Metallic oxides as fire retardants and smoke suppressants in flexible poly(vinyl chloride)

Combustion and smoke emission properties of PVC compounds, modified with copper (II), molybdenum, and zinc oxides, were studied using cone calorimeter, limiting oxygen index (LOI) and thermogravimetry coupled with mass spectrometry (TG/MS). Results showed that the metal oxides have a very significant effect on the combustion and smoke suppression properties of the PVC compounds. The results also confirmed the anticipation mechanisms of the dehydrochlorination reactions, reductive coupling, and elimination of benzene resulting from the presence of copper (II), molybdenum, and zinc, indicated by the increasing content of postcombustion char residue and the significant reduction in benzene production, indicated by the MS measurements performed. The results also provide indications that the combination of the copper (II) and molybdenum oxides is the one with the best balance of combustion properties, as it reduced the heat released and promoted the suppression of smoke more efficiently. The formulations containing ZnO, because of their strong Lewis acid character, indicated a less pronounced reduction of smoke released during the combustion process, when compared with copper (II) and molybdenum oxides. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Metal‐exchanged clay and zeolite additives as smoke suppressants and fire retardants for poly(vinyl chloride)

Cone calorimetry studies showed that various metal‐exchanged clays and zeolites containing only 3–4% of Cu(II), Cu(I), Zn(II), or Al(III) were effective smoke suppressants and fire retardants for plasticized poly(vinyl chloride). Copper(II)‐Zn(II) and Cu(II)‐Al(III) synergism for smoke and heat reduction was observed with binary blends of the clays, and the effectiveness of the additives was usually improved considerably by heating plasticizer‐additive mixtures under very high shear before combining them with the polymer. Possible mechanisms of action of the additives are described. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Metal smoke retarders for poly(vinyl chloride)

This article provides an overview of smoke-;retarding rigid PVC using metal compounds. It shows that a large variety of metals from throughout the Periodic Table can form compounds which are smoke retarders for PVC. These metals act to change the thermal degradation pattern of the PVC and promote the formation of char. Most of the active metals are transition metals, although many of the post-;transition metals and a few of the pretransition metals also are active. The activity of metal smoke retarders primarily is determined by the choice of metal and the environment surrounding the metal ion. Since most of the effective smoke retarders are transition metal compounds, the ability to undergo redox reactions may be important. The initial oxidation state, however, appears to be relatively unimportant. Particle and dispersion characteristics are secondary factors. Increasing the concentration of a smoke retarder can increase, decrease, or have no effect on its effectiveness. It is impossible to predict the influence of a tin stabilizer on a metal smoke retarder, but for many smoke retarders there is little effect. Transition metal compounds are the most effective metal smoke retarders. Smoke-;reducing synergisms result when molybdenum trioxide is combined with certain compounds of copper, iron, and tin.     

Tin dioxide coated calcium carbonate as flame retardant for semirigid poly(vinyl chloride)

The flame retardant and smoke suppressant properties of semirigid PVC treated with calcium carbonate (CaCO₃), tin oxide (SnO₂), the mixture of CaCO₃/SnO₂ and SnO₂‐coated CaCO₃ have been studied through the limiting oxygen index, char yield, and smoke density rating (SDR) methods. The thermal degradation in air of the treated semirigid PVC was studied by thermogravimetry (TG) and differential thermal analysis (DTA) from ambient temperature to 1073 K. The morphologies of the additives and the char formation were studied through SEM. The mechanical property was also studied. The results showed that the semirigid PVC treated with SnO₂‐coated CaCO₃ has a higher limiting oxygen index and char yield, lower SDR and MSDR, a more compact structure of char formation than the semirigid PVC without flame retardant and the semirigid PVC with the equivalent CaCO₃, or SnO₂, or the mixture of CaCO₃/SnO₂, a similar tensile property and greatly improved impact strength compared with that of the semirigid PVC without flame retardant. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 731–738, 2006     

氧化锌和氢氧化物对软聚氯乙烯阻燃性能的影响

引言 软质PVC制品中由于大量增塑剂的加入,大大提高了其可燃性,燃烧时还会产生大量有毒烟雾,因此对PVC制品的阻燃抑烟问题亟待解决.无机氢氧化物优点众多,在阻燃高分子材料中应用广泛,但阻燃效率低,常与其他阻燃剂复配使用.硼酸锌、锡酸锌、磷酸锌、氧化锌等可直接或与其他阻燃剂复合应用于PVC的阻燃消烟[1-3].     

