Chemical Modification of Styrene-Butadiene-Styrene Copolymer by Grafting of N-Carbamyl Maleamic Acid

V.L. LASSALLE; M.D. FAILLA; E.M. VALLÉS; J.M. MARTÍN MARTÍNEZ

JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY

Año: 2004 vol. 18 p. 1849 - 1869

0169-4243

A styrene-butadiene-styrene (SBS) block copolymer was functionalized using different amounts of N-carbamyl maleamic acid (NCMA) and benzoyl peroxide as initiator. The NCMA, which is a bifunctional monomer, was synthesized in our laboratories. The concentration of NCMA used in the functionalization of SBS ranged from 0.5 to 3%w/w based on the copolymer mass. Benzoyloxy radicals generated from the thermal decomposition of benzoyl peroxide initiated the grafting reaction. The concentration of the initiator was kept constant at 0.076% w/w.  FTIR spectroscopy was used to determine the amount of NCMA effectively grafted onto the SBS.  The maximum amount of monomer grafted was about 0.3%w/w when the SBS was modified with 1%w/w of NCMA. The effect of grafting on the surface properties and the adhesion to polyurethane adhesive of the modified SBS were evaluated. Contact angle values were obtained using liquid droplets.  When the concentration of the NCMA used in the grafting reaction was 1% w/w, the contact angles with water on original and modified SBS were 95° and 77°, respectively. Adhesion properties were evaluated by standard peel tests employing a commercial polyurethane adhesive. The modified SBS having the largest amount of NCMA displayed a T-peel strength value five times larger than the corresponding value measured with the original SBS.