approach to achieve green chemistry. In this study, a bio-based unsaturated polyester (ERM) was synthesized using epoxidized soybean oil and castor oil acid as raw materials. The reinforced modification of two fast-growing woods, Cunninghamia lanceolata (Chinese fir) and Pinus sylvestris var. mongolica (Pine), was investigated. The structure and molecular weight of the polyester at various stages were detected through infrared spectroscopy, proton nuclear magnetic resonance, and size exclusion chromatography. It was found that compared to the original wood, the density of the modified Cunninghamia lanceolata (Chinese fir) and Pinus sylvestris var. mongolica (Pine) increased from 0.36 g/cm3 and 0.45 g/cm3 to 0.9 g/cm3 and 0.78 g/cm3, respectively. Their compressive strength increased from 30.1 MPa and 32.1 MPa to 73.9 MPa and 73.8 MPa, respectively. The water absorption rate decreased from 167.3% and 103.8% to 16.86% and 16.59%, respectively, and thermal stability also showed a significant improvement.

Bacterial cellulose biosynthesis: Optimization strategy using iranian nabat industry waste

Bacterial cellulose (BC) is a biopolymer has found extensive applications across different fields due to its nanostructure and biomaterial performance. This study focused on optimizing yield of BC produced by Komagataeibacter xylinus CH1, isolated from kombucha SCOBY. The study aimed to use Nabat industry waste (NIW) as a cost-effective alternative carbon source for submerged fermentation. To optimize the fermentation criteria, the central composite design was used with the inoculation amount (1.5–4.5 % VV−1), NIW (0–1%), and fermentation time (3–7 days) as independent variables. The impressive results indicated the yield was enhanced up to 45.543 gL-1 at 3.013 % VV−1 of inoculation, 0.516 % NIW, and 7 days of stirred fermentation. SEM, XRD, FTIR, and TGA were applied to evaluate the characteristics of freeze-dried BC, such as the three-dimensional, porous structure, crystalline peaks, amorphous haloes, and thermal stability. The physicochemical properties of BC including high moisture content (93.022 ± 0.472 %), water absorption rate (569.473 ± 3.739 %), water-holding capacity (1333.016 ± 3.680 %), porosity (166.247 ± 2.055 %), and low water activity (0.296 ± 0.030 %) were achieved. Rheological properties of BC suspensions showed that G′ dominated over G″, with tan δ values lower than 1. These characteristics indicate NIW and stirred fermentation conditions are a promising method for producing BC in high yield.

Production of paver blocks from polyethylene terephthalate solid waste as partial replacement of sand

Plastic waste management is an international concern. Polyethylene terephthalate (PET) plastic waste is present everywhere in Addis Ababa relative to other types of plastic waste and it is an international concern regarding environmental problems. The amount of plastic trash produced globally is increasing at a rapid rate, and this pollution is caused by improper disposal, the waste’s non-biodegradability, and the harmful gases released during incineration pose a hazard to human health. Because it’s used in so many commonplace items, such as bottles and containers for the food and beverage sectors, polyethylene terephthalate, or PET, is one of the most widely used consumer polymers. Because of its many characteristics, including its inability to biodegrade and the gasses it releases when burned, it has grown to be a significant environmental problem. Waste made of polyethylene terephthalate (PET) must therefore be recycled and used efficiently. The purpose of this study was to produce paver blocks by partially replacing sand with waste Polyethylene Terephthalate (PET) material. Preparing the raw materials, mixing, vibrating, molding, curing, testing the flexural and compressive strengths, and curing are the steps in the production process. . The mixing proportion of paver blocks implemented for this study was 1:2:3, which is a predictable volume basis-mixing ratio of cement, aggregate, and sand correspondingly. Design-Expert 13.0.0 Three-level three factor Box–Behnken design was used for experimental design and statistical analysis of results based on the outcome and discussion. A total of 17 trials were carried out with the following parameters: 10, 20, and 30% of polyethylene terephthalate; 0.52, 0.55, and 0.58 as the water-to-cement ratio; and 7, 14, and 28 days for the curing period. The interaction effects were examined based on the examination of the experimental data. The physio-mechanical properties of Paver Blocks, including water absorption, compressive strength, and flexural strength, were examined. At a water-to-cement ratio of 0.55, obtained maximum flexural and compressive strength which is 4.92 MPa, and 29.74 MP respectively, and when PET plastic waste percentage increased, both flexural and compressive strength decreased but we got a good flexural and compressive strength value at 10% PET. And also water absorption rates were increased as PET plastic waste increased. The ideal process variables for polyethylene terephthalate percentage were 10 and 28. The paver blocks average and maximum water absorption rates were 3.39% and 3.95%, respectively. Compared to regular blocks, the resultant Paver Blocks are lighter and have superior physical and mechanical qualities. These are excellent illustrations of planned paver applications that can make use of prefabricated paver blocks.

