Hardeners glass transition temperatures

Glass transition temperatures of the uv-hardened films were measured with a Perkin Elmer Model DSC-4 differential scanning calorimeter (DSC) that was calibrated with an indium standard. The films were scraped from silicon substrates and placed in DSC sample pans. Temperature scans were run from -40 to 100-200 °C at a rate of 20 ° C/min and the temperature at the midpoint of the transition was assigned to Tg. 

Table VII. Glass Transition Temperatures and Film Shrinkage of UV-Hardened and Baked 7/3 NA-EBDMA Films...

Table 1. Volume expansion change at Tg density and glass transition temperature of amine hardened TGDDM-based resins...

Fig. 22a and b. Behavior of syntactic foams during thermal treatment. Key a Thermogram of the hardening process for (1) Unfilled epoxy and (2) Epoxy syntactic foam with phenolic microspheres, b Glass transition temperature of the epoxy binder versus concentration of phenolic microspheres 1621... 

If the host polymer does not have a high glass transition temperature then the structures of polymer and chromophore must be such that post-poling lattice hardening can be carried out to assure thermally stable electro-optic activity [2, 5,50,63,64,110,132-150]. 

Fig-1 Mechanical response of SAN to simple shear at an applied strain rate of 10 2/s and 10 4/s for isothermal or adiabatic conditions (solid and dashed lines, respectively). The temperature increase delays the hardening for a strain rate of 10 4/s which vanishes for 10 2/s. In this case, the material reaches the glass transition temperature and enters the rubbery state resulting in a small load-bearing capacity... 

The purpose of the study was a) to determine the effect of relative resin/hardener composition and ambient and elevated temperature curing schedules on the glass transition temperature, Tg, and on the degree of cure of the epoxy system, and b) to evaluate the agreement between the calculated degree of cure using the nth-order kinetic equation (1.1) (1, 2, 3) and the measured degree of cure. 

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