C-13 NMR-STUDY OF THE GRAFTING OF MALEIC-ANHYDRIDE ONTO POLYETHENE, POLYPROPENE, AND ETHENE-PROPENE COPOLYMERS

The reaction products from the radically initiated grafting of specifi cally C-13-enriched maleic anhydride ([2,3-C-13(2)]MA) Onto polyethene , isotactic polypropene and ethene-propene copolymers in the melt and in solution are investigated using noise-decoupled and 1D inadequate C -13 NMR spectroscopy. The sites of attachment and the structures of th e grafts depend oil (co)polymer composition. In random EPM, MA attache s to methylene and methine carbons in the backbone. In alternating EPM , MA attaches solely to polymer methines, indicating that (CH2)(m) seg uences with m > 3 are needed for MA attachment to backbone methylene c arbons. In the copolymers and in IPP, grafts are single succinic anhyd ride rings; in HDPE and LDPE short MA oligomers are also present. In p olyolefins containing polypropene sequences, chain scission can yield structures in which the anhydride ring is attached to the chain termin us via a fully substituted double bond.