| Cardanol is a main chemical component comes from cashew nut shell liquid, is extracted from cashew nut shell, is also a byproduct of cashew nut industry. So cardanol is a renewable, low cost and largely available resource. It possesses a phenolic hydroxyl group and a meta-substituted C15 long unsaturated alkyl chain, which offer many effective and reactive properties to cardanol, which not only has the characteristics of aromatic compounds, but also has the characteristics of saturated hydrocarbon and phenolic compounds. And so cardanol as a green, ecological resouce, which can replace phenol to react in a variety of chemical reactions and different kinds of products are synthesized based on it.A liquid benzoxazine monomer based on cardanol was synthesized via Mannich reaction with cardanol, allylamine and paraformaldehyde. Using this liquid benzoxazine monomer as raw material, through three aspects work, a liquid benzoxazine/GO composites and the flame retardance material contain phosphorous and molybdenum were prepared, the structure and morphology of the composites was characterized, and the flame retardant properties of the material was also tested, which would obtain the data support for the application of cardanol in the field of material.1. Preparation and modification of graphene oxide (GO)Oxidized graphite was prepared with expanded graphite via improved Hummer’s method, and then ultrasonication of the oxidized graphite, GO was obtained. IR and XPS spectra both demonstrated that there are many O-containing functional groups existed on the surface of GO. The XRD spectra showed the (001) diffraction peak of GO appeared at 20=9.8°, which informed that the interlayer space was increased; and displayed a thinly sheet-like structure.To promote the dispersion of GO in the resin matrix, two kinds of biomass of chitosan and cardanol were adapted to modification of GO. Modificated GO with Chitosan, which was called KGO; modificated GO with cardanol, which was called YGO in this paper. The XPS results confirmed that the elements existed on the surface of GO and their bond state had all changed after modification. The DSC and TGA curves all demonstrated that the curing behavior and the thermal stability of GO had changed after modification.2.Preparation of a liquid benzoxazine based on cardanol and its graphene oxide composite by blendingA liquid cardanol-allylamine-paraformaldehyde benzoxazine monomer (BZc-a) was synthesized via Mannich reaction and was performed in solvent.1HNMR, IR and DSC all confirmed that there is a oxazine ring exist in BZc-a. The oxazine ring would open to polymerization and formed polybenzoxazine during heating. Combined benzoxazine with different proportions of GO and obtained BZc-a/GO composite, benzoxazine-functional silane coupling agent (BFSca) made in our lab was chosen as a coupling agent to improve the dispersion and compatibility between benzoxazine matrix as organic domain and GO as inorganic domain. The stablities of the composite were greatly increased with the presence of GO and BFSca. Introduction of 4 wt% GO and 4 wt% BFSca obtained the best effective, which made the inital decompose temperature was increased to 399.8℃, and got 32.9% residual at 800℃.3. Fabrications of P-containing and flame retardance of benzoxazine based on cardanol, and their graphene oxide compositesFor P-H bond in DOPO (9,10-Dihydro-9-oxa-10-phosphaphenanthrene 10-oxide) with high activity could take reaction with olefin, epoxy bonds and carbonyl, two novel DOPO-containing resins P1B and P2B were generated via molecular designing by controlling the molar ration of DOPO:BZc-a based on the allyl-group containing in BZc-a. The structure and properties of PiB and P2B were tested by 1HNMR,13CNMR and DSC. The results demonstrated that P1B contains not only a oxazine ring but also a phosphaphenanthrene group, the content of phosphorus was 7.7%; while P2B contains two phosphaphenanthrene groups, its content of phosphorus up to 9.8%. Fire test demonstrated that the incorporation of P into BZc-a improved the flame retardance, turned BZc-a from flammable to a non-combustible material, and LOI was increased from 18.3 to 28 and 32, respectively. The thermal stability of PiB and P2B was both better than that of BZc-a and be characterized by TGA.Two kinds of P-containing cardanol-based benzoxazine/GO composites were fabricated via blending, that is P1B/3%GO and P2B/3%GO. The properties of them was characterized and compared with BZc-a/3%GO. We found an interesting phenomenon during the test, that was, GO couldn’t stay stable in BZc-a and deposited at the bottom of tube, however, it could stay stable in P1B and P2B, when 3%GO blended with BZc-a, P1B and P2B, respectively. The results of TGA demonstrated that the addition of GO made the thermal stabilities of these composites better than that of the single resin martix.4. Preparation of a kind molybdenum phenolic resin based on cardanol and its hybridization with P-containing benzoxazineCardanol was chosen as raw material, phenolic resin based on cardanol(CPF) was synthesized via condensation reaction in presence of NaOH. Ammonium molybdate tetrahydrate was chosen as to modify CPF and obtained Mo-CPF, which is linked by-Mo-O-groups. The results of 1HNMR, 13CNMR and EDX all demonstrated that there appeared molybdenum element and Mo-O groups in Mo-CPF after modification. SEC study indicated that there are many oligomers existed in CPF, and the molecular distribution of CPF is too broad to predict the molecular weight. However, the molecular distribution of Mo-CPF became narrow after modification, and obtained amount of polymers and the values of molecular weight distribution (MWD=Mw/Mn) is 1.072.Reacted Mo-CPF with PiB and got a Mo-CPF/P1B hybrid, which containing P and Mo elements. This paper will be mainly discuss the mechanical properties, flame retardancy, thermal stability of Mo-CPF/PiB before and after hybridization. DMA measurements was investigated in a Single Cantilever mode, the stress-strain curve showed that CPF, Mo-CPF and Mo-CPF/P1B all exhibited a plastic behaviour. As comparison, CPF appeared a typical plastic deformation for a phenolic resin, however, if make CPF, Mo-CPF and Mo-CPF/P1B performed the same elongations that Mo-CPF/PiB need the highest stress. Flexural modulus of Mo-CPF/P1B is 1019 Mpa, CPF is 123.7 MPa and Mo-CPF is 167.7 Mpa. DMA measurements also suggested that Tg of CPF, Mo-CPF and Mo-CPF/PIB were 98℃,170℃ and 131℃, respectively. LOI of CPF, Mo-CPF and Mo-CPF/P1B is 19.2,23 and 26.1, respectively. Mo-CPF/P1B exhibited better flame retardance after conjugating with molybdenum and phosphorus. TGA results suggested Mo-CPF/P1B exhibited better thermal properties. CPF obtained 15% residual at 800℃, Mo-CPF got 27% residual at 800℃, and Mo-CPF/P1B got 27% residual at 800℃. All these data confirmed that the mechanical properties of Mo-CPF/P1B was enhanced after hybridization, introduction molybdenum into Mo-CPF/P1B endow it better toughness, and brittle was decreased; introduction phosphorus into Mo-CPF/P1B endow it better flame retardance, which all make its application in engineering material field become possible. |
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