Formation of nanostructured epoxy networks containing polyhedral oligomeric silsesquioxane (POSS) blocks

Strachota, Adam; Whelan, Paul; Kříž, Jiří; Brus, Jiřı́; Urbanová, Martina; Šlouf, Miroslav; Matějka, Libor

doi:10.1016/j.polymer.2007.03.052

Cited by 100 publications

(95 citation statements)

References 41 publications

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“…It has been argued in the past, i.e. [31,32], that some of the benefits of incorporation of POSS into a polymeric matrix are due to the ability of POSS to structure a polymeric network on a nanometric level, which occurs by the formation of covalent bonds between the reactive POSS types used and the epoxy, and thus leads to a more homogeneous molecular structure of the epoxy/POSS network. This fact, plus a local reinforcement of the polymer chains with inorganic silica, should give rise to the enhanced BD strengths of the POSS composites.…”

Section: Ac Breakdown Strengthmentioning

confidence: 99%

Functional epoxy composites for high voltage insulation involving c-BN and reactive POSS as compatibilizer

2015

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Epoxy resins modified with only Polyhedral Oligomeric Silsesquioxanes (POSS) or cubic boron nitride (c-BN), as well as multiphase composites containing both, POSS and c-BN, were fabricated and investigated. Two different types of reactive liquid POSS with molecule sizes of approximately 2 nm, viz. Triglycidylisobutyl-POSS (TGIB-POSS) and Glycidyl-POSS were added in contents of 1 wt% to form single-phase and multiphase composites. Submicrometric c-BN, in contents of 5 wt%, was used for the respective single-phase composite as well as in the multiphase samples to create multifunctional nanostructured composites. All specimens were characterized by Broadband Dielectric Spectroscopy (BDS), dielectric breakdown experiments, Differential Scanning Calorimetry (DSC) and thermal conductivity measurements. The single-phase POSS composites have seen up to 15% improved dielectric breakdown strengths and enhanced thermal conductivities by up to 20%. The single-phase c-BN composite revealed the most distinct improvement in thermal conductivity of more than 25%, along with a reduction in dielectric breakdown strength of approximately 18%. Additionally, the dielectric and thermal properties of the multiphase composites containing 1 wt% POSS and 5 wt% c-BN, were found to be solely dictated by the submicrometric c-BN particles. SEM observations revealed a significantly improved dispersion of the c-BN particles in the presence of POSS for the multiphase composites, suggesting that POSS acts as a compatibilizer between organic epoxy matrix and inorganic filler particles.

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Section: Ac Breakdown Strengthmentioning

confidence: 99%

Functional epoxy composites for high voltage insulation involving c-BN and reactive POSS as compatibilizer

2015

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“…It is important to note that our calculation of n ¼ 11.2 attributes all of the increase in the rubbery modulus to an increase in crosslink density and it assumes that the rubber density changes with nanoparticle concentration in a way similar to the change measured in the glass density (see later). In addition to ignoring any reinforcement of the resin by the nanoparticles, the calculation based on eqs 2 and 3 also ignores the possibility of ring formation prior to gelation caused by the reaction of two (or more) epoxides on a given POSS cage with aminohydrogens from a single diamine molecule; in fact, such ring formation has been observed in molecular simulations of this or similar system 77,78 and such rings would result in mechanically ineffective loops that would decrease the effective functionality of the POSS. We suggest that perhaps in this system the increase in modulus due to nanoparticle reinforcement of the resin is offset by decreases resulting from loop formation; hence, we observe that the effective functionality appears to be only slightly lower than the value expected based on the POSS molecular structure.…”

Section: Viscoelastic Properties Of Epoxy and Epoxy/poss Nanocompositmentioning

confidence: 99%

Viscoelastic properties and residual stresses in polyhedral oligomeric silsesquioxane‐reinforced epoxy matrices

