Effects of milling on the thermal stability of synthetic hydromagnesite

Ibarra, Laia Haurie; Fernández, A. Inés; Velasco, José Ignácio; Chimenos, J.M.; Lopez-Cuesta, J. M.; Espiell, F.

doi:10.1016/j.materresbull.2006.09.020

Cited by 50 publications

(53 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These conclusions are all drawn through comparisons of theoretical mass losses compared to the mass losses measured using TGA, no analysis of the gases emitted during the decomposition appears to have been made. Comparing with other authors' work [8,25,29,30,32] the first two decompositions seem to occur at very low temperatures. Frost comments on this, referring to the fact that Beck [8] found decomposition temperatures between 275 and 325°C for loss of water, and loss of carbon dioxide at 485°C and again at 565 -600°C.…”

Section: Comparison Of Synthetic Hydromagnesite With Naturally Occurrsupporting

confidence: 66%

“…However, the suitability of both synthetic and natural hydromagnesite as a fire retardant for polymers could improve the cost effectiveness of the plan and lead to a future commercial source of hydromagnesite. There has also been interest in the literature [25,[27][28][29][30][31] in synthetic hydromagnesite as a fire retardant.…”

Section: Sources Of Hydromagnesite and Huntitementioning

confidence: 99%

“…This could have an influence on the decomposition due to thermal conduction within the particles and may explain some of the differences in decomposition temperatures and mechanisms reported at apparently similar test conditions. Haurie [30] has carried out some studies into the effect of particle size reduction through different milling processes on the thermal decomposition characteristics of synthetic hydromagnesite. It was found that mechanical milling methods could cause an increase in the decomposition rate between 400°C and 500°C and reduce the exothermic crystalli sation of magnesium carbonate.…”

Section: Influence Of Particle Size Milling and Surface Coating On Tmentioning

confidence: 99%

See 2 more Smart Citations

The thermal decomposition of huntite and hydromagnesite—A review

2010

View full text Add to dashboard Cite

Naturally occurring mixtures of hydromagnesite and huntite are important industrial minerals. Their endothermic decomposition over a specific temperature range, releasing water and carbon dioxide, has lead to such mixtures being successfully used as fire retardants, often replacing aluminium hydroxide or magnesium hydroxide. The current understanding of the structure and thermal decomposition mechanism of both minerals and their combination in natural mixtures is reviewed. The crystalline structure of both minerals has been fully characterised. The thermal decomposition of huntite has been characterised and is relatively simple. However, the thermal decomposition mechanism of hydromagnesite is sensitive to many factors including rate of heating and the composition of the atmosphere. The partial pressure of carbon dioxide significantly affects the decomposition mechanism of hydromagnesite causing magnesium carbonate to crystallise and decompose at a higher temperature instead of decomposing directly to magnesium oxide.Keywords: hydromagnesite, huntite, fire, flame, retardant, mineral This review critically examines the sometimes conflicting reports in the published literature. It draws together current knowledge of the structure and thermal decomposition of hydromagnesite and huntite, in order to provide an insight into the thermal behaviour of mixtures of these minerals and to optimise their selection and applications. Industrial use of Mineral Fillers as Fire Retardant AdditivesThe largest group of mineral fire retardants are metal hydroxides. Their endothermic decomposition and associated release of inert gasses or water vapour, above the processing temperature but below the thermal decomposition temperature of polymers suppresses the ignition, while the accumulation of a solid inert residue on the surface of the burning polymer reduces the heat release rate. Aluminium hydroxide (ATH) and magnesium hydroxide are the most widely used [1]. Globally aluminium hydroxide is the highest tonnage fire retardant [2,3]. It decomposes according to the following reaction:The endothermic loss of water resulting from the thermal decomposition of ATH has been variously reported [3][4][5] between 1170 and 1300 Jg Magnesium hydroxide is used less widely than ATH. It decomposes through a similar endothermic mechanism to ATH, giving off water. Mg(OH) 2(s) → MgO (s) + H 2 O (g)The endotherm for this reaction is quoted at values between 1244 to 1450 Jg -1 by various authors [3,[5][6][7]. It starts to decompose at about 300 -330°C giving off water [5]. L.A. Hollingbery, T.R. Hull / Thermochimica Acta 509 (2010) 1-112 Although ATH and magnesium hydroxide are the most well known mineral fire retardants, Rothon [5] has identified a number of minerals (Table 1) that could be of potential benefit in polymers. Each decomposes endothermically with the evolution of either carbon dioxide, water or both. Of these minerals, hydromagnesite is the one that has probably seen most commercial interest. Hydromagnesite is naturally occurring...

