Improving the flame retardant properties of polyester‐cotton blend fabrics by introducing an intumescent coating via layer by layer assembly

In-situ polymerization of phosphorus/nitrogen flame-retardant coating for polyester/cotton blend fabrics with superior durability

The durable flame-retardant functional coating of polyester/cotton (T/C) blend fabrics is both interesting and challenging. In this study, a novel in-situ polymerization strategy for phosphorus/nitrogen-based flame-retardant on T/C blend samples was developed through the polycondensation of tetramethylolphosphonium sulfate, dicyandiamide, and anionic cyclic phosphate ester. The chemical structure of the polycondensation compounds, as well as the surface morphology, combustion behavior, flame-retardant capacity, washing durability and flame-retardant mechanism of the coated T/C blend fabrics, were investigated. The coated T/C blend fabrics demonstrated excellent self-extinguishing performance, with the damaged length decreasing to as low as 8.0 cm and the LOI reaching 28 %. Moreover, the peak heat release rate of the coated T/C blend fabrics decreased by 39.7 %. The superior flame retardancy can be attributed to the enhanced dehydration and carbonization by phosphate groups in the condensed phase, as well as the quenching effect and diluting effect in the gas phase. Additionally, the coated T/C blend fabrics exhibited remarkable washing durability and still achieved self-extinguishing after 65 washing cycles, and the in-situ deposition of insoluble three-dimensional polycondensation compounds onto the T/C blend fabrics was beneficial. The flame-retardant coating had a minor impact on the whiteness, tensile strength and breathability of the T/C blend fabrics.

Eco-friendly multifunctional coating for polyester-cotton blended fabrics with superior flame retardancy and antibacterial properties

Since the fire hazards of polyester-cotton blended (PTCO) fabrics and the hidden dangers of bacterial infection concerns caused by the contained cotton fiber, the design of flame retardant and antibacterial PTCO fabrics has received considerable attention. In this work, flame-retardant PTCO fabrics with satisfactory antibacterial properties were fabricated via a convenient and eco-friendly impregnation treatment involving guanidine phosphate (GP) and polyethylenimine (PEI). The prepared PTCO fabrics demonstrated excellent flame retardancy with a high limiting oxygen index value of 30.5 % and self-extinguishing capability, the damaged length was only 34 mm in the vertical flammability test. Furthermore, the peak heat release rate and the total heat release of coated PTCO fabrics were reduced significantly by 49 % and 38 %, respectively, indicating a substantial enhancement in fire safety. According to the analysis of the char residues and volatiles, GP presented great catalytic carbonization property, and PEI assisted the formation of the dense and stable carbon layer. The stable carbon layer effectively restricted mass and oxygen transfer between the PTCO fabrics and the environment. In addition, the introduction of PEI also produced more nonflammable gases to enhance the flame retardancy of the PTCO fabrics. Importantly, the GP/PEI coating barely deteriorate the physical and mechanical properties of the PTCO fabrics. The antibacterial rate of the GP/PEI-coated PTCO fabrics against Escherichia coli and Staphylococcus aureus was 99.99 %, similar to that of GP-coated fabrics, indicating the efficacy antibacterial properties of GP, and the addition of PEI did not compromise the antibacterial properties of GP. This work offers an efficient and simple approach to producing multifunctional PTCO fabrics with excellent flame retardancy and antibacterial properties, which are hopeful to expand the promising application of PTCO fabrics.

Fabrication of P/N/B-Based Intumescent Flame-Retardant Coating for Polyester/Cotton Blend Fabric

Polyester/cotton (T/C) blend fabrics are highly flammable due to the particular "scaffolding effect". In this work, an intumescent flame retardant (IFR) agent containing P, N, and B was designed and synthesized using bio-based phytic acid, pentaerythritol, boric acid, and urea. The IFR compounds were deposited onto a T/C blend fabric by the surface-coating route. The chemical structure of IFR agent and its potential cross-linking reactions with T/C fibers were characterized. The morphology, thermal stability, heat-release ability, flame retardancy, and mechanism of coated T/C blend fabrics were explored. The self-extinguishing action was observed for the coated T/C blend fabric with a weight gain of 13.7%; the limiting oxygen index (LOI) value increased to 27.1% versus 16.9% for a pristine one. Furthermore, the intumescent flame retardant (IFR) coating imparted T/C blend fabrics with high thermal stability and significantly suppressed heat release by nearly 50%. The char residue analyses on morphology and element content confirmed the intumescent FR action for coated T/C blend fabrics. The prepared IFR coating has great potential to serve as an eco-friendly approach for improving the flame retardancy of T/C blend textiles.

