Thermo-oxidation behaviour

Darie and co-workers [25] studied the thermal and thermo-oxidative behaviour of isotactic polypropylene/polyamide-6 (PA6) and tertiary isotactic polypropylene, PA6-ethylene-propylene-diene blends by DSC and TGA. 

Thermo-oxidative destruction behaviour of the grafted rayon fabrics. 

Thus, let us denote the general features of PI, PPQ and SPPQ thermo-oxidation. The first important likeness of the degradation behaviour is O2 absorption at rather low temperatures (200 °C). At temperatures 250 °C or higher, when it becomes possible to search O2 absorption kinetics in real time, polymers display equal oxidation types independently of temperature - the three-stage kinetics, sequentially described by laws of the first and the zero orders with future autoacceleration. 

Analysis of kinetics and composition of TCP degradation products in the processing temperature range cleared up some general features in degradative behaviour of thermostable APH [40] structure graphitisation, H2 release, thermo-oxidation resistance increase as additives of transition metals and PCA are introduced. 

Studies on the effect of the level of acid end groups present on the thermo-oxidative stability of PBT [12] noted that increased carboxyl content lowered stability this behaviour matches that of PET. 

Degradation behaviour of polyamides continues to be the subject of many papers. The degradation of nylon-6 has been examined by hydrolysis,by photolysis, and ultrasonically. Kinetic studies on chain scission by means of e.s.r. spectroscopy showed that the concentration of free radicals originating from broken chains in nylon-6 fibres could be described by a model system in which crystalline and amorphous layers were sandwiched in the fibre direction. Oxyluminescence has also been used in a study of the kinetics of the thermo-oxidative degradation of nylon-6,6. 

Because of their potential for use in high-temperature environments the thermal and thermo-oxidative degradation behaviour of poly(pyromellitimides) continues to generate interest with e.s.r. studies on their thermal degradation behaviour and studies on the mechanism of thermal oxidation of bridging methylene groups in such polymers. 

This chapter reviews the research and the most relevant progresses in polycarbonates (PC)s science and provides a comprehensive source of information on history, synthesis, processing and applications. The application of different polymerization procedure of the commercial aromatic bisphenol-A polycarbonate (referred herein as PC) and the innovative enzymatic catalysed polymerization of aliphatic polycarbonate are summarized. Due to the high engineering performance of PC polymer, an extensive section on mechanical, electrical, chemical and thermal properties is included. The thermo and photo oxidative behaviours, the hydrolytic stability and the consequent modification on PC chemical structure are also discussed. The development of PC polymeric materials such as composites and blends are also addressed, emphasizing in particular the properties and the applications of impact modified PC blends and even of the PC/Polyester systems. 

Figure 2.5 shows the effect of the residual amount of stabiliser on the thermo-oxidative stability of LDPE/Chimassorb 944 exposed to various testing environments [154]. The differences in the oxidation behaviour of the polymeric matrix (as measured by DSC) are related to the differences in the consump-tion/migration rate of the stabiliser and the amount of stabiliser remaining in the polymeric matrix (as measured by UV spectroscopy). 

Calculation of sulphide capacities of multi-component slags. The thermo-dynamics and kinetics of desulphurisation are of great importance to iron and steel making and the ability to predict the behaviour of sulphur associated with multi-component slags is, therefore, very desirable. To this end Felton et al. (1993) recently described an approach to predict the sulphide-removing capacity in multi-component oxide slags. While a comprehensive database for oxides was already available, the inclusion of S had not yet been undertaken. Therefore it was not possible to calculate the necessary S activity and solubility directly throi h a... 

The first interesting point we should mention in connection with the reducibility of the mixed oxides under CO is that behaviour similar to that observed with Hg can be observed for the high-temperature redox aged oxides. Figure 2.13 shows the results of differential thermo-gravimetric (DTG) experiments run under both CO and for SR-MO and SR-SO oxides. Note that, qualitatively, the behaviour of the two oxides is the same under hydrogen and... 

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