Synthesis and rheological property of polyborosiloxanes

Abstract

In order to explore the influence of the physical crosslinking network structure of polyborosiloxanes(PBDMSs) on the viscoelasticity of the system, hydroxyl terminated polydimethylsiloxane (PDMS) with different hydroxyl contents were reacted with boric acid to prepare PBDMSs with different boronization crosslinking densities. Thereafter the structure, thermodynamics and rheological properties of the as prepared samples were characterized. The results show that PBDMSs contain Si—O—Si, Si—O—B, CH3—Si—CH3 and B—O—B structural units. And PBDMSs have excellent low temperature resistance, while their glass transition temperature increases with the increase of hydroxyl content in PDMS. And at low hydroxyl content of PDMS (1% and 2%, mass fraction), crystallization of PBDMSs are observed. Moreover, PBDMSs possess the characteristics of frequency sensitivity, good impact resistance, excellent damping dissipation and excellent resilience. The hydroxyl content of PDMS obviously affects the physical crosslinking network structure of PBDMSs, and thus has a significant impact on the dynamic modulus of PBDMSs. In practical application, the viscoelasticity of PBDMSs can be adjusted by changing the hydroxyl content of PDMS.

Keywords

• hydroxyl terminated polydimethylsiloxane
• glass transition temperature
• viscoelasticity
• impact resistance