Thermal degradation of polymer-fire retardant mixtures: Part IV—Mechanism of fire retardancy in polypropylene-chlorinated paraffin mixtures

From oxygen and nitrous oxide indices of polypropylene-chlorinated paraffin mixtures it can be deduced that, in addition to the flame poisoning effect of HCl eliminated by the chloroparaffin, the lower flammability of the volatile products formed by thermal degradation of polypropylene heated in the presence of this additive seems to contribute to its fire retardance activity.     

Study of the mechanism of intumescence in fire retardant polymers: Part I—Thermal degradation of ammonium polyphosphate-pentaerythritol mixtures

Interactions are shown to take place between ammonium polyphosphate and pentaerythritol in thermally degrading mixtures. Up to 500°C, gaseous products are evolved on programmed heating above 200°C in two steps with maximum rate temperatures differing by about 100–150°C. Swelling of the degrading mass seems, however, to be mainly due to gases evolved in the step occurring at the higher temperature. A strong dependence of the degradation process on the experimental conditions is observed.     

Thermal degradation of polymer-fire retardant mixtures: Part III—Degradation products of polypropylene-chlorinated paraffin mixtures

When polypropylene is thermally degraded in mixtures with a highly chlorinated fire retardant chloroparaffin, a smaller amount of the lighter hydrocarbon fraction, which is also modified in composition, is evolved compared with that evolved from pure polypropylene. A corresponding increase in the amount of high boiling chain fragments is obtained from the mixtures. This effect can be explained in terms of the interactions which occur between degrading polymer and additive.     

Thermal degradation of polymer-fire retardant mixtures—Part I: Polypropylene-chlorinated paraffin. Evidence of interactions

Evidence is given that the thermal behaviour of a mixture of polypropylene and a fire retardant chlorinated paraffin (Cl 70%) is not the sum of their individual behaviours. An interaction is shown to take place in the degrading mixtures which is related to the low temperature dehydrochlorination step of the chloroparaffin. This occurs at temperatures at which pure polypropylene is stable and leads to an increase in the overall rate of volatilisation of the mixtures compared with that of the separate components. A partial overlapping of volatilisation of polymer and additive, which otherwise degrade in two well separated temperature ranges when heated alone, is observed.The relevance of these observations to the mechanism of fire retardance is discussed.     

Thermal degradation of fire retardant chloroparaffin-metal compound mixtures—Part I: Antimony oxide

The main characteristics of the evolution of HCl and SbCl₃ during the thermal degradation of chloroparaffin-Sb₂O₃ mixtures, which are typical fire retardant additives for polymers, have been studied.Sb₂O₃ reacts with HCl evolved from the chloroparaffin without any apparent effect on the dehydrochlorination process itself. Evolution of SbCl₃ occurs at a maximum rate between 300 and 350°C and is somewhat delayed in the earlier stage of reaction, depending on the composition of the mixture.     

Thermal degradation of fire retardant chloroparaffin-metal compound mixtures: Part II—Bismuth compounds

The mechanisms of reactions which occur on heating mixtures of Bi compounds and a chloroparaffin, which are suitable fire retardant additives for polymers, have been studied.BiCl₃, which is evolved at a high initial rate by reaction of Bi compounds with HCl eliminated by the chloroparaffin, has a strong catalytic effect on the dehydrochlorination process of the chloroparaffin itself. BiCl₃ evolution occurs in a two-stage process: a fast step characterised by a maximum rate at 300°C followed by a slower step which occurs between 300 and 500°C.     

Thermal behaviour of bromine-metal fire retardant systems

Chemical reactions which occur on heating fire retardant mixtures of decabromodiphenyloxide (DBDPO) with antimony trioxide (AO) or bismuth carbonate (BC) have been studied by means of weight loss, elemental analysis, X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive system (EDS) microanalysis.

It has been shown that on rapid heating to 700°C, DBDPO volatilisation competes with debromination by AO or BC leading to volatile SbBr₃ or BiBr₃ which are formed by different mechanisms. BC is rapidly transformed into BiOBr which gives BiBr₃ by further debromination of DBDPO. At high conversion (high temperature) this process is in competition with reduction of BiOBr to metallic bismuth. In the case of AO slower formation of progressively bromine-richer antimony oxybromides takes place which liberates SbBr₃ by thermal degradation.

The formation of a rod-shaped Br-Sb containing phase is shown to relate to the progression of chemical reactions which occur on heating the AO-DBDPO mixture.     

Thermal degradation of polymer-fire retardant mixtures—Part II: Mechanism of interaction in polypropylene-chlorinated paraffin mixtures

The thermal degradation of polypropylene is accelerated when it is heated in mixtures with a fire retardant chlorinated paraffin (Cl 70%) whose dehydrochlorination rate is simultaneously reduced.The mechanism proposed to account for this behaviour involves the attack of the chlorine atoms, which propagate the dehydrochlorination reaction, on the tertiary hydrogen atoms of polypropylene with formation of HCl. The kinetic chain length of the dehydrochlorination is decreased and the rate of evolution of HCl is lowered, while the radicals formed on the polypropylene chain lead to its scission and volatilisation.The effects of these reactions on the fire retardant performance of the mixture are discussed.     

