高性能可回收环氧树脂及其复合材料的制备与性能研究

采用戊二酸酐为固化剂,乙酰丙酮锌为催化剂制备了一种综合性能优异的高性能可回收环氧树脂.系统研究了固化剂及催化剂含量对树脂结构、热学及动态性能的影响,实现了树脂组成的优化设计.基于酯交换反应的热可逆性,制备的vitrimer树脂通过物理热压方法可实现良好回收,力学强度保持率可达80%.采用RTM工艺制备的碳纤维织物增强vitrimer树脂复合材料表现出与传统热固性树脂基复合材料相当的力学性能,并且通过醇类溶剂热降解树脂的方法,可实现复合材料中碳纤维的高效无损回收,回收率近100%.

Preparation and Properties of Recyclable High-performance Epoxy Resins and Composites

Aiming at the demands for recyclable resins and composites in practical applications,high performance recyclable epoxy resins with excellent comprehensive properties are prepared using methyl teterahydrophthalic anhydride as the curing agent and zinc acetylacetonate hydrate as the catalyst.The effects of anhydride and catalyst concentrations on the structure,thermal and dynamic properties of epoxy vitrimers are systematically explored to achieve the resin formulation optimization.With the decrease of anhydride concentrations,the cross-linking densities decrease,and the epoxy vitrimers show decreased glass transition temperature(Tg)but enhanced dynamic properties,which is attributed to the sufficient hydroxyl groups in structure that could trigger the transesterification exchange reactions with ester bonds.The increase of catalyst concentrations can also lead to enhanced dynamic properties as a result of the accelerated transesterification rates.The epoxy vitrimer with epoxy/anhydride/catalyst ratios of 1:0.5:0.05 displays optimal comprehensive performance with intermediate thermal properties and excellent dynamic properties.Based on the dynamic transesterification reaction,the epoxy vitrimers can be well reprocessed by the physically hot pressing methods at 180℃for 6 h under a pressure of 10 MPa,and the recycling efficiency can be up to 80%.Moreover,the epoxy vitrimer-based carbon fiber reinforced composites are prepared by the resin transfer molding(RTM)technique.The prepared carbon fabric composites show a tensile strength of 479 MPa and tensile modulus of 58 GPa,revealing comparable mechanical properties to those of traditional thermoset composites.After heating the composites in ethylene glycol solvent at 180℃for 8 h,the clean carbon fiber fabric with the same dimension as fresh ones can be reclaimed due to the dissolution of epoxy vitrimer binder in alcohol solvent via transesterification.In addition,the collected dissolved polymers can form vitrimers again by evaporating the EG solvent in open air at 180℃for 12 h.It is demonstrated that the carbon fibers and epoxy polymers can both be fully recycled from the composites by the alcohol solvent dissolution method.