Synthesis Of Norbornene Derivatives And Their Copolymerizing Modification With Dicyclopentadiene

Dicyclopentadiene?DCPD?can be initiated by carbene catalyst and undergo ring opening metathesis polymerization to form polydicyclopentadiene?PDCPD?.PDCPD is an attractive,oxidation stable thermosetting material with excellent processing and mechanical properties.Research on PDCPD started as early as the 1960s.With the development of general plastics and resins industry,the requirements for the thermal and mechanical properties of materials have become higher and higher.Although PDCPD has many advantages,it still has many disadvantages such as insufficient heat resistance,certain brittleness of the product,low tensile and flexural strength,thereby limiting the application range.Therefore,it is particularly important to modify the thermal and mechanical properties of PDCPD.In recent years,the modification of PDCPD has become a hot topic by monomers with functional groups copolymerizing with DCPD.In this research,three norbornene imide derivatives,PNI,CHNI and NHNI,were successfully synthesized and characterized by ¹HNMR,¹³CNMR,FTIR and elemental analysis.Then,the imide monomers were respectively initiated by carbene catalyst and obtained their homopolymers.TGA analysis shows that the Td5%all above 400?,which proves the thermal properties of this three homopolymers is excellent.DTG curve shows only one exothermic peak,which indicates that the system cross-linked tightly and the thermal decomposition process is completed synchronously.Then,the norbornene derivatives PNI,CHNI and NHNI were copolymerized with DCPD to obtain P?PNI/DCPD?,P?CHNI/DCPD?,and P?NHNI/DCPD?copolymers,and their thermal and mechanical properties were researched respectively.The thermal stability of these three copolymers has been significantly improved than PDCPD:Td10%all above 400?,greater than PDCPD which is only about 146.9?.P?PNI/DCPD?has a maximum heat distortion temperature of 114.7?,increasing46.3%than PDCPD.P?CHNI/DCPD?has a maximum heat distortion temperature of109.5?,increasing 39.7%than PDCPD.P?NHNI/DCPD?has a maximum heat distortion temperature of 102.4?,increasing 30.6%than PDCPD.In terms of mechanical properties,with the increased of PNI content,the flexural strength of the P?PNI/DCPD?copolymerization system increased first and gradually stabilized.When added 3%content PNI,the flexural strength reached the maximum value 86.25MPa.The impact strength and tensile strength increased continuously and reached the maximum value after added 5%content PNI,which was increased by39%and 36.5%respectively compared with PDCPD.With the increased of CHNI content,the flexural strength of P?CHNI/DCPD?copolymerization system increased first and then decreased.When added 3%content CHNI,the flexural strength reached maximum value 85.87MPa.The impact strength and tensile strength increased continuously and reached the maximum value after added 5%content CHNI,which was increased by 70%and 32.5%respectively compared with PDCPD.With the increased of NHNI content,the flexural strength,impact strength and tensile strength of P?NHNI/DCPD?copolymerization system all increased first and then decreased.When added 4%content NHNI,the flexural strength reached the maximum value83.11MPa;when added 4%content NHNI,the impact and tensile strength reached the maximum value,which was increased by 44%and 30.1%respectively compared with PDCPD.