Glass Foams Produced from Glass and Yerba Mate (Ilex paraguarinensis) Waste

Abstract

Glass Foams Produced from Glass and Yerba Mate (Ilex paraguarinensis) Waste In this study, compositions containing green glass bottles and desiccated and crushed yerba mate (Ilex paraguarinensis) of different mass fractions (10-30%) were prepared to obtain glass foams for thermal insulation purposes. These compositions were uniaxially pressed (at 40 MPa), and the compact powders were fired at 850°C and 900°C for 60 min in order to investigate the effect of yerba mate and temperature on the formation of pores and the thermal and mechanical properties of the processed glass foams. The results indicated that the glass foams displayed porosities ranging from 65.3-88.3%, compressive strengths ranging from 15-1.5 MPa, and thermal conductivities ranging from 0.6-0.04 W·m-1 ·K-1. Cumulatively, these glass foams are candidate thermal insulators that have advantageous properties for various industrial applications.

Full text

© Faculty of Mechanical Engineering, Belgrade. All rights reserved FME Transactions (2016) 46, 70-79 70
Received: March 2017, Accepted: September 2017
Correspondence to: Prof. Carlos Perez Bergmann
Federal University of Rio Grande do Sul, Department of
Materials Engineering, Porto Alegre, Brasil
E-mail: bergmann@ufrgs.br
doi:10.5937/fmet1801070L
Lucas Lemos da Silva
Federal University of Rio Grande do Sul
Department of Materials Engineering
Brazil
Leila Cristina Nunes Ribeiro
Federal University of Rio Grande do Sul
Department of Materials Engineering
Brazil
Galileo Santacruz
Federal University of Rio Grande do Sul
Department of Materials Engineering
Brazil
Sabrina Arcaro
Federal University of Rio Grande do Sul
Department of Materials Engineering
Brazil
Annelise Koop Alves
Federal University of Rio Grande do Sul
Department of Materials Engineering
Brazil
Carlos Pérez Bergmann
Federal University of Rio Grande do Sul
Department of Materials Engineering
Brazil
Glass Foams Produced from Glass and
Yerba Mate (Ilex paraguarinensis)
Waste
In this study, compositions containing green glass bottles and desiccated
and crushed yerba mate (Ilex paraguarinensis) of different mass fractions
(10–30%) were prepared to obtain glass foams for thermal insulation
purposes. These compositions were uniaxially pressed (at 40 MPa), and
the compact powders were fired at 850°C and 900°C for 60 min in order to
investigate the effect of yerba mate and temperature on the formation of
pores and the thermal and mechanical properties of the processed glass
foams. The results indicated that the glass foams displayed porosities
ranging from 65.3–88.3%, compressive strengths ranging from 15–1.5
MPa, and thermal conductivities ranging from 0.6–0.04 W·m-1·K-1.
Cumulatively, these glass foams are candidate thermal insulators that have
advantageous properties for various industrial applications.
Keywords: glass foams, wastes, yerba mate.
1. INTRODUCTION
A growing interest in porous ceramics has been mainly
associated with their specific properties, such as high
surface area, high permeability, and low density and
thermal conductivity. These properties are all related to
the characteristics of ceramic materials, such as high
refractoriness and resistance to chemical attacks [1].
Several different materials can be used for the manu–
facture of porous ceramics, such as alumina, mullite,
silicon carbide, zirconia, and hydroxyapatite. However,
recent studies have shown numerous advantages and
possible uses for discarded glass in the synthesis of
glass foams [2-13].
Lately, the progressive demand for more sustainable
materials in industry, powered by the usage of
renewable and/or natural resources, have gained
importance from structural plastic composites [14-19] to
mobility solutions [20-23], aiming to provide, if not full
recyclability, at least an eco-friendlier supply chain on
diversified material applications. On that matter, the
glass used in the manufacturing of glass foams can be
glass that has been disposed of as waste. The recycling
and use of glass waste can generate large energy savings
because the production of 1 kg of new glass requires
4500 kJ of energy, while the production of 1 kg of
recycled glass requires only 500 kJ [24]. In order to
reduce production costs and obtain raw materials,
several modifications have been applied to the
processing techniques and starting materials [4].
