1. Mariella Constantinescu Rumanian, born at 11 01 1945 in Bucharest
In1967- graduated University “Bucharest”, Faculty of Chemistry, Thesis: “Isotopic Effects in Rotation Spectra”
In1968 started fundamental research in physical chemistry of materials in Institute of Physical Chemistry “Ilie Murgulescu” of the Rumanian Academy,
1980-PhD in Nature Sciences with Thesis “Self-diffusion Coefficients in Molten Salts”,
2001 for Academy Prize Gh.Spacu for: „The Physico-Chemical Funamentals of Some New Procedures involving Industrial Wastes and Residual Energies Recycling”. Since 1997 senior researcher 1

2. Shape stabilized Nano composite Elements based on Phase Change Materials (PCM)-Epoxy for Houses with low Energy Consumption Mariella Constantinescu*, Elena Maria Anghel*, Elena Buixaderas**, P. M.Pavel* ,V.T.Popa* * Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Molten Salts Department, Spl. Independentei 202, Bucharest, Romania, ** Institute of Physics, Academy of Science of the Czech Republic, Dielectrics Department, Na Slovance 2, Prague 8, Czech Republic.

3. Goal and novelty Objectives
Promoting energy efficiency in buildings in the European Union has gained prominence regarding reduction by 20% of the energetic consumption of houses starting with the year The innovative elements are represented by the introduction of Phase Change Materials – PCMs in the structure of building the envelope and of the indoor elements. Some PCM-epoxy nano composites as building materials with different destinations: passive flat multilayer composite envelopes and indoor building elements for heating and cooling.
Obtaining of shape stabilized nano-composite materials by mixing polyethylene glycol of different molecular weights (1000,1500 and 6000) with epoxy resin and aluminum powder, resulting chemically and mechanically stable composites, with no leaking, which can be cured in a desired shape.
Characterization of the obtained materials
regarding thermal and physico-chemical
properties.
Mathematical modeling of solidification
process in the lab-scale cells with various
geometries
4. If composites would be used in storage
units (TSU) with PCM-epoxy to be applied
in buildings with reduced energy
consumption based on the elaborated
simulated mathematical models. The
mathematical model is based on the modified
perturbed parameter method.
The novelty and originality of these materials consist in the fact that some of them (with lower melting point) can be used for cooling whereas the others P15-E, P60-E can be used for heating and respective warm water in active applications TSU-PCM with air or water as transport fluid.
They are echological products obtained by a clean technology, with a good reproducibility. Containerization is not necessary.

4. Obtaining of shape stabilized nano composite elements for heat storage
PEGs were chosen as PCMs in the low temperature domain (<70 C). The appropriate amounts were chosen to yield weight percent of:
PEG : Ropoxid 501 : Al : TETA = 70 : 26 : 1 : 3.
The manufacturing process of the epoxy-polyethylene glycols nano-composites occurs :
-in the first stage Ropoxid 501(the epoxy monomer) is mixed with different PEGs (1000,1500 and 6000) and with 1% sub micronized Al powder.
-In a second stage the hardener TETA is introduced under continuous stirring over the mixture made of PEG, Al and Ropoxid 501 in the blending vessel and homogenized.
-Further, the resin-containing mixture is transferred in a mold (Resin Transfer Molding) and allowed to polymerize into a three-dimensional solid material, with the desired shape during a 24 h span, the reaction being complete after 7 days.
Opaque envelope of multilayer
of PEG(P60/P15/P10)-Epoxy
Elements for heating floor in
active system HTU-PCM

5. Melting/solidification process
P15-E
40 °C
27 °C
48°C
46°C
50°C
50°C
The structural characterization from solid to molten phase of the PEG component was achieved by a RM-1000 RENISHAW Raman spectrometer equipped with A THMS-600 cell (LINKAM cell) at C with an accuracy of the 0.10 C. Raman spectra collected at different temperatures were temperature-reduced to account the first order Bose-Einstein distribution factor from the experimental spectra.
Then a multicomponent fit was performed using Igor Software. Polynomial baseline correction was performed.
The images and band at cm-1 indicate the influence of temperature at the phase change by cycling. Bands assignable to oxirane (epoxy ring) and methylene stretch at 1256 and 3010 cm-1 are ideal to monitor opening of the epoxy rings during curing reaction. Lack of the two bands at 1256 and 3010 cm-1 also indicate a complete cured epoxy resin.

