Synthesis And Properties Of Heat-Resistant Resins Bearing Phenyl-s-triazine Moieties In Backbones

Phenyl-s-triazine-based polymers possess a bunch of desirable comprehensive properties, such as desirable thermal-resistance, thermal stability, flame-resistance and chemical stability. However, traditional phenyl-s-triazine-based polymers are difficult to process, mainly due to their poor solubility and meltbility, which would restrict their application in composite material, adhesive and coating fields. This thesis aims at modifying the processability of phenyl-s-triazine-based polymers without sacrificing their thermal properties. From the standpoint of molecular design, for one hand, introducing the bulky diphenylfluorene moieties into the backbone of phenyl-s-triazine-based poly(aryl ether)s to promote their solubility, and simultaneously maintaining their thermal properties. For the other hand, a series of oligo(aryl ether phenyl-s-triazine)s end-capped with phthalonitrile moieties was synthesized, followed by thermal curing to prepare a series of phthalonitrile thermosetting resins with excellent thermal properties. Furthermore, the influence of the types and amounts of curing agent, the molar weights of the oligomers, the types of bisphenol and dihalo monomers used on the comprehensive performance of the thermosetting resins was systematically concerned. The main contents of this thesis are listed as follows:Phenyl-s-triazine-containing poly(aryl ether)s (PAEPs) exhibit outstanding heat-resistance. However, they could not dissolve in common solvents at room-temperature. Based on the molecular design, two series of copolymers, PAEPs and PEPs, were synthesized by introducing a type of bulky diphenylfluorene units into the skeletons of the insoluble poly(aryl ether) (PAE) containing phthalazinone and phenyl-s-triazine units in backbones for the first time. The resulting copolymers were characterized by FT-IR and NMR. The solubility of PAEPs and PEPs was improved, and they could be dissolved in solvents, such as NMP, at room temperature. When the content of diphenylfluorene segments higher than 50%, the copolymer PAEPs could solve in CHCb; simultaneously, the glass transition temperatures (Tgs) of the copolymers are exceeding 307 ?, and the 5% mass-loss temperature of the copolymers in N2(Td5%N2) could reach 580?, exhibiting excellent heat-resistance. Furthermore, the Tgs of PEPs increase with the diphenylfluorene contents as well. The research will undoubtedly broaden the application of PAEPs in membrane material and coating fields.For promoting the heat-resistant degrade of PAEPs, a series of phthalonitrile (PN) resins with variable molar weight was derived from biphenol (BP), 2-phenyl-4,4-bis(4-fluorophenyl)-1,3,5-triazine (BFPT), and 4-nitro-phthalonitrile (NPh). Their structures were confirmed by FT-IR and NMR, and they could solve in NMP and C2H2Cl4, which facilitate their processing. Bis(4-[4-aminophenoxy]phenyl)sulfone (BAPS) was selected to promote the curing reaction, and the gelation time could be readily controlled by the diamine concentration and the curing temperature. The curing procedure was optimized as 250?/3h+285?/1h+325?/3h+350?/2h+375?/8h to give high cross-linking density networks (Th-PBPs). Furthermore, the influence of the variation of the BAPS inclusion and the molar weight of the oligomeric precursor on the properties of the resulting thermoset was concerned. The results indicate that the heat-resistant (Td5%N2>530? Td5%air>539?) and long-term thermal degradation properties of Th-PBP1 scale linearly with the BAPS inclusion. The water uptake capacity (1.72?1.93%) decreases then increases as the the BAPS content increases. The Tg value (>400?) hardly depends on the change of BAPS concentration. As for the molar weights of oligomers, the decomposition temperature (Td5%N2>538?, Td5%air>543?) and water absorption (1.72%?8.32%) of the Th-PBPs increases on the increase of the molar weight of PBP-Phs, while the weight retention at 900?