Facile Synthesis of Hollow Glass Microsphere Filled PDMS Foam Composites with Exceptional Lightweight, Mechanical Flexibility, and Thermal Insulating Property

Abstract

The feature of low-density and thermal insulation properties of polydimethylsiloxane (PDMS) foam is one of the important challenges of the silicone industry seeking to make these products more competitive compared to traditional polymer foams. Herein, we report a green, simple, and low-cost strategy for synthesizing ultra-low-density porous silicone composite materials via Si-H cross-linking and foaming chemistry, and the sialylation-modified hollow glass microspheres (m-HM) were used to promote the HM/PDMS compatibility. Typically, the presence of 7.5 wt% m-HM decreases the density of pure foam from 135 mg/cm−3 to 104 mg/cm−3 without affecting the foaming reaction between Si-H and Si-OH and produces a stable porous structure. The optimized m-HM-modified PDMS foam composites showed excellent mechanical flexibility (unchanged maximum stress values at a strain of 70% after 100 compressive cycles) and good thermal insulation (from 150.0 °C to 52.1 °C for the sample with ~20 mm thickness). Our results suggest that the use of hollow microparticles is an effective strategy for fabricating lightweight, mechanically flexible, and thermal insulation PDMS foam composite materials for many potential applications.

Lightweight and flame retardant fluorosilicone rubber composited foam prepared by supercritical nitrogen

“…In addition, APP and EG had different effects on the foaming performance due to their different properties. As can be seen from Figure 2 b, the density of pure FSR foam was as low as 0.117 g/cm 3 . When the content of APP and EG was 20 phr, the density of FSR composite foam was 0.185 and 0.377 g/cm 3 , respectively.…”

“…As can be seen from Figure 2 b, the density of pure FSR foam was as low as 0.117 g/cm 3 . When the content of APP and EG was 20 phr, the density of FSR composite foam was 0.185 and 0.377 g/cm 3 , respectively.…”

“…The results showed that the increase of flame retardants content improved the flame retardance, but adversely affected the cell structures and increased the foam density. When there was 12.5 phr APP and 7.5 phr EG, the composite foam had the best combination performance, the density was only 0.254 g/cm 3 , LOI was up to 36.4%, UL-94 grade was V-0, ignition time up to 12 s, FPI value was 0.071 sÁm 2 /kW. The addition of flame retardants increased the hardness and tensile strength of foam by 63.7% and 38.3%, respectively, and reduced the elongation at break by 17.3%, but has no significant effect on the aging resistance, oil resistance and solvent resistance.…”

“…1 The lightweight FSR foam is extensively used in modern high-precision industries such as aerospace, automobile manufacturing and petrochemical equipment, whose importance in defense and aerospace application is irreplacable. [2][3][4] However, FSR foam is flammable and its working environment is featured with high concentration of flammable oils and organic solvents, as well as high temperature which further increases the probability of fire. 5 Therefore, strategies to improve the flame retardancy of FSR foam is necessary.…”

“…Fluorosilicone rubber (FSR) is a kind of specialty elastomer that excels in high‐temperature stability, chemical as well as oil and organic solvent resistance, which has a wide temperature usage range (−60°C to 220°C) 1 . The lightweight FSR foam is extensively used in modern high‐precision industries such as aerospace, automobile manufacturing and petrochemical equipment, whose importance in defense and aerospace application is irreplacable 2–4 . However, FSR foam is flammable and its working environment is featured with high concentration of flammable oils and organic solvents, as well as high temperature which further increases the probability of fire 5 .…”