6. Thermal characterization of materials
Thermal behavior of the composites depends on on:
molecular weights, matrix (epoxy) influence ( polymer chemistry),
thermal history, processing parameters
cooling rates, etc.
Matrix effect (on cooling)
DSC Data for (1 oC/min. rate)
Rate
Ton °C
Tpeak °C
Tof °C
ΔHkJ/kg
Cycle*
PEG6000
46.8
44.59
53.9
cooling
58.6
59.3
60.6
heating
60.2
61.7
62.55
P60-E
44.9
42.3
40.1
49.97
52.08
54.02
58.7
60.3
P1500-E
41.744
39.714
36.744
P15-E
41.523
39.01
36.80
*two-component model was used to fit the wide asymmetric peaks on heating
The very wide asymmetric peaks on melting were fitted with two components corresponding to the amorphous phase and the crystalline counterpart.

7. Thermal properties measurements
The level of crystallinity achieved by the polymer will have a major effect on its thermal properties as dimensional stability and high temperature performance
Material
wPEG
Latent Heat(J/g)
ΧC (%)
Tonset (0C)
Tp(0C)
Toffset (0C)
tmax(min.)
cycle
P 10-E
0.70
92.68
67.20
25.557
34.949
37.498
heating
65.152
33.872
31.606
26.875
2.266
cooling
P15-E
78.715
40.265
45.76
48.524
74.989
41.523
38.803
33.974
2.720
P 60-E
84.279
47.463
52.58
54.914
78.198
40.1
42.3
44.9
3.294
ΔH0m is full crystalline PEG enthalpy=197J/g , w is the weight fraction of the PEG component where crystallinity is:
Estimated degree of crystallinity and time of the fastest crystallization of the composites from the DSC data with heating/cooling rates Φ=1ºC/min

8. Thermal behavior DSC peak decomposition of the composites P15-E
DSC peak decomposition of the PEG 1500 and P15-E
Sample
Temperature (0 C)
Peak 1
Peak 2
Peak 3
Peg 6000
41.93
44.06
45.42
P60-E
40.82
42.34
Peg 1500
36.20 -
39.72
P15-E
36.80
39.01
Peg 1000
25.35
31.52
34.09
P10-E
26.68
31.38
32.24
DSC peak decomposition of P60-E
Peak 3 :crystal (extended chains)
Peak 1: amorphous (formed by chain ends)
Temperature (0 C)

9. Influence of heating/cooling rates
Ton
Tpeak
Tof ΔH
Cycle
0.2 47 46 45
cooling
54.4
57.8
58.8
(0.647)
heating
59.4
60.8
61.4
(0.336)
0.4
45.8
44.2
42.8 58
59.2
(0.754)
57.2
59.8
60.9
(0.2)
0.6
41.6
43.3
45.2
48.6
49.2
50.6
111.7(0.013)
54.2
58.3
60.1
111.7(1.004)
0.8
44.9
42.7
40.7
43.5
51.5
54.13
58.5
59.91
1.0
42.3
40.1
49.97
52.08
54.02
58.7
60.3
DSC curves collected at various heating/cooling rates for P60-E
Thermal history
-fast heating and slow cooling semi crystalline solid
-fast heating and fast cooling semi crystalline solid
-slow heating and fast cooling amorphous+some crystals

10. Mathematical modeling of solidification process in the lab-scale cells with various geometries
The mathematical model for solidification processes in the (P10/P15/P60)-E composites in lab-scale cells with various geometries takes into consideration the multiple solid fronts, i.e. amorphous and crystalline fronts.
The two-component decomposition simplified model was used for DSC curves of P15-E used further for mathematical modelling
The heat transfer during solidification can be characterized by the time evolution of both liquid and two solid radial fronts: the crystalline extended chains and the amorphous counterpart of the PEG 1500.The model was analytically solved using Megerlin approximation concerning ‘‘solidification with mushy zone’’, with the third order condition at the external frontier. The heat transfer during solidification can be characterized by the time evolution of both liquid and two solid radial fronts: the crystalline extended chains and the amorphous counterpart of the PEG 1500.The model was analytically solved using Megerlin approximation concerning ‘‘solidification with mushy zone’’, with the third order condition at the external frontier.
DSC curves and experimental discharge curves in an annular geometry for the P15-E nano composite

