Research On Preparation And Performance Of Hyperbranched Epoxy Resins With Silicone Skeleton

A comprehensive modification about toughening, reinforcing, heat-resistance and solvent-free of epoxy resins is an important developing trend. Hyperbranched epoxy resins as a class of excellent modifiers has been confirmed, which can efficiently toughen and reinforce common epoxy resins and apply without organic solvent, but it’s a disadvantage of low thermal performance results in that it can not be used to high-temperature-resistant materials fields. In order to resolve the challenge, hyperbranched epoxy resins with silicone skeleton were designed and synthesized successfully, which showed multi-functionality in modifying common epoxy resins. Detailed research results have been followed:(1) Synthesis and characterization of hyperbranched epoxy resins with silicone skeleton. Four generations allyl-ended hyperbranched resins with silicone skeleton (AHRSS) and four generations hyperbranched epoxy resins with silicone skeleton (HERSS) were synthesized by the main materials of phenyltrichlorosilane, allyl chloride,1,1,3,3-tetramethyl-disiloxane, Allyl glycidyl ether. Their chemical structures, molecular weights and distribution were also characterized by FT-IR, NMR and GPC. Distributions of molecular weights of both AHRSS and HERSS are a range of1.17～3.51, and their degrees of branching are a range of0.71-0.84.(2) Performance of HERS S/di glycidyl ether of bisphenol-A (DGEBA) composites. Increasing molecular weight and content of HERSS, mechanical performances of the composites increase first and then decrease; and their excellent performances are gained by incorporation of9wt%the third-generation HERSS. Compared with the performances of DGEBA, flexural strength, flexural modulus, impact strength and tensile strength would be increased about36.0%,37.6%,92.1%and88.6%, respectively, but the glass transition temperature impaired about5%. A distinct difference of solubility parameters between HERSS and DGEBA results in micro-phase separation during curing and sea-island microstructure appearing on the fractured surface.(3) Curing and thermal degradation kinetics of HERSS/DGEBAE composites. Exothermic energy decreases, curing reaction living energy increases first and then decrease, but curing reaction order remains constant with increasing of HERSS molecular weight. However, exothermic energy, curing reaction living energy and curing reaction order decrease with increase of HERSS content. Increases in HERSS molecular weights and content result in higher living energy of thermal degradation reaction in high-temperature stage and unchangeable in low-temperature stage.