The thermal degradation of the epoxy system diglycidyl ether of bisphenol A (DGEBA n=0) and m-xylylenediamine (mXDA) containing different concentrations of polyhedral oligomeric silsesquioxanes (POSS) nanoparticles was studied by thermogravimetric
analysis in order to determine the influence of both, the POSS concentration and the curing cycle on the degradation process
and to compare it with the results for the non modified system.
Glass transition temperatures for the same systems were also determined by differential scanning calorimetry. Different behaviors
have been observed, depending on the POSS concentration and on the curing selection.
Differential scanning calorimetry was applied to assess on seasonally soil organic matter changes. Soils were collected in
two sites located in Viveiro (Galicia, Spain). One of them has been used as arable land and the other one was under pinewood.
Soil samples were seasonally collected during a year. The heat of combustion and the ignition temperature of the soil organic
matter were calculated by analyzing the thermograms obtained by differential scanning calorimetry. The shape and the maximum
and end temperatures of the two exothermic peaks observed in the thermograms, yielded information about the relations between
the labile and recalcitrant pools, and hence information about carbon stabilization degree in both soils.
Calorific values and flammability changes during a year for forest waste originating from silviculture task in Galicia (NW
Spain) are reported. These waste materials are becoming to be used as alternative fuels.
The present study was made on several hardwood forest species. These forest species occupy nowadays approximately 30% of the
total forest surface of Galicia.
Calorific values were measured by static bomb calorimeter in an oxygen atmosphere. Flammability was determined using a standard
epiradiator. Simultaneously, some other parameters such as elementary chemical composition, heavy metal contents, moisture,
density, ash percentage after combustion in the bomb, and main bioclimatic characteristics, were also determined.
This paper shows an application of bomb calorimetry used in the procedure of regeneration of waste industrial mineral oils.
Using the treatment here reported a recovery of nearly 50% of the used oils was achieved. Furthermore, the oils so recovered
contain concentrations of potentially contaminant elements far below the requirements of the European Union (EU). Generally
speaking, it can be said that the used oil treatment is based on the proper combination of two main procedures, namely the
addition and mixture of certain chemicals-precipitant, flocculant and demulsifying agents- in a permanently stirred reactor,
at high temperature, and the centrifugation of the mixture. This oil, recovered through the technique of oil regenerating,
cleaning, and fitness, can be used either as a raw material for the elaboration of new oils or as a fuel to be used for cogeneration
of thermal or electric energy. The treatment described is highly remunerative, both as regards to cost -used oil is subject
to a low-cost process, especially if compared to its elaboration from raw materials- and as regards to ecology, since it is
recycled, thus saving a great amount of raw materials.
The rheological behaviour of the materials diglycidil ether of bisphenol A (n = 0), 1, 2 diamine-cyclohexane and the epoxy reactive diluent vinylcyclohexane dioxide have been studied both separately
and mixed before the beginning of the curing reaction. Different kinds of tests such as: preshear and time sweep, flow curve
and stress sweep experiments were carried out. From these experiments, interesting information about: viscosity-shear stress
and viscosity-shear rate dependences, storage modulus and the linear viscoelastic region were found out. Relationships between
concentration of diluent and the final viscosity of the mixed sample and also between percentage of diluent and storage modulus
This work is a ‘historical’
revision of the evolution of an experimental procedure developed by Prof.
Lisardo Nez and his research group TERBIPROMAT to study the
sustainability and the soil health state.
From the very beginning,
in 1993, the microbial activity was the main bioindicator selected to analyse
the ‘soil health state’. For this reason, a microcalorimetric
technique was used lately to analyse the influence of different human activities
such as reforestations, agricultural exploitation or pollution on the microbial
activity in different soils. Microcalorimetry is the main scientific technique
used in this research to follow the stimulation of the microbial activity
by addition of glucose. The data obtained were complemented by a study of
physical, chemical and biological parameters of soil and allowed to follow
the microbial activity in soils of Galicia (Spain) along the year.
The final results, still in revision, will be helpful in establishing
a data basis for real maps of the ‘health state’ of different
soils. Such maps could be used to design processes that help us to decide
how we should exploit soils ensuring their sustainability.
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.
Isothermal and Differential Scanning Calorimetry is applied to analyze the evolution of soil using its microorganisms and
organic matter as bioindicators of soil quality. This study was carried out with two similar soils under different agricultural
activities: culture and pasture. Sampling and measurements were performed through 1 year in order to check the sensitivity
of common calorimetric indicators of microbial activity and organic matter to the different climatic seasons in the sampling
place: spring, summer, fall and winter. Results show that these indicators are sensitive to changes related to climatic conditions
but the variability depended also on the nature of the soil: pasture or agricultural land. The results achieved through the
present study show that the procedure here proposed could be used on any soil everywhere, providing the determination of the
own parameters of soil and zones.
The diffusive, calorimetric and thermal degradation behavior of different
epoxy-amine systems was investigated during water sorption at different temperatures
(23, 40 and 70°C). Experimental results showed that the water absorption
at these temperatures fitted well to Fick’s law. Influence of water
immersion during different periods of time on the glass transition temperatures
was studied by differential scanning calorimetry. Thermal degradation of saturated
samples was studied by thermogravimetric analysis. Dependence on the selected
curing cycle was also checked.