Zinc compounds as flame retardants and smoke suppressants for rigid PVC

Abstract

The effect of the concentration of zinc hydroxy-stannate and zinc borate on the fire performance of rigid PVC formulations has been investigated. Fire testing was carried out using cone calorimetry as well as the limiting oxygen index (LOI) test. In addition, further testing was done to check that incorporation of the fire retardant additives did not have any detrimental effects on other properties of the formulated PVC, such as heat stability, colour or impact strength. The results demonstrated that zinc hydroxy-stannate is an excellent fire retardant and smoke suppressant at additions levels of 3 parts per hundred parts of PVC. Zinc borate did not have the excellent fire retardant properties of zinc hydroxy-stannate, but was found to be an efficient and cost-effective smoke suppressant, although the presence of free zinc oxide in the sample affected the thermal stability of the formulation.     

Smoke suppressants for plasticized poly(vinyl chloride)

Addition of plasticizers to poly(vinyl chloride) generally increases its flammability and frequently increases smoke production during its burning. Flame retardants added to plasticized PVC can reduce flammability, but increase smoke production. This study shows that proper choice of combined use of other polymers, phosphate plasticizers, fillers and other flame retardants, produces measured synergistic improvements in flame retardance and smoke suppression which could benefit applications such as PVC wire and cable insulation.     

Flame retardants and smoke suppressants for flexible vinyl compounds

This paper reviews a number of technologies employed to reduce flammability and suppress smoke in flexible vinyl compounds. Advantages and disadvantages of the various systems are discussed, along with postulated mechanisms of action. Typical applications, approximate market prices, and major suppliers are also listed.     

Application of metallic phytates to poly(vinyl chloride) as efficient biobased phosphorous flame retardants

Simple, direct precipitation was used to synthesize green, renewable, biobased flame retardants. Copper phytate (Cu–Phyt), zinc phytate, aluminum phytate, and tin phytate (Sn–Phyt) were synthesized. Thermogravimetric analysis performed in N₂ revealed that the metallic phytate (M–Phyt, where M is Cu, Zn, Al, or Sn) salts showed good charring. The limiting oxygen index (LOI), cone calorimetry (CONE) test data, tensile strength, and impact toughness were measured for flexible poly(vinyl chloride) (PVC) containing 15 wt % M–Phyt salts. The PVC/Sn–Phyt LOI rose from 24.9 to 30.3%, and the PVC/Sn–Phyt mechanical properties were on par with those of the pure PVC. The CONE test results indicate that PVC/Cu–Phyt showed the lowest total smoke production (TSP) and peak heat‐release rate (pHRR) among the samples. The TSP and pHRR of PVC/Cu–Phyt were 15.77 m² and 181.77 kW/m², respectively, 62.63 and 44.48% lower than those of the neat PVC. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46601.     