Furthermore, environmental and social concerns have
increased the need for novel methods of converting
waste into useful products while minimizing energy
consumption and the use of raw materials in order to
reduce environmental impacts [25,26].
Commercial glass foams are used for various
applications, such as the construction of roofs, walls,
floors, ceilings, fireplaces, and grills used at working
temperatures below 500°C [11]. These glass foams
display porosity values ranging from 85–95%, which
can be opened, closed, or mixed. They have comp–
ressive strength values ranging from 0.4–6 MPa and
thermal conductivity values of 0.04–0.08 W·m-1·K-1.
Furthermore, glass foams are chemically stable, non-
toxic, and non-flammable. Polymeric foams are
typically employed in industrial applications [4,11,27].
Several techniques for producing porous ceramics
are currently used, and the processing steps generally
consist of preparing a suspension of ceramic powder,
which is then formed and heat-treated (fired). The best
known forming methods include the replication method,
gelcasting, the template or sacrificial method, and
foaming and incorporation of porogenic agents (pore
formers) [11,28]. Because of its simplicity, one of the
techniques widely used for the production of glass
foams is the addition of a foaming agent to the
powdered glass, followed by its removal from the heat
treatment step to form a cellular structure [4,27]. The
foaming agents can be synthetic (polymers) or natural
(mineral or vegetable residues) [2,27].
The natural residues are composed of different
elements, such as cellulose, hemicellulose, and lignin,
which open many value-adding opportunities and can be
a low-cost alternative for use as foaming agents [29].

FME Transactions VOL. 46, No 1, 2018 ▪ 71
There is a worldwide trend towards the recycling of
waste with calorific value in the ceramic industry. Some
research studies have focused on various technologies,
such as the use of pulp and paper industry waste, urban
waste treatment plants, and agro-industrial residues
(including banana leaves, rice husks, and sugar cane
bagasse). This is because of the large volume of these
wastes and the large environmental impacts they have
on water resources and, therefore, society as a whole.
These residues can be used to obtain glassy foam. In
addition, glass foams represent an interesting use for
glass and vegetable wastes from an economic and envi–
ronmental point of view.
Significant plant waste in temperate and subtropical
regions of Brazil, Paraguay, and Argentina comes from
Yerba mate (Ilex paraguariensis) cultivation [2, 30-33].
Worldwide, the production of yerba mate is significant.
Brazil produces 860 thousand tons of green mate [34],
Argentina produces 690 thousand tons of green herbs
[35], and Paraguay produces 85 thousand tons [36].
Within this social context and the potential savings
associated with reuse of glass and yerba mate waste, this
article reports the production of glass foams from glass
bottles and yerba mate waste (as a pore forming agent).
Different samples were prepared to obtain materials
with controlled porosity for applications where thermal
insulation and non-flammability are the main require–
ments. The results of this work serve as a basis for
future studies aimed at applying these methods using
Ilex paraguariensis residues to produce industrial
products.
2. MATERIALS AND METHODS
In this study, green glass bottles (the soda-lime type)
and yerba mate (Ilex paraguariensis) were used as
alternative pore forming agents and raw materials. The
glass bottles were washed and dried at 110°C for 2 h. In
a subsequent step, the dried glass bottles were then
broken with a hammer and the resulting fragments were
milled for 180 min in a fast mill (Servitech, CT-242)
consisting of a porcelain jar containing alumina balls,
and powders with particle sizes less than 44 μm (325
Mesh) were obtained. The average particle size
distribution (d50 = 2.45 μm) of the resultant material was
determined using a laser scattering particle size analyzer
(CILAS 1180 Liquid).
