Modification And Functionalization Research Of Bisphthalonitrile Resin

Bisphthalonitrile polymers are an important class of high-performance polymers.These polymers are derived by heating the phthalonitrile derivatives for an extendedperiod of time at elevated temperatures by addition curing reaction of cyano groupsfrom phthalonitrile derivatives. Because of their outstanding thermal/thermal-oxidativestability, water and chemical resistance and good processability, bisphthalonitrilepolymers were recognized as a better class of excellent candidate matrices for advancedcomposites than other traditional high temperature/performance resin-based advancedcomposites, such as epoxy, cyanate resin, polyimide, BMI and so on. However, theperformances of bisphthalonitrile polymers are limited by the following disadvantages:(1) The mechanical properties of bisphthalonitrile polymers are adversely affect by theirintrinsic brittleness of the network structure;(2) High melting temperature, narrowprocessing window, high curing temperature, low curing rate and long curing time;(3)According to the existing report, the processing temperature of bisphthalonitrileresin-based composites were controlled at500°C or less, while there is less study on itsmaterials formed above500°C;(4) The functionalization of bisphthalonitrile resin hasnot been abundant enough and its application range need to be expanded.On this basis, the dissertation focuses on the modification and functionalization ofbisphthalonitrile resin. In this work bisphthalonitrile resin was modified by a variety ofmethods, the mechanical property of bisphthalonitrile has been improved. Moreovercarbon nanotubes with different morphology and microwave absorbing materials wereobtained by pyrolyse bisphthalonitrile resin with different metal iron catalysts in therange of600~900°C. A technical approach for functionalization of bisphthalonitrileresin was developed; meanwhile its application field was expanded. Specific researchcontents are as follows:(1) Polyarylene ether nitrile (PEN) was selected as the guest polymer in4,4’-Bis(3,4-dicyanophenoxy) biphenyl (BPh) matrix to improve the intrinsic brittleness of itsnetwork structure. The melting and curing behavior of prepolymers and polymers was studied by DSC, AR and FTIR. The thermal properties of the PEN/BPh compositeswere tested by TGA. Their phase separation behaviors, mechanical property, therelationship between structure and performance were also studied. The results indicatedthat PEN could increase the curing rate and the toughness of BPh resin withoutsacrificing the excellent thermal stability and modulus.(2) Based on the research above, PEN/BPh-glass fiber composites were preparedand their mechanical properties, flammability, water and chemical resistance werestudied. The results indicated that the PEN/BPh-glass fiber composites with10wt%ofPEN exhibit good mechanical properties and low flammability, water and chemicalresistance. Moreover, the preparation method we used is powder-layering method that isnovel, convenient, simple, no toxic solvent used and different from the traditionaldipping process of prepreg.(3) xGnP/BPh nanocomposites were prepared through a simple and efficientprocess. The effects of the xGnP (exfoliated graphite nanoplatelets) on the complexviscosity, storage modulus of the xGnP/BPh pre-polymer system and the mechanical,electrical and thermal properties of the final xGnP/BPh nanocomposites were studied.The as-prepared xGnP/BPh nanocomposites with high performance are expected tohave potential applications in military industry, aerospace, and other fields where hightemperature is necessary.(4) A simple and efficient method for in situ synthesis of multiwalled carbonnanotubes (CNTs) from the pyrolysis of a mixture formulated from Fe(CO)5powderand nano-iron powder respectively various high temperature bisphthalocyanine polymerunder nitro atmosphere was described. SEM, TEM, XRD were employed to figure thedetail structure information of the CNTs, meanwhile the conductive, dielectric andmagnetic properties were studied. This research opened up a new application area ofbisphthalocyanine resin which different with other traditional thermosetting resin.(5) BPh monomer and ferrocenecarboxaldehyde were employed to synthesize FePcvia a series of high temperature sintering:500oC,700oC and900oC. The products withbest electromagnetic properties were obtained after700oC sintering process. Thedissertation focuses on the microwave absorption properties of the FePc after700oCsintering process. Theoretical simulation for the microwave absorption using Cole-Cole semicircle theory agrees well with the experimental results: the microwave absorptionof these composites can be mainly attributed to the dielectric loss rather than magneticloss. Then we choose BPh resin as the vector of FePc absorbent to prepare FePc/BPhcomposites. After curing reaction, the FePc particles gave the composite with noveldielectric and microwave-absorbing properties and the mechanical properties of theresin were greatly improved. The high value of microwave reflection and mechanicalproperty suggests that the composite can be used as promising microwave-absorbingmaterials.