Authors:W. de Klerk, M. Schrader, and A. van der Steen
Compatibility is an important safety aspect related to the production and storage of energetic materials. To test different
combinations of materials a simple test method with clear criteria is advisable. At the last ESTAC the use of microcalorimetry
and the vacuum stability test for the compatibility testing of propellants were presented. This paper presents DSC, DTA/TG
and (pressure) vacuum stability test results for the same combination. For three polymers (PMMA, PVC and CA) the results for
all tests are the same. Only Nylon-6/6 gives a variable result for the different test methods.
A useful alternative to the standard techniques described by the North American Treaty Organization STANAG 4147 for determining
thermal compatibilities of an energetic with other materials could be a simple 2-gram scale Differential Thermal Analysis
(2gDTA). The 2gDTA system consists of samples introduced into standard size test tubes inserted into a controlled aluminum-heating
block. Relatively inexpensive thermocouples are used for both temperature control and data collection. Cost of the entire
system is much less than any commercial DSC. Since valuable instrumentation need not be protected, the 2gDTA allows thermal
decomposition reactions to proceed to complete runaway, mimicking the true worst-case scenario.
The compatibility of some technically important polymer blends, namely BR/NR, NR/NBR and CR/NBR, has been investigated using
the DSC method. In addition, dynamic mechanical measurements have been carried out for the NR/NBR blends over the frequency
range of 10−4 Hz –200 Hz and temperatures ranging from −70 to +70°C.
The results obtained show that the three rubber blends are not compatible over the entire composition range as proven by the
DSC and mechanical measurements. By analyzing the heat capacity increases at the glass transitions of the separate phases
in the NR/BR blend, it was possible to suggest the presence of a limited compatibility at the boundaries of the two phases.
By comparing this work with prior measurements, it was possible to conclude that the calorimetric method is a more efficient
tool for the study of compatibility of polymer blends when compared to ultrasonic and viscosity methods.
Furthermore, it was found that polymers that show compatibility when measured with an ultrasonic method could behave compatible,
semicompatible or incompatible when analyzed by DSC. On the other hand, blends that show incompatibility by the ultrasonic
method are always incompatible by the DSC method.
Authors:E. Krabbendam-La Haye, W. de Klerk, M. Miszczak, and J. Szymanowski
Compatibility is an important property for energetic materials and their additives such as a casing material or a binder.
If these substances are incompatible an extra risk is introduced in handling and storage of ammunition and explosives. As
part of a co-operation program between the Dutch TNO-PML and the Polish MIAT several compatibility tests are performed and
compared with each other. All tests are performed according to a NATO Standard in which several tests are described which
can be used to determine the compatibility of an energetic material and an additive. These tests were performed on a huge
set of energetic materials e.g. propellants (single and double base), explosives (RDX, PETN, HMX and TNT) and several additives
like Teflon, polypropylene, self-burning case, inhibitors etc. The results of pressure vacuum stability tests, dynamic thermogravimetry
measurements and differential scanning calorimetry tests with several combinations of energetic materials and additives used
during the co-operation program are presented and discussed.
This paper demonstrates the application of thermal analysis in compatibility and stability studies between an ACE inhibitor
(enalapril maleate) and excipients. The results have helped to elucidate the reason of a stability problem observed during
the storage of enalapril maleate tablets. Incompatibility between enalapril maleate and colloidal silicon dioxide was detected.
Besides, it was confirmed that the reaction between enalapril maleate and NaHCO3 increases the thermal stability of the drug. This study supports the importance of using thermoanalytical methods in the
development of pharmaceuticals.
Authors:M. Łaszcz, B. Kosmacińska, K. Korczak, B. Śmigielska, M. Glice, W. Maruszak, A. Groman, H. Beczkowicz, and Ł. Żelazko
Differential scanning calorimetry and thermogravimetric
analysis with the support of X-ray powder diffraction and infrared spectroscopy
were used as screening techniques for the compatibility testing of imatinib
mesylate, with following excipients: magnesium stearate, polyvinylpyrrolidone,
microcrystalline cellulose. In order to maximize the probability of interactions
1:1 (by mass) drug: excipient binary mixtures were analysed and compared to
individual components. Additionally an influence of storage at temperatures
of 25 and 40°C on physico-chemical stability on drug – excipient
binary mixtures was investigated.
The largest visible changes
were observed in the DSC curves of imatinib mesylate – magnesium stearate
Chemical compatibility of two drugs, namely, etamsylate and fluconazole was studied with lactose as excipient, employing differential
scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The DSC patterns recorded for the mixtures of both the
drugs with the common excipient (lactose) indicated that fluconazole as well as etamsylate were incompatible with lactose
at high temperatures. X-ray diffraction patterns recorded for pure drugs and lactose and the mixtures of individual drugs
with lactose prepared at room temperature by intimate grinding of the components revealed incompatibility of both the drugs
with lactose also at room temperature.
Authors:H. Stulzer, P. Rodrigues, T. Cardoso, J. Matos, and M. Silva
Captopril (CAP) was the first commercially available angiotensine-converting enzyme (ACE) inhibitor. In the anti-hypertensive
therapy is considered the selected drug has to be therapeutically effective together with reduced toxicity. CAP is an antihypertensive
drug currently being administered in tablet form. In order to investigate the possible interactions between CAP and excipients
in tablets formulations, differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis completed by X-ray powder
diffraction (XRPD) and Fourier transform infrared spectroscopy (FTIR) were used for compatibility studies. A possible drug-excipient
interaction was observed with magnesium stearate by DSC technique.