11. Thermo-physical properties of the nano composites PEG-Epoxy
The mathematical model and the obtaied solution give the possibility to correlate the variables with the dimensionless criteria and approximate the experimental values.
Type
Temperature 0C
Density ρ
Kg/m3
Dimensional variation, d
mm (L,B,W)
Tempe
rature
Thermal conductivity 
W/mK
Thermal diffusivity
Mean value
m2/s
Specific heat ,c, kJ/g K
P2000-E 20 40 50 60 70
1206.9
1182.7
1211.5
1186.9
1171.2
1168.5 15 30 Tm Tf
0.206
0.207
0.211
0.222
0.250
0.212
8.43 10-8
2.64
2.65
2.70
2.84
3.20
2.72
P1500-E
1208.8
1173.7
1219.1
1197.9
1171.5
0.233
0.234
0.238
0.254
0.267
0.241
6.55 10-8
2.31
2.32
2.36
2.52
2.39
P1000-E
1183.5
1183.2
1170.0
1177.1
0.216
0.218
0.232
0.214
Some thermophysical parameters (specific heat, thermal conductivity, density and dimensional variation) were also measured in order to establish the performance levels for modeling the heat transfer in the obtained nano composites at the laboratory set-up as a preliminary step in dimensioning the real buildings.
Thermal characterization of the obtained materials was obtained by using a SETARAM Micro DSC VII Evo calorimeter., stability and flammability tests (ASTM E84 Standard Test Method for Surface Burning Characteristics of Building Materials) were also carried out to determine the best use conditions..

12. Thermal stability and degradation of P15-E composite to be used as building materials
In order to use heat storage materials for buildings one of the most important requirements are the fire resistance, ignition and the spread or growth of the fire, therefore each product must be tested and certificated. Materials can be tested for the degree of flammability and combustibility in accordance with the German DIN [A1 100% noncombustible ,A2~98% noncombustible ,B1 Difficult to ignite, B2Normal combustibility wood].
In order to evaluate the damages of thermal degradations some special tests were used – the “Fire tests”. Fire tests are conducted both on active fire and on passive fire protection items for materials research, quality control, industry and regulatory requirements
Schematic representation of the experimental set-up for indirect fire retardation test for P15-E
Temperature evolution on the two sides of the test sample (1 and 2 define the two thermocouples in Fig.)

13. Thermal degradation of P15-E composite
The thermal degradation induces ( temperature over 200°C) a break of carbon-carbon or carbon –hydrogen bonds. The stability of polymer at heating, the decomposition velocity and the formed products depend on the chemical structure of the material.
DSC hysteresis (10 cycles) for P15-E before (RP15-E) and after (FP15-E) the indirect fire resistance test. The heat flow measurements were recorded with a rate of 10 C/min, during ten cycles to probe the thermal reproducibility.
Cycle number
ΔH (J/g)
TPk1 (o C)
ΔHpk1 (J/g)
TPk2 (o C)
ΔHpk2 (J/g) 1
31.7
25.91
33.7
82.35 2
32.7
67.12
35.0
41.38 3
31.8
10.87
33.6
97.33 4
32.9
56.56
35.3
52.03 5
32.5
28.17
34.3
80.39 6
32.8
29.88
34.6
78.94 7
31.9
36.43
35.1
72.28 8
41.82
35.2
66.97 9
32.6
58.08
36.0
50.66 10
32.2
27.80
80.90

14. The ATR spectra of the FP15-E and RP15-E
ATR spectra of the RP15-E and FP15-E samples
The IR spectra emphasize the changes produced inside the material
Gaussian deconvoluted IR spectra of the RP15-E and FP15-E samples within (a) cm-1 and cm-1 ranges, respectively (ether modes are marked by the green area) and (b) cm-1 range (COO-, -OH and –CO2- modes)

15. CONCLUSIONS
The research activities for using these nano composite materials involve:
a. Development of the PCM-type opaque quasi-adiabatic envelope
– Determination of the thermodynamic characteristics of PCM capable of leading to the development of the PCM passive-type composite multilayer quasi-adiabatic envelope/support of the solar-power ventilated space, by finding the most convenient PCMs to the requirements of the thermal response (phase change temperatures and thermal and physical properties);
– Mathematical modeling of the dynamic process of thermal response of the envelope to the natural outdoor environment conditions and to the anthropic conditions (indoor temperatures and humidity levels in the occupied space), as well as identification of the optimal structure of multilayer composite envelopes, for each climatic zone
b. Development of a building element system type Thermal Storage Units – Phase Change Materials (TSU-PCM) equipped with PCM included in non-structural building elements. TSU-PCM is the support of the free cooling system used in the summer and a decrease of the energy used for heating in winter time.
By using these elements the thermal comfort will be increased diminishing the internal thermal fluctuations and CO2 emissions. Elements can be easy processed in the desired shapes for each application: passive or active systems. Dimensioning of the systems and efficiency estimation involve an accurate knowledge of the thermal answer of the Thermal Storage Units (TSU) at charging taking into account the clime parameters and the necessary heat for the living space.

16. Acknowledgments:
This project was founded by Romanian National Project PNCDI 2 no and INFRANANOCHEM EU Program and carried out within inter- academic cooperation Czech Academy-Romanian Academy.
Results were presented in frame of COST Action TU0802 NeCoE-PCM
Thank you!