Manufacture and Characterization of Lightweight Sand-Plastic Composites Made of Plastic Waste and Sand: Effect of Sand Types

Over the past decade, many types of waste have been exploited as feedstocks in different industries. Recycled plastics are among the waste sought for several civil engineering applications. In this work, various plastic-bonded sand composites based on polypropylene waste and silica sand were produced to serve as building materials in many construction applications. Many tests and analysis were carried out in this investigation. First of all, two initial used compounds (waste PP and various silica sand) were analyzed by using ATR-FTIR, XRF, and grain size distribution. In the second time, the different plastic-bonded sand composites were analyzed by using ATR-FTIR to assess their composition. On the other hand, mechanical, and physical tests such as three-point flexural strength, compressive strength, water absorption, and optical observation were applied on different produced composite samples, then the results were examined and analyzed. The results showed that the developed composites exhibit commendable mechanical properties, especially flexural and compression resistance, and minimal water absorption. It is worth noting that the plastic-bonded sand containing Khobana sand showed the highest flexural and compressive strength at 11.56±0.36 and 26.19±0.27 MPa, respectively, along with the lowest water absorption rate of 0.46%. This study confirms its contribution to enhancing sustainability and promoting the principles of the circular economy.

An Experimental Study on The Effect of Chemical Composition on The Strength Behaviour of Geopolymer Mortar

Abstract Sustainable development in the construction industry aims to improve the lifetime standards of present and future generations. Among industrial by-products, Ground Granulated blast Furnace Slag (GGBS) powder is employed as a cementitious material. This work investigates the properties of geopolymer binders prepared using the GGBS without conventional cement. The individual properties of the Geopolymer mortar (GPM) samples such as compressive strength and chemical composition were evaluated as per relevant IS Standards. Cubes of size (70.6×70.6×70.6) mm were cast and cured at ambient conditions for molarity 8M, 10M, and 12M with different fine aggregates, i.e., River sand, M-Sand, and GGBS. Compressive strength for 3, 7, and 28 days was evaluated. The results exhibit higher improvement in strength for 12M GPM’s with higher strength for river sand-based mixes. The chemical composition of GPM samples after 28 days of curing is determined. Essential chemical constituents such as SiO2 in 12M GPM’s considerably increased compared to 8M and 10M. The water absorption rate of samples with M-sand is greatly lowered with increasing molarity compared to those with river sand. The dry density of samples with M-sand exhibited higher improvement with increased molarity than those with river sand.

Compósito à base de polipropileno reciclado para utilização em instalações agrícolas

ABSTRACT This study aims to develop an eco-friendly, recyclable, and cost-effective composite material for use in storage sheds and machine workshops. The new composite consists of stone dust and gravel bricks bonded by recycled polypropylene through heat treatment. The main focus of this study is to determine the effects of varying polymer proportions on the resistance and permeability properties of the studied composite, intending to achieve optimal properties, i.e., high resistance and low permeability. To do this, the 2² factorial arrangement was employed, comprising four treatments along with three central points, each replicated three times. The data was statistically analyzed at a 95% confidence level from an adapted methodology. This involved tests of compression strength, 3-point bending strength, Los Angeles abrasion, and water absorption by immersion, in which three percentages of polymer content (PC) - 15, 25, and 35% - and aggregates (fine sand, medium sand, and coarse sand - FS, MS, and CS) were used to prepare the composite. The developed composite was deemed suitable for use in storage warehouses and machine workshops, as it presented physical and mechanical appropriate characteristics, i.e., a low water absorption rate and high resistance to compression and abrasion, in addition to being an environmentally friendly composite.

