Intumescent fire-retardant systems

Design and UV-curable behaviour of boron based reactive diluent for epoxy acrylate oligomer used for flame retardant wood coating

Difunctional boron-containing reactive flame retardant for UV-curable epoxy acrylate oligomer was synthesized from phenyl boronic acid and glycidyl methacrylate. The synthesized reactive diluent was utilized to formulate ultraviolet (UV)-curable wood coatings. The weight fractions of reactive diluent in coatings formulation was varied from 5 to 25 wt % with constant photoinitiator concentration. The molecular structure of reactive flame retardant was confirmed by Fourier-transform infrared, Nuclear magnetic resonance (NMR) and ¹¹B NMR spectral analysis. Further, the efficacy of flame retardant behaviour of coatings was evaluated using limiting oxygen index and UL-94 vertical burning test. Thermal stability of cured coatings films were estimated from thermogravimetric and differential scanning calorimetry analysis. The effects of varying concentration of reactive diluent on the viscosity of coatings formulation along with optical, mechanical and chemical resistance properties of coatings were also evaluated. The coatings gel content, water absorption behaviour, contact angle analysis and stain resistance were also studied.

Poly(piperazinyl phosphamide): a novel highly-efficient charring agent for an EVA/APP intumescent flame retardant system

Poly(piperazinyl phosphamide) is a kind of novel charring agent, showing highly-efficient charring capacity and good interaction with another flame-retardant component APP in flame retarding EVA.

Flame-Retardant Paper from Wood Fibers Functionalized via Layer-by-Layer Assembly

The highly flammable character of cellulose-rich fibers from wood limits their use in some advanced materials. To suppress the flammability and introduce flame-retardant properties to individual pulp fibers, we deposited nanometer thin films consisting of cationic chitosan (CH) and anionic poly(vinylphosphonic acid) (PVPA) on fibers using the layer-by-layer (LbL) technique. The buildup of the multilayer film was investigated in the presence and absence of salt (NaCl) using model cellulose surfaces and a quartz crystal microbalance technique. Fibers were then treated with the same strategy, and the treated fibers were used to prepare paper sheets. A horizontal flame test (HFT) and cone calorimetry were conducted to evaluate the combustion behavior of paper sheets as a function of the number of bilayers deposited on fibers. In HFT, paper made of fibers coated with 20 CH/PVPA bilayers (BL), self-extinguished the flame, while uncoated fibers were completely consumed. Scanning electron microscopy of charred paper after HFT revealed that a thin shell of the charred polymeric multilayer remained after the cellulose fibers had been completely oxidized. Cone calorimetry demonstrated that the phosphorus-containing thin films (20 BL is ∼25 nm) reduced the peak heat release rate by 49%. This study identifies a unique and highly effective way to impart flame-retardant characteristic to pulp fibers and the papers made from these fibers.

Novel Multifunctional Organic-Inorganic Hybrid Curing Agent with High Flame-Retardant Efficiency for Epoxy Resin

A novel multifunctional organic-inorganic hybrid was designed and prepared based on ammonium polyphosphate (APP) by cation exchange with diethylenetriamine (DETA), abbreviated as DETA-APP. Then DETA-APP was used as flame-retardant curing agent for epoxy resin (EP). Curing behavior, including the curing kinetic parameters, was investigated by differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). The flame retardance and burning behavior of DETA-APP cured EP were also evaluated. The limiting oxygen index (LOI) value of DETA-APP/EP was enhanced to 30.5% with only 15 wt % of DETA-APP incorporated; and the UL-94 V-0 rating could be easily passed through with only 10 wt % of the hybrid. Compared with DETA/EP, the peak-heat release rate (PHRR), total heat release (THR), total smoke production (TSP), and peak-smoke production release (SPR) of DETA-APP/EP (15 wt % addition), obtained from cone calorimetry, were dropped by 68.3, 79.3, 79.0, and 30.0%, respectively, suggesting excellent flame-retardant and smoke suppression efficiency. The flame-retardant mechanism of DETA-APP/EP has been investigated comprehensively. The results of all the aforementioned studies distinctly confirmed that DETA-APP was an effective flame-retardant curing agent for EP.

Microencapsulation of ammonium polyphosphate with melamine-formaldehyde-tris(2-hydroxyethyl)isocyanurate resin and its flame retardancy in polypropylene

The reaction scheme of MFT resin pre-polymer.

Flame retardancy of clay–sodium silicate composite coatings on wood for construction purposes

Composites of clay minerals mixed with sodium silicate as new inorganic flame retardants for wood have been investigated.