Functionalization of cellulosic fibers with a kaolinite-TiO2 nano-hybrid composite via a solvothermal process for flame retardant applications

Phytic acid-induced durable fire-proof and hydrophobic complex coating for versatile cotton fabrics

To address the current development requirements for multifunctional cotton fabrics, a phytic acid-induced flame-retardant hydrophobic coating containing nitrogen (N), phosphorus (P), and silicon (Si) was grafted on the surface of cotton fabrics using a facile step-by-step immersion method. The limiting oxygen index value improved to 31.2 %, decreasing to 26.7 % after 50 laundering cycles, while the fabric remained self-extinguishing effect in the vertical flammability test and showed a water contact angle of 126.1°. Cone calorimetry test showed that the modified fabric could not be ignited at the irradiation heat flux of 35 kW/m2. When the irradiation heat flux was raised to 50 kW/m2, there was a significant decline in the peak heat release rate of the modified cotton fabric, which decreased by 43.2 % to a remarkably low value of 114.0 kW/m2, indicating excellent flame-retardant properties. The analysis of the flame-retardant mechanism uncovered that the modified coating exhibited a significant dual flame-retardant mechanism involving both the gaseous phase and the condensed phase. Additionally, the oil-water separation tests revealed that the separation efficiency of the modified cotton fabrics was as high as 97.1 % and remained around 96 % after 10 cycles, which made them reusable for the clean-up of hazardous chemicals.

Characterization of Atlantic Forest Tucum (Bactris setosa Mart.) Leaf Fibers: Aspects of Innovation, Waste Valorization and Sustainability

This study investigates the fibers of tucum (Bactris setosa Mart.), a palm species native to the Atlantic Forest. The fibers manually extracted from tucum leaves were characterized to determine important properties that help with the recognition of the material. The fibers were also subjected to pre-bleaching to evaluate their dyeing potential. The extraction and characterization of these fibers revealed excellent properties, making this material suitable not only for manufacturing high-quality textile products but also for various technical and engineering applications. The characterization techniques included SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy), TGA (Thermogravimetric Analysis), and tensile strength tests. These analyses showed that tucum fibers possess desirable properties, such as high tensile strength, with values comparable to linen but with a much finer diameter. The fibers also demonstrated good affinity for dyes, comparable to cotton fibers. An SEM analysis revealed a rough surface, with superficial phytoliths contributing to their excellent mechanical strength. FTIR presented a spectrum compatible with cellulose, confirming its main composition and highly hydrophilic nature. The dyeing tests indicated that tucum fibers can be successfully dyed with industrial direct dyes, showing good color yield and uniformity. This study highlights the potential of tucum fibers as a renewable, biodegradable, and sustainable alternative for the transformation industry, promoting waste valorization.

Relevance of the Iron Distribution in Natural Smectite Clays for the Thermal Stability of PMMA-Clay Nanocomposites

Polymer-clay nanocomposites have greater thermal stability compared to the pristine polymer matrix. This can be attributed to the physical barrier provided by the inclusion of 2D clay nanoparticles (especially of the smectite group), together with radical trapping related to the distribution of specific 3d atoms in the inorganic phase. To elucidate the relevance of the Fe3+ distribution in this synergic effect, the iron atoms present in octahedral sheets of natural nontronite clay (Non, 5.6 wt % Fe) or in maghemite (M) nanoparticles (γ-Fe2O3) were incorporated in a poly(methyl methacrylate) (PMMA) matrix. Na-laponite (Lap) clay was used to evaluate the contribution of the diffusion barrier effect to the increased thermal stability of a PMMA-Lap nanocomposite, as evidenced by the upshift of the thermogravimetric (TGA) curve compared to that for PMMA. The contribution of radical trapping to the thermal stability of the PMMA-Non nanocomposite was evidenced by a significant shift of the Fe K-edge rising edge position by -4.5 eV after iron reduction by heating in N2, while similar treatment of pristine nontronite did not lead to a significant rising edge shift in the X-ray absorption spectra (XAS). This downshift demonstrated the reduction of Fe3+ to Fe0, induced by the sequestration of radicals formed by PMMA depolymerization. Raman spectroscopy analysis evidenced the formation of graphitic char deposits above 400 °C, further improving the thermal stability of PMMA-Non by providing an additional physical barrier to mass transport. A fourth contribution of well-dispersed iron was the abstraction of carbon from the char by the iron carburization reaction, which hindered CO2 formation by oxidative coking. In contrast, no relevant contribution of graphitic layer deposition was observed for the PMMA-M-Lap nanocomposite, where its improved thermal stability was only due to the combined contributions of the gas diffusion barrier effect and radical trapping by iron atoms. The maghemite effectively captured the radicals confined by the clay sheets, resulting in significant stabilization of the nanocomposite, with a shift of the mass loss of the PMMA-M-Lap nanocomposite compared to PMMA-Lap.

Zinc Hydroxystannate/Carbon Nanotube Hybrids as Flame Retardant and Smoke Suppressant for Epoxy Resins

Novel hybrid flame retardants containing zinc hydroxystannate and carbon nanotubes (ZHS-CNTs) were synthesized using the coprecipitation method, and the structure and morphology of ZHS-CNTs were investigate using an X-ray powder diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and thermogravimetric analyzer (TGA). Then, the ZHS, CNTs and ZHS-CNTs were incorporated into EP, respectively, and the flame-retardant and smoke inhibition performance of the composites were compared and studied. Among the three composites, the EP/ZHS-CNT composites have the highest improvements on the fire resistance and smoke inhibition properties. With only 2.0 wt.% ZHS-CNT hybrids, the pHRR of EP/ZHS-CNT composite materials is reduced by 34.2% compared with EP. Moreover, the release of toxic gases including CO, CO2 and SPR from the composites was also effectively inhibited. The mechanisms of flame retardant and smoke inhibition were investigated and the improved properties were generally ascribed to the synergistic flame-retardant effects between ZHS and CNTs, the catalyzing effect of ZHS and the stable network structure of CNTs.

Fibrous microplastics released from textiles: Occurrence, fate, and remediation strategies

Microplastics (MP), i.e., particles measuring less than 5 mm in size, are considered emerging pollutants. The ubiquity of MP is causing great concern among environmental and public health agencies. Anthropogenic activities are responsible for the extensive dispersal of MP in nature. Adverse effects on living organisms, interactions with other contaminants occurring in the environment, and the lack of effective degradation/removal techniques are significant issues related to MP. Most MP found in nature are fibrous (FMP). FMP originate from textile products, mainly synthetic fibers (e.g., polyester). Synthetic fibers are intensively used to produce countless goods due to beneficial characteristics such as high mechanical resistance and economic feasibility. FMP are ubiquitous on the planet and impart lasting adverse effects on biodiversity. Data on the consequences of long-term exposure to these pollutants are scarce in the literature. In addition, few studies address the main types of synthetic microfibers released from textiles, their occurrence, adverse effects on organisms, and remediation strategies. This review discusses the relevant topics about FMP and alerts the dangers to the planet. Furthermore, future perspectives and technological highlights for the FMP mitigation/degradation are presented.