Samples of dried yerba mate were milled so that a
powder with a particle size below 90 μm (170 Mesh)
was obtained. The powder samples obtained were
characterized by proximate chemical analysis according
to procedures described in ASTM E1871-82 (2006) for
moisture, ASTM E872-82 (2006) for volatile materials,
ASTM E1755-01 (2007) for ash, and ASTM E1756-08
(2008) for total solids and fixed carbon.
The chemical characterization of the obtained glass
powders and yerba mate was performed using X-ray
fluorescence spectroscopy (XRF 1800, Shimadzu).
The samples of both wastes were dried at 110°C for
2 h and mixed (dry mixing in a ball mill for 5 min) with
different proportions of glass (70–90 wt%) and yerba
mate (10–30 wt%) with the addition of 10% water. The
prepared mixtures were uniaxial pressed (40 MPa) at a
later stage in a steel matrix by means of a hydraulic
press. The obtained powder compacts (30 mm diameter)
were dried at 110°C for 2 h.
The thermal behavior during the firing of the raw
materials was investigated using an optical dilatometer
(ODHT, Misura) and also by thermogravimetric
analyses, TG (TGA-50, Shimadzu) at 10°C/min with a
flow of synthetic air of 50 cm3/min.
Based on the thermal analyses, green compacts were
fired in a laboratory furnace (BTT 2374, Sanchis) at
different temperatures (850°C and 900°C) for 60 min
with a heating rate of 10°C/min followed by cooling to
room temperature (approximately 25°C).
The true densities (ρt) of the powdered glass waste
samples were determined using a helium pycnometer
(AccuPyc 1340, Micromeritics, USA). The apparent
densities (ρa) of the fired samples were determined by
relating their geometrical measurements obtained using
a caliper (Mitutoyo, accuracy ± 0.01 mm) and their
masses (Shimadzu AX200 at 0.001 g). From
measurements of geometrical and true densities, the
porosities (ε) of fired glass foams were calculated
according to equation 1.
ε (%) = [1 – (ρa / ρt )] x 100
The microstructure of the pores of the obtained glass
foams was observed and analyzed from images of
fracture surfaces of samples obtained in an optical
microscope (Olympus, 3Z61). Size and pore size
distributions for the glass foams were determined by
quantifications corresponding to the specified pore
diameter ranges. This was based on the linear intercept
method [37], where the ratio between the average length
string (t) and average sphere diameter (D) is given by
Eq. (1) to better represent the measurement of a 3D unit
(pore) by a 2D image.
D = 1.623t (1)
In this case, five images of the fracture surfaces of
each foam obtained were used, and 300 measurements
of each image, on average, were made with aid of
software (ImageJ®).
To determine the mechanical strength of the glass
foams, compressive strength tests were performed.
Samples with nominal dimensions of 10 × 10 × 10 mm
were tested in a universal test machine (Autograph AG-
X, Shimadzu) with a crosshead speed of 1 mm/min and
a load cell of 2 KN with a preload of 3 kg. Ethylene-
vinyl acetate sheets were used on the samples for
uniform charge distribution.
The thermal conductivity of the obtained materials
was determined by a TCi Thermal Conductivity C-
THERM TECHNOLOGIES on disk-shaped samples 30
mm in diameter.
3. RESULTS AND DISCUSSION
Table 1 shows the results of the proximate chemical
analysis of the yerba mate samples. The proximate
80.5% volatile solid content indicates the presence of
organic matter, which represents the lignocellulosic and
carbon fractions present in the samples. This also
expresses the weight of the components of the biomass,

72 ▪ VOL. 46, No 1, 2018 FME Transactions
which are first thermally degraded and then oxidized
during combustion [32,33]. After combustion, the
remaining material corresponds to the ashes, which was
approximately 8.5% for the yerba mate analyzed. The
yerba mate and yerba mate ashes are rich in CaO, K2O,
SiO2, MnO, P2O5, and MgO, which can be seen in Table
2. These components are in accordance with the
findings of previous studies [38], and their presence will
not affect the performance of the glass foams because
they are of low concentration and do not make up part
of the glass composition. Studies indicate low ash
concentrations in the biomass range from 0.3–1%, but in
agricultural residues including rice husks, ash may
represent 23%, while this is less than 3% for sugar cane
bagasse [29,39]. The fixed carbon content was
approximately 7% and it is related to the mass of the
material remaining after removal of the volatile
components during firing, excluding ash and moisture.
