Amine Salt Thickening of Intumescent Multilayer Flame Retardant Treatment

Durable multifunctional cotton fabric with superior biocidal efficacy and flame retardancy based on an ammonium phosphate N-halamine

Multifunctional textiles have become the mainstreams along with development of textile industry and the increased need of public. But a facile fabrication method with well-balance of multiple functions is still a challenge. In this work, an ammonium salt of tris(methylphosphonate)aminomethane (TAMPU), which can directly react with cellulose molecules and transform to N-halamine antibacterial structure, was easily synthesized and used to achieve multifunctional cotton fabric. As a result, the modified cotton fabric of 15.8 % weight gain exhibited excellent fire resistance with LOI value of 33.8 % and self-extinguishing behavior. Due to the good char-forming capacity of TAMPU, strong heat suppression was achieved and the peak of heat release rate (PHRR) and total heat release (THR) were decreased by 87.6 % and 60.8 %, respectively. Besides, the modified samples presented outstanding bactericidal effects, and all of S. aureus and E. coli could be inactivated within 5 min without dissolution phenomenon. Furthermore, the TAMPU-modified cotton fabric owned good washing durability and LOI value was remained at 29.8 % after 50 washing cycles. This TAMPU multifunctional modification had slight influence on the mechanical property and air permeability of cotton fabric. Thus, this work provides a convenient and friendly way to fabricate multifunctional flame-retardant and antibacterial cotton fabric.

Synergistic Fire Resistance of Nanobrick Wall Coated 3D Printed Photopolymer Lattices

Photopolymer additive manufacturing has become the subject of widespread interest in recent years due to its capacity to enable fabrication of difficult geometries that are impossible to build with traditional manufacturing methods. The flammability of photopolymer resin materials and the lattice structures enabled by 3D printing is a barrier to widespread adoption that has not yet been adequately addressed. Here, a water-based nanobrick wall coating is deposited on 3D printed parts with simple (i.e., dense solid) or complex (i.e., lattice) geometries. When subject to flammability testing, the printed parts exhibit no melt dripping and a propensity toward failure at the print layer interfaces. Moving from a simple solid geometry to a latticed geometry leads to reduced time to failure during flammability testing. For nonlatticed parts, the coating provides negligible improvement in fire resistance, but coating of the latticed structures significantly increases time to failure by up to ≈340% compared to the uncoated lattice. The synergistic effect of coating and latticing is attributed to the lattice structures' increased surface area to volume ratio, allowing for an increased coating:photopolymer ratio and the ability of the lattice to better accommodate thermal expansion strains. Overall, nanobrick wall coated lattices can serve as metamaterials to increase applications of polymer additive manufacturing in extreme environments.

Biorenewable Polyelectrolyte Nanocoating for Flame-Retardant Cotton-Based Paper

Cotton-based raw paper, made of 100% cellulose, is used to make humidity-sensing, cottonid for bio-architecture applications. Despite its renewability and excellent mechanical properties, it is inherently flammable. In an effort to reduce its flammability, thin films of fully renewable and environmentally benign polyelectrolytes, chitosan (CH) and phytic acid (PA), were deposited on raw paper via layer-by-layer (LbL) assembly. Only four bilayers (BL) of the CH/PA coating are required to achieve self-extinguishing behavior, with a 69% reduction in peak heat release rate measured by microscale combustion calorimetry. These results demonstrate that this renewable intumescent LbL-assembled film provides an effective flame-retardant treatment for these environmentally friendly, climate-adaptive construction materials and could potentially be used to protect many cellulosic materials.

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.

Efficient Heat Shielding of Steel with Multilayer Nanocomposite Thin Film

In an effort to protect metal substrates from extreme heat, polymer-clay multilayer thin films are studied as expendable thermal barrier coatings. Nanocomposite films with a thickness ranging from 2 to 35 μm were deposited on steel plates and exposed to the flame from a butane torch. The 35 μm coating, composed of 14 deposited bilayers of tris(hydroxymethyl)aminomethane (THAM)-buffered polyethylenimine (PEI) and vermiculite clay (VMT), decreased the maximum temperature observed on the back side of a 0.32 cm thick steel plate by over 100 °C when heated with a butane torch. Upon exposure to high temperature, the polymer and amine salt undergo pyrolysis and intumesce, subsequently forming a char and blowing gas. The char encases the nanoclay platelets, and a ceramic bubble is formed. The macro-scale bubble, in tandem with the nanocomposite coating properties, increases resistance to heat transfer into the underlying metal substrate. This heat shielding behavior occurs through radiative effects and low aggregate through-plane conductivity resulting from multilayer nanodomains and intumesced porosity (i.e., conduction through the gas as the film expands to form a ceramic bubble). These relatively thin and lightweight films could be used to protect important metal parts (in automobiles, aircraft, etc.) from fire-related damage or other types of transient high-temperature situations.

Mixed solvent synthesis of polydopamine nanospheres for sustainable multilayer flame retardant nanocoating

Mixed solvent synthesized polydopamine is used in a multilayer nanocoating for protecting foam from fire. The use of LbL technology significantly reduces the processing time often observed with traditional methods polymerized from buffer.