Expansive soil, characterized by significant swelling-shrinkage behavior, is prone to cracking under wet-dry cycles, severely compromising engineering stability. This study combines experimental and molecular dynamics (MD) simulation approaches to systematically investigate the improvement effects and micromechanisms of polyvinyl alcohol (PVA) on expansive soil. First, direct shear tests were conducted to analyze the effects of PVA content (0 %-4 %) and moisture content (30 %-50 %) on the shear strength, cohesive force, and internal friction angle of modified soil. Results show that PVA significantly enhances soil cohesive force, with optimal improvement achieved at 3 % PVA content. Second, wet-dry cycle experiments revealed that PVA effectively suppresses crack propagation by improving tensile strength and water retention. Finally, molecular dynamics simulations uncovered the distribution of PVA between montmorillonite (MMT) layers and its influence on interfacial friction behavior. The simulations demonstrated that PVA forms hydrogen bonding networks, enhancing interlayer interactions and frictional resistance. The improved mechanical performance of PVAmodified soil is attributed to both nanoscale bonding effects and macroscale structural reinforcement. This study provides theoretical insights and technical support for expansive soil stabilization.

The application of coating materials to regulate nitrogen release is a crucial strategy for minimizing fertilizer loss and alleviating agricultural nitrogen pollution. However, it remains a significant challenge to develop ecofriendly coatings that are both biodegradable and effective in slow-release. In this study, Ca/Al layered double hydroxides (LDHs) were incorporated into a conventional polyvinyl alcohol/polyvinylpyrrolidone (PVA/ PVP) matrix to create PVA/PVP-LDHs composite films. The inclusion of LDHs (1.0 %, w/w) resulted in a 32 % enhancement in water resistance, a 10 % reduction in water vapor/ammonia permeability, and a 16 % improvement in mechanical properties. These enhanced performances by addition of LDHs were attributed to the combined effects of the tortuous diffusion pathways, and the formation of robust hydrogen bonding networks between the hydroxyl groups of LDHs and PVA/PVP at the organic-inorganic interface. These interactions could reduce free hydroxyl groups on the film surface, leading to hydrophobicity and structural integrity. The composite films exhibited significantly reduced nitrogen permeability under various pH conditions, indicating the improved stability in both acidic and alkaline soil environments. Degradation experiments revealed that the composite film lost 40 % of its mass over 120 days, with a half-life only 8.0 % longer than pure PVA/PVP. These results indicated that the incorporation of LDHs had minimal impact on biodegradability, maintaining the environmental compatibility of the films. These findings highlight the potential of PVA/PVP-LDHs composite films as sustainable, eco-friendly, and efficient slow-release fertilizer coatings, offering a practical solution for improving nitrogen use efficiency and reducing agricultural nitrogen pollution.

Food packaging is one of the most commonly used materials today due to its affordability and convenience. However, this type of packaging is challenging to handle after use, leading to significant environmental waste since it is often made from petrochemical polymers that take a long time to decompose. Polyvinyl alcohol (PVA) is a low-cost, safe, and biodegradable polymer with high potential for food packaging, offering a solution to waste issues in the polymer industry. However, its limited hydrophilicity, bactericidal properties, and poor performance in humid conditions hinder its practicality. Enhancing the mechanical properties and water resistance of PVA-based composite films can significantly improve their applicability, particularly in food packaging. In this study, nanocomposite films based on PVA were reinforced with nanocellulose fiber (CNF) and Ag nanoparticles (AgNPs), and cross-linked using citric acid (CA) through the film casting method. The incorporation of CNF and AgNPs improved the structural integrity and thermal stability of the film, while CA crosslinking significantly enhanced water resistance and mechanical properties. The (PVA/CNF/Ag)-CA film exhibited the highest tensile strength (89.44 MPa), Young's modulus (3.29 GPa), and water contact angle (similar to 90 degrees), alongside the lowest water absorption (78.6 %) and a reduced water vapor transmission rate of 6.62 g x h(-1) x m(-2). Compared to pure PVA film, the resulting crosslinked nanocomposite films showed a 32.3 % increase in modulus and a 22.64 % increase in tensile strength. Additionally, the (PVA/CNF/Ag)-CA film exhibited higher thermal stability with 13 % more residue content than uncrosslinked counterparts, reduced moisture absorption, minimal swelling, and water insolubility. However, the CA crosslinking process promoted AgNP aggregation, reducing the antibacterial activity of the (PVA/CNF/Ag)-CA film against Staphylococcus aureus and Escherichia coli, and slowed down its biodegradation in soil. Nevertheless, after seven days of storage under both aerobic and anaerobic conditions, the nanocomposite coatings effectively minimized mass loss and microbial growth on fresh chili peppers. These results highlight the synergistic contribution of CNF/Ag reinforcement and CA crosslinking in enhancing the mechanical strength, thermal stability, and water resistance of PVA-based films for potential food packaging applications.

