Thermal stability determinations

The amplification by PCR of a DNA segment containing a functional RNA promoter together with an insert (probe sequence) under its control affords double stranded products which are suitable templates for transcription by DNA-dependent RNA polymerase.313 The RNA transcripts obtained are then useful for in situ RNA-RNA hybridization. By in vitro transcription of synthetic DNA templates, RNA hairpin sequences of 16-mer to 22-mer length containing homopolymer loops of 3 to 9 nucleotides, consisting of adenosine, cytidine or uridine residues have been prepared, and their thermal stabilities determined.3 The stability varied with loop... 

The non-isothermal thermal stability determination A quick impression of the thermal stability of a polymer is obtained by measuring its mass with a TGA as a function of the temperature at a constant heating rate. Figure 2.1 shows the results of four TGA scans on tP samples using a heating rate of l°C/minute. These results illustrate that ... 

The isothermal thermal stability determination. Isothermal mass/time curves of non-stabilised PP powder samples were measured during 1000 minutes at temperatures between 160°C and 280°C. The PP TGA samples (about 10 mg.) were flushed with nitrogen during one hour at 30°C before the experiment was started. 

Nearly all properties mentioned under group A are influenced by the temperature locations of the Tg/Tm values and the crystallinity level (Hf-value). The Tm-value and the thermal stability determine together the polymer s processing window. The moisture sensitivity, finally, is important in connection with the barrier properties of a polymeric system. Furthermore moisture absorption influences several physical properties considerably (see chapter 5.2). 

The determination of the right thermal decomposition temperature of an ionic liquid is not trivial. It is quite obvious from the above mentioned aspects that the thermal stability determined in a TGA experiment will be a strong function of the ionic liquid s quality, with many impurities significantly reducing the stability. Moreover, Ngo et al. [25] have shown that the thermal decomposition of ionic liquids, measured by TGA, varies depending on the sample pans used in some cases increased stabilization of up to 50 °C was obtained on changing from aluminum to alumina sample pans. Finally, and most importandy, the thermal decomposition of... 

Thermal oxidation of plastics can be assessed by various methods, amongst which heat measurement (DSC and DTA). Accelerated methods such as DTA and DSC and oxygen uptake measurements have been used quite extensively in studies of thermal oxidative stability of plastics [113]. The definition of thermal stability is very vague and is interpreted differently. Nikulicheva et al. [114] have summarised the diversity of methods of thermal stability determination using TA methods. Problems associated with the use of thermal analysis to determine the thermal stability of plastics have been discussed in detail [115,116]. 

Flexible ionomer networks can be built up via mixing polymeric acids and polymeric bases, obtaining networks that contain ionic cross-links formed by proton-transfer from the polymeric acid onto the polymeric base. It was observed that upon drying, acid-base blend membranes show reduced brittleness compared with un— cross-linked or covalently cross-linked ionomer membranes, which is possibly caused by the flexibility of ionic network. The developed acid-base blend membranes show outstanding thermal stabilities determined by DSC and TGA. 

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