Influence of thermal treatment on the water release and the glassy structure of perlite

Roulia, Maria; Chassapis, Konstantinos; Kapoutsis, J. A.; Kamitsos, E. I.; Savvidis, T.

doi:10.1007/s10853-006-0325-z

Cited by 79 publications

(105 citation statements)

References 23 publications

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“…The expansion of perlite started from the inner grain layers, which grew significantly and forced its structure to expand, thus forming the observed bubbles on the grain surfaces. Bubbles, upon further expansion, formed small holes, similarly to structures previously suggested by Roulia et al [11]. The differential, relative to the groundmass, volume increase of the larger size of crystallites, which do not soften, fuse or dissolve at these temperatures, causes flaws in the amorphous phase that allow their easier liberation.…”

Section: Expansion Of Perlite From Milos Islandsupporting

confidence: 69%

“…As it has been shown elsewhere, expansion occurs only in the amorphous phase of perlite [11] because of the presence of 2-6 wt % chemisorbed and interlayered water in its structure [12], after the heating of crude perlite to close to its softening point (700-1260˝C). In the present study, coarse crude industrial fractions of all perlite samples were treated under the same furnace operating conditions (wall temperature, temperature rate increase, air feed temperature and flow rate air flow), aiming to achieve expanded material with~90 kg¨m´3 loose bulk density.…”

Section: Expansion Of Perlite From Milos Islandmentioning

confidence: 99%

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Microstructural Control on Perlite Expansibility and Geochemical Balance with a Novel Application of Isocon Analysis: An Example from Milos Island Perlite (Greece)

et al. 2016

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Abstract:Representative perlite bulk rock samples from two areas of Milos Island, Greece were collected and the expansion properties of their industrial product were investigated. Coarse crude perlite from Tsigrado exhibits better expansibility, which is assigned to the presence of coarser crystallites in its bulk parent rock. During thermal treatment, the finer crystallites of the coarse crude perlite from Trachilas are entrapped in the groundmass and lead to overheating, which inhibits expansion and eventually results in shrinkage. Geochemical modification of the expanded perlites relative to their crude precursors were investigated, using the isocon method. Volatilisation of crystalline water is the main factor controlling mass reduction of the expanded perlites. Other elements, during the adequate expansion of the Tsigrado perlite, can be classified into three categories. The elements that participate preferentially in crystals decrease in the expanded material at amounts higher than the total mass loss of the rock, due to their escape controlled mainly by the removal of the crystalline phases. The elements equally participating in crystals and the groundmass show losses equivalent to the total mass loss of the rocks, as they escaped in the crystalline phases and airborne particles from the groundmass during thermal treatment. Decrease of highly incompatible elements, which mostly participate in the groundmass, in the expanded products is less than the total mass loss, as they escaped mainly in the airborne particles. The inadequate expansion and burst of the Trachilas perlite did not allow for a similar categorisation, due to random and unpredictable escape of the elements. We propose the application of this method to an artificial system to predict unexpandable mineral phases in bulk perlite, as well as elements that are most likely to participate in the amorphous perlite phase, which cannot be determined from a regular industrial production line. This graphical method may also predict environmental pollution of the atmosphere from the release of volatile compounds and airborne particles during thermal treatment of perlite or other processes of mineral treatment.

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Section: Expansion Of Perlite From Milos Islandsupporting

confidence: 69%

Section: Expansion Of Perlite From Milos Islandmentioning

confidence: 99%

Microstructural Control on Perlite Expansibility and Geochemical Balance with a Novel Application of Isocon Analysis: An Example from Milos Island Perlite (Greece)

et al. 2016

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“…The amount of volatile loss in the temperature range associated with magmatic water (~550-1000°C, Roulia et al, 2006;Giachetti et al, 2015) shows a very weak correlation with TVC. Bulk volatile results are therefore assumed to predominantly reflect the amount of meteoric (or secondary water) in RR samples i.e., hydration post-emplacement.…”

Section: Water Content Variabilitymentioning

confidence: 95%

“…Analysis of degassing rate with temperature indicates that several volatile phases contribute to the bulk TVC value ( Table 2). The patterns of volatile release on heating provide insights into the relative contributions of primary and secondary water in the glasses (Roulia et al, 2006;Denton et al, 2012;Tuffen et al, 2012b;Giachetti et al, 2015). In most samples the predominant dTG peak and mass loss is in the 250-550°C temperature range, which is thought to correspond to strongly bound molecular water present in pore spaces, usually ascribed to meteoric water (Roulia et al, 2006).…”

Section: Water Content Variabilitymentioning

confidence: 99%

“…The assumption made here that bulk volatile contents TVC largely reflect post emplacement rehydration of the lava by meteoric water is based upon the proposal that peak degassing temperatures reflect water speciation (e.g., Roulia et al, 2006;Denton et al, 2012;Tuffen et al, 2012b). A previous study by (Giachetti et al, 2015), however, found that experimental volcanic glass lost magmatic water in the temperature range 250-550°C, ordinarily associated with meteoric water.…”

