| Unsaturated polyester resin (UPR) is one sort of thermosetting resins with rapid development, and the amount of usage of UPR is the biggest in thermosetting resins. Raw material for UPR is easily available, and it can be solidified by simple process technique at normal temperature and pressure. UPR shows excellent mechanistic, electrical properties and good chemical corrosion resistance. In recent years, the development of UPR is very rapid and output keeps a double-digit growth in our country. However, due to the technical problem, most of domestic corporations just manufacture mid/low-grade products, which have no predominance in international market. So developing new UPR products to promote competitive power is a problem to be solved immediately. At the same time, with the deep recognition of environmental contamination and gradual establishment of corresponding environmental protection laws, green and environment-friendly concept has been emphasized in the research of high performance UPR.Since flame-retardant UPR containing halogen destroys environment and the additive flame retardant results in the performance loss, to solve the problem, preparation of UPR/SiO2 nanocomposite and synthesis of novel phosphorus-containing UPR have been studied in this thesis.(1) A novel phosphorus-containing unsaturated polyester resin/SiO2 hybrid nanocomposite was prepared from the in-situ sol-gel curing of UPR and triethoxysilane (DI) which was synthesized by the nucleophilic additional reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) and 3-(trieoxysilyl) isocyanate(icteos). Since the structure of nano-SiO2 derived from DI contains phenyl and amino group, which can form hydrogen bonds with–C=O bond on the UPR chain, nano-SiO2 networks can homogeneous disperse in UPR. The structure of SiO2 /UPR nanocomposite was confirmed by FTIR, DSC, SEM and EDS. With the increase of DI contents from 0 to 20%, the limiting oxygen index (LOI) value of the cured UPR-DIs raised from 19 to 29, suggesting a significant improvement in flame retardance. Thermogravimetric analyses (TGA) both in air and in nitrogen were used to estimate mechanism of thermal degradation, and activation energies (Ea) of different degree of conversion (α) were calculated by Ozawa's method. The UPR-DI containing 10%DI (UPR-DI10) had higher Ea than that of the pure UPR asα>5%. DMA results revealed that nano-SiO2 enhanced strength of the whole system and made the storage modulus higher than that of UPR.(2) With DMMP as flame retardant, the method of one step and two steps for preparing reactive flame-retarded UPR and the method of blending for preparing additive flame-retarded UPR were discussed. The results showed that one step method was the best for reactive flame-retarded P1-UPR. 31P-NMR confirmed that DMMP was imported into the main chain of P1-UPR by ester exchange reaction. Characteristic absorption peaks of phophorus-containing groups did not appear in the TG-FTIR for thermal degraded gas from P1-UPR. Char residues of burned P1-UPR with different usage of DMMP were analyzed by SEM. The results revealed that the layer of char residues became compact with increasing of phosphorus. These results indicated that phosphorus flame-retarded P1-UPR by condensation mechanism.(3) Bis-phenoxy (3-hydroxy) phenyl phosphine oxide (BPHPPO) was synthesized by phenyl phosphonic dichloride and resorcinol, and bis(hydroxyethyl)phenylphosphonate (BHEPP) was synthesized by phenyl phosphonic dichloride and ethylene glycol. P2-UPR and P3-UPR were prepared by condensation reaction with BPHPPO and BHEPP as flame retardant, respectively. UL94-V0 rating and limiting oxygen index (LOI) increased with the increase of flame retardant in the cured P2-UPR and P3-UPR. TG and DTG analysis indicated that decomposition temperature of 5% weight loss decreased from 275.5℃to 248.0℃with increase of BPHPPO content from 0 to 30% in P2-UPR. However, formation of phosphorus-containing acid from the decomposition of P—O—C bonds interfered effectively the further polymer decomposition. And the char residues increased from 0 to 4.6% at 600℃. Curing kinetic parameters of P2-UPR and P3-UPR were calculated by Kamal's equation using DSC. Compared with pure UPR, retarded effect of P2-UPR happened after the introduction of BPHPPO. Values of Ea increased from 46.5kJ/mol to 262.9kJ/mol with increasing of mass fraction of BPHPPO in P2-UPR from 0 to 18%. While the retarded effect didn't exist in P3-UPR which was synthesized by BHEPP without phenolic hydroxyl group.(4) DOPO-MA and DDP were synthesized by 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) with maleic acid(MA) and itaconic acid(ITA), respectively. P4-UPR was obtained by reacting PG with MAH, PAH and DOPO-MA, and P5-UPR was obtained by reacting PG with MAH, PAH and DDP. The chemical structures of these compouds were confirmed by EA, FTIR, 1H-NMR and 31P-NMR. The thermal stabilities of P4-UPR and P5-UPR were studied by thermogravimetric analysis (TGA). The results showed that the thermal stability of P4-UPR was close to that of pure UPR, but P5-UPR had higher thermal stability than pure UPR. The electric strength of P5-UPR was almost the same as that of pure UPR(22-25MV/m) at room temperature, while it was 6-7MV/m less than that of pure UPR at 155℃. The flame retardance of P5-UPR3 with the usage of 30% DDP could reach UL 94 V-0. The results of cone calorimeter showed that, in P5-UPR, an increase of phosphorus content from 0 to 1.62% decreased PHRR values from 655 to 375kW/m2 (a 42.7% reduction) and THR values from 146 to 83kJ (a 43.2% reduction). EHC was reduced to 40.7% of the control sample (UPR). With MEKP and cobalt isooctoate used as initiator system, calculated curing conditions for P4-UPR3 were as follow: Tgel =84℃,Tcure = 103℃,and Ttreat = 121℃. Curing kinetics of P5-UPR3 was researched by Malek model. The cure kinetic function could be described using S-B model in the function of f(a)1 =a0.82×(1-a)1.25, and the function for pure UPR was f(a)2 =a0.41×(1-a)0.84。... |
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