Tobacco is one of China's key economic crops, known for its wide distribution, high yield, and renewability. Tobacco stalk fibers (TSFs) share a similar chemical composition to wood fibers, making them a potential reinforcement for plant fiber composites. However, the waste tobacco stalk fibers raw material utilization rate is very low, and wasteful phenomenon is very serious. In this study, we prepared biodegradable TSF/PBAT composites using waste tobacco stalk fibers and polybutylene adipate-co-terephthalate (PBAT) through melt blending and injection molding techniques. The effects of different modifiers on the performance of the composites were systematically investigated, with a particular focus on their influence on the degradation behavior. The results showed that the waste tobacco straw fiber can be used as a reinforcing fiber for PBAT. The addition of modifiers significantly improved the mechanical properties of the composites and effectively slowed down the degradation rate in the soil environment. Among the modifiers, the combined use of maleic anhydride (MA) and hydroxylated multi-walled carbon nanotubes (OM) produced the best results, with the tensile strength and flexural strength of the composite reaching 17.3 MPa and 28.0 MPa, respectively-representing increases of 74.7% and 57.3% compared to the untreated composite. After 16 weeks of soil degradation, the mass loss rate of the MA/OM-modified composite decreased from 10.50 to 6.34%. This study provides a comprehensive exploration of the entire lifecycle of TSF-reinforced PBAT composites and offers important theoretical support for the resource utilization and value-added application of waste tobacco stalks in the field of green composite materials.

This study investigates the rheological and compression behavior of cement-solidified dredged slurry with varying rice straw fiber contents (0-12%). Laboratory tests, including flow tests, viscosity measurements, and compression tests, were conducted to evaluate the influence of straw fibers on material properties. Results show that the slump flow value increased by 8.4% when fiber content increased from 0% to 0.5%, reaching a peak at 3% fiber content. Beyond 5% fiber content, slump flow decreased due to fiber entanglement and water absorption. The dynamic viscosity initially decreased as straw fibers released glucose, retarding cement hydration, but increased as fiber content surpassed 1%, due to increased water absorption and the formation of a fiber network. Yield shear stress also increased with fiber content, peaking at 5% fiber content, and was higher in fiber-reinforced slurries compared to non-fiber mixtures. Compression tests revealed that the compressibility of the solidified slurry increased with higher fiber content at early curing stages (28 days) but decreased with longer curing times (90-180 days). Compression yield stress increased initially with fiber content up to 1% but declined beyond this threshold due to fiber-induced porosity and disrupted cement bonding.

Purpose Straw fiber (SF) is a natural and environmentally friendly material, which has great potential in improving the hydro-mechanical behavior of cemented dredge sediment. However, the treatment mechanisms and optimum application dosage of SF in cemented sediment at high water content are unclear. This study investigates the effect of SF on the shear strength and permeability of cemented sediment at high water content (3 times the liquid limit). Methods Various SF contents (0%, 0.3%, 0.5%, 1%, 3%, 5%, 8% and 12% by mass) and curing ages (3, 7, 14, 28, 60, 90, 180 days) were considered to improve cemented dredged sediment. The effectiveness of the improvement was evaluated through unconfined compression and permeability tests. Results The test results show that there is an optimum SF content of 0.5%, below which the unconfined compression strength (q(u)) of SF-reinforced cemented sediment (SFCS) increased with SF content. Beyond this point, q(u) decreased with SF content. The brittleness index (I-b), which indicates the ductility behavior, increased with SF content across the entire SF range (0-12%). When SF addition was relatively low (< 0.5%), pore filling and bridge effects increased the interface force between SF and sediment particles, resulting in positive effects on the improvement of SFCS strength. However, when SF content exceeded 0.5%, the higher organic matter from SF could suppress pozzolanic reaction, leading to weaker cemented bonding between sediment particles and hence lower sediment strength. Conclusion This study suggests that 0.5% SF should be applied in cemented dredged sediment at high water content to optimize its strength.