Mulching films serve various functions, such as temperature regulation, moisture retention, and weed suppression. They can substantially increase crop yields and are widely adopted in agricultural practices. However, the use of traditional plastic mulch films is limited by their difficult recycling processes and poor biodegradability, leading to soil contamination and negatively affecting crop growth. Consequently, eco-friendly alternatives are gaining attention as replacements for conventional petroleum-based films in agricultural applications. Enhancing the performance of these eco-friendly films remains a crucial challenge. Traditional polyvinyl alcohol (PVA) films have inherent limitations, including low mechanical strength and poor water resistance. In this work, a PVA/sodium alginate (SA)/glycerol (GLY)/glutaraldehyde (GA) film was prepared that is biodegradable, demonstrates superior mechanical properties, and offers exceptional transparency through glutaraldehyde crosslinking. The impact of GA on films was examined using characterization techniques. The findings revealed that the composite film has a uniform, compact surface with no observable holes or aggregation. The mechanical performance and water vapor barrier properties (WVP) of the film were significantly enhanced after GA crosslinking. The tensile strength and elongation at the break of the PVA/SA/GLY/GA film reached 33.73 MPa and 362.89%, respectively. This work offers a straightforward approach to the development of sustainable agricultural materials.

The growing significance of biodegradable plastics for environmental protection underscores the need to enhance their performance of degradation in natural environments. This study prepared PLA/PVA blends with varying ratios to assess the impact of PVA on their thermal properties, mechanical properties, and degradation behavior. Results indicated that as the PVA content increased from 0 to 100%, both tensile and flexural strengths initially decreased before increasing. Furthermore, the decomposition temperature of the blends decreased by 18-35 degrees C as the PVA content increased. Specifically, pure PLA exhibited a thermal degradation temperature of 332 degrees C; while, the blend with 80% PVA showed a reduced temperature of 296 degrees C. Hydrolysis tests showed that weight loss increased significantly with higher PVA content, with the 20PLA/80PVA blend losing 78.9% of its weight after 30 days, compared to only 0.13% for pure PLA. The mechanical properties of the 20PLA/80PVA blend decreased by 98.31% in tensile strength and 79.19% in hardness after 30 days of hydrolysis, demonstrating accelerated degradation. Soil degradation tests further revealed that the 20PLA/80PVA blend lost over 85% of its weight within 20 days; while, pure PLA lost less than 1%. These results suggest that altering the PLA/PVA ratio can substantially enhance degradation rates, offering valuable insights for the development of efficient biodegradable plastics.

Earthen sites of substantial significance have experienced considerable degradation. Chemical stabilization is a commonly used restoration technique, and temperature effects are a critical factor for this degradation, particularly for outdoor sites. However, significant gaps exist in research on the threats posed to stabilization materials by elevated temperatures. Therefore, this study investigates polyvinyl alcohol (PVA) as a representative organic stabilizer to examine the effects of temperature variations from 20 degrees C to 400 degrees C on mechanical properties and microstructure of PVA-stabilized soil. A combination of macro- and micro-scale characterization techniques, alongside theoretical modelling, is employed. The results show that constitutive models inspired by concrete effectively characterize the stress-strain behavior of PVA-stabilized soil under high-temperature conditions. Unconfined compressive strength of PVA-stabilized soil significantly decreases from 0.90-2.25 to 0.17-0.40 MPa as the temperature increases from 200 degrees C to 300 degrees C, which is attributed to structural changes of soil induced by thermal decomposition of PVA. The thermal degradation of PVA can generate harmful gases and cause a significant colour change. Therefore, organic materials like PVA are suitable for the restoration of earthen sites in non-fire-risk areas. However, caution is necessary when applying these materials in earthen sites at risk of fire hazards, especially those with vegetation cover.

