| Bisphthalonitrile polymers are an important class of high-performance polymers. These polymers were widely used for aerospace, marine and microelectronic industries owing to their outstanding thermal and thermo-oxidative stability, good mechanical properties, superior moisture resistance and fire resistance. However, the bisphthalonitrile resins also have many disadvantages, such as high melting point, low curing rate and a small processing window. So, to find some methods to lower the melting point, to increase the curing rate and to broaden the processing window are very inporment. There are three important methods to obtain high performance resins and composites: the development of novel bisphthalonitrile resins,the research of finding proper curing agents,the copolymerization with low melting monomer to promote the processability.Firstly, to lower the melting point, a kind of novel n=2 bisphthalonitrile oligomer containing biphenyl ethernitrile (2PEN-BPh) was synthesized from 2, 6-dichlorobenzonitrile, 4, 4'-biphenol and 4-nitrophthalonitrile via solution reaction, the solution is NMP and toluene mixer. And the structure of the 2PEN-BPh was characterized by FTIR, 1H-NMR spectra; the meilting and curing behaviors are studied by DSC; TGA and DMA are used for the investigation of the thermal properties and dynamic mechanism property.Secondly, to finding a proper curing agent to improve the curing rate of 2PEN-BPh, three aromatic amines: one nitrile side chain-containing diamine (BDB) and one sulfone-containing diamine (DDS), one amine containing a single amino-group (APN) are chosen as curing agent to study the effect of different amines on the properties of 2PEN-BPh. The results of the effect of three different aromatic amines (APN, BDB, and DDS) with the same concentration oc the curing rate showed that, all the amines could accelerate the curing reaction, and BDB was the best curing agent. The thermal property of the polymers cured with these amines demonstrated that the BDB cured system exhibitated the best thermal stability. When the concentration of the curing agent BDB was varying from 2wt% to 5wt%, the preferred concentration of BDB was 3 wt% and the polymer curd with 3wt% BDB displayed the best thermal stability.At last, the reaserch was carried out on the copolymerization of low meltng monomer 2PEN-BPh with bisphthalonitrile (BPh) to improve the processability. The studies on the copolymerization of 2PEN-BPh/BPh with the weight ratio are 75:25, 50:50 and 25:75 and the results showed that the processing temperature window was broaden indeed, and the extent of the curing reaction of belending systems was increasing with the increase of the curing temperature and the prolong of the curing time. For the fully cured 2PEN-BPh/BPh systems, 2PEN-BPh/BPh copolymer with the weight ratio is 50:50 possessed the best thermal and thermo-oxidative stabilities; the 5wt% decomposing temperature of this copolymer was achieve to 567.00 o, 559 oC, in nitrogen and in air, espectively; at the same time, the char yields could achieve up to 80% and above 90% at 600 oC in nitrogen or in air.According to the results of the investigations, incorporating flexible linkages into phthalonitrile terminals to obtain novel bisphthalonitrile could lower the melting temperater; the adding of aromatic amines as curing agents could increase the curing rate; the copolymerization of 2PEN-BPh and BPh could broaden the processing window without sacrificing the outstanding thermal and thermo-oxidative stability. |
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