Poly(dimethylsiloxane)‐toughened syntactic foams

Abstract

The potential of preformed elastomers as a toughening agent for epoxy–glass syntactic foam has been explored. Poly(dimethylsiloxane) microspheres were prepared by suspension polymerization. The microsphere dimensions could be varied from 58 to 255 µm by tuning the reaction parameters, particularly the stirring speed and feed concentration. Rheological studies indicated that the introduction of microballoons led to an increase in the viscosity of the resin, with the extent being proportional to the microballoon content. The zero shear viscosity increased from ∼103 mPa s at 30 °C to 105 mPa s as the microballoon loading was increased to 40%. Syntactic foams containing varying amounts of microballoons (40–60% v/v) were prepared, and an analogous set of toughened foams were also prepared, where a fraction of the microballoons was replaced with poly(dimethylsiloxane) microspheres (3–7%). The effect of increasing dimensions of the elastomeric microspheres on the mechanical properties was also studied. The improvement in properties was more pronounced when the microsphere size was equivalent to that of the constituent microballoons. An improvement of 40% and 185% in flexural strength and flexural toughness was observed upon the introduction of poly(dimethylsiloxane) microspheres of optimal dimensions (diameter ∼63 µm, 5% loading), without any undesirable increase in foam density. However, the compressive properties remained practically unaltered. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45882.

Enhancing the Fracture Resistance and Impact Toughness of Mechanically Frothed Epoxy Foams with Hollow Elastomeric Microspheres

“…The quasi‐static compressive modulus and strength of these rubber particle‐filled syntactic epoxy foams, on the other hand, decreased by 50% and 10%, respectively, compared to unfilled syntactic epoxy foams. Similar results were also observed for poly(dimethylsiloxane) (PDMS) particle‐filled syntactic epoxy foams . The toughness (evaluated from the area under the flexural stress–strain curves) of syntactic epoxy foams filled with 7 vol.% PDMS particles improved by up to 2.5 times compared to unfilled syntactic epoxy foams but their compressive strength decreased by 20%.…”

“…Similar results were also observed for poly(dimethylsiloxane) (PDMS) particle-filled syntactic epoxy foams. [12] The toughness (evaluated from the area under the flexural stress-strain curves) of syntactic epoxy foams filled with 7 vol.% PDMS particles improved by up to 2.5 times compared to unfilled syntactic epoxy foams but their compressive strength decreased by 20%. This is a direct result of using soft and nonporous elastomeric particles, which is necessary to enhance the toughness of epoxy foams but at the same time, these elastomeric particles are inherently inferior in mechanical performance, which led to a significant reduction in the quasi-static compressive properties of the nonporous elastomeric particle-filled epoxy foams.Therefore, a new strategy to enhance the fracture resistance and impact toughness of epoxy foams without sacrificing their quasi-static compressive properties is needed.…”

Epoxy-Glass Microballoon Syntactic Foams: Rheological Optimization of the Processing Window

“…Syntactic foams are lightweight composite materials prepared by incorporating hollow microballoons of glass [1], polymer [2,3], or metal [4] in a suitable matrix. The inclusion of these hollow counterparts allows for significant weight savings, which is crucial for certain applications, especially marine [5,6], aerospace [7,8], and blast mitigation [9].…”

Synthesis of multifunctional core–shell toughening agent with light stability and its application in polycarbonate

“…Hence, it can be imagined that the PSiO-acrylate elastomer toughening agent is a good candidate for improving the low-temperature impact resistance of PC. 24,25 Meanwhile, it can also improve the heat resistance, weather resistance, and aging resistance and lubrication properties of the material due to the special property of the silicone. 26,27 In this article, PSiO-acrylate-2-(2 0 -propionyloxy-5 0 -methylphenyl) benzotriazole (AMB) toughening agent (poly(D4-MMA-BA-AMB)] with both light stability and toughening effect was prepared by emulsion polymerization and the effects of AMB content on the photostability, conversion rate, and UV absorption properties of the polymer were studied.…”

“…Moreover, the SiOSi bond in the molecular structure of the PSiO has a large bond angle, good molecular chain flexibility, and low glass transition temperature ( T g about −123 °C). Hence, it can be imagined that the PSiO–acrylate elastomer toughening agent is a good candidate for improving the low‐temperature impact resistance of PC . Meanwhile, it can also improve the heat resistance, weather resistance, and aging resistance and lubrication properties of the material due to the special property of the silicone …”