Flame retardants mitigate the threat of fire from inherently flammable materials responsible for sustaining a high standard of living. Although bulk flame retardants have proven effective for many years, there is now increased interest in the use of surface treatments to localize flame-retardant chemistry at the exterior of a material, where combustion occurs, in an effort to preserve desirable bulk properties and minimize the amount of additive needed. This Review provides a historical overview that leads to the most promising surface treatments that will help pave the way for developing more effective and non-intrusive flame retardants in the future. The way in which a fire transpires, and the various chemistries and mechanisms used to counteract fire propagation, are discussed. Challenges that remain to improve current flame-retardant surface treatments are also addressed, as the success of these treatments depends on the scalability, durability and ability to impart desired functionality without conferring environmental problems. Fire endangers lives and property worldwide. Significant efforts are underway to develop flame-retardant surface treatments that minimize the weight added to a given object and preserve its intrinsic mechanical properties. This review summarizes the history and latest developments in flame-retardant treatments, as well as outlining the challenges ahead.

Flame-retardant surface treatments

Eco-friendly flame retardant and electromagnetic interference shielding cotton fabrics with multi-layered coatings

Alginate and alginate composites for biomedical applications.

Fully bio-based coating from chitosan and phytate for fire-safety and antibacterial cotton fabrics.

Bioderived flame retardants represent one class of the most promising sustainable additives for creating flame retardant polylactic acid (PLA) because of their marginal impact on the biodegradability of PLA. Ammonium polyphosphate (APP) has demonstrated high flame-retardant effectiveness in PLA but its flame-retardant efficiency remains unsatisfactory even if after modifications. Herein, we report the facile fabrication of core–shell bioderived flame retardants by using APP as the core, and the chitosan (CS)/alginate (AA) bilayer as the shell through self-assembly in aqueous solution. The resultant core–shell flame retardant, APP@CS@AA-nBL (where “BL” is a CS&AA bilayer and “n” denotes 1–3 BL), can endow PLA with improved flame retardancy without negatively affecting the thermal properties. The PLA containing 10 wt % APP@CS@AA-3BL shows the highest LOI value (30.6%) and achieves a UL94 V-0 rating in the vertical burning test. Meanwhile, the cone calorimetry results demonstrate that the peak of the heat release rate and total heat release are respectively decreased by 23% and 11% relative to the PLA bulk. Such enhanced flame retardancy is mainly due to the excellent char-forming capability of APP@CS@AA. Moreover, the inclusion of 10 wt % APP@CS@AA-3BL gives rise to ∼23% increase in the impact strength of PLA possibly because of their interfacial hydrogen-bonding interactions. This work provides a facile and green strategy for preparing highly effective bioderived flame retardants for PLA and thus is expected to expand the practical applications in industry.

Core–Shell Bioderived Flame Retardants Based on Chitosan/Alginate Coated Ammonia Polyphosphate for Enhancing Flame Retardancy of Polylactic Acid

Alginate/gelatin blended hydrogel fibers cross-linked by Ca2+ and oxidized starch: Preparation and properties

Effect of chitosan on the fire retardancy and thermal degradation properties of coated cotton fabrics with sodium phytate and APTES by LBL assembly

In this research, keratin was extracted from the waste wool fiber using sodium sulfite as dissolving agent. The reaction results showed that the optimum conditions were as follows: the dosage of so...

Study on dissolution and recovery of waste wool by sodium sulfide system

Pyrovatex CP which was used as a flame retardant was added into polyvinyl alcohol (PVA) and sodium alginate (SA) aqueous solution. PVA/SA composite fibers modified with Pyrovatex CP (PSC) were prep...

Preparation and characterization of polyvinyl alcohol/sodium alginate/Pyrovatex CP composite fibers

The invention discloses an alginate fiber-containing spunlace fabric capable of absorbing water for gelation, and a preparation method and application of the spunlace fabric. The spunlace fabric is characterized in that the spunlace fabric has an interpenetrating network structure and is composed of 20-30% of sodium alginate fibers and other hydrophilic fibers, wherein the content of the sodium alginate fiber is 20-30%; the spunlace fabric is gelatinized after absorbing water, and the water absorption capacity is greater than or equal to 30g/g; the spunlace non-woven fabric is prepared by adopting continuous production equipment of spunlace non-woven fabric, calcium alginate fibers and other hydrophilic fibers are blended and carded to prepare a fiber net with an interpenetrating network structure at first, then a sodium sulfate aqueous solution is adopted for high-pressure jet flow puncture reinforcement, and finally ultrasonic cleaning and drying are conducted to prepare the spunlacefabric containing the alginate fibers. The preparation method of the spunlace fabric containing the alginate fibers is simple and can be realized on existing industrial equipment with high efficiencyand appropriate in cost, the gelation is generated after water absorbing, and the moisturizing time is more than or equal to 40 minutes, so the spunlace fabric can be used for manufacturing high-grade skin care mask base cloth and high-end medical dressings.

Quan-Quan Wang

Papers

Alginate/gelatin blended hydrogel fibers cross-linked by Ca2+ and oxidized starch: Preparation and properties

Effect of chitosan on the fire retardancy and thermal degradation properties of coated cotton fabrics with sodium phytate and APTES by LBL assembly

Study on dissolution and recovery of waste wool by sodium sulfide system

Preparation and characterization of polyvinyl alcohol/sodium alginate/Pyrovatex CP composite fibers

Alginate fiber-containing spunlace fabric capable of absorbing water for gelation, and preparation method and application of spunlace fabric