Thermally expandable microspheres (TEMS) with low foaming temperature were synthesized under abnormal atmosphere by suspension polymerization.Acrylonitrile (AN)

methyl acrylate (MA) and vinyl acetate (VAc) were used as main monomers

and n-hexane was used as propellant.The results of light scattering measurements

derivative thermogravimetric (DTG) and thermomechanical analysis (TMA) showed that the TEMS possessed excellent low-temperature foaming property.The increasing proportion of AN had good effect on improving Dmax of TEMS

but excessive AN had the opposite effects due to bigger diameter and the formation of two-phase polymers.TEMS showed bad expanding characteristics when the addition of MA was low because of the formation of two-phase polymers.The foaming Dmax of TEMS was significantly improved when VAc was used.Scanning electron micrographs (SEM) showed that the morphologies of TEMS containing 0.46 wt% crosslinking agent kept shriveled morphology when the amount of n-hexane increased but turned from irregular concave shape to sphere following the content increase of n-hexane when the amount of crosslinking agent reduced to 0.26 wt% or 0

the spherical TEMS may have faster foaming speed and higher foaming Dmax.