The low-temperature specific heat of PTFE (Teflon) at pressures to 5.2 kbar

The specific heat of PTFE (Teflon) has been measured between 0.3 and 20 K at zero pressure, and between 1 and 20 K at five other pressures ranging up to 5.2 kbar. The specific heat anomalies typical of amorphous materials were observed. The linear term is smaller than for other organic polymers and is closer in magnitude to those of high purity glassy insulators. At zero pressure the T³ term in the specific heat exceeds that calculated from the sound velocities by 24%. The evolution with pressure of the T³ term and of the maximum in C/T³ are very similar, suggesting a close relation between the vibrational modes that contribute to these features in the specific heat. This result and the relatively simple structure of Teflon rule out independent localized oscillators as the source of the maximum in C/T³.