show abstract

Section: Comparison Of Synthetic Hydromagnesite With Naturally Occurrsupporting

confidence: 66%

Section: Sources Of Hydromagnesite and Huntitementioning

confidence: 99%

Section: Influence Of Particle Size Milling and Surface Coating On Tmentioning

confidence: 99%

See 1 more Smart Citation

The thermal decomposition of huntite and hydromagnesite—A review

2010

View full text Add to dashboard Cite

show abstract

“…There has been much work published regarding the structure [18][19][20][21][22][23] and thermal decomposition [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] of hydromagnesite and huntite. A recent article [40], by the current authors, reviews this body of work in detail.…”

Section: Hydromagnesite and Huntite As Fire Retardant Additivesmentioning

confidence: 99%

“…It is stated that "since hydromagnesite has a release temperature of 320 -350°C, we used Mg(OH) 2 as the hydroxide control sample". It has been shown by many authors [24,25,29,33,[35][36][37][38][39]62] that hydromagnesite decomposes over a range of about 220 -550°C. Morgan also states that in his electron micrographs the hydromagnesite particles "can be clearly seen amongst the larger huntite particles".…”

Section: Heat Release Studies By Cone Calorimetrymentioning

confidence: 99%

The fire retardant behaviour of huntite and hydromagnesite – A review

Hollingbery

Hull

2010

Polymer Degradation and Stability

136

View full text Add to dashboard Cite

Naturally occurring mixtures of hydromagnesite and huntite have found important industrial use. Their endothermic decomposition over a temperature range similar to that of commonly used polymers and their release of water and carbon dioxide, has led to such mixtures being successfully used as fire retardants. They have replaced aluminium hydroxide and magnesium hydroxide in many applications. The current understanding of the thermal decomposition mechanism of both minerals and their combination in natural mixtures has been reviewed and related to their fire retardant action. Both minerals contribute to the reduction in flammability of polymers although the extent of these interactions has not been fully investigated. However, the fire retardant mechanism of these minerals appears more complicated than either aluminium hydroxide or magnesium hydroxide. This paper critically examines the literature on the fire retardant behaviour of mixtures of hydromagnesite and huntite, providing information of particular use to formulators of fire retardant polymers using these minerals. It also highlights the gaps in understanding of the fire retardant mechanisms of mixtures of hydromagnesite and huntite and areas that require further research.

show abstract

Halogen‐free flame‐retardant rigid polyurethane foams: Effect of alumina trihydrate and triphenylphosphate on the properties of polyurethane foams

Thirumal

Singha

Khastgir

et al. 2010

J of Applied Polymer Sci

119

View full text Add to dashboard Cite

Rigid polyurethane foam (PUF) filled with mixture of alumina trihydrate (ATH) and triphenyl phosphate (TPP) as fire retardant additive was prepared with water as a blowing agent. In this study, the ATH content was varied from 10 to 100 parts per hundred polyol by weight (php), and TPP was used at a higher loading of ATH (75 and 100 php) in a ratio of 1 : 5 to enhance the processing during PUF preparation. The effects of ATH on properties such as density, compressive strength, morphological, thermal conductivity, thermal stability, flame-retardant (FR) behavior, and smoke characteristics were studied. The density and compressive strength of the ATH-filled PUF decreased initially and then increased with further increase in ATH content. There was no significant change in the thermal stability with increasing ATH loading. We determined the FR properties of these foam samples by measuring the limiting oxygen index (LOI), smoke density, rate of burning, and char yield. The addition of ATH with TPP to PUF significantly decreased the flame-spread rate and increased LOI. The addition of TPP resulted in easy processing and also improved FR characteristics of the foam.

show abstract

Effects of milling on the thermal stability of synthetic hydromagnesite

Cited by 50 publications

References 15 publications

The thermal decomposition of huntite and hydromagnesite—A review

The thermal decomposition of huntite and hydromagnesite—A review

The fire retardant behaviour of huntite and hydromagnesite – A review

Halogen‐free flame‐retardant rigid polyurethane foams: Effect of alumina trihydrate and triphenylphosphate on the properties of polyurethane foams

Contact Info

Product

Resources

About