The moisture is approximately 5%. The volatile solid
content and the fixed carbon may be responsible for the
vitreous foam formation.
Table 1. Proximate chemical and elemental analysis of
yerba mate samples.
Parameters Content (wt%)
Moisture 4.37±0.5
Volatile solids 80.60±0.4
Fixed carbon 6.96±0.4
Ashes 8.44±0.2
Table 2 shows the chemical composition of the glass
bottle, yerba mate, and yerba mate ashes used in this
study.
Table 2. Chemical analysis (X-ray fluorescence) of the
glass waste, yerba mate, and yerba mate ashes.
Constituent
oxides
Glass waste
(wt%)
Yerba mate
(wt%)
Yerba mate
ashes (wt%)
SiO2 68.3 0.7 8.57
Al2O3 2.07 0.3 3.38
Fe2O3 0.41 0.5 1.30
CaO 8.94 1.2 23.43
K2O 0.44 1.7 25.55
MgO 1.80 0.3 3.85
Na2O 17.95
P2O5 0.01 0.3 4.23
TiO2 0.06
MnO - 0.2 5.33
P2O5 - 0.3
SO3 - 0.4 2.06
CO2 - 94.3 22.5
It can be verified that the glass bottles samples are
abundant in SiO2, Na2O, and CaO in amounts typically
found in soda-lime-silica glasses. The iron oxide
(Fe2O3) present in the sample is due to the green
coloration of the glass bottles used. Because the
applications envisaged in this work mainly relate to
panels for thermal insulation used in buildings in
general, no aesthetic requirements are necessary in
terms of a specific color.
Figure 1 shows linear shrinkage curves for the
recycled glass bottle samples, in addition to mass loss
for yerba mate and yerba mate ashes (in detail) as a
function of temperature. These data were obtained by
optical dilatometry and thermogravimetric analysis.
Glass densification (black line) starts at approximately
600°C and its softening begins at 700°C (Littleton
softening point). From approximately 900°C (when the
glass reaches its highest shrinkage and densification),
the glass expansion occurs at temperatures up to 1000°C
as a result of viscous liquid phase formation. At
temperatures higher than 1000°C, the viscosity of the
glass gradually decreases. The yerba mate (blue line)
showed three stages of thermal degradation. The first
(from room temperature to about 150°C) is related to
moisture loss from the sample, corresponding to a
weight loss of 6%. These values are close to those found
by proximate analysis, which was presented earlier. In
the second stage, between 150–580°C, the largest
weight loss attributed to volatile materials and
degradation of hemicellulose (the cellulose and lignin
portion, which are constituents of the biomass) is
registered. Mass loss for the yerba mate samples is 93%.
At this stage, it is also possible to identify the ignition
temperature of the biomass combustion process. The
thermal degradation of biomass products consists of
moisture, volatiles, and ash. The volatiles are
subdivided into gases, such as light hydrocarbons,
carbon monoxide, carbon dioxide, and tar. Yields
depend on the temperature and heating rate [39]. A third
stage of mass loss can be observed above 580°C. These
are the ashes of the yerba mate. Ashes have a large
amount of carbon that cause the formation of gases at
temperatures between 600–1000°C, which can be seen
in detail in Figure 1.
