Glass-transition temperature bond dissociation

According to Borders [52], the strength of synthetic rubbers runs parallel to their glass-transition temperature. This tendency is explained by Eq. (81) involving the cohesion heat of the f>-sized link, that is, hHQ, or the dissociation energy of the bond to be broken ... 

Polyurethane thermoplastic elastomers (PTE) are characterized by microphase separation into an SS microphase and HS microdomains. In fact, the versatile physical and thermomechanical properties of TPE, which make them attractive for several technological applications, are based on their microphase-separated structure. The glass transition temperature, Tg, of the amorphous SS microphase is typically below 0°C, so that at room temperature the material behaves as an elastomer. At high temperatures (typically above 100°C), dissociation of the physical bonds occurs, the HS microdomains are destroyed and the material flows as a linear polymer. In addition to microphase separation, intermolecular hydrogen bonding and partial crystallization of the SS microphase often contribute to the thermoplastic elastomeric behavior of PTE. 

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