This study focused on synthesizing polyvinyl alcohol (PVA) utilizing glutaraldehyde (GA) as a crosslinking agent and silicon dioxide (SiO2) nanopowder with titanium dioxide (TiO2) nanopowder to reduce or prevent the hydrophilic property of PVA. Integrating SiO2 and TiO2 into the PVA boosted the hydrophobicity, thermal properties, and self-cleaning of the PVA film. The characteristic properties of PVA/GA, PVA/SiO2/GA, and PVA/SiO2/TiO2/GA nanocomposites polymer membranes were investigated by gel content, swelling capacity, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction patterns (XRD), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), and contact angle. The resulting PVA/5%SiO2/1%TiO2/GA nanocomposite exhibits much better physical properties than PVA/GA hydrogel (water absorbency from 3.1 g/g to 0.07 g/g and contact angel from 0 degrees to 125 degrees). In addition, the nanocomposite retains very low swelling properties. These prepared nanocomposites are promising in a variety of applications such as sand soil stabilizers, construction, and building works where they exhibit excellent water resistance performance. This study introduces a novel approach for creating hydrophobic polymeric membranes from hydrophilic polymeric materials to stabilize sandy soil effectively.

Conventional biochar-based fertilizers, which typically consist of a mixture of biochar, chemical fertilizers, and additives, offer benefits but often exhibit rapid nutrient release, limiting their long-term effectiveness. Herein, we explored the enhancement of slow-release performance in biochar-based compound fertilizers by incorporating a kaolinite-infused polyvinyl alcohol/starch (K-PVA/ST) coating, resulting in a new formulation denoted as KPVA/ST-BCF. The results demonstrated that, compared to traditional NPK fertilizers, nitrogen leaching from KPVA/ST-BCF in soil column leaching tests was reduced to 19.1 % over 29 days, while phosphorus and potassium leaching were reduced to 48.5 % and 72.3 %, respectively. Mechanistic investigations revealed that the inclusion of kaolinite in the PVA/ST matrix reduces swelling, improves water retention, and enhances mechanical properties, leading to a more gradual and sustained release of nutrients. Field trials on reclaimed land showed that KPVA/ST-BCF increased wheat yield by up to 100 % compared to conventional NPK treatment. It also enhanced soil nitrogen content and organic matter, with organic matter reaching 22.7 g/kg at grain maturity. The economic assessment indicated that despite higher initial production costs compared to conventional NPK fertilizers, K-PVA/ST-BCF offers higher nutrient use efficiency, reduced management costs, and a net profit increase of $1525.86 per hectare.

The research focused on enhancing the preservation and flowability of palm date powder using isomalt-incorporated polyvinyl alcohol (PVAC/ISO) films for food storage applications. Various concentrations of isomalt (ISO) were integrated into PVAC films, and their properties were thoroughly analyzed. The incorporation of ISO led to significant changes in the films' characteristics, including increased thickness (from 0.09 mm for pure PVAC to 0.31 mm for PVAC/ISO3) and moisture content (from 10.15% in PVAC to 16.36% in PVAC/ISO3). Mechanical properties also improved, with tensile strength reaching 84.95 MPa and elongation at break increasing to 79.38% for PVAC/ISO2. Additionally, antioxidant properties were enhanced, as evidenced by the total phenolic content of 128.09 mu g/g, DPPH radical scavenging activity of 21.55%, and ABTS radical scavenging activity of 38.21% for PVAC/ISO3. The films showed a significant reduction in water vapor permeability (2.756 x 10-10 g. m-1 s-1 pa-1 for PVAC/ISO3) and increased solubility in water (32.68% for PVAC/ISO3). Furthermore, the biodegradability of the films in moist soil conditions improved with the addition of ISO. The storage tests with palm date powder demonstrated that PVAC/ISO films effectively maintained the powder's flowability and prevented moisture-induced caking, confirming their potential as an effective food packaging material for powdered food products. This study highlights the benefits of using PVAC/ISO films in extending the shelf life and preserving the quality of palm date powder while also offering a sustainable solution for the packaging industry. However, further studies are needed to explore the long-term stability and applicability to other hygroscopic food products.

This research investigates the production of biodegradable films using a combination of gum odina (GO) and polyvinyl alcohol (PVA) with varied ratio. The study focuses on the chemical, physical, and mechanical properties of PVA-GO composite films, emphasizing how versatile and biodegradable they may be for a range of packaging applications. Solvent-cast PVA-GO films with different ratios are subjected to a methodical analytical process to determine several parameters like mechanical qualities, thermal stability, biodegradability in soil, contact angle, transparency, water vapor permeability, moisture content, thickness, density, water solubility, microstructure, and FTIR analysis. The outcomes demonstrate that GO improves UV barrier qualities and water vapor permeability. Additionally, the films showed notable biodegradability, acceptable thermal stability, and mechanical qualities. In short, PVA-GO films can provide an eco-friendly packing substitute with adaptable qualities fit for a range of uses. Therefore, this research may further contribute promising information in the field of biodegradable packaging materials in the future. image