200 400 600 800 1000 1200 1400
100
80
60
40
20
0
400 600 800 1000
75
80
85
90
95
100
Mass loss yerba mate ashes
Mass loss (%)
Temperatur e (ºC)
Mass loss (%)
shrinkage (glass)
Mass loss (yerba mate)
Temperature (ºC)
0
20
40
60
80
100
Linear Shrinkage (%)
Figure 1. Linear shrinkage curve of the recycled glass bottles
(black line) and mass loss for yerba mate (blue line) and
yerba mate ashes (in detail) as a function of temperature.
The firing temperature for the production of glass
foams is critical because it is directly related to the glass
viscosity, and its expansion is caused by the gas release
from the foaming agent decomposition [3,40]. In this
case, two pore forming processes are effective. Initially,
pores are formed in the vitreous matrix due to pyrolysis
of the yerba mate, which acts as sacrificial material or
template. These pores form, but do not cause matrix
expansion. They only occupy the place previously
occupied by the yerba mate. Thereafter, at temperatures
above 600ºC, the carbon resulting from the pyrolysis of
the yerba mate is responsible for the second process of
pore formation. That is, there is an expansion of the
vitreous matrix due to the release of gas (Figure 1- yerba

FME Transactions VOL. 46, No 1, 2018 ▪ 73
mate ashes) at the temperature at which there is an
adequate viscosity in the glass. The most convenient vis–
cosity range for the expansion of the glass foam produc–
tion with maximum porosity corresponds to temperatures
between 800–1000°C for soda-lime glasses [3,40].
Figure 2 shows the porosity of glass foams produced
with different amounts of yerba mate fired at 850ºC and
900ºC for 60 min.
As can be seen, the porosity of the produced glass
foams ranges from 63.3–88.3%. In general, with
increasing amounts of yerba mate, there is increase in
porosity. As the firing temperature increases from 800–
900°C, the porosity remains practically constant for all
studied compositions. This suggests that the main factor
that influences porosity in this temperature range (850–
900ºC) is the amount of yerba mate. Studies show [13]
that with higher firing temperatures, there is a decrease
in the glass viscosity, which was not sufficient to
maintain the cell structure because 950°C, for example,
is very close to its melting temperature.
Commercial glass foams have porosity values
between 85–95% [11]. Therefore, some glass foam
samples show porosity values higher than those found in
commercial products processed under similar
conditions, which was reported in previous studies [2-4,
6, 10].
10 15 20 25 30
50
55
60
65
70
75
80
85
90
95
100
88.24±0.6
84.54±0.3
82.36±0.9
80.17±0.8
72.73±0.6
75.25±0.5
63.27±0.8
Porosity (%)
Yerba mate content (wt%)
850 ºC
900 ºC
64.98±0.4
Figure 2. Porosity of glass foams produced with different
contents of yerba mate (10, 15, 20 and 30%) fired at 850ºC
and 900ºC for 60 min.
2 mm
2 mm 2 mm
(a)
(c) (d)
2 mm
(b)
Figure 3. Optical micrograph of glass foams produced with
different contents of yerba mate (10% [a], 15% [b], 20% [c],
and 30% [d]) fired at 850ºC for 60 min.
2 mm
2 mm 2 mm
(a)
(c) (d)
2 mm
(b)
Figure 4. Optical micrograph of glass foams produced with
different contents of yerba mate (10% [a], 15% [b], 20% [c],
and 30% [d]) fired at 900ºC for 60 min.
Figures 3 and 4 show optical micrographs of glass
foams produced with different contents of yerba mate
(10 [a], 15 [b], 20 [c], and 30% [d]) fired for 60 min at
850ºC (Figure 3) and 900ºC (Figure 4), respectively.
From a visual inspection of the images, the samples
are free of cracks (at least within the field of obser–
vation) with uniformly distributed pores having closed
porosity, and very similar morphologies are observed
for all glass foams obtained. These results are in
agreement with the data shown in Figure 2. The porosity
also increases with higher amounts of yerba mate.
