Halogen-free Flame Retardant Additives Research Articles

Synthesis and Characterization of Melamine Polyphosphate and its Flame Retardance

The halogen free flame retardant additives always attract scientists for the research and applications due to its superior characteristics compared to the halogen based ones. Melamine polyphosphate (MPP) which contain both nitrogen and phosphorus can be prepared by two step method, the precipitation of melamine phosphate (MP) in aqueous mother liquor at room temperature, and the heat treatment of the intermediates into MPP at 340°C for 8 to 10 h. The MPP can be used as the flame retardant additives for various types of flammable materials such as paper, both as coatings and the blends or the epoxy composite. The flammable tests of the show that the prepared specimens suppresses the flame when the content of MPP is higher than 5%, and the grades of HB and V-1 to V-0, the limiting oxygen indices of 32% to 35% are obtained.

Composites of Semi-Rigid Polyurethane Foams with Keratin Fibers Derived from Poultry Feathers and Flame Retardant Additives.

Semi-rigid composites of polyurethane foams (SRPUF) modified with the addition of keratin flour from poultry feathers and flame retardant additives were manufactured. Ten percent by mass of keratin fibers was added to the foams as well as halogen-free flame retardant additives such as Fyrol PNX, expandable graphite, metal oxides, in amounts such that their total mass did not exceed 15%. Thermal and mechanical properties were tested. Water absorption, dimensional stability, apparent density and flammability of produced foams were determined. It was found that the use of keratin fibers and flame retardant additives changes the foam synthesis process, changes their structure and properties as well as their combustion process. The addition of the filler made of keratin fibers significantly limits the amount of smoke generated during foam burning. The most favorable reduction of heat and smoke release rate was observed for foams with the addition of 10% keratin fibers and 10% expandable graphite. Systems of reducing combustibility of polyurethane foams using keratin fillers are a new solution on a global scale.

Synthesis of DOPO-Based Phosphonamidates and their Thermal Properties

Synthetic strategies for the preparation of 9,10-dihydro-9,10-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivatives are of special interest for polymer industry as well as academia involved in development of halogen-free flame retardant additives. In this work, various amino-DOPO derivatives (phosphonamidates) were synthesized by employing three different synthetic methods involving various chlorinating agents. The synthetic methods were compared with regards to purity and yield of the resulting amino-DOPO derivatives. The chlorinating agents that were used in this work are namely CCl4, trichloroisocyanuric acid and sulfuryl chloride. Some compounds, e.g., amine substituted DOPO derivative, could be synthesized using sulfuryl chloride with a yield >94% and a purity >99%. As proof of possible future industrial scale-up, up-scaling laboratory trials at the 500 g scale were also performed for two methods. The synthesized compounds were characterized for their melting point and thermal stability by using the...

HALOGEN-FREE FLAME RETARDANTS FOR WIRE AND CABLE APPLICATIONS

AbstractFlame retardants play a very important role in avoiding fire risks in wire and cable applications due to heat generation by current or outside sources. Halogen flame retardants are typically used to ensure good flammability. The halogen flame retardants, however, are under close scrutiny because of their potential to give off corrosive compounds when the materials are burned, as well as other safety, environmental, and health issues. For wire and cable industries, halogen-free flame retardant additives, such as nanoclays, nanotubes, aluminium trihydrate, or magnesium hydroxide are potential alternatives. Types of halogen-free flame retardant additives used in wire and cable constructions are reviewed and discussed.

Dynamic FTIR studies of thermo-oxidation of expandable graphite-based halogen-free flame retardant LLDPE blends

The dynamic thermo-oxidative degradation of expandable graphite (EG)-based intumescent halogen-free flame retardant (HFFR) LLDPE blends in the condensed phase at 300 or 400°C has been studied in situ by real time Fourier transform infrared spectroscopy. The kinetic characteristics and dynamic changes of various kinds of pyrolysis products during the thermo-oxidative degradation were examined extensively for several LLDPE/EG blends with different HFFR additives, such as the phosphorus–nitrogen compound NP28, ammonium polyphosphate (APP), red phosphorus (RP), and zinc borate (ZB). It has been found (i) that the dynamic monitoring of the LLDPE/EG/HFFR blends during the pyrolysis shows that the breakdown of LLDPE main chains and formation of various kinds of carbonyl products increase with increasing thermo-oxidation time and temperature; the latter have been identified as carboxylic acids, ketone, lactone and cyclic anhydrides; (ii) that the fast formation rate and high initial concentrations of P–O–P and P–O–C products in the phosphorus-containing HFFR systems have a crucial importance for decreasing the thermo-oxidative degradation rate of LLDPE efficiently (the NP28 system is the most efficient in the present study); and (iii) that the pyrolysis temperature has a significant effect on the efficiency of flame retardants, which requires the LLDPE/EG/HFFR formulation should be optimized at certain temperature range in order to form compact intumescent charred layers immediately at the beginning of the thermo-oxidative degradation of the LLDPE blends.

Expandable graphite systems for halogen‐free flame‐retarding of polyolefins. I. Flammability characterization and synergistic effect

AbstractThe use of some types of expandable graphite (EG) as an intumescent flame‐retardant additive in polyolefins was studied using the cone calorimeter test (CCT), thermogravimetric analysis (TGA), the limiting oxygen index (LOI), and the‐UL 94 test and through measurement of EG's mechanical and electrical properties. The present study has shown that some suitable EG systems combined with other organic and inorganic halogen‐free flame‐retardant (HFFR) additives apparently can improve the flame‐retardant capacity with good mechanical properties of polyolefin blends. For linear low‐density polyethylene and/or ethylene vinyl acetate/EG/HFFR blends the limiting oxygen index can reach a rating above 29, and the UL‐94 test can produce a value of V–0. The CCT and TGA data show that the EG and EG/HFFR additives not only promoted the formation of carbonaceous char but also greatly decreased the heat release rate and the effective heat of combustion and increased the residues after burning. The synergistic effect of EG with other HFFR additives, such as zinc borate, the phosphorus–nitrogen compound NP28, and microcapsulated red phosphorus is examined and discussed in detail in this article. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1181–1189, 2001

Synergistic effects of expandable graphite with some halogen-free flame retardants in polyolefin blends

The synergistic effects of expandable graphite (EG) with some halogen-free flame retardant (HFFR) additives in the polyolefin (PO) blends have been studied by cone calorimeter test (CCT), thermal analysis (TGA and DTA), limiting oxygen index (LOI), and mechanical properties measurements etc. The results in this work show that EG combined with some HFFR additives, such as ammonium polyphosphate, zincborate, phosphorus-nitrogen containing compound NP28, and microcapsulated red phosphorus, can apparently increase the LOI values and improve the flammability properties of PO blends. The data obtained from the CCT indicate that the heat release rate (HRR) and effective heat of combustion (EHC) decrease and the residues of carbonaceous chars increase remarkably with addition of EG and/or the other HFFR additives. The TGA and DTA data give the positive evidence that the decreases of HRR and EHC values of the retarded PO materials are due to the increase of oxidative degradation temperature and the decrease of oxidization heat. By optimizing the formulation system and using ethylene vinylacetate copolymer as a compatilizer, the PO/EG/HFFR blends with good flame-retardant and mechanical properties have been obtained in this study.