Study on Fast Liquefaction and Characterization of Produced Polyurethane Foam Materials from Moso Bamboo.

Although bamboo is widely distributed in Japan, its applications are very limited due to its poor combustion efficiency for fuel. In recent years, the expansion of abandoned bamboo forests has become a social issue. In this research, the possibility of a liquefaction process with fast and efficient liquefaction conditions using moso bamboo as raw material was examined. Adding 20 wt% ethylene carbonates to the conventional polyethylene glycol/glycerol mixed solvent system, the liquefaction time was successfully shortened from 120 to 60 min. At the same time, the amount of sulfuric acid used as a catalyst was reduced from 3 wt% to 2 wt%. Furthermore, polyurethane foam was prepared from the liquefied product under these conditions, and its physical properties were evaluated. In addition, the filler effects of rice husk biochar and moso bamboo fine meals for the polyurethane foams were characterized by using scanning electron microscopy (SEM) and thermogravimetry and differential thermal analysis (TG-DTA), and the water absorption and physical density were measured. As a result, the water absorption rate of bamboo fine meal-added foam and the thermal stability of rice husk biochar-added foam were improved. These results suggested that moso bamboo meals were made more hydrophilic, and the carbon content of rice husk biochar was increased.

Optimization and Modelling of the Physical and Mechanical Properties of Grass Fiber Reinforced with Slag-Based Composites Using Response Surface Methodology.

The construction industry's high energy consumption and carbon emissions negatively impact the ecological environment; large-scale construction projects consume much energy and emit a significant amount of CO2 into the atmosphere. Statistics show that 30% of energy loss and 40% of solid waste in the construction industry are generated during construction. Therefore, reducing emissions during construction has significant research potential and value. Many scholars have recently studied eco-friendly building materials to facilitate the use of high-carbon emission materials like cement. Adding fibers to composite materials has become a research hotspot among these studies. Although adding fibers to composite materials has many advantages, it mainly reduces the compressive strength of the composite material. This research used the response surface methodology (RSM) to optimize the raw material ratios and thus improve the performance of plant fiber composite materials. Single-factor experiments were conducted to analyze the effects of grass size, grass content, and quicklime content on the composite materials' compressive strength, flexural strength, and water absorption. The influencing factors and levels for the response surface experiment were determined based on the results of the single-factor analysis. Using the response surface methodology (RSM), a second-order polynomial regression model was established to analyze the interaction effects of the three factors on the composite materials' compressive strength, flexural strength, and water absorption rate. The optimal ratio was determined: the optimized options for grass size, grass content, and quicklime content are 2.0 mm, 8.2 g, and 38 g, respectively. The actual values of compressive strength, flexural strength, and water absorption rate of the composite materials made according to the predicted ratio are 11.425 MPa, 2.145 MPa, and 21.89%, respectively, with a relative error of 8% between the actual and predicted values. X-ray diffraction and scanning electron microscopy were also used to reveal the factors contributing to the relatively high strength of the optimized samples.

Advancing sustainable construction: Terracotta component development through extrusion-based 3d printing with local clay

This study examines the use of 3D printing technology in construction, specifically the use of local clay as the primary material for developing Terracotta components. The results demonstrate the feasibility and high print quality achievable with clay, establishing it as a viable material for 3D printing in construction. The analysis of physical properties, such as shrinkage, density, and water absorption, provides valuable insights. Thermal conductivity, also examined, contributes to a comprehensive understanding of material performance. The article identifies the optimal extrusion parameters for terracotta components. The evaluations show that the water absorption rates are within standards, and the density variation ranges from 1420 to 1466 kg/m³. Additionally, there is a direct correlation between thermal conductivity and density. The compressive strengths are diverse, ranging from 18 MPa to 33 MPa. While modulus of elasticity provides essential quantitative data for understanding the mechanical behavior of printed samples when subjected to various stresses. The internal structure significantly influences compression resistance in 3D printed bricks, emphasizing its importance in design. This research highlights the potential of 3D printing, specifically with clay, in sustainable construction. It encourages further exploration of its practical applications in the industry.

