Authors:Daniele Bergamasco, Franco Bulian, Andrea Melchior, Davide Menotti, Paolo Tirelli, and Marilena Tolazzi
their mechanical behavior is similar both to solid materials (elastic properties) and to liquid substances (viscous properties). This complex mechanical behavior can be deeply studied by using DMA [ 19 – 22 ].
The data obtained from DMA [ 17
segments. Both of these processes can be investigated using differential scanning calorimetry (DSC). The glass transition region can be investigated very well using dynamic mechanical analysis (DMA).
However, Saiani et al. [ 2 ] indicate that
Authors:M. Odlyha, N. Cohen, G. Foster, A. Aliev, E. Verdonck, and D. Grandy
DMA and solid state 13C NMR techniques were used to measure historical parchment samples within the framework of the project (MAP) Micro Analysis
of Parchment (EC contract No. SMT4-96-2101) in collaboration with the School of Conservation in Copenhagen. DMA was used in
both thermal scan and creep modes. Thermal scans provided information on the transitions associated with the collagen polymer.
Microthermal analysis was also used to obtain information on the topography and thermal conductivity of sample areas of 100
μm. Localised heating enabled measurements of softening transitions in the sample. This behaviour is influenced by the chemical
composition of parchment. 13C NMR provided information on the carbon atoms associated with the polypeptide chains of the collagen
in parchment. The behaviour of samples immersed in water and measured in DMA creep mode was used to measure the shrinkage
behaviour of the parchment samples. The different but complementary techniques provided a means for characterising the physicochemical
state of parchment samples.
Authors:L. Barral, J. Cano, J. López, I. López-Bueno, P. Nogueira, M. Abad, and C. Ramírez
The physical aging of a system containing tetraglycidyl-4-4′-diaminodiphenylmethane (TGDDM), with a multifunctional novolac
glycidyl ether resin hardened by 4,4′-diaminodiphenylsulphone (DDS) has been investigated by differential scanning calorimetry
(DSC) and dynamic mechanical analysis (DMA). Samples fully cured were aged at temperatures between 200 and 250C, during periods
of time from 1 to a maximum of 336 h. Furthermore, the dynamic mechanical relaxation behaviour annealed at temperature of
220C, was studied, aging during 24 and 168 h. The effect of the enthalpy relaxation during DSC heating scan is shown by the
presence of an endothermic peak whose position and intensity depends on the aging conditions, both temperature and time. DSC
studies suggest that enthalpy relaxation increases gradually with aging time to a limiting value for each temperature where
structural equilibrium is reached. DMA results show that the effect of aging is to cause chain stiffening and a decrease in
the height of the peak value of the loss factor.
Authors:F. Fraga, T. Salgado, J. Rodríguez Añon, and L. Nuñez Regueira
Mechanical behaviour play an important role in the election of an epoxidic formulation of well determined properties as it
has a marked influence on both structural and external factors.
Temperature and time strongly act on polymers properties owing to their viscoelastic nature.
Knowledge of the dynamic moduli and properties of polymeric materials is indispensable for the design of this materials. At
the same time, the influence of the temperature on polymers behaviour may be studied once the activation energy is known.
In this paper the different dynamic moduli and activation energy are measured using a Perkin Elmer DMA 7.
The relationships between the dynamic mechanical properties and the molecular weight of the polymers make possible the calculation
of the molecular weight.
Results reasonably agree with literature values.
Authors:Gonzalo Vázquez, Jorge Santos, M. Sonia Freire, Gervasio Antorrena, and Julia González-Álvarez
(DMA), which normally completes before [ 11 , 13 ]. Then, the simultaneous use of both techniques is recommended to optimise the process.
In this article, chestnut shell tannin adhesives were prepared using different hardeners, namely, tris
Authors:B. Ormsby, G. Foster, T. Learner, S. Ritchie, and M. Schilling
Issues encountered with dynamic mechanical analysis of artists’ acrylic emulsion paint films are presented alongside modifications
to improve controlled relative humidity (RH) experiments using isothermal and thermal scanning conditions. Free films of titanium
white (PW6) artists’ acrylic emulsion paints were cast as free films and their viscoelastic properties measured using the
tensile mode of the dynamic mechanical analyser (DMA). Artists’ acrylic emulsion paints are within their glass transition
temperature region at room temperature and are highly responsive to changes in ambient temperature and relative humidity,
hence controlling relative humidity during analysis is vital to the successful analysis of these paints.
Authors:Hengfeng Li, Kaiyuan Tan, Zeming Hao, and Guowen He
CTFE content have been characterized by a series of thermal analysis techniques, including Thermogravimetric analysis (TG), Differential scanning calorimetry (DSC), Dynamic mechanical analysis (DMA), and Thermal mechanical analysis (TMA). The work
The Advanced Crew Escape Suit (ACES) is a pressurized suit worn by astronauts during launch and landing phases of Space Shuttle
operations. In 2008, a large tear (12.7–25.4 mm long, between the pinky and ring finger) in the ACES left-hand glove made
of neoprene latex rubber was found during training for Shuttle flight STS-124. An investigation to help determine the cause(s)
of the glove tear was headed by the NASA Johnson Space Center (JSC) in Houston, Texas. Efforts at JSC to reproduce the actual
glove tear pattern by cutting/tearing or rupturing were unsuccessful. Chemical and material property data from JSC such as
GC-MS, FTIR, DSC, and TGA mostly showed little differences between samples from the torn and control gloves. One possible
cause for the glove tear could be a wedding ring/band worn by an astronaut. Even with a smooth edge, such a ring could scratch
the material and initiate the tear observed in the left-hand glove. A decision was later made by JSC to not allow the wearing
of such a ring during training or actual flight. Another possible cause for the ACES glove tear is crystallinity induced by
strain in the neoprene rubber over a long period of time and use. Neoprene is one among several elastomers known to be susceptible
to crystallization, and such a process is accelerated with exposure of the material to cold temperatures plus strain. When
the temperature is lowered below room temperature, researchers have shown that neoprene crystallization may be maintained
at temperatures as high as 7.2–10 °C, with a maximum crystallization rate near −6.7 to −3.9 °C (Kell et al. J Appl Polym Sci
2(4):8–13, 1959 [<cite>1</cite>]). A convenient conditioning temperature for inducing neoprene crystallization is a typical freezer that is held near −17.8
°C. For work at the NASA Marshall Space Flight Center (MSFC), samples were cut from several areas/locations (pinky/ring finger
crotch, index finger and palm) on each of two pairs of unstrained ACES gloves for DSC and DMA thermal analysis testing. The
samples were conditioned in a freezer for various times up to about 14 days. Some rectangular conditioned samples were unstrained,
while most were subjected to strains up to 250% with the aid of two slotted aluminum blocks and two aluminum clamps per sample.
Trends were observed to correlate DSC data (heat of fusion) and DMA data (linear CTE and stress for iso-strain testing) with
(a) sample location on each glove; and (b) percent strain during conditioning. Control samples cut “as is” from each glove
location were also tested by DSC and DMA.