Use of Silane Agents and Poly(propylene-g-maleic anhydride) Copolymer as Adhesion Promoters in Glass Fiber/Polypropylene Composites D. BIKIARIS, 1 P. MATZINOS, 1 A. LARENA, 2 V. FLARIS, 3 C. PANAYIOTOU 1 1 Department of Chemical Engineering, University of Thessaloniki, 54006 Thessaloniki, Greece 2 Departamento de Ingenieria Quimica Industrial, Escuela Tecnica Superior de Ingenieros Industriales, Universidad Politecnica de Madrid, Jose Guetierrez Abascal 2, 28006 Madrid, Spain 3 Huntsman Corporation, 118 Huntsman Way, Longview, Texas 75603 Received 24 January 2000; accepted 26 September 2000 Published online 3 May 2001 ABSTRACT: Two organofunctional silanes and a copolymer were used to increase the interfacial adhesion in glass fiber polypropylene (PP) reinforced composites. The per- formance of the coupling agents was investigated by means of mechanical property measurements, scanning electron microscopy (SEM), and dynamic mechanical analy- sis. The increased adhesion between the glass fibers and PP matrix observed with SEM resulted in an improvement of the mechanical and dynamic mechanical properties of the composites. Coupling achieved with the copolymer poly(propylene-g-maleic anhy- dride) (PP-g-MA) proved to be the most successful compared with 3-aminopropyltrime- thoxysilane and 3-aminopropyltriethoxysilane. The combination of PP-g-MA with the silanes resulted in further property improvements because of the ability of the MA groups to react with the amino groups of the silanes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 701–709, 2001 Key words: polypropylene; glass fiber; silane; copolymer; adhesion INTRODUCTION Glass fiber reinforcement provides an attractive means of enhancing the mechanical and thermal properties of polymers required for engineering ap- plications. Incorporation of short glass fibers in thermoplastic matrices imparts stiffness, strength, and thermal stability to these materials with some sacrifice of strain to failure. The importance of good adhesion between the fiber and matrix has long been recognized. Good adhesion between the fibers and matrix results in efficient stress transfer from the continuous poly- mer matrix to the dispersed fiber reinforcement and can increase the ability of the material to absorb energy. 1,2 The development of methods for controlling the interfacial adhesion between chemically and physi- cally different, incompatible phases has been the subject of considerable research efforts. It is well known that interfacial agents, such as organofunc- tional silane compounds, are capable of promoting adhesion in fiber reinforced plastics. It has also been demonstrated that for some types of compos- ites and polymer blends the concept of adhesion is operationally the same. For instance, graft or block polyolefin copolymers can be equally effective as Correspondence to: C. Panayiotou (cpanayio@mailhost. ccf.auth.gr). Journal of Applied Polymer Science, Vol. 81, 701–709 (2001) © 2001 John Wiley & Sons, Inc. 701