The application of hydrated mineral fillers as fire retardant and smoke suppressing additives for polymers

The characteristics of hydrated mineral fillers are discussed with reference to their use as fire retardant additives for polymers. Particular consideration is given to their mode of action and criteria which influence their performance, both in reducing polymer flammability and in suppressing smoke evolution during combustion. Methods for reducing their adverse effect on mechanical properties of the host polymer are also highlighted.     

Thermal degradation of chlorinated rubber: Evidence for an alternative cyclic structure for chlorinated rubber

The thermal degradation under vacuum or in nitrogen of commercial chlorinated rubber (ICI Alloprene, 64.5 wt.-% chlorine) was studied by isothermal thermogravimetry and by simultaneous TG/TVA with programmed heating by using a Cahn RG thermobalance built into a thermal volatilization analysis (TVA) system. Analysis of volatile products was performed by titration and by spectroscopic methods. The only major degradation product is hydrogen chloride; five-sevenths of the total available hydrogen chloride is lost with great ease, and complete dehydrochlorination is very much easier than in poly(vinylidene chloride). Conjugation develops early in the degradation, but the minor products methane, ethylene, and hydrogen are observed in the later stages of reaction. These features cannot be reconciled with the previously proposed cyclic structure for chlorinated rubber, and an alternative structure which accounts well for the degradation behavior is suggested.     

Capillary gas chromatographic analysis of highly brominated fire retardant compounds

We report the development of a capillary gas chromatographic method, superior to existing packed column methods, for the analysis of highly brominated additive fire-retardants, including decabromodiphenyl ether (1) and decabromodiphenoxyethane (II). Neither compound has been analyzed previously by capillary GC, and there are no published methods for (II). For (I), the new method is 5–10 times faster than an analogous packed column method, and it has 100 times lower detection limits and twice the precision of a gas chromatographic/mass spectrometric method. For (II), the capillary method is 30–50% faster than an unpublished liquid chromatographic method. The greater efficiency of the capillary method makes possible the complete resolution (R ≥ 1.25) of structurally very similar compounds (e.g. compound (II) and its Br₉Cl₁ and Br₈Cl₂ analogues). With the new method, commercial preparations of (I) and (II) can be rapidly analyzed, and samples from combustion and pyrolysis experiments can be evaluated for compositional changes.     

The suitability of halloysite nanotubes as a fire retardant for nylon 6

This work presents the first study on the fire behaviour of halloysite nanotubes-nylon 6 composites. The nylon 6-halloysite composites were prepared at 5-30 wt% of halloysite loadings by a simple melt extrusion process. A range of standard fire tests and characterization techniques were used to assess the efficacy and mechanism by which the halloysite nanotubes inhibited the burning of nylon. We found that for such systems, relatively high concentrations of additive (≥15 wt%) were required to achieve the levels of fire retardant property normally associated with nanoclay (or layered silicate) additives. We proposed that the primary mechanism of flame inhibition for halloysite nanotubes was similar to that of conventional nanoclays; however, the ease of composite preparation is an attractive consideration for further development or study of such systems.     

Thermal degradation of some coordination polymers

Coordination polymers of Co(II), Ni(II) and Cu(II) were synthesized using two ligands, 5- benzylidene pseudothiohydantoin and 5-cinnamylidene pseudothiohydantoin. These polymers were characterized by dynamic and static TG, and their relative thermal stabilities were compared. The thermal stabilities found by dynamic and static TG were in harmony. The structure of the polymeric unit for each polymer was predicted with the help of thermoanalytical data. The data reveal one pattern for Co(II) and Cu(II), i.e. an (ML ₂ ) _n -type polymerkc unit, and another pattern for Ni(II), i.e. an (ML ₂ · 2H ₂ O)_n-type polymeric unit. The static (isothermal) TG data were analysed by use of (i) the difference equation method, and (ii) the Avrami-Erofeyev method. The activation energies of the coordination polymers were calculated, and it was observed that the chelate polymers of Ni(II) with both ligands were more stable than those of Co(II) and Cu(II). This prediction on the basis of static TG data is in agreement with the prediction based on the activation energies and initial decomposition temperatures calculated from the dynamic TG curves.

---

Zusammenfassung Koordinationspolymere von Co(II), Ni(II) und Cu(II) mit 5-Benzylidenpseudothiohydantoin bzw. 5-Cinnamyliden-pseudothiohydantoin als Liganden wurden dargestellt, durch dynamische und statische TG charakterisiert und hinsichtlich der relativen thermischen Stabilität miteinander verglichen. Die durch statische und dynamische TG ermittelte thermische Stabilität stimmen überein. Ausgehend von thermoanalytischen Daten wurde die Struktur der Polymereinheit für jedes Polymer vorausgesagt. Ein Thermogrammtyp - (ML ₂ )_n - wird für Co(II) und Cu(H) und ein anderer - (ML ₂ · 2H ₂ O)_n - für Ni(II) erhalten. Die statischen (isothermen) TG-Daten wurden nach der Differenzgleichungsmethode und der Avrami-Erofeyev-Methode analysiert. Die Aktivierungsenergien der Zersetzung der Koordinationspolymere wurden berechnet, und es wurde festgestellt, daß Chelatepolymere von Ni(II) mit beiden Ligandtypen stabiler als die entsprechenden Co(II)- und Cu(II)- Komplexe sind. Diese auf Grund von statischen TG-Daten getroffene Voraussage ist in Übereinstimmung mit der, die auf aus dynamischen TG-Kurven berechneten Aktivierungsenergien und Anfangszersetzungstemperaturen beruht.

