Study On Synthesis And Thermal Properties Of Bisphenol Fluorene Epoxy Resin With Crystal Structure

Epoxy resins are widely applied in polymer industry fields as coatings, structural adhesives, insulating materials, polymer matrixes for composite materials, and so on. However, the widespread use of epoxy resins is limited in many high-performance applications because of their thermal properties and low toughness. Modifications of preparing novel epoxy resin and increasing in the number of epoxide group functionalities are the common methods employed to improve their thermal properties.The compound which contains fluorene ring usually has excellent heat resistance, high refractive index, high transparency and low linear expansion coefficient. In this paper, we synthesized diglycidyl ether of 9,9-bis(4-hydroxyphenyl) fluorene (DGEBF) by introduction of fluorene group into epoxy resins. DGEBF with crystal structure was characterized by IR, 1H-NMR, X-ray, Single-crystal X-ray and DSC. The results showed that the DGEBF crystal structure was tetragonal system, the epoxy value of DGEBF epoxy resin achieved theoretical value(0.43). All other characterizations was coincided with DGEBF molecular backbone.Bismaleimide resin (BMI) has good excellent characteristics for high thermostability, low expansion coefficient, high bending strength and modulus. However, BMI is brittle fracture due to the high rigidity of molecular backbone. In our work, we prepared a new long-chain backbone curing agent by the Michael addition reaction of 4,4-diaminodiphenylsulfone (DDS) and BMI. Thus, we can use this curing agent to modify to DGEBF and make the cured polymer containing both excellent properties of DGEBF and BMI. We designed orthogonal experiment to study the experiment condition impact on the crosslinking density of target product.In this paper, DGEBF was cured by both DDS and synthesized new curing agent. The curing kinetics of DGEBF/DDS and DGEBF/BMI/DDS system were studied with nonisothermal dynamic DSC method. We obtained kinetic parameters and the curing condition. Thermal properties of cured DGEBF polymer was measured by DMA and TGA. We applied Kissinger and Ozawa’s methods to evaluate the activation energies of the decomposition, Ed. The results indicated that cured DGEBF compounds had good thermal properties and sweat resistance, and the polymer meet the requirements of lead free electronic packaging materials in the future.