Study on the salt-dissipating and settlement-preventing performance of composite modified cushion layers in the roof-propping body of earthen sites' basal sapping zone

Cushion layer replacement is currently an important method for preventing and treating salinized deterioration in the earthen sites' basal sapping zone. The water resistance, salt-dissipating property, and load-bearing capacity are key indicators for evaluating the effectiveness of capping replacement. In this study, gravel is an inorganic admixture for the calcareous soil base material. Prepared 19 soil samples through the cross-combination of gravel with three types of organic binders. These samples were subjected to tests on wave velocity, volume shrinkage, permeability, capillary rise, and consolidation. The suitability of the composite materials for reinforcing the rammed earth heritage capping layers was further studied using the AHP-CRITIC-TOPSIS method. The results show that: (1) The wave velocity and volume shrinkage rate of the samples increased over time and reached stability after 7 days. Moreover, the water resistance, salt dissipation, and load-bearing capacity of the samples were significantly enhanced; (2) Comprehensively evaluating the suitability of the composite materials for the capping layers in the earthen sites' basal sapping zone using six indicators: wave velocity, volume shrinkage rate, permeability coefficient, capillary water absorption rate, compression coefficient, and final settlement, it was found that the SMS-S: G7:3 mixture showed the best suitability. This study provides a reliable theoretical basis for the restoration of earthen sites in the arid areas of Northwest China.

An Investigation of the Mechanical and Durability Properties of Hollow Concrete Blocks Made with Copper Mine Tailings as a Partial Cement Replacement

The increase in copper productivity in Zambia has resulted in the expansion of disposal areas occupied by mineral wastes and tailings. This not only consumes land but also, due to insufficient management, poses negative environmental impacts and health risks to people. Therefore, efficient and sustainable approaches for the proper management of these waste materials must be developed. In this study, the potential utilization of copper mine tailings was assessed. After analyzing the physical and chemical properties of copper mine tailings from Kitwe Tailings Dam (TD25), hollow concrete block specimens were prepared. Copper mine tailings were used as a partial replacement for cement in the mix design, with replacement ratios as follows: 0% for CBCMT O% (control specimen), 10% for CBCMT1O%, 20% for CBCMT2O%, 30% for CBCMT3O%, 40% for CBCMT4O%, and 50% for CBCMT5O%, all aimed at achieving a target strength of 5 MPa. Specimen compressive strength was evaluated, and it was found that CBCMT1O% and CBCMT2O% achieved the target compressive strength at 28 days of age. Water absorption rates and resistance to acid attack were also assessed. Findings revealed that all specimens outperformed the control specimen in terms of these properties. Furthermore, the environmental feasibility of the hollow concrete blocks specimens was examined, and the results showed limited leaching of heavy metals from the specimens, with concentrations within permissible thresholds. Additionally, a statistical analysis was conducted to study the influence cell shape has on the specimens’ compressive strength. Aimed at identifying the optimal specimen type for achieving compressive strength at an early age, results indicated that cell shape had a significant impact on the 28-day age of hollow concrete blocks. The study proposes a novel copper mine tailings (waste) management approach, by utilizing the potential it has to replace cement in the production of hollow concrete blocks, evident from the observed enhancement of the mechanical and durability properties.

Preparation of waste Camellia oleifera shell and high‐density polyethylene composites: Effect of pretreatment on fiber and materials properties

AbstractThe preparation of wood‐plastic composites (WPCs) with high filling fibers and excellent physical properties remained a great challenge. This study used Camellia oleifera shell (COS, agroforestry product waste) as raw material, and prepared 60 wt% COS/high‐density polyethylene (HDPE) WPCs using profile extrusion method through pretreating fibers including hot water, hot steam, alkali, acid, extraction, and fine fiber screening. After pretreatments, the relative contents of cellulose and lignin increased, the relative contents of hemicellulose and extract decreased significantly, and the length‐diameter ratio was improved. The flexural strength, tensile strength and impact strength of hot water and steam heat treated composites reached 31.4, 17.1 MPa and 6.9 kJ/m2, 31.8, 16.8 MPa and 6.7 kJ/m2, respectively. Compared with untreated 28.8, 14.7 MPa and 5.5 kJ/m2, the advantages were more obvious. Alkali treatment and acid treatment improved the thermal stability and residue rate of the material. Extraction treatment and alkali treatment significantly reduced the processing torque force, which was conducive to processing, while acid treatment was the opposite. The highest water absorption and thickness expansion rate were 13.75% and 3.60% respectively at 7 days after alkali treatment, which were considerably higher than 5.60% and 0.78% without treatment, while other pretreatments improved the dimensional stability of the material.Highlights High filling Camellia oleifera shell waste/HDPE composites were prepared. Physical and chemical pretreatments improved interfacial adhesion of the composites. Heat treatments significantly improved mechanical performance of the composites.

