Morphology and Mechanical Properties of Polypropylene/Maleated Styrene-Butadiene-Styrene Triblock Copolymer Blends
Wilhelm HM, Felisberti MI
JOURNAL OF APPLIED POLYMER SCIENCE

86 (2): 359-365 OCT 10 2002

Abstract:
The morphology and mechanical properties of blends of isotactic polypropylene (i-PP) and a maleated butadiene-styrene-butadiene triblock copolymer with maleic anhydride (SBS-MAH), i-PP/SBS-MAH, were investigated and compared with those of corresponding blends of i-PP and a styrene-butadiene-styrene triblock copolymer (SBS), i-PP/SBS. The blends were prepared in a mixer at 190degreesC with 5-25 wt % elastomer compositions. The blends exhibited a two-phase morphology with a disperse elastomer phase in the continuous i-PP matrix. The size and shape of the elastomer particles and the mechanical properties of the blends depended on the nature and concentration of the elastomer. The i-PP/SBS-MAH blends showed an impact strength superior to that of the corresponding i-PP/SBS blends. These results were attributed to the formation of the graft copolymer during the melt blending, which was verified by Fourier transform infrared.

Reactive Compatibilization of Maleated Polypropylene and Maleated Poly(Styrene-b-Butadiene-b-Styrene) Blends
Wilhelm HM, Felisberti MI
JOURNAL OF APPLIED POLYMER SCIENCE

86 (2): 366-371 OCT 10 2002

Abstract:
Blends of maleated polypropylene with maleic anhydride (PP-MAH) and maleated styrene-butadiene-styrene triblock copolymer with maleic anhydride (SBS-MAH) were compatibilized with 4,4'-diaminediphenylmethane, at various concentrations, as the coupling agent for the functionalized polymers. Their properties were compared with those of the corresponding blends of PP-MAH and styrene-butadiene-styrene triblock copolymer. The blends containing 15 and 50 wt % elastomers were prepared in a mixer at 190degreesC and 55 rpm. Torque measurements and solubility tests suggested a graft copolymerization during the melt blending of PP-MAH and SBS-MAH. Infrared spectroscopy was used to characterize the graft copolymer formed during the melt blending of the maleated polymers. The blends presented a morphology of a disperse elastomer phase in a continuous PP-MAH matrix. The size of the elastomeric domains decreased as the diamine and anhydride molar ratio increased.

Blends of i-PP and SBS. I. Influence of the In Situ Compatibilization on the Morphology
Wilhelm HM, Felisberti MI
JOURNAL OF APPLIED POLYMER SCIENCE

85 (4): 847-855 JUL 25 2002

Abstract:
This article concerns the in situ compatibilization of immiscible isotactic polypropylene/butadiene-styrene-butadiene triblock copolymer blends (i-PP/SBS) by means of a reactive mixture. For this purpose, maleated PP (PP-MAH) and SBS (SBS-MAH) were used as functionalized polymers and 4,4'-diaminediphenylmethane was used as a coupling agent between maleated polymers, resulting in a graft copolymer. Binary blends i-PP/SBS, nonreactive ternary blends i-PP/PP-MAH/SBS, and reactive ternary blends i-PP/PP-MAH/SBS-MAH with varying diamine and anhydride molar ratios were prepared. Torque measurements suggest a graft copolymerization during the melt blending for ternary reactive blends, but the extension of the grafting does not vary with the diamine and anhydride molar ratio, but with the elastomer concentration. The morphology of the blends was investigated by scanning electron microscopy. The morphology of binary and ternary nonreactive blends is similar, exhibiting elastomer domains disperse in the i-PP matrix, whose sizes increase with elastomer concentration, On the other hand, the elastomer domain size in the ternary reactive blends is practically independent of the blends composition and of the diamine and anhydride molar ratio.

Bulk Modification of Styrene-Butadiene-Styrene Triblock Copolymer with Maleic Anhydride
Wilhelm HM, Felisberti MI
JOURNAL OF APPLIED POLYMER SCIENCE

83 (13): 2953-2960 MAR 28 2002

Abstract:
The bulk modification of SBS rubber with maieic anhydride in a mixing chamber of a Haake rheomixer was studied. The effect of temperature, maleic anhydride, and benzoyl peroxide concentrations on the grafting efficiency was evaluated. High grafting efficiency was achieved when the ratio of peroxide and maleic anhydride concentration was high. On the other hand, on this condition high insoluble fraction was generated. The addition of a diamine, 4,4'-diaminediphenylmethane to the reaction mixture minimizes the amount of insoluble polymer. However, the grafted MAH content also decreases. The graft copolymer was characterized by infrared spectroscopy and the grafting extension was determined by titration.

Polystyrene and Polyether Polyurethane Elastomer Blends Compatibilized by SMA: Morphology and Mechanical Properties
Cassu SN, Felisberti MI
JOURNAL OF APPLIED POLYMER SCIENCE

83 (4): 830-837 JAN 24 2002

Abstract:
Blends of polystyrene (PS) and the polyether polyurethane elastomer (PU-et) were prepared by melt mixing using poly(styrene-co-maleic anhydride) (SMA) containing 7 wt % of maleic anhydride as a compatibilizer. The polyurethane in the blends was crosslinked using dicumyl peroxide or sulfur, The content of maleic anhydride was varied in the blends through the addition of different SMA amounts. The morphology of the blends was analyzed by SEM and a drastic reduction of both the domain size and its distribution was observed with increase of the anhydride content in the blends. The morphology of the PU-et blends also showed dependence on the crosslinker agent used for the elastomer, and larger domains were obtained for the clastomer phase crosslinked with dicumyl peroxide. The mechanical properties of the blends were evaluated by flexural and impact strength tests. The blend containing 0.5 wt % of maleic anhydride and 20 wt % of PU-et crosslinked with sulfur showed the highest strength impact, which was three times superior to the PS strength impact, and the blends containing 20 wt % of PU-et crosslinked with dicumyl peroxide showed the highest deflection at break independent of the anhydride content.