Synthesis And Properties Of Epoxy Resins And Curing Agents Containing Naphthalene

With the development of microelectronic packaging technology, epoxy molding compound which occupies the entire microelectronics packaging materials market is simple and suitable for large-scale production due to its high reliability and low cost production process. However, there are some disadvantages which may affect the further applications of epoxy resins, such as weak toughness, poor moisture and flammability. Therefore, the synthesis and modification of the novel epoxy resin and harderen have become a hot spot.Novel epoxy resins and curing agents containing naphthalene were synthesized and the properties of cured polymers were investigated by several methods. The relationship of properties and structures of the epoxy resins and curing agents was studied. Meanwhile, the cure kinetics of R1-R6/DDM curing systems was also carefully investigated.1. Six epoxy resins which were isomers and both contained naphthalene moiety and two symmetric flexible aliphatic ester chains terminated by epoxy groups were designed according to three factors:the length of the flexible chains, the size of the molecular skeleton, and isomers. The six epoxy resins were successfully synthesized via esterification and epoxidation. Their chemical structures were characterized by nuclear magnetic resonance (-NMR), infrared spectroscopy (IR). Moreover, we investigated the relationship of the melting point temperature and structure by differential scanning calorimetry (DSC).2. To investigate the influence of different epoxy resin (R1-R6) structure on the cure kinetics,4,4’-diaminodiphenylmethane (DDM) was chosen as the curing agent. The curing technical temperature of their curing systems was obtained from extrapolated plots of T-β curve at different heating rates. In comparison, it proved that the more symmetrical of the molecular structure, longer of the flexible chain length and the bigger of the molecular skeleton resulted in lower reactivity and higher curing temperature. The curing kinetic paramenters, the activation energy (Ea), the reaction order (n), the reaction rate (K) and the apparent activating factor (A) of their curing systems were calculated by Kissinger and Ozawa methods. From the results we conclud that the value of Ea depends on the chemical structure of the epoxy resin, the shorter chains, the bigger and symmetrical molecular skeleton structure will lead to higher Ea. The reaction order of six curing systems is basically the same. Meanwhile, A and K increased with the increase of the heating rate, the phenomenon shows that the reaction of them is the same type. The Ea of the R1, R2and R3with DDM curing systems increase with the increase of the conversion degree (a), while the Ea which are calculated by the Ozawa’s isoconversional method of the R4, R5and R6with DDM curing systems decrease with the increase of a. The results shows that the resins contained short chain can accelerate the reaction with the autocatalytic effect. They have good solubility in most solvent.3. A series of cured polymers which consist of the synthesized epoxy resins and DDM and their curing temperature procedure were designed according to the temperature obtained from extrapolated plots of T-β curve. Their mechanical properties,moisture absorption, thermal properties and the temperature of glass transition (Tg) were investigated. We conclude from the relationship of properties and structures that the longer length chains will bring about the better mechanical properties, the more bigger and symmetrical molecular skeleton structure will lead to the higher Tg and lower water absorption.4. The synthesized epoxy resin R1and R4were composited with commercial epoxy resin NC-3000/GPH-65at1.3.5.7wt%loading levels. The modification effect of R1and R4on the curing behaviors, gel time, moisture resistance, thermal and mechanical properties of NC-3000/R2composites were investigated. From the DSC and gelation time experimental results, it is evident that R1have a delay effect on curing system and increase the curing time, on the contrary, R4have accelerate effect on the curing system and decrease the curing time. The mechanical properties, moisture resistance and Tg of the cured polymers were improved. The results of the fracture surfaces morphology of the composites shows the fracture mode is from typical brittle break to ductile fracture.5. Six novel curing agents (G1-G6) which were linked by eater and C=N bond and contained naphthalene and biphenyl moiety terminated by hydroxyl group were designed and synthesized. Their chemical structures were characterized by1H-NMR technology. The flame retardancy test was investigated by UL-94V. While six curing agents added into YX-4000/GPH-65system with5wt%loading level, the flame retardant property of the G4/YX-4000/GPH-65reached the FV-1level. The retardant properties flame retardant properties reached the FV-0level when G4added the mount of15wt%. Then, the further flame retardant mechanism was studied by thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The char yield at800℃of cured polymers decreased with the increase of G4content and the char yield could be as high as50%when G4added the amount of20wt%. The char residues were analyzed by SEM and the compact char layers could be observed on the residues surface of the cured polymers added with15wt%and20wt%G4, the char layers effectively reduce the fuel gases in the combustion process.