Improved thermal stability and flame resistance of flexible polyimide foams by vermiculite reinforcement

Yao

et al. 2017

Adv Polym Technol

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Polyurethane-imide (PUI) foams containing both polyimide and polyurethane segments combined the advantage of fine mechanical properties as well as high thermal stability of the two polymers. To further improve the thermal stability and flame resistance of PUI foams, a series of PUI composite foams with different content of SiC (silicon carbide) as fillers were prepared. The cell structure, mechanical properties, flame resistance, and thermal properties of resulting PUI/SiC composite foams were characterized in detail. The experimental results showed that the cell size distribution became uneven, the apparent density was increased, and the compressive strength decreased with the increase in silicon carbide content. Meanwhile, the limiting oxygen index (LOI) showed an increase from 24.7% to 28.1% with increasing of SiC content from 0% to 9.6%. The thermogravimetric analysis showed that the addition of SiC could significantly enhance the thermal stability and flame retardancy of PUI foams. K E Y W O R D Sflame retardant, polyurethane-imide foam, silicon carbide, thermal properties

Section: Introductionmentioning

confidence: 99%

Enhanced thermal stability and flame resistance of polyurethane‐imide foams by adding silicon carbide

Yao

et al. 2017

Adv Polym Technol

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“…Polyimide (PI) foams possess high temperature resistance properties and excellent flame resistant properties, and are used in demanding aerospace applications. [ 21‐23 ] However, PI foams exhibit poor processing performance and are expensive. [ 24 ] Therefore, a foam needs to be developed that can be used at high temperatures and is low cost.…”

Section: Introductionmentioning

confidence: 99%

Mechanical and flame‐resistance properties of polyurethane‐imide foams with different‐sized expandable graphite

Xiong

Liu

Polymer Engineering & Sci

et al. 2020

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Polyurethane‐imide (PUI) composite foams with expandable graphite (EG) of different sizes were prepared by a polyimide prepolymer method. EG particles were treated with a silane coupling agent to improve compatibility with the foam. The effect of EG particle size on cell morphology, thermal degradation, flame‐resistance and mechanical properties of PUI foams was investigated. Results showed that the mean cellular diameter of foams with EG particle was much higher than that of foams with surface‐modified EG particle at the same filler loading. When filler particle diameter increased from 20 to 90 μm, the compressive strength, density and closed‐cell ratio of foams increased, and then decreased when filler particle diameter further increased from 90 to 150 μm. Thermal stability of foams increased with the increasing filler particle diameter from 20 to 50 μm, and decreased with the increasing filler particle diameter from 50 to 90 μm. The limited oxygen index (LOI) value of foams with surface‐modified EG increased from 24.8% to 32.1% when EG particle diameter was below 90 μm. Foams with surface‐modified EG exhibited enhanced mechanical properties, thermal stability and flame resistance than foams with neat EG at the same loading.

“…Incorporating vermiculite into polymer matrix could enhance the thermal stability, mechanical, flame‐retardant properties dramatically . In our previous studies, vermiculite/polyimide foams prepared by a PI prepolymer method exhibit the improved thermal stability by the filler.…”

Section: Introductionmentioning

confidence: 99%

Enhanced mechanical and thermal properties of polyurethane‐imide foams with the addition of expended vermiculite

Xiong

et al. 2019

Polymer Composites

Self Cite

Polyurethane‐imide (PUI) foams, in combination with the mechanical performance of polyurethane and flame retardancy of polyimide, were prepared by polyimide prepolymer method. Expended vermiculite (EV), with a wider layer spacing than vermiculite, was used as the filler to further enhance the mechanical and thermal properties of the PUI foams. The effect of filler content on the morphology of foams was also investigated. The results showed that the mean cell diameter of foams became smaller and the cell size distribution was more uniform at low filler content. The addition of EV resulted in a substantial increase in thermal stability. The compression strength increased from 0.024 to 0.065 MPa with an increase in EV content from 0% to 9.6%. The limited oxygen index values increased from 24% to 30.8% with an increase in filler content from 0% to 9.6%. Hence, PUI foams could significantly enlarge its application range with the addition of EV.