Recent advances in vegetable oil-based polymers and their composites

The ubiquity of polymeric materials in daily life comes with an increased fire risk, and sustained research into efficient flame retardants is key to ensuring the safety of the populace and material goods from accidental fires. Phosphorus, a versatile and effective element for use in flame retardants, has the potential to supersede the halogenated variants that are still widely used today: current formulations employ a variety of modes of action and methods of implementation, as additives or as reactants, to solve the task of developing flame-retarding polymeric materials. Phosphorus-based flame retardants can act in both the gas and condensed phase during a fire. This Review investigates how current phosphorus chemistry helps in reducing the flammability of polymers, and addresses the future of sustainable, efficient, and safe phosphorus-based flame-retardants from renewable sources.

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Molecular Firefighting—How Modern Phosphorus Chemistry Can Help Solve the Challenge of Flame Retardancy

Phosphorus-containing flame retardant epoxy thermosets: Recent advances and future perspectives

An assessment of the toxicity of polypropylene microplastics in human derived cells.

The development of a green and facile strategy for fabricating ecofriendly, highly effective flame retardants has remain a major challenge. Herein, supermolecular aggregates of piperazine (PiP) and phytic acid (PA) have been self-assembled onto the graphene oxide (GO) surface in water to fabricate functionalized GO (PPGO). The chemical structure and morphology of PPGO are determined by the X-ray photoelectron spectroscopy, transmission electron microscopy and scanning electron microscopy along with the energy dispersive spectroscopy. Due to the introduction of organic component onto the surface of graphene oxide, the adhesion between PPGO and the epoxy resin (EP) matrix is enhanced. As a result, the storage modulus (E′) of EP composites is increased in addition to a better dispersion of PPGO. Compared with the pure EP, the flame resistance of EP/PPGO is significantly improved, exhibiting a 42% decrease in peak heat release rate (pHRR), 22% reduction in total heat release (THR). The reduced flammability of EP is attributed to the synergistic effects afforded by the gas dilution effect of piperazine, char-forming promotion effect of phytic acid and the creation of "tortuous path" barrier effect of GO during burning. This work offers a green and facile approach for creating highly effective graphene-based flame retardants.

Improved flame resistance and thermo-mechanical properties of epoxy resin nanocomposites from functionalized graphene oxide via self-assembly in water

We found in our previous study that ethylenediamine- or ethanolamine-modified ammonium polyphosphates could be used alone as an intumescent flame retardant for polypropylene (PP), but their flame-retardant efficiency was not very high. In this present work, a novel highly-efficient mono-component polymeric intumescent flame retardant, piperazine-modified ammonium polyphosphate (PA-APP) was prepared. The oxygen index value of PP containing 22 wt % of PA-APP reached 31.2%, which increased by 58.4% compared with that of PP with equal amount of APP, and the vertical burning test (UL-94) could pass V-0 rating. Cone calorimeter (CC) results indicated that PP/PA-APP composite exhibited superior performance compared with PP/APP composite. For PP containing 25 wt % of PA-APP, fire growth rate (FGR) and smoke production rate (SPR) peak were reduced by 86.4% and 78.2%, respectively, compared with PP blended with 25 wt % APP. The relevant flame-retardant mechanism of PA-APP was investigated by Fourier transform infra...

An Efficient Mono-Component Polymeric Intumescent Flame Retardant for Polypropylene: Preparation and Application

Ammonium polyphosphate (APP) is not an efficient flame retardant for polypropylene (PP) when it is used alone. In order to improve its flame-retardant efficiency, ethanolamine (ETA) was used to chemically modify APP via ion exchange reaction. The resulting ethanolamine-modified ammonium polyphosphate (ETA-APP) was alone applied to flame retard PP, the limiting oxygen index (LOI) value could reach 35.0% and the vertical burning test (UL-94) could pass the V-0 rating at a loading of 35 wt% ETA-APP. Moreover, cone calorimeter (CC) test results showed that the heat release rate (HRR), the total heat release (THR), the mass loss rate (MLR), the smoke production rate (SPR) and the total smoke production (TSP) of PP/35 wt% ETA-APP composite largely decreased, for example, by 77.2%, 88.5% and 77.9% for THR, TSP and the fire growth rate (FGR), respectively, compared with PP containing an equal amount of APP. In addition, the residual char of PP/35 wt% ETA-APP increased by 195.6% compared with that of PP/35 wt% APP. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to analyze the flame retardant mechanism of ETA-APP. It was confirmed that the formation of P–O–C and P–N–C structures, resulting from the incorporation of ETA could greatly improve the stability of intumescent char layer and consequently lead to the much better flame retardancy of ETA-APP than that of unmodified APP. Experimental results demonstrated that the prepared ETA-APP acted not only as the acid source and blowing source as efficient as unmodified APP, but also as an excellent charring agent beyond the unmodified APP.

Ammonium polyphosphate chemically-modified with ethanolamine as an efficient intumescent flame retardant for polypropylene

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...

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

A novel nitrogen–phosphorus flame retardant, 2-carboxyethyl(phenyl)phosphinic acid melamine salt (CMA), was synthesized by the reaction of 2-carboxyethyl(phenyl)phosphinic acid with melamine in aqueous solution, and it was characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), inductively coupled plasma-atomic emission spectrometry (ICP-AES), elemental analysis, and thermogravimetric analysis (TGA). Halogen-free flame-retardant flexible polyurethane foams (FPUF) were prepared successfully by using CMA as a flame retardant. The effects of CMA content on the mechanical, thermal, and flame-retardant properties of FPUF were investigated by tensile test, TGA, limiting oxygen index (LOI), flame propagation test (Cal T.B. 117A-Part I standard), and cone calorimeter. The foam morphology of FPUF was studied via scanning electron microscopy (SEM). The results showed that CMA endowed FPUF with good flame-retardant properties. FPUF containing only 12 wt % CMA can pass Cal ...

Zhu-Bao Shao

Papers

An Efficient Mono-Component Polymeric Intumescent Flame Retardant for Polypropylene: Preparation and Application

Ammonium polyphosphate chemically-modified with ethanolamine as an efficient intumescent flame retardant for polypropylene

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

Halogen-Free Flame-Retardant Flexible Polyurethane Foam with a Novel Nitrogen–Phosphorus Flame Retardant

Flame retardation of polypropylene via a novel intumescent flame retardant: Ethylenediamine-modified ammonium polyphosphate