Journal of the Korean Physical Society, Vol. 44, No. 3, March 2004, pp. 523∼526
Brillouin Scattering and DSC Studies
of Glass Transition Temperatures of Glucose-Water Mixtures
Jeong-Ah Seo, Su Jae Kim, Jiyoung Oh, Hyung Kook Kim and Yoon-Hwae Hwang∗
RCDAMP and Department of Physics, Pusan National University, Busan 609-735
Y. S. Yang
Institute of Nanoscience and Technology, Pusan National University, Busan 609-735
(Received 8 October 2003)
We studied glass transition temperatures of glucose-water mixtures by using Brillouin scattering
and differential scanning calorimetry (DSC). We fitted the polarized components of the Brillouin
spectra measured by back scattering geometry to simple Lorentzian form and estimated the glass
transition temperature from the slope of the temperature dependent Brillouin peak shift. We
also measured glass transition temperatures by using DSC. The results from both experiments
were consistent with each other, indicating that the Brillouin-scattering technique can be used to
determine the glass transition temperature.
PACS numbers: 78.35.+c, 78.66.Jg
Keywords: Brillouin scattering, Differential scanning calorimetry, Glass transition
I. INTRODUCTION
sition temperatures of monosaccharide (D-glucose and
D-galactose) and disaccharide sucrose sugar were studied by using a differential scanning calorimetry (DSC)
method [4]. We found that the glass transition temperatures of all sugar materials lie above room temperature,
indicating that those sugars are good candidates for aging studies.
In this paper, we report Brillouin scattering and DSC
studies of glass transition temperatures of glucose-water
mixtures. We found that glass transition temperatures
estimated from the simple Lorentzian fit of Brillouin doublets and from DSC measurements agreed well, so that
the Brillouin scattering technique can be used to determine the glass transition temperature of a sample.
Carbohydrates constitute three-quarters of the biological world and about 80 % of the caloric intake of humankind. The ability of sugars to preserve biomolecules
has been recognized for years in food, pharmaceutical,
and biological science [1, 2]. Glass forming sugar has
very great significance in nature. Nature makes use of
glasses to preserve biological tissues in the dehydrated
state. On the other hand, we were interested in sugar
glasses mainly for two reasons. There have been no
published studies of glass-transition dynamics in sugars designed to reveal the full structural relaxation process and sugars are also useful materials for studying
aging phenomena. Aging phenomena are a special property of the non-equilibrium state of a glass phase, and
the study of aging phenomena including two-time scaling, fluctuation-dissipation violations and rejuvenation
effects is a relatively unknown area. The motivation for
selecting glucose as the material for this study was that
glucose is one of the abundant sugars in nature, and the
glass transition temperature of glucose lies above room
temperature. The glass transition temperature of glucose is around 300 K [3,4]. This characteristic is particularly attractive for physical aging experiments, which
require a rapid temperature quench in order to study
the evolution of relaxation dynamics with time.
In our previous study [3], the melting and glass tran∗ E-mail:
II. EXPERIMENTS
Glucose was purchased from Sigma Chemical Co. and
was used without further purification. Double-distilled
deionized water was used to make a glucose water mixture. We used a microwave oven (Samsung RE-M20N)
for uniform and quick melting of sugars. The microwave
frequency of the oven was 2.45 GHz. For more effective
heating, we mixed the sugar powder with water, and
the weight %(percent) of water was 50 %. We used an
open cylindrical-shape glass vessel as a sample holder,
and the sample holder was 30 mm in diameter and 25
mm in height. The microwave power to melt glucose
was 700 watts. During heating, we had a break every
[email protected]; Fax: +82-51-582-3040
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Journal of the Korean Physical Society, Vol. 44, No. 3, March 2004
Fig. 1. Polarized component of Brillouin spectra of the
glucose-water mixture (90/10) at 200, 230, 260, 290, 320 and
350 K (from top to bottom). The open circles are experimental results, and the solid lines are fitting results. The
peak position moved to lower frequencies and the peak width
increased as the temperature increased.
10 seconds to prohibit overheating and to support the
evaporation of water. After we had melted sugars without caramelization, we quenched the melted sugar by
dipping the sample holder into liquid nitrogen. We also
found that dipping the melted sugar into cold water was
enough to avoid cystallization.
In Brillouin-scattering experiments, a backscattering
geometry was used. The incident beam was vertically polarized 488-nm blue light from an Ar ion laser (coherent,
300C) with 500 mW power. The polarized component
of the scattered light was measured by using a six-pass
tandem Fabry-Perot interferometer (JAS Scientific Iinstruments). For light scattering, we used a cylindricalshape glass cell, and the sample cell was 12 mm in diameter and 20 mm in height. The cell was sealed by a
silicon plug. The temperature of the sample cell was controlled by a cryostat (Cryo Industries of America, INC.
110-637-DND) and a temperature controller (Lake Shore
330 USA). A single-phase induction motor (Shi Dae Elecrtonic, Co. HOD SDP-4004) was used to produce a
vacuum inside the cryostat. We also used a differential
scanning calorimetry (Mac Science, DSC3100, Japan) to
measure the glass transition temperature of the glucosewater mixture.