Figure 5 shows histograms of the pore size
distributions for the glass foams produced with different
contents of yerba mate (10, 15, 20, and 30%) fired for
60 min at 850ºC (a) and 900ºC (b), respectively.
According to the measurements in the histograms, it
can be observed that the sample containing 10% yerba
mate has the diameter for all pores below 1 mm for all
firing temperatures. The small pores observed are
mainly due to the low amount of porogenic agents. The
sample containing 15% mate grass has a pore size
distribution for which approximately 75% of the pores
are smaller than 1 mm and 25% of the pores are 1–2
mm when the firing temperature is 850°C. The pore
diameters increase significantly when the firing
temperature increases. The pore diameter increases with
increasing temperature for the 15% sample because
there is a larger amount of carbon residue resulting from
the pyrolysis process of the yerba mate. Subsequently,
there is an expansion of the vitreous matrix as a result of
the higher release of gas. This can be observed in the
samples containing 20–30% yerba mate. For the sample
containing 30% yerba mate, pores ranging from 3–4
mm in diameter are also observed. From the analysis of
Figures 3 and 4, there is a tendency for pore diameter to
increase with increasing porosity. This is because
increasing the amount of air inside the foam results in
greater porosity. Such insertion is obtained by
increasing the number of pores or their diameters.
Figure 6 shows the compressive strength results for
the glass foams supplemented with 10, 15, 20, and 30%
yerba mate and fired at 850ºC and 900ºC for 60 min.
The mechanical strength is greatly influenced by the
porosity. Specifically, the sample with the highest

74 ▪ VOL. 46, No 1, 2018 FME Transactions
porosity (30% yerba mate) has the lowest compressive
strength (approximately 1.5 MPa) and the sample with
one of the lowest porosity values (10% yerba mate) has
the highest compressive strength (approximately 15
MPa). This result is in good agreement with the
observed porosity results: it increases as the comp–
ressive strength decreases. There were no significant
variations in compressive strength with increases in
temperature. This can be explained by little variations in
the porosity following the increase in temperature.
0,01-0,99 1,0-1,99 2,0-2,99 3,0-3,99
0
10
20
30
40
50
60
70
80
90
100
Frequency (%)
Pore diameter (mm)
10%
15%
20%
30% Yerba mate
(a)
0,01-0,99 1,0-1,99 2,0-2,99 3,0-3,99
0
10
20
30
40
50
60
70
80
90
100 (b) 10%
15%
20%
30% Yerba mate
Frequency (%)
Pore diameter
(
mm
)
Figure 5. Pore diameters of glass foams produced with
different contents of yerba mate (10, 15, 20, and 30%) fired
at 850ºC (a) and 900ºC (b) for 60 min.
10 15 20 25 30
0
5
10
15
20
25
1.96±0.91
1.42±0.68
2.09±0.35
2.11±1.09
4.58±1.82
4.57±2.42
14.90±8.59
14.74±7.07
Compressive strength (MPa)
Yerba mate content (wt%)
850 ºC
900 ºC
Figure 6. Compressive strength of glass foams produced
with different contents of yerba mate (10, 15, 20, and 30%)
fired at 850ºC and 900ºC for 60 min.
Commercial glass foams typically have compressive
strength values between 0.4–6 MPa [11]. In this case, as
shown in Figure 2, glass foams obtained with yerba
mate contents between 15–30% achieve the
compressive strength range established. Thus, the glass
foams obtained in this study satisfy the minimum
requirements in terms of compressive strength.
Figure 7 shows the thermal conductivity results for
the glass foams produced following the addition of 10,
15, 20, and 30% yerba mate and firing at 850ºC and
900ºC for 60 min. In general, the thermal conductivity
decreases as the porosity increases (due to the yerba
mate content). This is the result of the contribution of a
higher porosity, which reduces thermal conductivity,
especially in cases where the pores are closed and are
not interconnected. In contrast, with the increase in
temperature from 850°C to 900°C, the thermal
conductivity decreases. In this case, although the
porosities are very similar, there is a greater
contribution of the larger pore sizes in the glass foams
obtained at 900ºC.
