A series of novel phosphaphenanthrene/phenylsiloxane bigroup macromolecules (DDSi-n) were synthesized and applied to obtain high-performance epoxy thermosets. DDSi-n macromolecules simultaneously enhanced the anti-impact and flame-retardant performance of epoxy thermosets. The impact strength of the DDSi-n-containing thermoset (DDSi-n/EP) was maximally increased by nearly 140% in 8% DDSi-1/EP because of the flexible phenylsiloxane block and the polar phosphaphenanthrene group interacting with matrix in DDSi-n macromolecules. Meanwhile, the evidently elevated anti-ignition and self-extinguishing performance, the suppressed combustion heat, and the enhanced charring capability of DDSi-n/EP were all caused by the flame-retardant group synergistic effect of phosphaphenanthrene and phenylsiloxane groups of DDSi-n macromolecules in thermosets. Compared with the individual phosphaphenanthrene or phenylsiloxane group in monogroup contrasts, the phosphaphenanthrene and phenylsiloxane groups in bigroup DDSi-n macro...

Toughening Effect and Flame-Retardant Behaviors of Phosphaphenanthrene/Phenylsiloxane Bigroup Macromolecules in Epoxy Thermoset

Co-based metal–organic framework (Co-MOF) nanosheets were successfully synthesized by the organic ligands with Schiff base structure. The laminated structure gives Co-MOF nanosheets a great advantage in the application in the flame retardant field. Meanwhile, −C═N– from Schiff base potentially provides active sites for further modification. In this work, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) was used to modify Co-MOF (DOPO@Co-MOF) to further enhance its flame retardant efficiency. It is attractive that DOPO has a synergistic effect with Co-MOF on improving fire safety of poly(lactic acid) (PLA). The obvious decrease in the values of peak heat release (27%), peak smoke production (56%), and total CO yield (20%) confirmed the enhanced fire safety of PLA composites. The possible flame retardant mechanism was proposed based on characterization results. Moreover, the addition of DOPO@Co-MOF had a positive influence on the mechanical performance, including tensile properties and impact resis...

DOPO-Modified Two-Dimensional Co-Based Metal-Organic Framework: Preparation and Application for Enhancing Fire Safety of Poly(lactic acid).

High-efficiency flame retardant behavior of bi-DOPO compound with hydroxyl group on epoxy resin

Polymer nanocomposite flame retardancy has become a critical parameter in industrial material application. Recent environmental policies have prohibited the incorporation of halogenated flame-retardant compounds into polymers owing to the high level of environmental degradation caused by high levels of toxic gas and smoke emission. The demand for zero-halogen flame-retardant compounds by both researchers and manufacturers is due to the inherent advantages accruable from their incorporation like very minimal toxic emission, minimal smoke release, zero corrosive gas release, reduced corrosion activities and absence of dripping in fire condition. This has necessitated the quest for eco-compliant replacements for halogenated flame suppressants. Recent insight has shown the eco-compliancy of exfoliated graphene nanoplatelets as flame retardants when incorporated into polymer nanocomposites (PNCs). Relative to the propensity to retard flame, increasing quantities of exfoliated graphene nanoplatelets have exhibited the capability to significantly repress critical flammability parameters like heat release rate (HRR), peak HRR (PHRR), rate of carbon monoxide production, smoke production rate and total mass loss rate while simultaneously increasing limiting oxygen index, time of ignition and total PHRR, thereby retarding flammability and creating better chance to reduce loss and casualty in real-life fire situation through the formation of even layers of carbonaceous char in the condensed phase capable of efficiently suppressing the thermal decomposition caused by oxygen and heat to the polymer matrix and cutting off the flaming path. This paper gives an insight into recent developments in flame retardancy of PNCs, with special emphasis on the flame-retardancy propensity of exfoliated graphite nanoplatelets.

A review of recent developments in flammability of polymer nanocomposites

The latest techniques used to prove, describe and analyze the gas phase activity of a fire retardant used in polymeric materials are briefly reviewed. Classical techniques, such as thermogravimetric analysis or microscale combustion calorimetry, as well as complex and advanced analytical techniques, such as modified microscale combustion calorimeter (MCC), molecular beam mass spectroscopy and vacuum ultra violet (VUV) photoionization spectroscopy coupled with time of flight MS (TOF-MS), are described in this review. The recent advances in analytical techniques help not only in determining the gas phase activity of the flame-retardants but also identify possible reactive species responsible for gas phase flame inhibition. The complete understanding of the decomposition pathways and the flame retardant activity of a flame retardant system is essential for the development of new eco-friendly-tailored flame retardant molecules with high flame retardant efficiency.

Lea Bommer

Papers

Bridged DOPO derivatives as flame retardants for PA6