III. RESULTS
We measured the polarized component of Brillouin
spectra (VV) in the glucose-water mixture at different
temperatures ranging from 180 K to 310 K. Brillouinscattering experiments were a good method for measuring the acoustic phonon modes in the material [5,6]. A
typical Brillouin spectrum consists of three peaks. The
central peak is the Rayleigh peak, and the two shifted
peaks are the Brillouin doublet [7–9]. Fig. 1 shows the
Brillouin doublets of a glucose-water mixture (90/10) at
different temperatures. In this measurement, the central
peak was cut off by the shutter to avoid a strong elastic laser line. We could observe that the Brillouin peak
position moved to lower frequencies and the peak width
changed with increasing temperatures [10,11]. The open
circles are experimental results, and the solid lines are fits
of the data to simple Lorentzian form.
In a Brillouin-scattering experiment, the Brillouin
peak is convoluted by a gaussian-shape laser line (instrumental factor). Therefore, it is necessary to deconvolute
the measured data or to modify the fitting function with
the laser line. In our fitting process, we convoluted the
Lorentzian form with a gaussian-shape laser line. The
fitting function used in this study was
2Aµ
Γ
(
+ Γ2 )
π 4(ω − ωc )2
√
(1 − µ) 4 ln 2
4 ln 2
√
exp(− 2 (ω − ωc )2 ).
+
Γ
πΓ
I(ω) = I0 +
Here, I(ω) is the intensity of scattered light, µ is an
adjustable parameter which depends on the instrument
factor, Γ is a damping factor related to the bulk and
shear viscosity of the system, ω is the frequency, and ωc
is the position of the Brillouin shift.
Figs. 2(a) and 2(b) respectively show the temperaturedependent Brillouin peak shift and the peak width for
glucose samples with 5 %, 10 %, and 20 % of water.
We can observe in Fig. 2(a) that the slope of frequency
shift changed at a certain temperature. Around that
temperature, the Brillouin peak width also started to
increase abruptly, as can be seen in Fig. 2(b). The origin
of the slope change can be attributed to the fact that
the temperature dependence of viscosity in a supercooled
liquid is higher than that in a glass [12]. We estimated
the crossover temperatures of 95/5, 90/10, and 80/20
weight percent glucose-water mixture samples as about
272, 249, and 230 K.
We also measured the glass transition temperatures
of 95/5, 90/10, and 80/20 weight percent glucose-water
mixture samples by using differential scanning calorimetry (DSC) for comparison, and the results are shown in
Figs. 3 (a) - 3(c). The heating rates used in this measurement were 2, 4, 5, and 8 K/min. As we expected, the
glass transition temperature decreased with decreasing
heating rate. The glass transition temperature was taken
to be the mid-point between the onset and end temperatures. We estimated the glass transition temperatures
of 95/5, 90/10, and 80/20 weight percent glucose-water
mixture samples as about 270, 250, and 228 K. The results were consistent with those from Brillouin-scattering
experiments, within experimental error.
IV. CONCLUSIONS
Brillouin Scattering and DSC Studies· · · – Jeong-Ah Seo et al.
Fig. 2. Fitting results of Brillouin spectra. (a) Temperature dependence of the Brillouin shift. The slope of the
frequency shift changed at the glass transition temperature.
The glass transition temperatures of 95/5, 90/10, and 80/20
glucose-water mixtures are 272, 249 and 230 K, respectively.
(b) Temperature dependence of the Brillouin peak width.
The peak width started to increase abruptly at the glass transition temperature.
We studied the glass transition temperature of a
glucose-water mixture by using Brillouin scattering and
DSC experiments, and found that, in addition to the conventional DSC technique, the Brillouin-scattering technique can also be used to determine the glass transition
temperature of the sample. We measured the polarized
Brillouin spectra and analyzed the data by reference to
the simple Lorentzian form. The glass transition temperatures were estimated from the slope change in the Brillouin shift vs. temperature graph. The estimated glass
transition temperatures of glucose-water mixtures which
contain 5, 10 and 20 % water were 272, 249 and 230 K,
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Fig. 3. DSC results for glucose-water mixtures. Four different heating rates were used; 2, 4, 5, and 8 K/min from
top to bottom . (a) Glucose 95 % and water 5 %. The glass
transition temperatures ranged from 267.2 to 271.8 K. (b)
Glucose 90 % and water 10 %. The glass transition temperatures ranged from 247.8 to 253.6 K. (c) Glucose 20 % and
water 20 %. The glass transition temperatures ranged from
225.5 to 230.2K.
respectively. Those results were highly consistent with
glass transition temperatures measured by using differential scanning calorimetry (DSC).
ACKNOWLEDGMENTS
We thank H. Z. Cummins for suggesting sugars for
a glass transition study. This work was supported by
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Journal of the Korean Physical Society, Vol. 44, No. 3, March 2004
Grant No. R01-2002-000-00038-0 from the Basic Research Program of KOSEF.
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