| Plastics today form a sizable fraction of solid wastes and recycling these waste plastics would be an attractive solution to one of the ever-increasing environmental problems. However, most of the polymers are thermodynamically immiscible with each other. Processing of the mixtures of polymer wastes is not likely to yield products with excellent mechanical properties. Since the separation of waste plastics is not yet economically feasible, compatibilization is the potentially practical route to explore in the high-value applications of recycled plastics. Besides the traditional compatibilization by block or graft copolymers, recently, an in situ compatibilization technique has been developed in which the compatibilizers are formed during the compounding of polymer blends with functional polymers as precursors.; This research was devoted to the synthesis, characterization, and applications of functional monomers grafted polyolefins. The functional monomers, including maleic anhydride (MA), glycidyl methacrylate (GMA), and 2-isopropenyl-2-oxazoline (IPOZ), were utilized and compared in this investigation. Three major grafting techniques, solid-state, melt, and solution grafting, were studied. Meanwhile, the reactivities of the grafted polyolefins with other functional groups were compared. The thermal degradation of polypropylene caused by the peroxide during grafting was also rheologically studied. A novel crosslinking method by multifunctional monomer was employed to compensate for the chain scission by the peroxide and to restore the mechanical and rheological properties of the grafted polypropylene.; Due to their high reactivities, GMA melt grafted polyolefins were used in the reactive compatibilization of HDPE/PET, polyolefin/PVC, and PP/ABS blends. The differences between reactive and nonreactive blends in terms of processability, morphologies, mechanical and thermal properties have been investigated. The compatibilization mechanisms were also analyzed by FTIR detecting, torque measurements, and lap shear adhesion measurements. It was found that GMA grafted polyolefins can effectively form interfacial bonds with other phases by interfacial reaction during melt processing. The high compatibilizing efficiency of the GMA grafted polyolefins was manifested by the dramatically improved mechanical and morphological properties of the compatibilized blends with the addition of a small amount of the GMA grafted polyolefins. |
