Tailoring dielectric properties using designed polymer-grafted ZnO nanoparticles in silicone rubber

Wåhlander, Martin; Nilsson, Fritjof; Andersson, Richard L.; Sánchez, Carmen Cobo; Taylor, Nathaniel; Carlmark, Anna; Hillborg, Henrik; Malmström, Eva

doi:10.1039/c6ta11237d

Cited by 38 publications

(21 citation statements)

References 61 publications

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“…The dispersities of the PBMA grafts were narrow ( Đ M < 1.1), which indicated well‐controlled polymerizations ( Table 1 ). Interestingly, the apparent rate of polymerization was lower in the presence of rGO than in the presence of metal‐oxide NPs and resulted in more narrow dispersities, probably due to the radical scavenging effect of the rGO, in accordance with observations using carbon black …”

Section: Resultssupporting

confidence: 87%

“…Polymer nanocomposites provide new opportunities in this context since percolation can be achieved at very low filler content . For example, the percolation threshold (φ c ) can be decreased using particles with higher aspect ratio ( A r ) or designing self‐assembled superstructures by the controlled surface modifications of low‐ A r particles . By adjusting the size distribution, dispersion, and interparticle distance of the nanoparticles (NPs), the relationship between resistivity and E‐field can be controlled.…”

Section: Introductionmentioning

confidence: 99%

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Reduced and Surface‐Modified Graphene Oxide with Nonlinear Resistivity

Wåhlander

Nilsson

Andersson

et al. 2017

Macromol. Rapid Commun.

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Field-grading materials (FGMs) are used to reduce the probability for electrical breakdowns in critical regions of electrical components and are therefore of great importance. Usually, FGMs are heavily filled (40 vol.%) with semi-conducting or conducting particles. Here, polymer-grafted reduced graphene oxide (rGO) is used as a filler to accomplish percolated networks at very low filling ratios (<2 vol.%) in a semi-crystalline polymer matrix: poly(ethylene-co-butyl acrylate) (EBA). Various simulation models are used to predict the percolation threshold and the flake-to-flake distances, to complement the experimental results. A substantial increase in thermal stability of rGO is observed after surface modification, either by silanization or subsequent polymerizations. The non-linear DC resistivity of neat and silanized rGO and its trapping of charge-carriers in semi-crystalline EBA are demonstrated for the first time. It is shown that the polymer-grafted rGO improve the dispersibility in the EBA-matrix and that the graft length controls the inter-flake distances (i.e. charge-carrier hopping distances). By the appropriate selection of graft lengths, both highly resistive materials at 10 kV mm and FGMs with a large and distinct drop in resistivity (six decades) are obtained, followed by saturation. The nonlinear drop in resistivity is attributed to narrow inter-flake distance distributions of grafted rGO.

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Section: Resultssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Reduced and Surface‐Modified Graphene Oxide with Nonlinear Resistivity

Wåhlander

Nilsson

Andersson

et al. 2017

Macromol. Rapid Commun.

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“…where V 0 is the molar volume of the solvent, χ is Flory-Huggins interaction parameter between polymer and solvent, here is 0.465 [11] and ϕ is the volume fraction of SR in the swelling rubber, which can be obtained through Equation (2).…”

Section: Cross-link Density Testmentioning

confidence: 99%

“…Furthermore, 10 g of Zr-POSS, 30 g of SiO 2 , and 500 mL toluene were added in a 1000 mL round bottom flask. Then the mixture was stirred at room temperature for 1 h. Afterwards, the toluene was removed to obtain the Zr-POSS/SiO 2 mixture.…”

Section: Preparation Of Sr/zr-poss Nanocompositesmentioning

confidence: 99%

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Synthesis of Zirconium-Containing Polyhedral Oligometallasilsesquioxane as an Efficient Thermal Stabilizer for Silicone Rubber

Qiu

Lai

et al. 2018

Polymers

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Abstract:Free radicals play a negative role during the thermal degradation of silicone rubber (SR). Quenching free radicals is proposed to be an efficient way to improve the thermal-oxidative stability of SR. In this work, a novel zirconium-containing polyhedral oligometallasilsesquioxane (Zr-POSS) with free-radical quenching capability was synthesized and characterized. The incorporation of Zr-POSS effectively improved the thermal-oxidative stability of SR. The T 5 (temperature at 5% weight loss) of SR/Zr-POSS significantly increased by 31.7 • C when compared to the unmodified SR. Notably, after aging 12 h at 280 • C, SR/Zr-POSS was still retaining about 65%, 60%, 75%, and 100% of the tensile strength, tear strength, elongation at break, and hardness before aging, respectively, while the mechanical properties of the unmodified SR were significantly decreased. The possible mechanism of Zr-POSS for improving the thermal-oxidative stability of SR was intensively studied and it was revealed that the POSS structure could act as a limiting point to suppress the random scission reaction of backbone. Furthermore, Zr could quench the free radicals by its empty orbital and transformation of valence states. Therefore, it effectively suppressed the thermal-oxidative degradation and crosslinking reaction of the side chains.

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Facile preparation and flame retardancy mechanism of cyclophosphazene derivatives for highly flame‐retardant silicone rubber composites

Yang

et al. 2020

J of Applied Polymer Sci

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A novel and efficient flame retardant cyclophosphazene derivative Hexa (p‐acetamidophenoxy) cyclotriphosphazene (HACP) was successfully prepared via a facile one‐step reaction. The chemical structure of HACP was characterized and confirmed by FT‐IR, 1H and 13C NMR. Then the as‐prepared HACP was incorporated into addition‐cure liquid silicone rubber (ALSR) matrix to prepare highly flame‐retardant rubber composites. It was found that the incorporation of HACP can significantly enhance the flame resistance of ALSR. Typically, the ALSR composites filled with 30 phr HACP achieved UL‐94 V‐0 rating and meanwhile the total heat release and total smoke release were decreased by 26.9% and 41.5%, respectively. Moreover, the flame‐retardant mechanism of ALSR/HACP composites was investigated by TGA, Py‐GCMS, FT‐IR, SEM and EDX, confirming that HACP plays a significant role in capturing free‐radicals and forming protective layers. This work designed a novel cyclophosphazene‐based flame retardant to significantly enhance the flame retardancy of ALSR, which may offer some valuable inspiration for the fabrication of highly flame‐retardant polymer composites.

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Tailoring dielectric properties using designed polymer-grafted ZnO nanoparticles in silicone rubber

Abstract: Tuning of the dielectric properties of PDMS–ZnO nanocomposites by the control of inter-particle distances and self-assembled NP-morphologies via polymer grafting.

Cited by 38 publications

References 61 publications

Reduced and Surface‐Modified Graphene Oxide with Nonlinear Resistivity

Reduced and Surface‐Modified Graphene Oxide with Nonlinear Resistivity

Synthesis of Zirconium-Containing Polyhedral Oligometallasilsesquioxane as an Efficient Thermal Stabilizer for Silicone Rubber

Facile preparation and flame retardancy mechanism of cyclophosphazene derivatives for highly flame‐retardant silicone rubber composites

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