Layer-by-Layer Deposition: A Promising Environmentally Benign Flame-Retardant Treatment for Cotton, Polyester, Polyamide and Blended Textiles

A detailed review of recent developments of layer-by-layer (LbL) deposition as a promising approach to reduce flammability of the most widely used fibers (cotton, polyester, polyamide and their blends) is presented. LbL deposition is an emerging green technology, showing numerous advantages over current commercially available finishing processes due to the use of water as a solvent for a variety of active substances. For flame-retardant (FR) purposes, different ingredients are able to build oppositely charged layers at very low concentrations in water (e.g., small organic molecules and macromolecules from renewable sources, inorganic compounds, metallic or oxide colloids, etc.). Since the layers on a textile substrate are bonded with pH and ion-sensitive electrostatic forces, the greatest technological drawback of LbL deposition for FR finishing is its non-resistance to washing cycles. Several possibilities of laundering durability improvements by different pre-treatments, as well as post-treatments to form covalent bonds between the layers, are presented in this review.

Functionalization of PET with Phosphazene Grafted Graphene Oxide for Synthesis, Flammability, and Mechanism

Significant improvement in the fire resistance of polyethylene terephthalate (PET) while ensuring its mechanical properties is a tremendous challenge. A novel flame retardant (GO-HCCP, graphene oxide-hexachlorocyclotriphosphazene) was synthesized by nucleophilic substitution of the graphene oxide (GO) and hexachlorocyclotriphosphazene (HCCP) and then applied in PET by an in situ polymerization technique. The scanning electron microscope (SEM) showed a better dispersion of GO-HCCP than GO in the PET matrix. The char yield at 700 °C increased by 32.5% with the addition of GO-HCCP. Moreover, the peak heat release rate (pHRR), peak smoke produce rate (pSPR)and carbon monoxide production (COP)values significantly decreased by 26.0%, 16.7% and 37.5%, respectively, which indicates the outstanding fire and smoke suppression of GO-HCCP. In addition, the composites exhibited higher elastic modulus and tensile strength without compromising the toughness of PET matrix. These significantly reduced fire hazards properties are mainly attributed to the catalytic carbonation of HCCP and the barrier effect of GO. Thus, PET composites with good flame-retardant and mechanical properties were prepared, which provides a new strategy for further flame retardant PET preparation.

Eco-friendly flame retardant and dripping-resistant of polyester/cotton blend fabrics through layer-by-layer assembly fully bio-based chitosan/phytic acid coating

Polyester/cotton blend fabrics are widely used in clothing and household textiles which combine the comfort of cotton and excellent mechanical strength of polyester. However, their high flammability due to the special "wick effect" resulting from the different thermal decomposition process of cotton and polyester causes greatly potential fire hazards. In this study, fully bio-based intumescent flame retardant (IFR) coating of chitosan/phytic acid (CS/PA) was layer-by-layer (LBL) assembly constructed on polyester/cotton blend fabrics. The LOI value of polyester/cotton blend fabric which was LBL assembly coated by 20 bilayers CS/PA reached 29.2%. And the dripping of coated fabric was eliminated. The results of cone calorimetry test confirmed CS/PA coating greatly improved the flame retardancy of polyester/cotton blend fabrics. Thermogravimetric analysis (TGA) results showed CS/PA coating changed the thermal decomposition process to promote the char formation of polyester/cotton blend fabrics. CS/PA coating on fabric could form the IFR system which acts through both condensed phase action by the catalysis dehydration reaction to forming stable char and gas phase action by the blowing effect. This research provides a new strategy to eco-friendly flame retardant and dripping-resistant for polyester/cotton blend fabrics by bio-based IFR system through facile LBL assembly method.