(Cy 900?,60%?71%) and Tg (298?400?) behave conversely. Additionally, the T700 CF reinforced Th-PBP composites are fabricated via solution dipping and lamination technology. The results show that Th-PBP/T700 laminates possess high flexural strengths (1339?1855 MPa) and interlaminar shear strengths (71.8?92.2 MPa). Furthermore, the residual flexural strength and interlaminar shear strength of T700/Th-PBPl at 450? are 255 MPa and 36 MPa, respectively, demonstrating good heat-resistance.8 types of diamines (see Section 4.1) with different structures were selected to co-cure with PBP-Ph1 resin for investigating the relationship between diamine structure and the network properties from several facets like the curing reaction kinetics, rheologic behavior, thermal stability, thermal mechanical property, and water uptake capacity. The activation energies of PBP-Phl cured with complexly structural diamine are higher than that with simply structural diamine, implying a more sensitive dependence of the curing reaction on the temperature. Rheologic measurement more intuitively shows that the ether bonds para to amine groups and the electron withdrawing units are beneficial to promote the curing rate of the diamines. The water absorption of the cured networks varies as the types of the diamines change:the BAPS network exhibits the lowest water absorption; the water absorptions of simple diamine networks are lower than those of complex diamine networks. The Tgs of all the networks are lying between 357?400?. However, the overall thermal stabilities of the networks less depend on the diamine type:in nitrogen atmosphere, their Td5%s range from 543 to 561?, and the Cy900?S are lying between 65%?71%. Such data also show their outstanding thermal resistance. After thoroughly considering all the results, BAPS or DDS is reckoned as the optimal curing additive for the PBP-Phl resin.6 types of bisphenol monomers (see Section 5.2.3) were selected to homopolymerize with BFPT, followed by end-capped with NPh, to prepare a series of low molar weight PN resins (PEP-Phs), for disclosing the relationship between bisphenol structure and resin properties. The resulting PEP-Phs could be dissolved in NMP and C2H2CI4, and they could also be molten before 240?. After the addition of DDS, the gelation took place at 5.8-26.0 min, depending on bisphenol structures. When totally cured, the obtained networks (Th-PEPs) possess excellent thermal stabilities with the Td5%N2S lying between 515?562? and Cy900?N2: ranging from 64%-74%. More specifically, the biphenyl groups render the resins more desirable heat-resistance, and the meta-phenyl links enable the promotion of the initial decomposition temperature. Otherwise, the structures such as aliphatic carbon and N-N bonds are thermally weak units. The Tgs of Th-PEPs are from 355 to 400?, and the rigid phthalazinone units endow the network the best thermal mechanical property. The water absorptions of Th-PEPs range from 2.12%to 2.56%, lower than those of many other PN counterparts. This merit will benefit for the application at high humidity or aqueous environment.For investigating the relationship between dihalo structure and the network properties, two series of PN resins (PPEN/S/K/P-Ph and PPEP-Phs) were constructed with the phthalazinone-containing monomer, named as DHPZ, as a core. PPEN/S/K/P-Ph could adapt both solution and molten processing technology. With the addition of DDS, the gelation of the mixture occurred at 4.9?12.0min at 250?, demonstrating commendable processability. After cure, the obtained networks exhibit several desirable properties (i.e., Td5%N2,509?518?; Td5%air,494?522?; Cymvs,,65%?76%; Tg,>400?; Water absorption,2.02%-2.42%). The introduction of phenyl-s-triazine moieties mainly contributes to the elevation of thermal stability, whereas the excellent thermal mechanical property could be attributed to the presence of phthalazinone units. The influence of precursor molar weights on the properties of the thermoset was also investigated, When the precursor molar weights increase, PPEP-Phs exhibit impossible processing trend. After cured with DDS, the Tgs of Th-PPEPs were all exceeding 400?, which decrease slightly with the increase of precursor molar weights. Meanwhile, the decomposition temperature and water uptake capacity of Th-PPEPs linearly depends on the precursor molar weights.