High-transparency polysilsesquioxane/glycidyl-azide-polymer resin and its fiberglass-reinforced composites with excellent fire resistance, mechanical properties, and water resistance

New high-performance polymer composites are desirable for various industrial applications. Two unsaturated polysilsesquioxanes (AcPhPOSSⅠ and AcPhPOSSⅡ) were designed and synthesized successfully, and their thermosetting resins (AcPhPOSS@GAP) and fiberglass-doped composites (AcPhPOSS@GAP@GF) were prepared by thermal curing of AcPhPOSS and glycidyl azide polymer (GAP). AcPhPOSS@GAP exhibited excellent transparency, especially AcPhPOSSⅡ@GAP with a transparency and haze of 84.0% and 3.0%, respectively. The heat and smoke release rates of AcPhPOSS@GAP@GF were about 69% and 50% lower, respectively, than those of AcPhPOSS@GAP. Further, the flexural strength and flexural modulus of AcPhPOSS@GAP@GF remained above 80 MPa and 11,000 MPa, respectively, after water treatment. This was due to the strong adhesion between the fiberglass and the matrix, which enabled them to effectively withstand the impact of adverse external conditions. AcPhPOSS@GAP@GF presented a low dielectric loss and high thermal conductivity, which prevented damage caused by heat accumulation. Thus, the prepared materials have excellent application prospects.