Preparation and origin of thermally resistant biobased epoxy resin with low internal stress and good UV resistance based on SiO2 hybridized cellulose for light emitting diode encapsulation

Big internal stress and poor UV resistance are two bottlenecks of epoxy resins for light emitting diode (LED) encapsulation, and how to solve them with a green method is still a great challenge. Herein, a unique hybrid was synthesized by forming SiO 2 particles on surface of cellulose, the hybridized cellulose (mCNC@SiO 2 ) was then used to develop new high performance epoxy resin (mCNC@SiO 2 /EP) for LED encapsulation. The effect of the content of mCNC@SiO 2 on the comprehensive performances of mCNC@SiO 2 /EP resins was studied. Results show that the presence of mCNC@SiO 2 not only greatly reduces the internal stress and improves UV resistance, but also increases moisture resistance while maintaining high heat resistance. When the content of mCNC@SiO 2 is only 2.0 wt%, the internal stress is reduced by 62%, thanking to the significant decrease in thermal expansion coefficient, and curing stress derived from the flexibility of Si-O-Si segment in mCNC@SiO 2 . In addition, mCNC@SiO 2 /EP resin has good transmittance, proving that the presence of mCNC@SiO 2 can effectively alleviate yellowing and improve UV resistance. These excellent comprehensive properties of mCNC@SiO 2 /EP resin demonstrate that mCNC@SiO 2 is a green and multifunctional modifier of epoxy resin for high performance LED encapsulation.