Atom-economic synthesis of an oligomeric P/N-containing fire retardant towards fire-retarding and mechanically robust polylactide biocomposites

Renewable and biodegradable polylactide (PLA) has excellent mechanical strength but is highly flammable which restricts its practical applications. Many phosphorus/nitrogen (P/N)-based flame retardants are ef- fective in PLA, but their high addition loading usually decreases the mechanical strength of the PLA bulk. For polyphosphoramides, despite high fire-retardant efficiency, their chemical synthesis often generates chemical wastes as byproducts. Herein, we report an atom-economic and highly efficient oligomeric P/N fire retardant (APN) prepared using a mild Michael addition polymerization with no byproducts. Using only 3 wt% APN, the resulting PLA exhibits desired fire retardancy including a UL-94 V-0 rating and a limiting oxygen index of 37.6%. Furthermore, the toughness of the fire-retardant PLA increases by 85% compared to pure PLA, with both tensile strength and thermal stability preserved. This work offers an atom-economic strategy for synthesizing highly efficient P/N fire retardants for use in the creation of fire-resistant PLA with robust mechanical properties.

Recent development and challenges in enhancing fire performance on wood and wood-based composites:A 10-year review from 2012 to 2021

Due to their durability,versatility,and aesthetic value,wood and wood-based composites are widely used as building materials.The fact that these materials are flammable,however,raises a major worry since they might cause fire hazards and significant loss of life and property.The article investigates the variables that affect fire performance as well as the various fire-retardant treatments and their mechanisms.The current developments and challenges in improving the fire performance of wood and wood-based composites treated with fire-retardant materials are summarized in this paper.Nanoparticles,organic chemicals,and densification are some recent developments in fire-retardant treatments that are also emphasized.Key points from the review are summarized,along with potential areas for further research and development.

聚丙烯纤维阻燃技术的开发与应用

介绍了适应于聚丙烯树脂及纤维的阻燃剂、阻燃技术，概括了国内外阻燃聚丙烯树脂及纤维生产开发现状。提出了发展和推广阻燃聚丙烯纤维的有关建议。

Effects of Halloysite Nanotube Reinforcement in Expandable Graphite Based Intumescent Fire Retardant Coatings Developed Using Hybrid Epoxy Binder System

In this study, the effects of halloysite nanotubes （HNTs） reinforcement in expandable graphite based intumescent fire retardant coatings （IFRCs） developed using a polydimethylsiloxane （PDMS）/phenol BA epoxy system were investigated. Intumescent coating formulations were developed by incorporating different weight percentages of HNTs and PDMS in basic intumescent ingredients （ammonium polyphosphate/melamine/boric acid/expandable graphite, APP/MEL/BA/EG）. The performance of intumescent formulations was investigated by furnace fire test, Bunsen burner fire test, field emission electron microscopy （FESEM）, thermogravimetric analysis （TGA）, transmission electron microscopy （TEM）, and Fourier transform infrared analysis （FTIR）. The Bunsen burner fire test results indicated that the fire performance of HNTs and PDMS reinforced intumescent formulation has improved due to the development of silicate network over the char residue. Improved expansion in char residue was also noticed in the formulation, SH（3）, due to the minimum decomposition of char carbon. FESEM and TEM results validated the development of silicate network over char layer of coating formulations. A considerable mass loss difference was noticed during thermal gravimetric analysis （TGA） of intumescent coating formulations. Reference formulation, SH（0） with no filler, degraded at 300 ~C and lost 50% of its total mass but SH（3）, due to synergistic effects between PDMS and HNTs, degraded above 400 ~C and showed the maximum thermal stability. XRD analysis showed the development of thermally stable compound mulltie, due to the synergism of HNTs and siloxane during intumescent reactions, which enhanced fire performance. FTIR analysis showed the presence of incorporated siloxane and silicates bonds in char residue, which endorsed the toughness of intumescent char layer produced. Moreover, the synergistic effect ofHNTs, PDMS, and other basic intumescent ingredients enhanced the polymer cross-linking in binder system and improved fire resistive performance of coatings.

