Acoustic properties of transparent polysiloxanes

✍ Scribed by D. Bosc; P. Mauguen

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 321 KB
• Volume: 40
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1990.070400112

✦ Synopsis

Abstract

It is well known that the glass transition temperature of polydimethylsiloxane elastomers lies close to −120°C. According to the time temperature superposition principle, we may state that these materials keep their caoutchoutic state when they are excited by a 10 MHz mechanical wave. This is an important point particularly for acoustooptic applications. Thus, in the range of 1–10 MHz, materials with good efficiency are missed; low acoustic wave velocity is needed to give the best conditions, which means to be in a caoutchoutic state for polymeric materials. With this work, we show that three polysiloxanes, polymerized under different conditions, do not fulfill this condition. Thus the shift of T~g~ with frequency is very large and these polymers reach their glassy state at relatively low frequency. The acoustic wave velocity is in good agreement with mechanical predictions provided by master curves of the Young modulus.