In this work thermogravimetric analysis is applied to examine pyrolysis of single waste components and their blends in order
to determine the composition of an unknown waste mixture. The superposition property is assumed, i.e. the mixture thermal
degradation curve is obtained as the sum of the curves corresponding to its constituents. The results show that if blended,
the individual components are more clearly recognised from the differential mass loss curves. This allows a better identification
of the composition. Inaccuracy in determining the composition increases if interactions occur between components, which is
the case for PVC-newspaper blend.
The curing of composition containing epoxy bond is complicated chemical and technological process where under temperature
and pressure conditions a change of its structure occurs. The structure changes are possible to know by thermal methods as
DSC, DTA, etc. and also by measurement of dielectrical response under the low frequency electrical field.
Authors:Y. Rubtsov, A. Kazakov, V. Nedelko, Al. Shastin, Tatyana Larikova, Tamara Sorokina and B. Korsounskii
The thermal stability of the ammonium nitrate (AN)/sodium salt of 1,3-dichlor-2,4,6-trioxo-1,3,5-triazacyclohexane (DC) composition
has been studied. The factors of influence on the rates of reactions in the composition, namely, a water content, composition
wetting methods, a dispersion of composition components, sample mass values, have been examined. The water presence in the
composition reduces its thermal stability. The mechanism includes the partial dissociation of AN to HNO3 and NH3 and the hydrolysis of DC with the formation of some unstable Cl-containing compounds (chloramines, nitrogen chloride). The
reaction of ammonium cation with active chlorine has been found to give rise to the explosion of the AN/DC composition. Such
a situation is typical for other ammonium salt/DC compositions.
The calorimetric data of blended shrinkage-compensating binders with different compositions were measured at 25C at different
water-binder ratios using an isothermal calorimeter. The hydration characteristics of shrinkage-compensating binders were
evaluated and their influence on the expansive properties of blended shrinkage-compensating binders was determined. Composition
and w/b ratio significantly affect the hydration rate and degree of shrinkage-compensating binders, as well as their expansive
and mechanical properties. The total heat of hydration of binders decreases with w/c ratios. Its final hydration degree also
decreases with w/c ratio. The ternary binders composed with Portland cement, mineral admixture and expansive agent show low
hydration heat and rate of heat evolution, but their total heat of hydration increases continuously and surpasses that of
binary binder in later period at low w/b ratio.
The EU Chocolate Directive 2000/36/EC allows the use of the vegetable fats CBEs and CBIs up to a maximum of 5% in chocolate. Manufacturers and users must know how this has an influence on the properties of chocolate. The objective of the work reported here was to find out by systematic investigations, which effect CBEs/CBIs have on the quality parameters, hardness and heat resistance of chocolate. The influence on the hardness was tested also under extreme practical storage conditions. The quality monitoring was performed up to one year. For the determination of the heat resistance the penetrometric method was used in the temperature range 25–32 °C measuring the maximum loading force, occurring during the penetration of a cylindrical probe of 2 mm diameter with 4 mm penetration. The correlation between the average maximum loading force, relevant to the hardness of chocolate, and the temperature can be described by a linear regression at 95% confidence level. Statistical analyses (correlation analysis, residual analysis, Durban-Watson statistic) showed that it is possible to define the heat resistance of solid chocolate in the temperature range of 25–32 °C by the slope and the ordinate intercept of the regression line of the loading force vs. temperature for given parameters (composition, storage, experimental layout, etc.). For the determination of the hardness of the chocolate also the penetrometric method was used to measure the maximum loading force occurring during the penetration of a needle probe with 2 mm deformation. The hardness of the chocolate samples determined with the penetrometric method and statistical analysis (One-Way, Two-Way Analysis of Variance, Dunnett’s comparisons) is significantly dependent on the composition and storage conditions, where the storage conditions are the dominant factor. The results show that the differences in hardness between the chocolate samples with CBE/CBI and those without CBE/CBI, both stored in the cellar (cold storage), are marginal. After one week of storage the sample with CBI has nearly the same hardness as the standard sample with CB, whereas the sample with CBE was slightly softer. The differences are slightly clearer for the northern storage room (moderate temperature) and for the southern room (warm temperature). After a definite storage time the hardness of all samples increased and was in the case of the southern storage room (warm temperature) up to twice as high. The quality monitoring up to one year showed that the reason for this increase in hardness is not a special storage time but the increasing temperatures with the beginning of the warm season and the cyclic change of the temperature during day and night. So an explanation for this unexpected increase in hardness can be a thermocyclic hardening of the chocolate samples under these storage conditions.
Authors:J. Chalchat, M. Özcan, G. Figueredo and P. Chalard
Akgül, A. (2007): Variability of essential oil composition of Echinophora tenuifolia ssp. sibthorpiana (Guss.) Tutin by harvest location and year and oil storage. — Chem. Nat. Compounds 43 (2): 225–227.