阻燃抑烟剂对软聚氯乙烯材料燃烧性能的影响

针对氢氧化镁、硼酸锌、三氧化二锑等常用的阻燃抑烟剂对在软聚氯乙烯燃烧时的热释放速率和一氧化碳释放量进行了研究 ,发现氢氧化镁和硼酸锌虽然可以降低材料的热释放性能和发烟量 ,但是会大大增加烟气中一氧化碳的释放量 ;而三氧化二锑会增加材料的发烟量 ,但却能大大降低烟气中的一氧化碳的释放量     

Melaminium molybdate smoke and fire retarders for poly(vinyl chloride)

Melaminium molybdates are shown to be very effective smoke and fire retarder additives for PVC. In a simple tin stabilized rigid PVC compound the preferred melaminium β-octa-molybdate outperformed MoO₃ and other common molybdenum smoke retarders. Combinations of melaminium molybdates with compounds of copper formed very efficient smoke-reducing and char-forming synergistic additive systems for PVC. For example, combining the octamolybdate with a series of different copper compounds consistently gave smoke reductions of about 85% in the flaming mode of the NBS Smoke Chamber at a total additive level of 5 parts per hundred parts of PVC. These large reductions in smoke were accompanied by large increases in the amount of char formed and retained as combustion residues.     

Zinc hydroxystannate‐coated metal hydroxides as flame retardant and smoke suppression for flexible poly vinyl chloride

Zinc hydroxystannate (ZHS)‐coated metal hydroxides were prepared. The effects of ZHS‐coated metal hydroxides on flame retardancy and smoke suppression of flexible poly vinyl chloride were studied by means of the limiting oxygen index, smoke density rating and the char yield test. The mechanism was investigated by thermogravimerty (TG), differential thermal analysis, and differential TG analysis and scanning electron microscopy. The results showed that ZHS‐coated metal hydroxides are more effective flame retardant and smoke suppressant than metal hydroxides, and it appears that tin compound may exert its action in both the condensed and vapor phases, but mainly in condensed phases as a Lewis acid. Copyright © 2009 John Wiley & Sons, Ltd.     

Zinc stannate–coated fillers: Novel flame retardants and smoke suppressants for polymeric materials

Novel zinc hydroxystannate- or zinc stannate-coated hydrated fillers are shown to be highly effective flame-retardant and smoke-suppressant additives for chlorinated polymers. The performance of these systems is discussed, with reference to PVC, polychloroprene, halogenated polyester resin and polypropylene formulations. Relative to unmodified magnesium hydroxide and alumina trihydrate, coated variants of these fillers can achieve similar fire-retardant properties at significantly lower additive levels.     

Main functions of iron compounds as smoke suppressant in poly(vinyl chloride) combustion

Whatever the state of the iron compounds as smoke suppressant during the combustion of poly(vinyl chloride), they lead rapidly to native αFe₂O₃ in the char residue left after dehydrochlorination. It causes incandescence of the char residue and catalyzes its oxidation into carbon monoxide and carbon dioxide that contributes to decreasing the amount of available carbon for the soot formation after self-ignition. FeCl₂ and FeCl₃ are the precursors of αFe₂O₃, which is the true compound as smoke suppressant. Nevertheless, as intermediate, iron chlorides are able to modify the degradation processes, and they favor the formation of light tars instead of heavy tars. For that reason the iron compounds cause the formation of smoke at lower temperature than for pure PVC, but, as αFe₂O₃ is formed, the smoke production levels off and then decreases. The higher the ease of the iron compounds to give chlorides through reaction with HCI and further native αFe₂O₃, the higher the ease of the additive to cause the oxidation of the char residue sooner and in consequence to decrease the smoke level. In the PVC combustion three main steps may be distinguised: dehydrochlorination step between 200–300°C; tars aerosols formation from the char residue between 300°C and self-ignition; at temperature higher than self-ignition, formation of soot from the previous tars as precursors.     

