Polyolefin Grafting onto Polystyrene by Friedel Crafts Alkylation Reaction

MÓNICA F. DÍAZ; SILVIA E. BARBOSA; NUMA J. CAPIATI

Quantitative Level of Chemical Reactions

Nova Science Publishers

Lugar: New York; Año: 2003; p. 67 - 82

The compatibilization of polyolefin blends has been carried out, in molten state, by an adequate in-situ reaction. The main advantages are high efficiency, solventless and easy process. The application of Friedel-Crafts alkylation reaction to the compatibilization of PE/PS and PP/PS blends was assessed. Either polyethylene or polypropylene macrocarbocation are grafted onto the PS benzene ring by aromatic electrophilic substitution. Reaction conditions and catalyst/co-catalyst concentrations were assessed in terms of the amount of copolymer formed. The amount of copolymer was followed in terms of emulsification effect up to the critical micelle concentration. Subsequently, the structure of the copolymers generated was studied by a combination of SEC and FTIR. The amount of PS grafting and possible appearance of crosslinking and chain scission side reactions was also analyzed. PE was not affected by the reaction. However, PP and PS showed chain scission reaction. Instead, crosslinking reactions were not detected. On the other hand, the PE MW effect on the balance between reaction yield and grafted chain length was investigated. The results were discussed in terms of theories describing the reaction site and the chain length concentration at the interface.