LOW TEMPERATURE SPECIFIC HEAT OF HETEROCYCLIC POLYMER NETWORKS: EFFECT OF NETWORK DENSITY

Giovanni Carini (1) , Giuseppe Carini (2) , Giovanna d'Angelo (1) , Gaspare Tripodo (3) , A. Bartolotta (4) , Gabriele Salvato (4) , Liang Hong (5)

1 physics
2 Dept of Physics
3 Physics
4 IPCF - CNR Istituto per i Processi Chimico-Fisici
5 Department of Polymer Science

Measurements of low frequency Raman scattering and low temperature specific heat between 2 and 20 K have been performed in two glassy, heterocyclic polymer networks. The effective network densities of heterocyclic polymer networks are varied by changing the ratio of bi- and mono-functional isocyanate monomers leaving the overall chemical structure essentially unchanged. A boson peak at about 20 cm-1 characterizes the Raman spectra at room temperature of both the samples. Below 10 K, the specific heats deviate from a cubic temperature dependence, as predicted by the Debye theory, and reveal an excess specific heat having the shape of a well-defined peak in a Cp/T3 plot with a maximum at about 5 K. The increase of the effective network density is accompanied by a slight decrease of the excess specific heat. These observations have been explained in terms of additional low-energy vibrations associated to the monomers building up the polymer networks.

Mots clés: Physical Sciences

Giovanni Carini, Giuseppe Carini, Giovanna d'Angelo, Gaspare Tripodo, A. Bartolotta, et al.. LOW TEMPERATURE SPECIFIC HEAT OF HETEROCYCLIC POLYMER NETWORKS: EFFECT OF NETWORK DENSITY. Philosophical Magazine, 2008, 88 (33-35), pp.3999-4005. ⟨10.1080/14786430802459545⟩. ⟨hal-00513971⟩