Characterization of bimodal bigraft ABS

In the final product of a bimodal bigraft ABS, consisting of crosslinked polybutadiene particles (diameter 100 nm) with grafted and ungrafted poly (styrene-co-acrylonitrile) (=SAN) with an acrylonitrile (=AN) content of 28 weight %, crosslinked polybutadiene particles (diameter 300 nm) with grafted and ungrafted SAN with an AN content of 12 weight % and an added SAN with an AN content of 28 weight % the following parameters can be determined: degree of grafting of the small polybutadiene particles, degree of grafting of the large polybutadiene particles, acrylonitrile content of the grafted chains of the small polybutadiene particles, acrylonitrile content of the grafted chains of the large polybutadiene particles, grafting efficiency of the large particles, average particle diameter and particle diameter distribution of the small particles, average particle diameter and particle diameter distribution of the big particles, molar mass distribution of the ungrafted chains of the large particles, chemical distribution of the ungraftd chains of the large particles, molar mass distribution of the SAN resin added, chemical distribution of the SAN resin added.Preparative differential ultracentrifugation in acetone/-butyrolacrone (volume ratio 0.550.45), FTIR spectrometry and electron microscopy of the floating and sedimentating fraction yield the degree of grafting and AN content of the graft chains of the large particles and the degree of grafting and AN content of the graft chains of the small particles.Preparative differential centrifugation, FTIR spectrometry and electron microscopy of the fractions give nearly equivalent results. Fractional demixing with the demixing solvents ethylene carbonate/tetraline of the acetone-soluble part yields the SAN with 12 weight % AN in the upper-phase and the SAN with 28 weight % AN in the lower phase.Size exclusion chromatography (SEC) and high-performance precipitation liquid chromatography (HPPLC) of the fractions yield the molecular distribution and chemical distribution of the different SAN resins. SEC, coupled with turbidimetric titration of the acetone-soluble fractions withn-hexane as precipirant, indicates SAN resin with lower AN content in addition to the SAN resin with 28 weight % AN.Dedicated to Prof. Dr. Dr. h.c. mult. Karl Heinz Büchel on the occasion of his 60th birthday