Processing and properties of syntactic foams reinforced with carbon nanotubes

Abstract

This article presents synthesis and mechanical characterization of carbon nanotube (CNT)-reinforced syntactic foams. Following a dispersion approach (comprising ultrasonic, calendering, and vacuum centrifugal mixing), single-and multi-walled functionalized CNTs (FCNTs) were incorporated into two foam composites containing various commercially available microballoon grades (S38HS, S60HS, and H50 from 3M). The FCNT-reinforced composites were tested for compressive strength and apparent shear strength before and after hot/wet conditioning. The results showed that the FCNT-reinforced composites' mechanical properties depended on the vacuum pressure used during processing. Compared with pristine and commercially available syntactic foam (EC-3500 from 3M), the FCNT-reinforced composites processed at high vacuum (0.2 kPa) showed significant increase in compressive strength and apparent shear strength before and after hot/ wet conditioning. Dynamic mechanical analysis showed an increase of about 22 C in glass transition temperature for composites processed at high vacuum with 0.5 wt % FCNT and 45 wt % S38HS-5 wt % S60HS microballoons. Thermogravimetric analysis indicated water absorption and lower decomposition temperature for the FCNT-reinforced composite mixed at atmospheric pressure, whereas no significant change was observed for the compound processed at high vacuum. Fracture analysis showed matrix failure for the composite processed at high vacuum and microballoon crushing for the composite mixed at atmospheric pressure.

Morphology and mechanical characterization of carbon nanotubes/epoxy based material filled with hollow glass microsphere

“…Also properties can be tailored as per the demand by varying the proportion of HGM and selecting appropriate wall thickness to a considerable extent [1][2][3][4][5][6][7]. Among other hollow micro spheres HGM possess significant lower density, higher thermal insulation and high dielectric constant [8][9][10][11]. Syntactic foams have commendable applications in high pressure deep oil wells, sea buoyancy structure and aerospace structures [12][13][14][15][16].…”

Plackett–Burman experimental design to facilitate syntactic foam development

“…1 They have been studied in many syntactic foams based on numerous types of polymer matrices. 11 A key aspect of this study is the implementation of a Plackett-Burman experimental design (Table I) to screen for significant variables by assessing many experimental factors simultaneously. 9 Microsphere systems may be additionally reinforced by nanoclay to improve tensile strength 10 or carbon nanotubes to improve compressive strength.…”

“…9 Microsphere systems may be additionally reinforced by nanoclay to improve tensile strength 10 or carbon nanotubes to improve compressive strength. 11 A key aspect of this study is the implementation of a Plackett-Burman experimental design (Table I) to screen for significant variables by assessing many experimental factors simultaneously. Plackett-Burman designs, first described in 1946, 12 reduce the number of experiments needed to screen for main effects when compared to full factorial experimental designs.…”

Transport Properties of One-Step Compression Molded Epoxy Nanocomposite Foams

“…Carbon nanotubes (CNTs) reinforced epoxy foams showed an improvement in compressive modulus by 35%–41% while the strength remained unchanged [11]. Guzman et al [12] used functionalized CNTs and various commercially available microballoons to produce syntactic epoxy foams showing a significant increase in compressive strength and apparent shear strength. Carbon nanofibers and graphene platelets have also improved the mechanical properties of syntactic foams in tension mode [13,14,15] while the compressive modulus and strength were slightly affected [13,15,16,17].…”