Thermoplastic Resin Based On The Structure And Its Thermal Behavior

The structure of polymer is very important to its property. To study the relationship between structure and property of polymers plays a very important role in the designing, synthesize, quantity controlling, utility, development of polymers.Through long term of study and practice we find that besides the unit composition of polymers the end-group structure is of great affect on the thermal stability. And it is related to the property of processing of polymers directly. This research choose two kinds of thermoplasticity resin, i.e. polycarbonate ( PC ) , perfluorosulfacid , as the sample to study the relationship between their end-group structure and thermal stability. We have established a new method which can study the relationship between structure of polymers especially the eng-group structure and thermal stability in terms of microcosmos. This method combines in-situ thermal crack and dynamic thermal crack and other modern analytical means such as NMR, GC-MS, FTIR and thermal weight analysis and so on. The characteristics of this method is that it trace and test sample in real-time, especially the dynamic state process and combine with the test of its stability. This method has improved the realization of relationship between end-group structure and thermal stability of thermoplasticity resin from qualitative and macroscopic level to half quantitative and microscopic level. Our research work mainly engaged in the following works: 1.The method of studying the end-group of polymers by in-situ-pyrolysis, pyrolysis-FTIR and GC-MS has been established. The research of PC's end-group show that this method is feasible.2. Study the end-group of the domestic and import PC specimens by pyrolysis-IR. GC-MS and TG. The result shows that the end-capping of the import PC specimens are better than that of the domestic goods. The end-group structureof the import PC are simple, while the domestic specimens's are complicated. The end-capping reagents used in PC samples have been identified.3. Contrasting the pyrolysis of domeatic and foreign PC samples ,we find that there are difference between their molecular structures. In domestic samples, there are molecular isomerization and the molecular weight distribution are not uniform.4. We also find that the temperature range of end-group pyrolysis of PC is related to the molecular weight distribution. The more extent of the temperature range of end-group pyrolysis of PC is, the more the distribution index and molecular weight distribution are. Thus, we can evaluate the quality of different PC by testing the related molecular weight distribution using in-situ pyrolysis.5. The mechanism of pyrolysis of PC has been discussed through synthesize the results of infrared dynamic pyrolysis and in-situ pyrolysis in persevere temperature and continue rasing temperature, respectively.6. The thermal behavior of an unstable end-group in perfluorosulfacid resin was studied by in-situ-pyrolysis and TG methods. It is shown by the experimental results that a great number of gaseous bubbles and "crystal dots ",existing in the thermal - pressed resin film , mainly result from the thermolytic decomposition of the unstable end-guoup in the resin when the perfluorosulfacid resin was molded by heating . By the study of the thermal decomposition mechanism : (1) decarboxylation with release of CO2 and (2) cross-linking and dearboxylation with release of CO2 and H2O . The former results in the gaseous bubbles and the later leads to the "crystal dots " existing in the final product.7. The thermal decomposition mechanism (25 ℃ -560 ℃ )of perfluorosulfacid resin was studyed by in-situ-pyrolysis , pyrolysis-FTIR and TG .