Adhesives Halthane 73-series

This section is subdivided into two parts based on the two types of LLNL Halthane adhesives. The basic distinction between these adhesives is the modulus of the rubbery plateau. Halthane 73-series adhesives are tough, rubbery polyurethanes with a modulus of about 10 Pa at room temperature. On the other hand, Halthanes 87-1, 87-2, and 88-2 are stiff, almost glassy adhesives with a modulus of about 10 Pa at room temperature. 

Figure L The low-temperature dynamic mechanical spectrum of Halthane 73-14 is typical of the 73-series polyurethane adhesives. Two secondary relaxations, Tp and Ty, are shown as peaks in the loss modulus at —100° and —150°C. The soft segment glass transition, Tg(SS), occurs at about —50°C. The frequency of oscillation was held constant during the measurement at 0.1 Hz.

Figure 5. Thermogravimetric analysis cruves of 73-series Halthanes show bimodal pyrolysis behavior starting at about 250°C. The rate of change in weight of the adhesive with time, dW/dt is plotted against temperature for a programmed heating rate...

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