# Dynamics of segmental relaxations for cyanurate-containing semi-interpenetrating polymer networks

Bartolotta, Antonio and Di Marco, Gaetano and Farsaci, Francesco (2001) Dynamics of segmental relaxations for cyanurate-containing semi-interpenetrating polymer networks. Accademia Peloritana dei Pericolanti - Classe di Scienze FF.MM.NN., 78-79 (1). pp. 131-146.

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Two series of semi-interpenetrating polymer networks (semi-IPNs) of the same linear polyurethane (LPU) and two different heterocyclic polymer networks (HPN-1 and HPN-2) based on thermally cured dicyanic ether of Bisphenol-A, were characterized by differential scanning calorimetry (DSC), complex dynamic modulus E* = E' + iE" and mechanical loss tangent (tan $\delta$ = E"/E', where E' and E" are the storage and loss components of the loss modulus, respectively). The temerature dependence of $\alpha_a$ and $\gamma$ relaxations were studied as a function of HPNs content. By the experimental results no large-scale structural heterogeneities were detected in sample with HPN-1. It has been observed that the inclusion of LPU softens both the HPN-1 and HPN-2 rigid networks which, on the contrary, affects the LPU chain motion by restricting the cooperative long-range segmental dynamics. Single glass transitions are observed in semi-IPN-1 which indicate an affinity between LPU and HPN-1 and also a large scale structural homogeneity. Differently from semi-IPN-1, two glass transitions are observed in semi-IPN-2, where the absence of chemical intermolecular interactions is thought to give rise to a double phase amorphous network, each phase preserving the main morphological characteristics of the pure components. Keywords: Anelasticity; Internal friction; Anharmonicity Pacs index: 61.40 km or 62.40+i