Studies on grafting of cellulosic materials isolated from Agave lechuguilla and fourcroydes Rocio Antonio Cruz 1 , Ana M. Mendoza 1 , Matilde Calado Vieira 2 , Thomas Heinze 2, * 1 Division de Estudios de Posgrado e Investigacion del Instituto Tecnologico de Madero, Juventino Rosas y Jesus Urueta s/n, Col. Los Mangos, Ciudad Madero, Tam., Mexico 2 Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University of Jena, D-07743 Jena, Germany (Received 26 July 1999) SUMMARY: The grafting reaction of styrene onto cellulosic material isolated from Agave lechuguilla and fourcroydes, using the initiator ceric ammonium nitrate with nitric acid, under variation of concentration of components, reaction conditions, and pretreatment of starting material with aqueous NaOH was investigated. By determination of the maximal load it was revealed that a graft yield of about 6% gave products with the best mechanical properties, although graft yields of up to 15% can be realized. The samples were character- ized by means of FTIR spectroscopy, DSC measurements, and SEM. Preliminary studies show that the graf- ted materials are thermally more stable compared to the starting material and that they are biodegradable. ZUSAMMENFASSUNG: Die Pfropfcopolymerisation von Styrol auf cellulosereiche Materialien, die aus Agave lechuguilla und fourcroydes isolierbar sind, wurde unter Variation der Konzentration der Komponen- ten, der Reaktionsbedingungen und einer Vorbehandlung des Ausgangsmaterials mit wa ¨ßriger Natronlauge studiert. Als Initiator diente Cerammoniumnitrat mit Salpetersa ¨ure. Durch die Ermittlung der Reißfestigkeit wurde gezeigt, daß Proben mit einem Styrolgehalt von 6% die besten mechanischen Eigenschaften aufwei- sen, obwohl Styrolgehalte bis zu 15% realisiert werden ko ¨ nnen. Die Proben wurden mittels FTIR Spektrosko- pie, DSC-Messungen und REM charakterisiert. Orientierende Untersuchungen haben gezeigt, daß die Pfropf- copolymeren im Vergleich zum Ausgangsmaterial eine ho ¨here thermische Stabilita ¨t besitzen und daß sie bio- abbaubar sind. Introduction Grafting is an important technique to modify the proper- ties of biopolymers such as cellulose. A particular advan- tage of grafting is the possibility to carry out the reaction without altering the shape of fibers, beads or particles. Moreover, selected properties may be imparted without significantly altering others as, e. g., elasticity, thermal stability and resistance to biological attack 1) . Grafting can be used to make the hydrophilic biopolymer more hydro- phobic and hence to improve the compatibility of blends with synthetic polymers. Long-chain grafting was usually accomplished by radi- cal polymerization of vinyl compounds after creating a radical site at the cellulose chain, e.g., by a redox reac- tion 2) . Also block copolymers of cellulose have been pre- pared by free radical polymerization onto a cellulose- based macro-initiator 3) . Grafting of vinyl acetate onto a sulfite dissolving pulp by means of the redox system Fe(II)/H 2 O 2 has been reported 4) . Cellulose-rich biomass from various sources was applied to graft reactions as well. Patra and Singh studied the optimum conditions of graft polymerization of acrylo- nitrile and methyl methacrylate onto purified jute fibers 5) . Also much research has been done on graft copolymeriza- tion of acrylonitrile onto pineapple leaf fibers 6) , purified jute fibers 7, 8) and cotton 9) using redox initiator as, e. g., Ce(IV)/Fe(NH 4 )(SO 4 ) 2 , Ce(IV)/hippuric acid, KMnO 4 / thioacetamide, and IO 4 – /CuSO 4 . Oxidation of alcohol and glycol groups involving free radicals has been used to develop a technique of graft copolymerization onto starch and cellulose. The system most widely used is that initiated by ceric ions, in which high grafting efficiencies have been obtained 10) . Studies of graft copolymerization of styrene onto cot- ton cellulose using the photoinitiators uranyl nitrate, ceric ammonium nitrate and benzoin ethyl ether under UV radiation were reported 11) . It was shown that pre-swelling of the substrate or using divinylbenzene in the grafting bath gave an increased level of grafting, the later tech- nique being more efficient. The maximum graft add-on value was obtained at 35% (w/v) styrene and initiation with ceric ammonium nitrate. In the course of studies on biopolymer-based products our interest was focused on natural fibrous materials iso- * Correspondence author. Die Angewandte Makromolekulare Chemie 273 i WILEY-VCH Verlag GmbH,D-69451 Weinheim 1999 0003-3146/99/0112–0086$17.50+.50/0 86 Die Angewandte Makromolekulare Chemie 273 (1999) 86–90 (Nr. 4724)