Chemical modification of styrene-butadiene-styrene (SBS) rubber by reactive grafting with maleic anhydride

VERÓNICA L. LASSALLE; MARCELO D. FAILLA; ENRIQUE M. VALLÉS; CARMEN CEPEDA-JIMÉNEZ; ROSA TORREGROSA-MACIÁ; JOSÉ M. MARTÍN MARTÍNEZ

JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY

BRILL ACADEMIC PUBLISHERS

Lugar: Leiden; Año: 2003 vol. 17 p. 1713 - 1726

0169-4243

A procedure to increase the adhesion of block styrene?butadiene?styrene (SBS) rubberconsisting of the reactive grafting with maleic anhydride (MA) in the presence of an organic peroxideradical initiator is proposed. The in? uence of the reactive grafting on the surface properties ofSBS has been studied with special emphasis on the improvement of the adhesion to polyurethaneadhesive. The grafting of MA onto SBS was carried out in the presence of different concentrationsof 2,5-dimethyl-2,5-di(tertbutyl peroxy) hexane (DBPH) as initiator to generate oxygen radicals bythermal decomposition, which induce the grafting reaction. The modi? cation process was performedin the molten state using a Brabender mixer to premix the reactants and a hot press to initiate thefunctionalizing reaction. ATR-IR and XPS spectroscopies were employed to verify the grafting ofMA on SBS. The changes in wettability on the modi? ed SBS rubber were determined by contact anglemeasurements. Adhesion properties were evaluated from T-peel tests of SBS rubber/ polyurethaneadhesive joints. Reasonable extents of MA grafting on SBS were obtained (evidenced by the presenceof a weak carbonyl vibration at 1700 cm¡1 in the ATR-IR spectra and by the carbon? oxygen band ata binding energy of 287.0 eV in the XPS spectra). The higher the DBPH amount, the higher the MAamount grafted onto the SBS surface. The maximum grafting level was obtained using 2 wt% MA.Grafted species seemed to be mainly concentrated on the surface of the SBS-molded sheets. Thewettability of the modi? ed rubber increased with respect to the original polymer, new carbon?oxygenmoieties were created and the C/O ratio increased. A noticeable enhancement in peel strength valueswas observed, which was ascribed to the creation of interfacial interactions between the polyurethaneand the SBS rubber surfaces