High Performance Polymers glass transition temperatures

In recent years, considerable attention hcis been devoted to the preparation of fluorine-containing polymers due to their unique properties and high-temperature performance. The incorporation of fluorine atoms (or groups containing fluorine atoms) into polymer chains changes solubility of polymers, glass transition temperature (T ) and thermal stability, while also led to decreased moisture absorption and dielectric constant. The aromatic fluoropolymers have currently been used as films, coatings microelectronics devices [37,55-60]. 

BMI polymers have glass transition temperatures in excess of 260°C and continuous-use temperatures of 200-230°C. BMI polymers lend themselves to processing by the same techniques used for epoxy polymers. They are finding applications in high-performance structural composites and adhesives (e.g., for aircraft, aerospace, and defense applications) used at tem-peratrues beyond the 150-180°C range for the epoxies. Bisnadimide (BNI) polymers are similar materials based on bisnadimides instead of bismaleimides. 

Summary In this chapter, a discussion of the viscoelastic properties of selected polymeric materials is performed. The basic concepts of viscoelasticity, dealing with the fact that polymers above glass-transition temperature exhibit high entropic elasticity, are described at beginner level. The analysis of stress-strain for some polymeric materials is shortly described. Dielectric and dynamic mechanical behavior of aliphatic, cyclic saturated and aromatic substituted poly(methacrylate)s is well explained. An interesting approach of the relaxational processes is presented under the experience of the authors in these polymeric systems. The viscoelastic behavior of poly(itaconate)s with mono- and disubstitutions and the effect of the substituents and the functional groups is extensively discussed. The behavior of viscoelastic behavior of different poly(thiocarbonate)s is also analyzed. 

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