CONVERSION OF PLASTIC CELLULOSE WASTE INTO COMPOSITES .1. MODEL OF THE INTERPHASE

This article proposes a mechanism for a significant improvement in the mechanical performance of a simulated waste fraction, composed of an immiscible low-density polyethylene (LDPE) and high-impact polystyrene (HIPS) blend (70:30 proportion), when chemithermomechanical pulp (CTM P) fibers and maleic acid anhydride grafted styrene-ethylene/butylene- styrene block copolymer (MAH-SEBS) were added. SEM micrographs of comp osites showed an increased contact between the continuous LDPE phase a nd CTMP fibers when the functionalized compatibilizer (MAH-SEBS) was u sed. By employing a model study using LDPE and regenerated cellulose, we investigated the interphase properties between the plastic phase an d the cellulosic component. The model study utilized ESCA, FTIR, and c ontact angle analysis to follow the reaction between the cellulose sur face and the functionalized compatibilizer. All three methods showed t hat MAH-SEBS was bonded to the surface of the cellulose. The single-fi ber fragmentation test showed that the adhesion between cellulose fibe rs and the plastic matrix was significantly improved for MAH-SEBS-modi fied samples. The effect of enhanced adhesion on increased mechanical properties of cellulose composites is also discussed, and a prediction of composite strength given, based on interfacial adhesion promotion and fiber properties. (C) 1995 John Wiley and Sons, Inc.