It is noteworthy that glass foams that contain 15, 20,
and 30% yerba mate fired at 900ºC have values of
thermal conductivity within the range of values
corresponding to the commercial glass foams (Figure 6,
blue area), which range from 0.04–0.08 W·m-1·K-1 [11].
10 15 20 25 30
0,00
0,05
0,10
0,15
0,55
0,60
0,65
0.045±0.03
0.065±0.04
0.083±0.05
0.166±0.03
0.594±0.02
0.158±0.04
0.146±0.05
Thermal conductivity (W.m-1K-1)
Yerba mate content (%)
850ºC
900ºC
0.087±0.03
Comercial glass foams
Figure 7. Thermal conductivity of glass foams produced
with different contents of yerba mate (10, 15, 20, and 30%)
fired at 850ºC and 900ºC for 60 min.
4. CONCLUSION
Discarded glass bottles (90–70 wt%) can be suc–
cessfully converted into glass foams using Ilex
paraguariensis (10–30 wt%) as foaming agents, thus
contributing to the sustainable life cycle of these
materials, which are usually deposited in landfills, by
recycling the glass and yerba mate wastes.
The glass foams produced after firing at 850°C and
900°C for 60 min have porosities between 66.3–88.3%
and compressive strengths ranging from 15–1.5 MPa.
Their thermal conductivity ranges from 0.6–0.04 W·m-
1·K-1.
This glass foam synthesis process is simple and does
not require the use of toxic additives. The additive
manufacturing can represent the right option for a
gamma of industrial products [41,42]. Moreover,
additional savings could be realized using an integrated

FME Transactions VOL. 46, No 1, 2018 ▪ 75
approach for the full cost optimization of the process as
a whole, instead of moving toward single steps of
reduction for additive manufacturing and, separately,
vacuum casting. Finally, the benefits provided by these
new techniques toward a modern manufacturing also
has to be considered in terms of eco-sustainability, evi–
dent when compared with conventional methods [43].
The properties we obtained for the end-products show
that this method is adequate when the objective is to
obtain materials with homogeneous microstructures,
porosity, and good mechanical strength. The evaluated
properties indicate that the glass foams generated can be
used as heat insulation panels, which require an
appropriate combination of thermal conductivity,
porosity, and mechanical strength.
ACKNOWLEDGMENTS
The authors thank CAPES and CNPq for the financial
support.
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СТАКЛЕНЕ ПЕНЕ ПРОИЗВЕДЕНЕ ИЗ
СТАКЛА И ОТПАДА БИЉКЕ МАТЕ (Ilex
paraguarinensis)
Л. Л. да Силва, Л. Ц. Н. Рибеиро, Г.
Сантакруз, С. Аркаро, А. К. Алвес, Ц. П. Бергман
У овом истраживању припремљени су препарати који
садрже зелене стаклене бочице и осушену и дробљену
биљку мате (Ilex paraguarinensis) различитих масених
фракција (10-30%) за добијање стаклене пене за
потребе топлотне изолације. Ове композиције су
једноосно притиснуте (за 40 MPa), а компактни
прахови печени су на 850° C и 900° C у трајању од 60
минута како би се испитао утицај биљке мате и
температуре на формирање пора и термичких и меха–
ничких особина обрађених стаклених пена. Резултати
указују да стаклене пене показују порозности у рас–
пону од 65,3-88,3%, јачину притиска у распону од 15-

FME Transactions VOL. 46, No 1, 2018 ▪ 79
1,5 MPa и топлотну проводљивост у распону од 0,6-
0,04 Wm-1K-1. Кумулативно, ове стаклене пене су
кандидати за термичке изолаторе који имају погодне
особине за различите индустријске примене.