Section: Discrimination Between Magmatic and Meteoric Watermentioning

confidence: 99%

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Unravelling textural heterogeneity in obsidian: Shear-induced outgassing in the Rocche Rosse flow

Shields

Mader

Caricchi

et al. 2016

Journal of Volcanology and Geothermal Research

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Obsidian flow emplacement is a complex and understudied aspect of silicic volcanism. Of particular importance is the question of how highly viscous magma can lose sufficient gas in order to erupt effusively as a lava flow. Using an array of methods we study the extreme textural heterogeneity of the Rocche Rosse obsidian flow in Lipari, a 2 km long, 100 m thick,~800 year old lava flow, with respect to outgassing and emplacement mechanisms. 2D and 3D vesicle analyses and density measurements are used to classify the lava into four textural types: 'glassy' obsidian (b15% vesicles), 'pumiceous' lava (N 40% vesicles), high aspect ratio, 'shear banded' lava (20-40% vesicles) and low aspect ratio, 'frothy' obsidian with 30-60% vesicles. Textural heterogeneity is observed on all scales (m to μm) and occurs as the result of strongly localised strain. Magnetic fabric, described by oblate and prolate susceptibility ellipsoids, records high and variable degrees of shearing throughout the flow. Total water contents are derived using both thermogravimetry and infrared spectroscopy to quantify primary (magmatic) and secondary (meteoric) water. Glass water contents are between 0.08-0.25 wt.%. Water analysis also reveals an increase in water content from glassy obsidian bands towards 'frothy' bands of 0.06-0.08 wt.%, reflecting preferential vesiculation of higher water bands and an extreme sensitivity of obsidian degassing to water content. We present an outgassing model that reconciles textural, volatile and magnetic data to indicate that obsidian is generated from multiple shear-induced outgassing cycles, whereby vesicular magma outgasses and densifies through bubble collapse and fracture healing to form obsidian, which then re-vesiculates to produce 'dry' vesicular magma. Repetition of this cycle throughout magma ascent results in the low water contents of the Rocche Rosse lavas and the final stage in the degassing cycle determines final lava porosity. Heterogeneities in lava rheology (vesicularity, water content, microlite content, viscosity) play a vital role in the structural evolution of an obsidian flow and overprint flow-scale morphology. Post-emplacement hydration also depends heavily on local strain, whereby connectivity of vesicles as a result of shear deformation governs sample rehydration by meteoric water, a process previously correlated to lava vesicularity alone.

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The potential use of natural expanded perlite as a flame retardant additive for acrylonitrile‐butadiene‐styrene based composites

Çelen,

Balçik Tamer,

Berber

2023

Vinyl Additive Technology

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This study aimed to reveal the effect of expanded perlite (EP) additive as a flame retardant for acrylonitrile‐butadiene‐styrene (ABS) copolymer based composites. Before composite preparation, fine powdered EP was characterized by Fourier transform infrared spectroscopy, x‐ray diffraction, thermogravimetric analysis, and scanning electron microscopic analyses. Also, maleic anhydride grafted ABS (MAH‐g‐ABS) with a grafting degree of 3.9 wt% was synthesized and used as a polymeric compatibilizer. ABS/EP composites with different ratios of EP were prepared by a continuous one‐step melt mixing method. Thermogravimetric and morphological analysis, tensile tests, limiting oxygen index (LOI) and UL‐94 vertical burning tests of the composite materials were investigated. EP significantly decreased the decomposition rate of ABS and promoted char formation. EP provided a UL‐94 V‐1 flammability rating with great fire resistance and self‐extinguishing properties to the ABS matrix without any melt dripping. The LOI of ABS was greatly improved, reaching a value of 28.5% by adding only 5 phr EP. Zinc borate (ZB) also played a significant role in enhancing thermal stability and flame retardancy by creating a good synergism with EP. The composite containing 5 phr ZB showed a flame retardant grade of UL‐94 V‐0 and an LOI value of 27.5%.Highlights Flame retardant ABS/EP composites were successfully prepared by melt mixing. The EP ratio of 10 phr provided the highest resistance to flammability. ZB showed good synergy with EP in enhancing the flame retardancy of ABS. ABS/EP10/ZB‐5 composite had a UL‐94 V‐0 rating with an LOI value of 27.0%. This study proved the potential use of natural EP as a flame retardant filler.

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Influence of thermal treatment on the water release and the glassy structure of perlite

Cited by 79 publications

References 23 publications

Microstructural Control on Perlite Expansibility and Geochemical Balance with a Novel Application of Isocon Analysis: An Example from Milos Island Perlite (Greece)

Microstructural Control on Perlite Expansibility and Geochemical Balance with a Novel Application of Isocon Analysis: An Example from Milos Island Perlite (Greece)

Unravelling textural heterogeneity in obsidian: Shear-induced outgassing in the Rocche Rosse flow

The potential use of natural expanded perlite as a flame retardant additive for acrylonitrile‐butadiene‐styrene based composites

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