Abstract:An improved method is developed to synthesize octavinylsilsesquioxanes (VPOSS) with shorter time and higher yield, and then VPOSS is used to prepare new hybrids based on bismaleimide‐triazine (BD/CE) resin, coded as VPOSS/BD/CE. The effect of the content of VPOSS on the key properties including curing behavior, thermal, mechanical, and dielectric properties as well as water resistance of VPOSS/BD/CE hybrids were systematically discussed. Compared with BD/CE resin, hybrids show similar curing behavior but diffe… Show more
“…A strategy used to provide thermooxidative protection in cyanurate polymer networks that has been explored through much recent investigation is the incorporation of silicon or siloxy moieties in the form of monomers and cocuratives, blends and modifiers, silica nanoparticles, clay nanoplatelets, or other silicon‐containing nanostructures including oligomeric silsesquioxanes . While the addition of silicon in fully oxidized form (i.e., as SiO 2 ) can provide an in‐place barrier to oxygen permeation, the use of unoxidized organosilicon moieties or partly oxidized silicates allows for the in situ generation of a protective barrier during high‐temperature oxidation or exposure to energetic forms of oxygen (such as atomic oxygen in low Earth orbit) .…”
The synthesis and physical properties of new silicon-containing polyfunctional cyanate ester monomers methyl[tris(4-cyanatophenyl)]silane and tetrakis(4-cyanatophenyl)silane, as well as polycyanurate networks formed from these monomers are reported. The higher crosslinking functionality compared to di(cyanate ester) monomers enables much higher ultimate glass transition temperatures to be obtained as a result of thermal cyclotrimerization. The ability to reach complete conversion is greatly enhanced by cocure of the new monomers with di(cyanate ester) monomers such as 1,1-bis(4-cyanatophenyl)ethane. The presence of silicon in these polycyanurate networks imparts improved resistance to rapid oxidation at elevated temperatures, resulting in char yields as high as 70% under nitrogen and 56% in air in the best-performing networks. The water uptake in the siliconcontaining networks examined is 4-6 wt % after 96 h of immersion at 85 C, considerably higher than both carbon-containing and/or di(cyanate ester) analogs. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 767-779
“…A strategy used to provide thermooxidative protection in cyanurate polymer networks that has been explored through much recent investigation is the incorporation of silicon or siloxy moieties in the form of monomers and cocuratives, blends and modifiers, silica nanoparticles, clay nanoplatelets, or other silicon‐containing nanostructures including oligomeric silsesquioxanes . While the addition of silicon in fully oxidized form (i.e., as SiO 2 ) can provide an in‐place barrier to oxygen permeation, the use of unoxidized organosilicon moieties or partly oxidized silicates allows for the in situ generation of a protective barrier during high‐temperature oxidation or exposure to energetic forms of oxygen (such as atomic oxygen in low Earth orbit) .…”
The synthesis and physical properties of new silicon-containing polyfunctional cyanate ester monomers methyl[tris(4-cyanatophenyl)]silane and tetrakis(4-cyanatophenyl)silane, as well as polycyanurate networks formed from these monomers are reported. The higher crosslinking functionality compared to di(cyanate ester) monomers enables much higher ultimate glass transition temperatures to be obtained as a result of thermal cyclotrimerization. The ability to reach complete conversion is greatly enhanced by cocure of the new monomers with di(cyanate ester) monomers such as 1,1-bis(4-cyanatophenyl)ethane. The presence of silicon in these polycyanurate networks imparts improved resistance to rapid oxidation at elevated temperatures, resulting in char yields as high as 70% under nitrogen and 56% in air in the best-performing networks. The water uptake in the siliconcontaining networks examined is 4-6 wt % after 96 h of immersion at 85 C, considerably higher than both carbon-containing and/or di(cyanate ester) analogs. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 767-779
“…These differences are resulted from their different structure and different pore constant. 32 It is obvious that the composites prepared by extraction method have higher exural strength and exural modulus than the composites made by the calcinations method. The D2000 in the extraction method prevents the POSS from entering the mesopores, which allows POSS to graed on the surface of MPS and interact with CE, thus improving the compacity.…”
Section: Mechanical Properties Of Compositesmentioning
“…With the increase of the content of G-POSS, the composites exhibit more and more obvious ductile fracture morphology, which presents a water wave shape or a scaled flake section structure, suggesting a typical ductile fracture behavior. 18 This can be attributed to the formation of chemical bonds between G-POSS and the polymer matrix. Subsequently, the induced microcracks absorb much energy to prevent crack propagation.…”
Section: Microstructure Of G-poss/ce Compositesmentioning
In this article, a high-performance hybrid material was prepared by melt blending from glycidyl polyhedral oligomeric silsesquioxane (G-POSS) and bisphenol-A cyanate ester (CE), using triethylamine as the curing agent. The structure of the hybrid was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM), and the transparency properties, mechanical properties, dielectric properties, thermal performance, and wet fastness were studied. The results showed that G-POSS was uniformly distributed in the CE matrix and could obviously accelerate the curing reaction of the resin. Large amounts of corrugated and scaled structures were observed on the fractures of G-POSS/CE by the SEM photos. When the G-POSS content increased to 7 phr, the tensile strength (75.45 MPa), elongation at break (3.19%), and impact strength (23.76 kJ m−2) reached maximum values, representing increases of 21.75%, 27.6%, and 157.98% relative to that of pure CE, respectively, which indicated that the addition of G-POSS can significantly improve the toughness of G-POSS/CE composites. When the G-POSS content increased to 4 phr, the dielectric constant decreased from 3.27 to the minimum value of 3.05. The heat resistance and wet fastness of G-POSS/CE hybrid materials decreased with increasing G-POSS content.
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