A study on the flame‐retardance of poly(vinyl chloride) incorporated with metal hydroxystannates

In this article some metal hydroxystannates were synthesized. It shows that the ZHS with Fe₂SnO₃.3H₂O imparts fairly good flame retardance to the plasticized poly (vinyl chloride) (PVC). The thermal stability and flammability on heating and burning were explored by TG/DTA. Study on mechanical properties of PVC had also been performed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical properties,flame retardancy,and smoke suppression of lanthanum organic montmorillonite/poly(vinyl chloride) nanocomposites

A dimethyl dioctadecyl ammonium chloride modified organic montmorillonite (OMMT_‐I.44P)/poly(vinyl chloride) (PVC) nanocomposite and anionic‐surfactant‐modified lanthanum organic montmorillonite (La‐OMMT)/PVC nanocomposites (with three different anionic surfactants for the La‐OMMTs) were prepared via melt‐intercalation technology. The effects of the La‐OMMTs and OMMT_‐I.44P on the mechanical properties, flame retardancy, and smoke suppression of PVC were studied. X‐ray diffraction characterization showed that the La‐OMMTs were exfoliated in the PVC matrix. The mechanical properties of the nanocomposites were enhanced by the incorporation of the La‐OMMTs. Cone calorimetry and gas chromatography–mass spectrometry analyses indicated that the incorporation of the La‐OMMTs enhanced the flame retardancy and smoke suppression of the PVC nanocomposites. Scanning electron microscopy photos further showed that the residual char surfaces of La‐OMMT/PVC were all intact and, thus, provided better barriers to energy and smoke transport. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43951.     

Diamide derivatives as photostabilizers for plasticized poly(vinyl chloride)

Some diamide derivatives have been prepared, characterized, and investigated as photostabilizers for plasticized poly(vinyl chloride) (PVC), containing dioctyl phthalate and dibutyl phthalate in a concentration of 30% by weight of the polymer. The stabilizing efficiency of the prepared diamides was evaluated by determining the weight loss percentage that resulted from HCl evolution during the photodegradation process. Moreover, the efficiency was evaluated by determining the amount of gel formed as well as the intrinsic viscosity of the soluble fractions of the photodegraded polymer. The extent of discoloration of the photodegraded stabilized and plasticized PVC was also investigated. The stabilization mechanism and the effect of plasticizers on the photostability of PVC are discussed. J. Vinyl Addit. Technol., 2008. © 2008 Society of Plastics Engineers     

Polycaprolactone as a permanent plasticizer for poly(vinyl chloride)

Polycaprolactone at moderate usage levels has been determined to provide desirable modifications of both rigid and plasticized poly(vinyl chloride). In rigid PVC it effected significant improvement in melt processing as well as good modulus, tensile strength, and kerosene resistance. Impact strength was not measurably altered, but heat-distortion temperature was appreciably lowered. In flexible PVC, polycaprolactone contributed increased tensile strength and ultimate elongation, reduced volatility, and kerosene extraction. Lowering of modulus and flex temperatures were similar to conventional liquid polymeric plasticizers, but melt processability was not as good as lower-molecular-weight plasticizers.     

Metal chelates as synergistic flame retardants for flexible PVC

The thermal degradation of flexible PVC treated with various metal chelates containing Cr, Al, Fe, Co, Ni, Cu, or Zn combined with two compounds, Al(OH)₃ and Mg(OH)₂, was studied by thermal analysis. Limiting Oxygen Index (LOI), Smoke Density Rating (SDR), and mechanical properties were investigated. The structure of the char formed after combustion of the PVC compounds was observed through scanning electron microscopy (SEM). The high LOI and char yield of flexible PVC treated with flame retardants showed that there was a good synergistic effect between Al(OH)₃, Mg(OH)₂, and metal chelates. J. VINYL. ADDIT. TECHNOL., 11:70–75, 2005. © 2005 Society of Plastics Engineers.     

Processing aids for poly(vinyl chloride)

Processing aids are an important class of additives for poly(vinyl chloride) (PVC). At relatively low concentration, processing aids enable the melt processing of rigid PVC and enlarge its processing windows. Discussed in this presentation are some major functions of processing aids, such as promoting PVC fusion, modifying PVC's melt rheology, and lubricating to prevent adherence of PVC melt to the processing equipment. Some examples are given to show the effects of processing aids on PVC die swell, melt fracture, melt viscosity, and PVC fusion. Commercial sources of various processing aids and typical PVC formulations for various applications are also discussed.