Transparent Multiphasic Polystyrene/Epoxy Blends

C.E. HOPPE; M.J .GALANTE; P.A.OYANGUREN; R.J.J. WILLIAMS; E. GIRARD-REYDET; J,P. PASCAULT

POLYMER ENGINEERING AND SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 2002 vol. 42 p. 2361 - 2368

0032-3888

Blends of polystyrene (PS) with an epoxy monomer (DGEBA) and a tertiary amine(BDMA), were initially miscible at 120°C but phase-separated at very low conversionsin the course of polymerization. Although there was a significant differencebetween the refractive indices of polystyrene and the DGEBA/BDMA solution, therefractive index of the epoxy network increased in the course of polymerization, attaininga value close to that of PS at complete conversion. A sharp decrease of thelight transmittance was observed at the cloud-point, observed at very low conversions.However, the continuous increase of the refractive index of the epoxy phasewith conversion produced an approximate matching of both refractive indices, leadingto transparent materials at complete conversion. Morphologies generated by reaction-induced phase separation depended on the molar mass distribution of polystyreneand its mass fraction in the blend. For a PS with a high value of themass-average molar mass (Mw), it was possible to generate a dispersion of PS particlesin the epoxy matrix (blends containing 5 wt% PS), phase-inverted morphologies(blends containing 15 wt% PS) and double-phase morphologies (blends with 10wt% PS). Therefore, PS/DGEBA/BDMA blends could be used to obtain transparentepoxy coatings toughened by polystyrene particles or transparent polystyrene partsreinforced by a dispersion of epoxy particles.