---

, 5-- 5- - . . . . (ML2)_n - (ML₂ · 2H₂O)_n. - -. . , ' , . , , .

---

---

We express our thanks to the Head of the Department of Chemistry, Nagpur University, for providing the necessary facilities. One of the authors (V. N. I.) is thankful to U. G. C., New Delhi for awarding Junior Research Fellowship.     

Synthesis and fire retardant properties of vinylic polymers bearing phosphonated groups

To overcome the use of halogenated compounds, which are usually incorporated in plastics as flame retardant additives, the authors investigated the synthesis possibilities, to introduce with covalent bonds, the flame retarder groups at different positions of the polymer chains. They established correlations between the topology of the phosphonated groups and the flame retardant properties. They attempt to determine the origin of the flame resistance obtained in several cases. Their goal is to extend their interesting results obtained from oligomers, to polymer of high molecular weight.     

Thermal degradation characteristics of a novel flame retardant coating using TG-IR technique

A novel phosphate acrylate monomer (TGMAP) has been synthesized by allowing phosphoric acid to react with glycidyl methacrylate. Its structure was characterized by Fourier transformed infrared spectroscopy (FTIR) and ¹H nuclear magnetic resonance spectroscopy (¹H NMR). The thermal degradation mechanism was characterized using thermogravimetric analysis/infrared spectrometry (TG-IR). The char yield was 36.3% at 600 °C. TG data indicate that the material undergoes degradation in three characteristic temperature stages, which can be attributed to the decomposition of the phosphate, thermal pyrolysis of aliphatic chains, and degradation of an unstable structure in char, respectively. The volatilized products formed on thermal degradation of TGMAP indicated that the volatilized products are CO, CO₂, carboxylic acid, acid anhydride, water, alkane, and aromatic compounds according to the temperature of onset formation.     

Thermal degradation of polymers and flame retardants

We have carried out simultaneous Thermal Analysis/Mass Spectrometry by use of a Netzsch STA 429 Thermal Analyzer (TG-DTG-DTA) combined with a Balzers QMG 511 quadrupole Mass Spectrometer.The combined apparatus is interfaced to a Digital Equipment PDP 11/23+ microcomputer. The complete set of the TA/MS data obtained simultaneously after each run results in detailed information about the thermal degradation of a sample material in general and in addition about the structure-temperature dependent fragmentation. Experiments by use of a Perkin-Elmer DSC 7 Thermal Analysis Station leads to quantitative determination of the characteristic data.

---

Zusammenfassung Es wurden simultane thermoanalytische — massenspektrometrische Untersuchungen mit Hilfe einer Gerätekombination Netzsch STA 429 (Thermowaage) und Balzers QMG 511 (Quadrupol Massenspektrometer) durchgeführt. Dieses Kopplungssystem ist mit einem Digital Equipment PDP 11/23+ Microcomputer verbunden. Der komplette Datensatz, der aus einer TA/MS Messung erhalten wird, charakterisiert in sehr detaillierter Weise das thermische Abbauverhalten von Substanzen und gibt Aufschluß über die temperatur-struktur-abhängige Fragmentierung der Verbindungen.

---

, /-/ - 511. 11/23. /MC, , - . , - 7, .

     

Effect of inorganic additive flame retardant on fire hazard of polyurethane exterior insulation material

Journal of Thermal Analysis and Calorimetry - The effect of inorganic additive flame retardant on fire hazard of polyurethane exterior insulation material was experimentally investigated by the...     

Performance of intumescent fire retardant for wood

Performance characteristics of new fire-retardant formulations are studied, including their water resistance and the effect of additives.     

Thermal analysis and flammability of polymers Effect of halogen-metal additive systems

Thermal analyses have been carried out on systems containing a thermoplastic polymer (ABS or HDPE), a halogenated hydrocarbon (decabromobiphenyl or a chlorinated wax) and one or two metal-containing compounds. The results were compared with flammability measurements on the same systems, as determined by limiting oxygen index. Thermal analyses of the additives on their own has shown the extent to which the metal compounds are volatilised as their metal halides, thus indicating their possible similarity to the mechanism of flame-retardant action of antimony oxide. Such results are shown to be misleading in terms of providing an indication of flame-retardant efficiency. However it is possible to obtain meaningful correlations between the information obtained from thermal analysis of complete systems, i.e. including the polymeric substrate, and comprehensive studies (e.g. by triangular diagrams) of the flammability.