Mechanical characteristics of optimized alkali-treated Similax Zelanica/glass fiber/nanosilica composites in an epoxy matrix: An experimental investigation and numerical study

The demand for environmentally conscious materials has led the research on natural fiber composites as an alternative to synthetic materials in various industries. This study focuses on the optimization and preparation of alkali-treated Similax Zelanica/glass fiber and nanosilica-reinforced epoxy composites. The weight % of Similax Zelanica/glass and nanosilica was optimized using the grey relational analysis (GRA) multiparameter optimization technique and DOE of L9 orthogonal was used. Mechanical properties including tensile, flexural, impact, rock well hardness, and dynamic mechanical analysis were evaluated. Results indicate that increasing fiber volume fraction up to 30% enhances mechanical properties, with subsequent declines beyond this threshold. Tensile strength peaked at 30% fiber volume (75 MPa), while flexural strength also peaked at 30% substrate (140 MPa). The impact test showed a maximum of 1.84 kJ/m2 at 30% volume fraction. Maximum hardness of 85 RHN is observed for 30% S and 60% E specimens. Weibull distribution plots results, aligned well with the expected distribution pattern, indicating consistent and reliable mechanical behavior. Water absorption rates increase with fiber volume percentage increase, but optimal alkali treatment improves, absorption resistance to some extent. Dynamic mechanical analysis reveals reduced glass transition temperature Tg (97° C) for composite due to their better interaction nature between fiber/silica nanoparticles and matrix. Further characterization reveals thermal stability (374°C), crystalline properties (crystalline index: 56.87%, crystalline size: 21.23 nm), and functional group composition. Numerical analysis using ANSYS validates experimental results, giving confidence in repeatability. Scanning electron microscope analysis confirms good interfacial bonding, crack propagation details, and absence of impurities in the composite. These results like Mechanical properties, thermal stability, crystalline properties, and functional group composition of the composite confirm its suitability for various applications.

Polydimethylsiloxane enabled triple-action water-resistant coating with desirable relaxation rate in clear aligner

Clear aligners undergo rapid stress relaxation in warm, moist oral environments, compromising therapeutic effectiveness and longevity of treatment. To develop an innovative multilayer composite material with improved stability and reduced stress release, we have engineered an innovative coating characterized by the surface aggregation of polydimethylsiloxane (PDMS), which imparts a pronounced hydrophobic effect. In addition, the chemically and physically cross-linked structure of the coating reduces the free volume created by molecular chain rearrangement owing to the presence of water molecules, thereby minimizing water penetration into the coating. Concurrently, the coating’s internal structure is enriched with numerous polar functional groups to capture water molecules that penetrate into the inside of the coating. Through combination of these mechanisms, water molecules are effectively sequestered, thereby impeding their penetration into the polyethylene terephthalate glycol (PETG) substrate. The impact of the polydimethylsiloxane content on the triple-action water-resistance mechanisms was thoroughly examined using attenuated total reflection (ATR)-Fourier transform infrared (FTIR), water absorption rate, water swelling rate, and X-ray photoelectron spectroscopy. The low surface energy cross-linked polyurethane coating is applied to the polyethylene terephthalate glycol (PETG) substrate to create a novel composite material with specific mechanical properties and reduced stress relaxation. The composite material remains stable in simulated oral environment with linear swelling rate of 0.58 % upon water absorption. Additionally, the stress release rate of the composite material within 336 h is notably lower (23.64 %) than that of PETG (62.29 %).