Preparation of a novel oligomer type compatibilizer for polypropylene/polystyrene blend

A polystyrene-g-2,2,6,6-tetramethylpiperidine 1-oxyl radical (PS-g-TEMPO) copolymer was formed during thermal-oxidative degradation of PS/hindered amine light stabilizer (HALS) under heat treatment by thermal equilibrium. The optimum preparation condition was identified at 150 degrees C for 21 h by assessment of the tem-perature and aging time dependences of the molecular weight and thermal properties. The optimized copolymer was reacted with polypropylene (PP). A PS-g-PP grafted copolymer-type compatibilizer was reactively prepared with the copolymer/PP at 200 degrees C melt mixing temperature. The tetrahydrofuran-soluble part of the PP/PS/PS-g-TEMPO blend was analyzed as the PS-g-PP copolymer. The PS-g-PP showed a broad melting peak in the range from 125 degrees C to 160 degrees C. The PP grafting ratio was approximately 4%, as calculated by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) analysis. The reactive polymer blend of the PP/PS/ PS-g-TEMPO showed significant improvement in mechanical properties and ductile fracture surface as compared with PP/PS. The HALS loading easily produced an excellent compatibilizer for PP/PS mechanical improvement.

Automated summary

A PS-g-TEMPO copolymer was formed during thermal-oxidative degradation of PS/HALS, with the optimal preparation condition identified at 150°C for 21 hours. The copolymer was then reacted with PP to produce a PS-g-PP grafted copolymer, resulting in significant improvement in mechanical properties and ductile fracture surface when used for reactive polymer blend of PP/PS/PS-g-TEMPO. The addition of HALS loading easily produced an excellent compatibilizer for mechanical improvement in PP/PS.