Dr. Jianxiong Li, Associate Professor, School of Materials Science and Engineering, South China University of Technology, Guangzhou, China

Biography: Dr. Jianxiong Li received his BS (Rubber Technology) in 1982 and MPhil (Polymer Materials) in 1986 both from South China Institute of Technology and PhD (Materials) from Hong Kong University in 1997. He joined Chemical Dept., Hong Kong University of Science and Technology as Research Associate in 1998 and worked for ASM Pacific as Senior Engineer from 2001 to 2008. Thereafter, he joined South China University of Technology as Associate Professor in polymers. Dr. Li has worked on materials science and engineering for more than 30 years and accumulated extensive experience in academy and industrial. The involved areas include crystalline polymers, engineering plastics, polymeric blends and composites, electronic packaging materials, photochemistry and UV curing, functional materials and sensors, conducting polymers and optoelectronic devices.

Speech Title: Reducing melt viscosity of PP with phthalimide and fabricating long glass fiber reinforced PP
Abstract: Long glass fiber reinforced plastics are normally produced by melt impregnating and it requires the used resins have low melt viscosity. To reduce the melt viscosity of PP and fabricate long glass fiber reinforced PP (LGFR-PP), phthalimide (PTI) was investigated as a phase transition plasticizer of PP. PTI was incorporated to a maleimide modified PP compound on a twin screw Haake Rheometer at 230℃. The phase structures of the PP compound were analyzed with DSC and XRD and the effects of the added PTI on the MFR, impact strength, the heat distortion temperature (HDT) were investigated. The PP compound with high fluidity was used to produce LGFR-PP on melting impregnating device and the microstructure and properties of the composite were examined.

PTI could dissolve in maleimide modified PP melt at processing temperature and enhance the MFR of the melt remarkably at PTI content below 2 phr. But during cooling after molding, the dissolved PTI would precipitate and recrystallize in the PP matrix, therefore, improved the HDT and impact strength. At 1 phr N-PMI, 0.5 phr BMI and 1 phr PTI, the MFR of the modified PP compound could be as 3 times high as that of original PP, while the HDT increased 12 oC and the impact strength increased 20 %. The modified PP compound could be used to produce LGFR-PP by melt impregnating efficiently. SEM revealed that the dispersion of glass filaments became more even with the modified PP compound and PP resin could envelop almost all filaments. After injection molding, the LGFR-PP with 30 % of glass fiber exhibited a flexural modulus of 11 GPa, flexural strength of 180 MPa, impact strength of 240 J/m and HDT of 160 oC.