Hutcheson

McKenna

et al. 2008

J Polym Sci B Polym Phys

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Fiber-filled thermosetting polymer composites are extensively used in aerospace industries. One disadvantage of these materials is cure induced or thermally induced residual stresses in the matrix, which may result in deteriorated performance and premature failure. This article explores the use of epoxy/multifunctional polyhedral oligomeric silsesquioxane (POSS) nanocomposites as resins with reduced thermal stress coefficients that result in mitigated residual stresses. The effect of POSS loading on the thermal stress coefficient of the epoxy/POSS nanocomposite resins was investigated from below the b-relaxation to the a-relaxation, or glass transition temperature, (i.e., from À100 to 180 C) by measuring the shear modulus and linear thermal expansion coefficient. The thermal stress coefficient of the epoxy/POSS nanocomposites is found to be a strong function of temperature, decreasing rapidly with decreasing temperature through the a-relaxation region, increasing in the vicinity of the b-relaxation, and then decreasing below the temperature associated with the peak in the b-relaxation. With increasing POSS content, the thermal stress coefficient is reduced compared with the neat resin in the vicinity of the a-relaxation; however, the thermal stress coefficient increases with increasing POSS content below the temperature of the b-relaxation peak.

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“…The viscoelastic properties were characterized by a Q800 AT DMA apparatus with a single-cantilever clamp using rectangular specimens of size 35 × 10 × 2 mm 3 . The characterization of the specimens was performed under the following conditions: heated from room temperature (≈ 23°C) to 160 °C at a heating rate of 3 °C.min -1 , data sampling at 1 Hz frequency and strain amplitude of 0.08%.…”

Section: Dynamic-mechanical Thermal Analysis (Dmta)mentioning

confidence: 99%

“…Initially, POSS monomers were composed of aliphatic chain substituent groups of silicon (Si) atoms. After the discovery of hybrid POSS monomers, several modifications were performed [3] . Currently, these monomers are structurally well-defined molecules that have the form of a cage with typical size of approximately 1.5 nm [4,5] .…”

Section: Introductionmentioning

confidence: 99%

“…Whereas the nanocomposite properties depend on the dispersion, the dispersion depends on the functionality of the POSS. Strachota et al [3] demonstrated that the POSS monomers with different concentrations of epoxy groups can agglomerate due to the intra-and inter-molecular reactions between the cages. By forming nanocomposites of epoxy and POSS that also contain epoxy groups [13] , we demonstrated that the degradation mechanism of the epoxy (random nucleation with one nucleus of an individual particle) was changed to D n (diffusion model).…”

Section: Introductionmentioning

confidence: 99%

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Influence of the Polyhedral Oligomeric Silsesquioxane n-Phenylaminopropyl - POSS in the Thermal Stability and the Glass Transition Temperature of Epoxy Resin

2013

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Abstract:In this study, epoxy nanocomposites containing different fractions of n-phenylaminopropyl (POSS) were prepared. The nanocomposites were studied by transmission electron microscopy (TEM), gel content, dynamicmechanical analysis (DMA) and thermogravimetric analysis (TGA). The parameters for Avrami's equation were calculated from the degradation curves. The dispersions used to form the nanocomposites were effective above 5 wt % of POSS, and the gel content increased with the addition of POSS. The DMA analysis exhibited an increase in the storage modulus (E') and a shifting of T g to higher temperatures upon POSS incorporation. The weight loss indicated that the POSS promoted an increase in thermal stability of the epoxy resin. The Avrami parameters demonstrated that the addition of POSS decreased the Avrami constant (k'), increased the half-life (t 1/2 ) of degradation and promoted changes in the Avrami exponent (n). These results suggest that the increase in the glass transition temperature and thermal stability depend on the reactive groups in the POSS nanoparticles.

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Formation of nanostructured epoxy networks containing polyhedral oligomeric silsesquioxane (POSS) blocks

Cited by 100 publications

References 41 publications

Functional epoxy composites for high voltage insulation involving c-BN and reactive POSS as compatibilizer

Functional epoxy composites for high voltage insulation involving c-BN and reactive POSS as compatibilizer

Viscoelastic properties and residual stresses in polyhedral oligomeric silsesquioxane‐reinforced epoxy matrices

Influence of the Polyhedral Oligomeric Silsesquioxane n-Phenylaminopropyl - POSS in the Thermal Stability and the Glass Transition Temperature of Epoxy Resin

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