Flame-retardant and anti-dripping coating for PET fabric with hydroxyl-containing cyclic phosphoramide

Enhancing the flame retardancy of polylactic acid nonwoven fabric through solvent-free transparent coating

Polylactic acid (PLA) nonwovens, recognized as eco-friendly substitutes for petroleum-based synthetic fibers, face a significant challenge due to their inherent flammability. This work addresses this concern by synthesizing a hyperbranched polyphosphoramide flame retardant (TPDT) through a one-step polycondensation process without using solvent and catalyst. TPDT is subsequently applied to PLA nonwovens using a dip-pad finishing technique. Notably, with a mere 7 wt% weight gain of TPDT, the PLA nonwovens exhibit a substantial increase in the limited oxygen index (LOI) value, reaching 32.3 %. Furthermore, the damaged area in the vertical burning test is reduced by approximately 69.2 %. In the cone calorimeter test, 17 wt% weight gain of TPDT results in a 51.4 % decrease in peak heat release rate and a 56.0 % reduction in total heat release compared to the control PLA. Additionally, char residue increases from 1.5 wt% to 31.1 wt% after combustion. The strong affinity between TPDT and PLA molecules persists even after repeated abrasion, ensuring sustained flame retardancy. Importantly, the introduction of TPDT also imparts increased softness to the PLA nonwovens. This work addresses this concern by synthesizing a hyperbranched polyphosphoramide flame retardant (TPDT) through a solvent-free, catalyst-free, and one-step polycondensation process.

Environmental benign foam finishing with a hyperbranched polyphosphonate flame retardant for polyethylene terephthalate fabric

It is still a big challenge for textile industry in improving fire resistance and reducing melt dripping with minimal loss on the physical properties of polyethylene terephthalate (PET) fabrics. In this work, a highly-effective hyperbranched flame retardant (DT) was first synthesized by ester exchange without using any organic solvent. Then, the DT foam was prepared and blade coated on PET fabric to improve the fire performance. The prepared PET fabric with only 2.7% weight gain of DT was self-extinguished and did not produce any molten dripping during the vertical flammable test. The peak heat release rate and total heat release of the PET fabric sample with 19.4% DT were decreased by 42.0% and 57.1%, respectively compared with that of the control PET. Besides, the as-prepared PET fabric sample showed better physical properties such as breaking strength, vapor permeability, air permeability, antistatic property, and softness than the control PET fabric sample. The DT foam finishing process did not involve any organic solvent and consumed less water and energy compared with conventional fabric treatments. It is expected that this work provides a facile and eco-friendly strategy for fabricating flame retardant PET fabric with excellent comprehensive performances.

Mechanical, Thermal Stability, and Flame Retarding Properties of Phosphorus-Modified PET Blended with DOPO-POSS

In this study, an antidroplet flame retardant system based on FRPET (phosphorus-containing copolyester) is constructed with DOPO-POSS (polyhedral oligomeric silsesquioxane containing DOPO) as an additive flame retardant. It is demonstrated that DOPO-POSS has good dispersibility at a lower amount. When the amount of DOPO-POSS is 9 wt %, the residual char of DOPO-POSS/FRPET at 700 °C increases to 23.56 from 18.16% of FRPET, and the maximum thermal weight loss rate also reduces. What is more is that the limiting oxygen index increases to 33 from 26% of FRPET. The flame burning time is shortened to 4.95 from 20.8 s, the phenomenon of self-extinguishing of the fire occurs, and the vertical combustion level is increased from V-2 to V-0. Compared with FRPET, the peak of the heat release rate decreases by 66.0%, the total heat release decreases by 32.4%, the flame retardancy index (FRI) reaches an excellent value, and the condensed-phase products significantly improve. The Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), thermogravimetric-FTIR (TG-FTIR), and pyrolysis-gas chromatograph/mass spectrometry (Py-GC/MS) results indicate that DOPO-POSS contributes to the formation of char layers and decomposes to generate free radicals with a quenching effect. In a word, DOPO-POSS is an effective radical trapper and charring agent for PET and exerts a flame retardancy effect in gaseous and condensed phases simultaneously.

Designing Photothermal Superhydrophobic PET Fabrics via In Situ Polymerization and 1,4-Conjugation Addition Reaction

This study demonstrates a simple and fast method to integrate superhydrophobicity, UV protection, and photothermal effect onto PET fabrics. The surface of PET fabric forms a hierarchical rough structure through in situ oxidative polymerization of the pyrrole (Py). The 1,4-conjugate addition reaction between pentaerythritol tetraacrylate, 3-aminopropyltriethoxysilane, and octadecyl acrylate not only endows the PET fabric with superhydrophobicity but also forms a cross-linked network structure which improves the stability of multifunctional coatings on the surface of the PET fabric. In addition, the wettability of the prepared PET fabric is investigated by adjusting the Py monomer and octadecyl acrylate concentration. The results reveal that the prepared PET fabrics exhibit obviously superhydrophobic behavior with a contact angle of 155.8°. The surface temperature of the superhydrophobic PPy/PET fabric can rise to 91 °C under a simulated sunlight which is much higher than the pristine PET fabric, while reaching basically the same steady-state in five heating/cooling cycles. The prepared PET fabric also possesses excellent self-cleaning, UV shielding, and solar light absorption performances. Furthermore, the superhydrophobic PET fabric exhibited excellent stability against 180 °C high temperature, strong UV radiation, different pH solutions and organic solvent erosion, 8 h washing tests, and 25 sandpaper abrasion cycles. These findings provide a path for the future development of multifunctional fabrics using fluorine-free environmentally friendly materials.