High-temperature polymer chemical structures

Diamantane-based polymers are synthesized to take advantage of their stiffness, chemical and thermal stability, high glass transition temperature, improved solubility in organic solvents, and retention of their physical properties at high temperatures. All these special properties result from their diamantane-based molecular structure [90]. Polyamides are high-temperature polymers with a broad range of applications in different scientific and industrial fields. However, their process is very difficult because of poor solubility and lack of adequate thermal stability retention [90]. Incorporation of 1,6- or... 

Boyer, R.F. The relation of transition temperature to chemical structure in high polymers. Rubber Chem. Tech. 36,1303-1421 (1963). 

Irradiation (e-beam or y-irradiation) is classified among the high-energy solid-state processes. Some similarities between mechanical milling and irradiation to compatibilize nonmiscible blends have been observed by different authors. 1- Smith et al. considered that these processes lead to the same phenomena (chain scission, cross-linking, amorphization), and they claimed that the factors influencing these phenomena (polymer chemical structure and temperature) are not dependent on the process. ... 

High-Temperature Polymer Electrolyte Fuel Cells, Fig. 1 Chemical structures of PBI and TPS variants (a) m-PBI,... 

Gourdoupi N, Papadimitriou K, Neophytides S et ai (2008) New high temperature polymer electrolyte membranes. Influence of the chemical structure on their properties. Fuel Ceils 8 200-208... 

The polymer chemical structure also plays a decisive role in the choice of fibre production process (Section 14.8). A sufficiently broad temperature interval between the melting temperature and the thermal stability limit, and an appropriate melt viscosity (determined by the molecular weight and MWD) are essential for successful melt processing. For polymers which do not have an adequate melt processing window , the availability of suitable solvents, sufficiently high solubility and appropriate rheological behaviour of the resulting solutions are essential features dominated by the polymer chemical structure. 

Based on the rigid conformation of many high temperature polymers, it is expected that the criteria for miscibility of such polymers will be even stricter than for random coil polymers. However, several high temperature miscible polymer blends have been discovered and reported in the litera-ture2-6. 2-i6 Yvhich are based on poly(2,2 (m-phenylene)-5-5 bibenzimidazole) (FBI), the chemical structure of which is shown in Fig. 1.1. Chapter 7... 

One of the most highly studied high temperature polymers in miscible blends is poly (2,2" (m-phenylene)-5-5" bibenzimidazole) or PBI, the chemical structure of which is shown in Rg. 4.1. The fundamental reason for the observation of miscibility in PBI-based systems is the presence of the N-H functional group that can interact with the functional groups which are present on the backbone of other polymers. Thus, miscibility in these types of systems is an example of a specific interaction that leads to a negative enthalpy of mixing. 

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