Polydicyclopentadiene (PDCPD) is flammable

its polymerization process is complicated and the period is long. In this paper

a flame retardant monomer NB-DOPO were designed and synthesized by introducing 9

10-dihydro9-oxaze-10-phosphoxene-10-oxide (DOPO) into the norbornene. This monomer can be copolymerized with dicyclopentadiene (DCPD) by frontal ring-opening metathesis polymerization (FROMP) to prepare the PDCPD/NB-DOPO copolymers with intrinsic flame retardant properties. The effects of the introduction of NB-DOPO on the FROMP process and the dynamic mechanical properties

thermal stability

mechanical properties as well as the flame-retardant properties of the copolymers were studied. On that basis

the possible flame retardant mechanism of the PDCPD/NB-DOPO copolymer was explored further. The results indicated that NB-DOPO could copolymerize with DCPD randomly

and thus the frontal polymerization velocity of the copolymerization was reduced. According to this

a controllable FROMP was achieved while maintaining a high curing degree of the material. When the content of NB-DOPO was below 10%

the introduction of NB-DOPO with high ring tension promoted the formation of cross-linking points in the system

reduced the molecular weight of cross-linking points (Mc)

and enhanced the storage modulus and mechanical properties of the copolymer; When the concentration of NB-DOPO reached 30%

the cross-linking density of PDCPD/NB-DOPO declined

the rigid structures in the NB-DOPO acted as physical cross-linking points

hence the mechanical properties of the material could be kept at a high level accompanied by a markedly enhanced flame retardancy

and the limiting oxygen index (LOI) of the material was increased by 38% in comparison to that of PDCPD

that material exhibited superior comprehensive properties.