Heat evolved during polymerization temperature

More reliable AH values can be obtained from direct measurements of the heat evolved during polymerization [34—39], or from the difference between the heats of combustion of the amorphous polymer and the liquid monomer. With respect to the very low AHp values, as compared with the heats of combustion, the latter method is very inaccurate. The evaluation of calorimetric data is more difficult for partially crystalline polymers, for which the crystallinity as well as heat of crystallization must be known [38]. Equations (19)-(21) can be applied to such monomer polymer equilibria for which the equilibrium monomer concentrations at different temperatures are available with sufficient precision [28—30, 40]. The latter method is also limited to completely amorphous polymers because the crystalline ordered areas do not take part in the monomer-polymer equilibrium [21]. 

Figure 3. Heat evolved during polymerization of BCB-1 as a function of temperature.

Bending beam theory calculation of elastic modulus, 361-362 calculation of glass temperature, 362 calculation of thermal expansion coefficient, 362 layer stress determination, 361 Benzophenone-3,3, 4,4 -tetracarboxydi-anhydride-oxydianiline-m-phenylenediamine (BTDA-ODA-MPDA) polyimide, properties, 115-116 Bilayer beam analysis schematic representation of apparatus, 346,348/ thermal stress, 346 Binary mixtures of polyamic acids curing, 116-124 exchange reactions, 115 Bis(benzocyclobutenes) heat evolved during polymerization vs. 

As the heat of polymerization is quite high, sufficient water has to be present to control the temperature that may evolve during the process. 

For these studies it was desirable to maintain a constant temperature of about 22 C (room temperature). Since the amine-epoxy polymerization is an exothermic process, the syringes must have sufficient surface area to dissipate the evolved heat rapidly. Tests with Leeds and Northrup Potentiometer and a small alumel-chromel thermocouple, inserted into the center of the syringe, showed a maximum temperature rise of less than 2 C during the entire reaction time. This was sufficiently small to assume that isothermal conditions were maintained. 

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