Synthesis, Crystal Structure and Thermal Properties of N,N′-Bis(5,5-dimethyl-2-phospha-2-thio-1,3-dioxan-2-yl) Ethylene Diamine

The title compound N,N＇-bis（5,5-dimethyl-2-phospha-2-thio-1,3-dioxan-2-yl） ethylene diamine （DPTDEDA, C12H26N2O4P2S2） was synthesized by the reaction of neopentyl glycol, phosphorus thio-chloride and 1,2-ethylenediamine, and characterized by elemental analysis, IR and ^1H NMR spectra. Its crystal structure was determined by single-crystal X-ray diffraction analysis and the thermal property was analyzed by TG analysis. The crystal structure belongs to monoclinic, space group P21/c, with a = 14.557（16）, b = 11.299（12）, c = 12.163（13）A,β = 98.707（19）^o, Dc = 1.305 g/cm^3, Z = 4, γ = 0.71073A,μ（MoKa） = 0.447 mm^-1, Mr = 388.41, V = 1977（4）A3, F（000） = 824, S = 1.107, the final R = 0.0478 and wR = 0.0810 for 1738 observed reflections （I 〉 2σ（I））. X-ray analysis reveals that the crystal structure is centrosymmetrically distributed through 1,2-ethylenediamine to join two distorted six-membered rings. The weak N-H…S interactions are observed and link the molecules into sheets. TG analysis shows that the title compound has good thermal stability and char-forming capability, which are required for an excellent intumescent fire retardant.

A Review on Self-Cleaning Coatings for Tunnels

Self-cleaning coatings for tunnels can effectively remove dust and stains accumulated over the surface of tunnel linings and their appurtenances due to the closed environment and poor ventilation.This paper systematically introduces the current research status of self-cleaning coatings for tunnels,focusing on the development of super-hydrophobic self-cleaning coatings,superamphiphobic self-cleaning coatings,exhaust gas degradation coatings,fire retardant coatings,and tunnel de-icing coatings.The advantages and disadvantages of the five functional coatings are then briefly described,and the problems of self-cleaning coatings for tunnels at the present stage are pointed out.Finally,the development direction of self-cleaning coatings for tunnels is proposed to provide a reference for the research and application of self-cleaning coatings for tunnels.

Effects of processing parameters and addition of flame-retardant into moulding sand on the microstructure and fluidity of sand-cast magnesium alloy Mg-10Gd-3Y-0.5Zr

In this study, the effects of processing parameters（such as pouring temperature and mould pre-heating temperature） and flame-retardant content on the microstructure and fluidity of sand-cast magnesium（Mg） alloy Mg-10Gd-3Y-0.5Zr（GW103K） were systematically investigated. It was found that the increase of pouring temperature leads to coarsened microstructure and decreased fluidity of sand-cast GW103 K alloy. Increase of mould pre-heating temperature incurs coarsening of as-cast microstructure and increase of fluidity. The addition of flame-retardant into moulding sand has a negligible influence on the microstructure of sand-cast GW103 K alloy. With the increase in flame-retardant content,fluidity of the alloy initially increases and then decreases. The optimized process parameters and flameretardant addition were obtained to be pouring temperature of 750？C, mould temperature of 110？C, and flame-retardant addition of 1%. The fire retardant mechanism of moulding sand was determined.

Separation and comprehensive utilization of valuable elements in Ti-bearing electric arc furnace molten slag

A novel route to comprehensive utilization of valuable elements such as Ti, A1, Si and Mg in Ti-bearing electric arc furnace molten slag （Ti-bearing EAF slag） was proposed. The route can be expressed as a three-step process including alkali fusion, water leaching and acidolysis. Following these processes under the optimum conditions, the recovery ratios of TiO2, Al2O3, SiO2 and MgO were about 97.5, 93.5, 27.9 and 53.5%, respectively. Meanwhile, nanostructured TiO2, NaA zeolite and Mg（OH）2 fire retardant were synthesized simultaneously by using Ti-bearing EAF slag as raw materials. In addition, the photocatalytic activity of prepared nanostructured TiO2 and the adsorption property of obtained NaA zeolite were investigated. The results showed that the photodegradation efficiency of as-prepared TiO2 was 80% for rhodamine B and the adsorption efficiency of NaA zeolite was 61% for Cu2＋ under the optimum conditions.